feat(ui): canvas-first redesign with a self-hosted draw.io (#957)

The canvas now fills the window and the chat floats on its right. draw.io is
served from our own origin (public/drawio, downloaded at build time and
checked against the release's SHA-256), so the app can drive the editor
directly:

- every AI change becomes a version card with a thumbnail; compare, restore
  or undo it, and Ctrl+Z on the canvas takes an AI change back in one step
- shapes the AI just changed are highlighted on the canvas
- selected shapes appear as a chip and are sent to the model
- draw.io's own simple UI: its toolbar, menus (auto layout, Mermaid, CSV
  import) and page tabs; the shape library starts closed
- new start screen, session rename and switcher, open .drawio files
- settings split into Models & keys, Appearance, Advanced and About
- Bedrock in the model settings also takes an API key instead of access keys
- phones switch between canvas and chat
- dark mode uses draw.io's own dark mode, with neutral greys around it

With an external draw.io (NEXT_PUBLIC_DRAWIO_BASE_URL) the features above
that need same origin are off.

The chat logic moved from the 1500-line chat panel into a chat engine plus
small UI components; zustand holds canvas, versions, settings and UI state.

components/canvas/canvas-stage.tsx

@@ -0,0 +1,176 @@
+import { useParams } from "next/navigation"
+import { useEffect, useRef, useState } from "react"
+import { DrawioFrame } from "@/components/canvas/drawio-frame"
+import { SelectionAsk } from "@/components/canvas/selection-ask"
+import { useChatEngine } from "@/components/chat/chat-engine"
+import { useDiagram } from "@/contexts/diagram-context"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { DRAWIO_CSS, getDrawioSrc } from "@/lib/drawio/drawio-config"
+import { keepCenter, refitIfRecent } from "@/lib/drawio/editor-bridge"
+import { i18n, type Locale } from "@/lib/i18n/config"
+import { STORAGE_KEYS } from "@/lib/storage"
+import { cn } from "@/lib/utils"
+import { useCanvasStore } from "@/stores/canvas-store"
+import { useSettingsStore } from "@/stores/settings-store"
+
+/**
+ * The draw.io canvas, with draw.io's own toolbar, menus and page tabs, and
+ * the "ask AI" button laid over it (only when the page can drive draw.io
+ * directly, not with an external cross-origin draw.io).
+ */
+export function CanvasStage({
+    className,
+    style,
+    hideOverlays = false,
+}: {
+    className?: string
+    style?: React.CSSProperties
+    /** Hide the "ask AI" button (e.g. while the start screen covers the canvas) */
+    hideOverlays?: boolean
+}) {
+    const dict = useDictionary()
+    const params = useParams<{ lang: string }>()
+    const lang = (
+        i18n.locales.includes(params.lang as Locale)
+            ? params.lang
+            : i18n.defaultLocale
+    ) as Locale
+    const {
+        drawioRef,
+        handleDiagramAutoSave,
+        handleDiagramExport,
+        onDrawioLoad,
+        resetDrawioReady,
+        isDrawioReady,
+    } = useDiagram()
+    const engine = useChatEngine()
+    const isDark = useSettingsStore((s) => s.isDark)
+    const hasEditor = useCanvasStore((s) => s.hasEditor)
+    // The model sees the first page only, so asking about shapes elsewhere
+    // would change the wrong page
+    const onFirstPage = useCanvasStore(
+        (s) => s.pages.length === 0 || s.pages[0]?.id === s.currentPageId,
+    )
+    // Canvas width when the chat panel starts sliding in or out
+    const slideStartWidthRef = useRef(0)
+
+    const [src, setSrc] = useState<string | null>(null)
+    // null until draw.io tells us whether we can drive it directly
+    const [editorAccess, setEditorAccess] = useState<boolean | null>(null)
+    const stageRef = useRef<HTMLDivElement>(null)
+    const [size, setSize] = useState({ width: 0, height: 0 })
+
+    useEffect(() => {
+        // The page is about to switch to the language picked last time
+        // (useSavedLocale): load draw.io once, in that language
+        const saved = localStorage.getItem(STORAGE_KEYS.locale)
+        if (saved && saved !== lang && i18n.locales.includes(saved as Locale)) {
+            return
+        }
+        const isElectron = !!(window as { electronAPI?: unknown }).electronAPI
+        // The theme class is set before the page renders; the settings store
+        // may not have read it yet
+        const dark = document.documentElement.classList.contains("dark")
+        setSrc(getDrawioSrc({ lang, isElectron, dark }))
+    }, [lang])
+
+    // A new iframe starts over: draw.io reports load and access again
+    useEffect(() => {
+        resetDrawioReady()
+        setEditorAccess(null)
+    }, [src])
+
+    // Cross-origin draw.io only takes its dark mode when it starts: reload
+    // it when that is not the theme now (also one switched while it
+    // loaded). Same-origin switches it in place.
+    useEffect(() => {
+        if (editorAccess !== false || !src) return
+        const startedDark = new URL(src).searchParams.get("dark") === "1"
+        if (startedDark === isDark) return
+        const isElectron = !!(window as { electronAPI?: unknown }).electronAPI
+        setSrc(getDrawioSrc({ lang, isElectron, dark: isDark }))
+    }, [isDark, editorAccess, lang, src])
+
+    useEffect(() => {
+        const stage = stageRef.current
+        if (!stage) return
+        // React passes no transitionstart
+        const onSlideStart = (event: TransitionEvent) => {
+            if (event.target !== stage || event.propertyName !== "right") return
+            slideStartWidthRef.current = stage.clientWidth
+        }
+        stage.addEventListener("transitionstart", onSlideStart)
+        const observer = new ResizeObserver(([entry]) => {
+            setSize({
+                width: entry.contentRect.width,
+                height: entry.contentRect.height,
+            })
+            refitIfRecent()
+        })
+        observer.observe(stage)
+        return () => {
+            observer.disconnect()
+            stage.removeEventListener("transitionstart", onSlideStart)
+        }
+    }, [])
+
+    const showOverlays = hasEditor && isDrawioReady && !hideOverlays
+
+    return (
+        <div
+            ref={stageRef}
+            className={cn("absolute overflow-hidden bg-canvas", className)}
+            style={style}
+            data-testid="canvas-stage"
+            // The chat panel slides in or out (the canvas's right edge moves):
+            // once the canvas has its final size, fit a diagram just drawn,
+            // or keep the view's middle
+            onTransitionEnd={(event) => {
+                if (event.target !== event.currentTarget) return
+                if (event.propertyName !== "right") return
+                const stage = event.currentTarget
+                // Let draw.io take the new size first
+                setTimeout(() => {
+                    if (refitIfRecent(4000)) return
+                    keepCenter(slideStartWidthRef.current, stage.clientWidth)
+                }, 60)
+            }}
+        >
+            {src && (
+                <DrawioFrame
+                    key={src}
+                    ref={drawioRef}
+                    src={src}
+                    configCss={DRAWIO_CSS}
+                    editorCss={DRAWIO_CSS}
+                    dark={isDark}
+                    onLoad={onDrawioLoad}
+                    onAutoSave={handleDiagramAutoSave}
+                    onExport={handleDiagramExport}
+                    onEditorAccess={setEditorAccess}
+                />
+            )}
+
+            {/* Covers the iframe until draw.io has loaded and been styled */}
+            {(!isDrawioReady || editorAccess === null) && (
+                <div
+                    className="absolute inset-0 flex items-center justify-center bg-canvas"
+                    data-testid="canvas-loading"
+                >
+                    <div className="flex items-center gap-2.5 text-[13px] text-muted-foreground">
+                        <span className="size-3.5 animate-spin rounded-full border-2 border-muted-foreground/30 border-t-muted-foreground" />
+                        {dict.workspace.canvasLoading}
+                    </div>
+                </div>
+            )}
+
+            {showOverlays && (
+                <SelectionAsk
+                    width={size.width}
+                    height={size.height}
+                    hidden={engine.isBusy || !onFirstPage}
+                />
+            )}
+        </div>
+    )
+}

components/canvas/drawio-frame.tsx

@@ -0,0 +1,265 @@
+"use client"
+
+import { forwardRef, useEffect, useImperativeHandle, useRef } from "react"
+import {
+    DRAWIO_CONFIG,
+    EMPTY_DRAWIO_DOCUMENT,
+} from "@/lib/drawio/drawio-config"
+import {
+    attachEditor,
+    detachEditor,
+    watchForEditorUi,
+} from "@/lib/drawio/editor-bridge"
+
+export interface DrawioExportEvent {
+    event: "export"
+    format: string
+    data: string
+    xml: string
+    message: { message?: string; [key: string]: unknown }
+}
+
+export interface DrawioFrameHandle {
+    load: (data: { xml: string }) => void
+    exportDiagram: (data: {
+        format: string
+        message?: string
+        [key: string]: unknown
+    }) => void
+}
+
+interface DrawioFrameProps {
+    src: string
+    /** CSS sent with the configure message (works cross-origin too) */
+    configCss: string
+    /** CSS injected once the editor is reachable directly (same origin) */
+    editorCss: string
+    /** draw.io's dark mode, switched in place when the editor is reachable */
+    dark: boolean
+    onLoad?: () => void
+    onAutoSave?: (data: { xml?: string }) => void
+    onExport?: (data: DrawioExportEvent) => void
+    /** Called once we know whether the editor can be driven directly */
+    onEditorAccess?: (hasEditor: boolean) => void
+}
+
+const STYLE_ID = "next-ai-drawio-theme"
+
+/**
+ * The draw.io editor in an iframe, speaking draw.io's postMessage embed
+ * protocol (same messages react-drawio used). When the iframe is same-origin
+ * it also hands the editor object to editor-bridge for direct control.
+ */
+export const DrawioFrame = forwardRef<DrawioFrameHandle, DrawioFrameProps>(
+    function DrawioFrame(
+        {
+            src,
+            configCss,
+            editorCss,
+            dark,
+            onLoad,
+            onAutoSave,
+            onExport,
+            onEditorAccess,
+        },
+        ref,
+    ) {
+        const iframeRef = useRef<HTMLIFrameElement>(null)
+        const editorUiRef = useRef<any>(null)
+        const attachedRef = useRef(false)
+        const configCssRef = useRef(configCss)
+        configCssRef.current = configCss
+        const editorCssRef = useRef(editorCss)
+        editorCssRef.current = editorCss
+        const darkRef = useRef(dark)
+        darkRef.current = dark
+        // Handlers change on every render; the message listener reads refs
+        const handlersRef = useRef({
+            onLoad,
+            onAutoSave,
+            onExport,
+            onEditorAccess,
+        })
+        handlersRef.current = { onLoad, onAutoSave, onExport, onEditorAccess }
+
+        // draw.io's origin: messages go only there, and only its messages
+        // count (the frame could be navigated to another site)
+        // (read on use: there is no window while the page renders on the server)
+        const drawioOrigin = () => new URL(src, window.location.href).origin
+
+        const send = (action: string, data: Record<string, unknown> = {}) => {
+            iframeRef.current?.contentWindow?.postMessage(
+                JSON.stringify({ action, ...data }),
+                drawioOrigin(),
+            )
+        }
+
+        useImperativeHandle(ref, () => ({
+            load: ({ xml }) => send("load", { xml, autosave: 1 }),
+            exportDiagram: (data) => send("export", data),
+        }))
+
+        // Same-origin only: keep the theme CSS current without a reload
+        const applyThemeCss = () => {
+            if (!attachedRef.current) return
+            try {
+                const doc = iframeRef.current?.contentDocument
+                if (!doc?.head) return
+                let style = doc.getElementById(STYLE_ID)
+                if (!style) {
+                    style = doc.createElement("style")
+                    style.id = STYLE_ID
+                    doc.head.appendChild(style)
+                }
+                style.textContent = editorCssRef.current
+            } catch {
+                // Cross-origin: the configure message already applied it
+            }
+        }
+
+        useEffect(() => {
+            applyThemeCss()
+        }, [editorCss])
+
+        // Same-origin only: draw.io's own dark mode, without a reload
+        const applyDarkMode = () => {
+            if (!attachedRef.current) return
+            try {
+                // Runs on every load: switch only when it differs
+                const frameWindow = iframeRef.current?.contentWindow as any
+                if (frameWindow?.Editor?.isDarkMode?.() === darkRef.current) {
+                    return
+                }
+                editorUiRef.current?.setDarkMode?.(darkRef.current)
+            } catch (error) {
+                console.warn("Failed to set draw.io's dark mode:", error)
+            }
+        }
+
+        useEffect(() => {
+            applyDarkMode()
+        }, [dark])
+
+        useEffect(() => {
+            const iframe = iframeRef.current
+            if (!iframe) return
+            editorUiRef.current = null
+            attachedRef.current = false
+            let reported: boolean | null = null
+            const report = (value: boolean) => {
+                if (reported === value) return
+                reported = value
+                handlersRef.current.onEditorAccess?.(value)
+            }
+
+            // Watch for draw.io's scripts so the editor object can be caught
+            // as it starts. Stops once hooked, or when the frame turns out to
+            // be cross-origin.
+            const startedAt = Date.now()
+            const poll = setInterval(() => {
+                const frameWindow = iframe.contentWindow as any
+                if (!frameWindow) return
+                let ready = false
+                try {
+                    ready =
+                        frameWindow.location.href !== "about:blank" &&
+                        !!frameWindow.EditorUi
+                } catch {
+                    clearInterval(poll)
+                    report(false)
+                    return
+                }
+                if (ready) {
+                    clearInterval(poll)
+                    // Called on every action state update: once per editor
+                    const ok = watchForEditorUi(frameWindow, (ui) => {
+                        if (editorUiRef.current === ui) return
+                        editorUiRef.current = ui
+                        // draw.io follows the system's theme on its own:
+                        // keep the app's
+                        ui.addListener?.("darkModeChanged", () =>
+                            applyDarkMode(),
+                        )
+                    })
+                    if (!ok) report(false)
+                } else if (Date.now() - startedAt > 60_000) {
+                    clearInterval(poll)
+                }
+            }, 5)
+
+            const handleMessage = (event: MessageEvent) => {
+                if (event.source !== iframe.contentWindow) return
+                if (event.origin !== drawioOrigin()) return
+                if (typeof event.data !== "string") return
+                let data: any
+                try {
+                    data = JSON.parse(event.data)
+                } catch {
+                    return
+                }
+                const handlers = handlersRef.current
+                switch (data.event) {
+                    case "init":
+                        send("load", {
+                            xml: EMPTY_DRAWIO_DOCUMENT,
+                            autosave: 1,
+                        })
+                        break
+                    case "configure":
+                        send("configure", {
+                            config: {
+                                ...DRAWIO_CONFIG,
+                                css: configCssRef.current,
+                            },
+                        })
+                        break
+                    case "load": {
+                        const tryAttach = () => {
+                            const ui = editorUiRef.current
+                            if (!ui || !iframe.contentWindow) return false
+                            attachEditor(ui, iframe.contentWindow)
+                            attachedRef.current = true
+                            applyThemeCss()
+                            applyDarkMode()
+                            report(true)
+                            return true
+                        }
+                        // The editor object is usually caught before the
+                        // first load; give it a moment, then fall back to
+                        // draw.io's own toolbar
+                        if (!tryAttach()) {
+                            setTimeout(() => {
+                                if (!tryAttach()) report(false)
+                            }, 800)
+                        }
+                        handlers.onLoad?.()
+                        break
+                    }
+                    case "autosave":
+                        handlers.onAutoSave?.(data)
+                        break
+                    case "export":
+                        handlers.onExport?.(data)
+                        break
+                }
+            }
+
+            window.addEventListener("message", handleMessage)
+            return () => {
+                clearInterval(poll)
+                window.removeEventListener("message", handleMessage)
+                detachEditor()
+            }
+        }, [src])
+
+        return (
+            <iframe
+                ref={iframeRef}
+                src={src}
+                title="draw.io"
+                allow="clipboard-read; clipboard-write"
+                className="block h-full w-full border-0"
+            />
+        )
+    },
+)

components/canvas/selection-ask.tsx

@@ -0,0 +1,71 @@
+import { Sparkles } from "lucide-react"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { modKey } from "@/lib/platform"
+import { useCanvasStore } from "@/stores/canvas-store"
+import { useUiStore } from "@/stores/ui-store"
+
+const BUTTON_HEIGHT = 32
+const GAP = 10
+
+/**
+ * "Ask AI to change this" next to the selected shapes. Clicking it moves
+ * focus to the chat input, where the selection already shows as a chip.
+ */
+export function SelectionAsk({
+    width,
+    height,
+    hidden,
+}: {
+    /** Size of the canvas area, for keeping the button inside it */
+    width: number
+    height: number
+    hidden: boolean
+}) {
+    const dict = useDictionary()
+    const rect = useCanvasStore((s) => s.selectionRect)
+    const selection = useCanvasStore((s) => s.selection)
+    const isFreehand = useCanvasStore((s) => s.isFreehand)
+    const popupOpen = useCanvasStore((s) => s.isDrawioPopupOpen)
+    const focusComposer = useUiStore((s) => s.focusComposer)
+
+    if (hidden || popupOpen || !rect || selection.length === 0 || isFreehand) {
+        return null
+    }
+    // Selection scrolled out of view
+    if (
+        rect.x + rect.width < 0 ||
+        rect.y + rect.height < 0 ||
+        rect.x > width ||
+        rect.y > height
+    ) {
+        return null
+    }
+
+    // Above the selection's top-right corner, kept inside the canvas
+    const approxWidth = 168
+    const left = Math.min(
+        Math.max(8, rect.x + rect.width - approxWidth / 2),
+        width - approxWidth - 8,
+    )
+    const above = rect.y - BUTTON_HEIGHT - GAP
+    const top =
+        above > 64
+            ? above
+            : Math.min(rect.y + rect.height + GAP, height - BUTTON_HEIGHT - 72)
+
+    return (
+        <button
+            type="button"
+            onClick={focusComposer}
+            className="pointer-events-auto absolute z-10 flex h-8 items-center gap-1.5 rounded-xl bg-card pr-2.5 pl-2 text-[13px] font-medium text-foreground shadow-pop transition-transform animate-fade-in hover:-translate-y-px"
+            style={{ left, top }}
+            data-testid="selection-ask"
+        >
+            <Sparkles className="size-4 text-marker-ink" />
+            {dict.workspace.askAi}
+            <kbd className="ml-1 font-sans text-[11px] text-muted-foreground">
+                {modKey}/
+            </kbd>
+        </button>
+    )
+}

components/chat-example-panel.tsx

@@ -1,227 +0,0 @@
-"use client"
-
-import {
-    Cloud,
-    FileText,
-    GitBranch,
-    Palette,
-    Terminal,
-    Zap,
-} from "lucide-react"
-import { useDictionary } from "@/hooks/use-dictionary"
-import { getAssetUrl } from "@/lib/base-path"
-
-interface ExampleCardProps {
-    icon: React.ReactNode
-    title: string
-    description: string
-    onClick: () => void
-    isNew?: boolean
-}
-
-function ExampleCard({
-    icon,
-    title,
-    description,
-    onClick,
-    isNew,
-}: ExampleCardProps) {
-    const dict = useDictionary()
-
-    return (
-        <button
-            onClick={onClick}
-            className={`group w-full text-left p-4 rounded-xl border bg-card hover:bg-accent/50 hover:border-primary/30 transition-all duration-200 hover:shadow-sm ${
-                isNew
-                    ? "border-primary/40 ring-1 ring-primary/20"
-                    : "border-border/60"
-            }`}
-        >
-            <div className="flex items-start gap-3">
-                <div
-                    className={`w-9 h-9 rounded-lg flex items-center justify-center shrink-0 transition-colors ${
-                        isNew
-                            ? "bg-primary/20 group-hover:bg-primary/25"
-                            : "bg-primary/10 group-hover:bg-primary/15"
-                    }`}
-                >
-                    {icon}
-                </div>
-                <div className="min-w-0">
-                    <div className="flex items-center gap-2">
-                        <h3 className="text-sm font-medium text-foreground group-hover:text-primary transition-colors">
-                            {title}
-                        </h3>
-                        {isNew && (
-                            <span className="px-1.5 py-0.5 text-[10px] font-semibold bg-primary text-primary-foreground rounded">
-                                {dict.common.new}
-                            </span>
-                        )}
-                    </div>
-                    <p className="text-xs text-muted-foreground mt-0.5 line-clamp-2">
-                        {description}
-                    </p>
-                </div>
-            </div>
-        </button>
-    )
-}
-
-export default function ExamplePanel({
-    setInput,
-    setFiles,
-    minimal = false,
-}: {
-    setInput: (input: string) => void
-    setFiles: (files: File[]) => void
-    minimal?: boolean
-}) {
-    const dict = useDictionary()
-    const isSelfHosted = process.env.NEXT_PUBLIC_SELFHOSTED === "true"
-
-    const handleReplicateFlowchart = async () => {
-        setInput("Replicate this flowchart.")
-
-        try {
-            const response = await fetch(getAssetUrl("/example.png"))
-            const blob = await response.blob()
-            const file = new File([blob], "example.png", { type: "image/png" })
-            setFiles([file])
-        } catch (error) {
-            console.error(dict.errors.failedToLoadExample, error)
-        }
-    }
-
-    const handleReplicateArchitecture = async () => {
-        setInput("Replicate this in aws style")
-
-        try {
-            const response = await fetch(getAssetUrl("/architecture.png"))
-            const blob = await response.blob()
-            const file = new File([blob], "architecture.png", {
-                type: "image/png",
-            })
-            setFiles([file])
-        } catch (error) {
-            console.error(dict.errors.failedToLoadExample, error)
-        }
-    }
-
-    const handlePdfExample = async () => {
-        setInput("Summarize this paper as a diagram")
-
-        try {
-            const response = await fetch(getAssetUrl("/chain-of-thought.txt"))
-            const blob = await response.blob()
-            const file = new File([blob], "chain-of-thought.txt", {
-                type: "text/plain",
-            })
-            setFiles([file])
-        } catch (error) {
-            console.error(dict.errors.failedToLoadExample, error)
-        }
-    }
-
-    return (
-        <div className={minimal ? "" : "py-6 px-2 animate-fade-in"}>
-            {!minimal && (
-                <>
-                    {/* MCP Server Notice, hidden on self-hosted deployments */}
-                    {!isSelfHosted && (
-                        <a
-                            href="https://github.com/DayuanJiang/next-ai-draw-io/tree/main/packages/mcp-server"
-                            target="_blank"
-                            rel="noopener noreferrer"
-                            className="block mb-4 p-3 rounded-xl bg-gradient-to-r from-purple-500/10 to-blue-500/10 border border-purple-500/20 hover:border-purple-500/40 transition-colors group"
-                        >
-                            <div className="flex items-center gap-3">
-                                <div className="w-8 h-8 rounded-lg bg-purple-500/20 flex items-center justify-center shrink-0">
-                                    <Terminal className="w-4 h-4 text-purple-500" />
-                                </div>
-                                <div className="min-w-0">
-                                    <div className="flex items-center gap-2">
-                                        <span className="text-sm font-medium text-foreground group-hover:text-purple-500 transition-colors">
-                                            {dict.examples.mcpServer}
-                                        </span>
-                                    </div>
-                                    <p className="text-xs text-muted-foreground">
-                                        {dict.examples.mcpDescription}
-                                    </p>
-                                </div>
-                            </div>
-                        </a>
-                    )}
-
-                    {/* Welcome section */}
-                    <div className="text-center mb-6">
-                        <h2 className="text-lg font-semibold text-foreground mb-2">
-                            {dict.examples.title}
-                        </h2>
-                        <p className="text-sm text-muted-foreground max-w-xs mx-auto">
-                            {dict.examples.subtitle}
-                        </p>
-                    </div>
-                </>
-            )}
-
-            {/* Examples grid */}
-            <div className="space-y-3">
-                {!minimal && (
-                    <p className="text-xs font-medium text-muted-foreground uppercase tracking-wider px-1">
-                        {dict.examples.quickExamples}
-                    </p>
-                )}
-
-                <div className="grid gap-2">
-                    <ExampleCard
-                        icon={<FileText className="w-4 h-4 text-primary" />}
-                        title={dict.examples.paperToDiagram}
-                        description={dict.examples.paperDescription}
-                        onClick={handlePdfExample}
-                        isNew
-                    />
-
-                    <ExampleCard
-                        icon={<Zap className="w-4 h-4 text-primary" />}
-                        title={dict.examples.animatedDiagram}
-                        description={dict.examples.animatedDescription}
-                        onClick={() => {
-                            setInput(
-                                "Give me a **animated connector** diagram of transformer's architecture",
-                            )
-                            setFiles([])
-                        }}
-                    />
-
-                    <ExampleCard
-                        icon={<Cloud className="w-4 h-4 text-primary" />}
-                        title={dict.examples.awsArchitecture}
-                        description={dict.examples.awsDescription}
-                        onClick={handleReplicateArchitecture}
-                    />
-
-                    <ExampleCard
-                        icon={<GitBranch className="w-4 h-4 text-primary" />}
-                        title={dict.examples.replicateFlowchart}
-                        description={dict.examples.replicateDescription}
-                        onClick={handleReplicateFlowchart}
-                    />
-
-                    <ExampleCard
-                        icon={<Palette className="w-4 h-4 text-primary" />}
-                        title={dict.examples.creativeDrawing}
-                        description={dict.examples.creativeDescription}
-                        onClick={() => {
-                            setInput("Draw a cat for me")
-                            setFiles([])
-                        }}
-                    />
-                </div>
-
-                <p className="text-[11px] text-muted-foreground/60 text-center mt-4">
-                    {dict.examples.cachedNote}
-                </p>
-            </div>
-        </div>
-    )
-}

components/chat-input.tsx

@@ -1,669 +0,0 @@
-"use client"
-
-import {
-    BookmarkPlus,
-    Download,
-    History,
-    Image as ImageIcon,
-    Link,
-    Send,
-    Square,
-} from "lucide-react"
-import type React from "react"
-import {
-    type Dispatch,
-    forwardRef,
-    type SetStateAction,
-    useCallback,
-    useEffect,
-    useImperativeHandle,
-    useRef,
-    useState,
-} from "react"
-import { toast } from "sonner"
-import { ButtonWithTooltip } from "@/components/button-with-tooltip"
-import { TemplateCreateDialog } from "@/components/chat/TemplateCreateDialog"
-import { ErrorToast } from "@/components/error-toast"
-import { HistoryDialog } from "@/components/history-dialog"
-import { ModelSelector } from "@/components/model-selector"
-import { SaveDialog } from "@/components/save-dialog"
-
-import { Button } from "@/components/ui/button"
-import { Textarea } from "@/components/ui/textarea"
-import { UrlInputDialog } from "@/components/url-input-dialog"
-import { useDiagram } from "@/contexts/diagram-context"
-import { useDictionary } from "@/hooks/use-dictionary"
-import { formatMessage } from "@/lib/i18n/utils"
-import { isPdfFile, isTextFile } from "@/lib/pdf-utils"
-import { STORAGE_KEYS } from "@/lib/storage"
-import type { FlattenedModel } from "@/lib/types/model-config"
-import { extractUrlContent, type UrlData } from "@/lib/url-utils"
-import { isRealDiagram } from "@/lib/utils"
-import { FilePreviewList } from "./file-preview-list"
-
-const MAX_IMAGE_SIZE = 2 * 1024 * 1024 // 2MB
-const MAX_FILES = 5
-// Image formats every supported model provider accepts (SVG is read as text)
-const SUPPORTED_IMAGE_TYPES = [
-    "image/png",
-    "image/jpeg",
-    "image/gif",
-    "image/webp",
-]
-
-function isValidFileType(file: File): boolean {
-    return (
-        SUPPORTED_IMAGE_TYPES.includes(file.type) ||
-        isPdfFile(file) ||
-        isTextFile(file)
-    )
-}
-
-function formatFileSize(bytes: number): string {
-    const mb = bytes / 1024 / 1024
-    if (mb < 0.01) return `${(bytes / 1024).toFixed(0)}KB`
-    return `${mb.toFixed(2)}MB`
-}
-
-function showErrorToast(message: React.ReactNode) {
-    toast.custom(
-        (t) => (
-            <ErrorToast message={message} onDismiss={() => toast.dismiss(t)} />
-        ),
-        { duration: 5000 },
-    )
-}
-
-interface ValidationResult {
-    validFiles: File[]
-    errors: string[]
-}
-
-function validateFiles(
-    newFiles: File[],
-    existingCount: number,
-    dict: any,
-): ValidationResult {
-    const errors: string[] = []
-    const validFiles: File[] = []
-
-    const availableSlots = MAX_FILES - existingCount
-
-    if (availableSlots <= 0) {
-        errors.push(formatMessage(dict.errors.maxFiles, { max: MAX_FILES }))
-        return { validFiles, errors }
-    }
-
-    for (const file of newFiles) {
-        if (validFiles.length >= availableSlots) {
-            errors.push(
-                formatMessage(dict.errors.onlyMoreAllowed, {
-                    slots: availableSlots,
-                }),
-            )
-            break
-        }
-        if (!isValidFileType(file)) {
-            errors.push(
-                formatMessage(dict.errors.unsupportedType, { name: file.name }),
-            )
-            continue
-        }
-        // Only check size for images (PDFs/text files are extracted client-side, so file size doesn't matter)
-        const isExtractedFile = isPdfFile(file) || isTextFile(file)
-        if (!isExtractedFile && file.size > MAX_IMAGE_SIZE) {
-            const maxSizeMB = MAX_IMAGE_SIZE / 1024 / 1024
-            errors.push(
-                formatMessage(dict.errors.fileExceeds, {
-                    name: file.name,
-                    size: formatFileSize(file.size),
-                    max: maxSizeMB,
-                }),
-            )
-        } else {
-            validFiles.push(file)
-        }
-    }
-
-    return { validFiles, errors }
-}
-
-function showValidationErrors(errors: string[], dict: any) {
-    if (errors.length === 0) return
-
-    if (errors.length === 1) {
-        showErrorToast(
-            <span className="text-muted-foreground">{errors[0]}</span>,
-        )
-    } else {
-        showErrorToast(
-            <div className="flex flex-col gap-1">
-                <span className="font-medium">
-                    {formatMessage(dict.errors.filesRejected, {
-                        count: errors.length,
-                    })}
-                </span>
-                <ul className="text-muted-foreground text-xs list-disc list-inside">
-                    {errors.slice(0, 3).map((err) => (
-                        <li key={err}>{err}</li>
-                    ))}
-                    {errors.length > 3 && (
-                        <li>
-                            {formatMessage(dict.errors.andMore, {
-                                count: errors.length - 3,
-                            })}
-                        </li>
-                    )}
-                </ul>
-            </div>,
-        )
-    }
-}
-
-export interface ChatInputRef {
-    focus: () => void
-}
-
-interface ChatInputProps {
-    input: string
-    status: "submitted" | "streaming" | "ready" | "error"
-    onSubmit: (e: React.FormEvent<HTMLFormElement>) => void
-    onChange: (e: React.ChangeEvent<HTMLTextAreaElement>) => void
-    onStop?: () => void
-    files?: File[]
-    onFileChange?: (files: File[]) => void
-    pdfData?: Map<
-        File,
-        { text: string; charCount: number; isExtracting: boolean }
-    >
-    urlData?: Map<string, UrlData>
-    onUrlChange?: Dispatch<SetStateAction<Map<string, UrlData>>>
-
-    sessionId?: string
-    error?: Error | null
-    // Model selector props
-    models?: FlattenedModel[]
-    selectedModelId?: string
-    onModelSelect?: (modelId: string | undefined) => void
-    onConfigureModels?: () => void
-    showUnvalidatedModels?: boolean
-    // Focus control props
-    shouldFocus?: boolean
-    onFocused?: () => void
-}
-
-export const ChatInput = forwardRef<ChatInputRef, ChatInputProps>(
-    function ChatInput(
-        {
-            input,
-            status,
-            onSubmit,
-            onChange,
-            onStop,
-            files = [],
-            onFileChange = () => {},
-            pdfData = new Map(),
-            urlData,
-            onUrlChange,
-            sessionId,
-            error = null,
-            models = [],
-            selectedModelId,
-            onModelSelect = () => {},
-            onConfigureModels,
-            showUnvalidatedModels = false,
-            shouldFocus = false,
-            onFocused,
-        },
-        ref,
-    ) {
-        const dict = useDictionary()
-        const {
-            chartXML,
-            diagramHistory,
-            saveDiagramToFile,
-            showSaveDialog,
-            setShowSaveDialog,
-        } = useDiagram()
-
-        const textareaRef = useRef<HTMLTextAreaElement>(null)
-        const fileInputRef = useRef<HTMLInputElement>(null)
-        const [isDragging, setIsDragging] = useState(false)
-
-        // Expose focus method via ref
-        useImperativeHandle(ref, () => ({
-            focus: () => {
-                textareaRef.current?.focus()
-            },
-        }))
-
-        // Focus the textarea when shouldFocus becomes true
-        // Use setTimeout to ensure focus happens after drawio iframe settles
-        useEffect(() => {
-            if (shouldFocus) {
-                const timer = setTimeout(() => {
-                    textareaRef.current?.focus()
-                    onFocused?.()
-                }, 150)
-                return () => clearTimeout(timer)
-            }
-        }, [shouldFocus, onFocused])
-
-        const [showHistory, setShowHistory] = useState(false)
-        const [showUrlDialog, setShowUrlDialog] = useState(false)
-        const [showSaveAsTemplate, setShowSaveAsTemplate] = useState(false)
-        const [isExtractingUrl, setIsExtractingUrl] = useState(false)
-        const [sendShortcut, setSendShortcut] = useState("ctrl-enter")
-        // Allow retry when there's an error (even if status is still "streaming" or "submitted")
-        const isDisabled =
-            (status === "streaming" || status === "submitted") && !error
-        // Block sending until attached files and URLs have their text, otherwise
-        // their content would be silently dropped
-        const isExtractingAttachments =
-            files.some((file) => pdfData.get(file)?.isExtracting) ||
-            Array.from(urlData?.values() ?? []).some((d) => d.isExtracting)
-
-        const adjustTextareaHeight = useCallback(() => {
-            const textarea = textareaRef.current
-            if (textarea) {
-                textarea.style.height = "auto"
-                textarea.style.height = `${Math.min(textarea.scrollHeight, 200)}px`
-            }
-        }, [])
-        // Handle programmatic input changes (e.g., setInput("") after form submission)
-        useEffect(() => {
-            adjustTextareaHeight()
-        }, [input, adjustTextareaHeight])
-
-        // Load send shortcut preference from localStorage and listen for changes
-        useEffect(() => {
-            const stored = localStorage.getItem(STORAGE_KEYS.sendShortcut)
-            if (stored) setSendShortcut(stored)
-
-            const handleChange = (e: CustomEvent<string>) =>
-                setSendShortcut(e.detail)
-            window.addEventListener(
-                "sendShortcutChange",
-                handleChange as EventListener,
-            )
-            return () =>
-                window.removeEventListener(
-                    "sendShortcutChange",
-                    handleChange as EventListener,
-                )
-        }, [])
-
-        const handleChange = (e: React.ChangeEvent<HTMLTextAreaElement>) => {
-            onChange(e)
-            adjustTextareaHeight()
-        }
-
-        const handleKeyDown = (e: React.KeyboardEvent) => {
-            // Enter that confirms an IME candidate must not send the message
-            if (e.nativeEvent.isComposing || e.keyCode === 229) return
-
-            const shouldSend =
-                sendShortcut === "enter"
-                    ? e.key === "Enter" &&
-                      !e.shiftKey &&
-                      !e.ctrlKey &&
-                      !e.metaKey
-                    : (e.metaKey || e.ctrlKey) && e.key === "Enter"
-
-            if (shouldSend) {
-                e.preventDefault()
-                const form = e.currentTarget.closest("form")
-                if (
-                    form &&
-                    input.trim() &&
-                    !isDisabled &&
-                    !isExtractingAttachments
-                ) {
-                    form.requestSubmit()
-                }
-            }
-        }
-
-        const handlePaste = async (e: React.ClipboardEvent) => {
-            if (isDisabled) return
-
-            const items = e.clipboardData.items
-            const imageItems = Array.from(items).filter((item) =>
-                item.type.startsWith("image/"),
-            )
-
-            if (imageItems.length > 0) {
-                const imageFiles = (
-                    await Promise.all(
-                        imageItems.map(async (item, index) => {
-                            const file = item.getAsFile()
-                            if (!file) return null
-                            return new File(
-                                [file],
-                                `pasted-image-${Date.now()}-${index}.${file.type.split("/")[1]}`,
-                                { type: file.type },
-                            )
-                        }),
-                    )
-                ).filter((f): f is File => f !== null)
-
-                const { validFiles, errors } = validateFiles(
-                    imageFiles,
-                    files.length,
-                    dict,
-                )
-                showValidationErrors(errors, dict)
-                if (validFiles.length > 0) {
-                    onFileChange([...files, ...validFiles])
-                }
-            }
-        }
-
-        const handleFileChange = (e: React.ChangeEvent<HTMLInputElement>) => {
-            const newFiles = Array.from(e.target.files || [])
-            const { validFiles, errors } = validateFiles(
-                newFiles,
-                files.length,
-                dict,
-            )
-            showValidationErrors(errors, dict)
-            if (validFiles.length > 0) {
-                onFileChange([...files, ...validFiles])
-            }
-
-            if (fileInputRef.current) {
-                fileInputRef.current.value = ""
-            }
-        }
-
-        const handleRemoveFile = (fileToRemove: File) => {
-            onFileChange(files.filter((file) => file !== fileToRemove))
-            if (fileInputRef.current) {
-                fileInputRef.current.value = ""
-            }
-        }
-
-        const triggerFileInput = () => {
-            fileInputRef.current?.click()
-        }
-
-        const handleDragOver = (e: React.DragEvent<HTMLFormElement>) => {
-            e.preventDefault()
-            e.stopPropagation()
-            setIsDragging(true)
-        }
-
-        const handleDragLeave = (e: React.DragEvent<HTMLFormElement>) => {
-            e.preventDefault()
-            e.stopPropagation()
-            setIsDragging(false)
-        }
-
-        const handleDrop = (e: React.DragEvent<HTMLFormElement>) => {
-            e.preventDefault()
-            e.stopPropagation()
-            setIsDragging(false)
-
-            if (isDisabled) return
-
-            // Let validateFiles show a toast for unsupported types
-            const { validFiles, errors } = validateFiles(
-                Array.from(e.dataTransfer.files),
-                files.length,
-                dict,
-            )
-            showValidationErrors(errors, dict)
-            if (validFiles.length > 0) {
-                onFileChange([...files, ...validFiles])
-            }
-        }
-
-        const handleUrlExtract = async (url: string) => {
-            if (!onUrlChange) return
-
-            setIsExtractingUrl(true)
-
-            // Use functional updates so a removal or send made while extracting
-            // is not overwritten when the request finishes
-            try {
-                onUrlChange((prev) =>
-                    new Map(prev).set(url, {
-                        url,
-                        title: url,
-                        content: "",
-                        charCount: 0,
-                        isExtracting: true,
-                    }),
-                )
-
-                const data = await extractUrlContent(url)
-
-                // Skip if the URL was removed while extracting
-                onUrlChange((prev) =>
-                    prev.has(url) ? new Map(prev).set(url, data) : prev,
-                )
-
-                setShowUrlDialog(false)
-            } catch (error) {
-                // Remove the URL from the data map on error
-                onUrlChange((prev) => {
-                    const next = new Map(prev)
-                    next.delete(url)
-                    return next
-                })
-                showErrorToast(
-                    <span className="text-muted-foreground">
-                        {error instanceof Error
-                            ? error.message
-                            : "Failed to extract URL content"}
-                    </span>,
-                )
-            } finally {
-                setIsExtractingUrl(false)
-            }
-        }
-
-        return (
-            <form
-                id="chat-form"
-                onSubmit={onSubmit}
-                className={`w-full transition-all duration-200 ${
-                    isDragging
-                        ? "ring-2 ring-primary ring-offset-2 rounded-2xl"
-                        : ""
-                }`}
-                onDragOver={handleDragOver}
-                onDragLeave={handleDragLeave}
-                onDrop={handleDrop}
-            >
-                {/* File & URL previews */}
-                {(files.length > 0 || (urlData && urlData.size > 0)) && (
-                    <div className="mb-3">
-                        <FilePreviewList
-                            files={files}
-                            onRemoveFile={handleRemoveFile}
-                            pdfData={pdfData}
-                            urlData={urlData}
-                            onRemoveUrl={
-                                onUrlChange
-                                    ? (url) =>
-                                          onUrlChange((prev) => {
-                                              const next = new Map(prev)
-                                              next.delete(url)
-                                              return next
-                                          })
-                                    : undefined
-                            }
-                        />
-                    </div>
-                )}
-                <div className="relative rounded-2xl border border-border bg-background shadow-sm focus-within:ring-2 focus-within:ring-primary/20 focus-within:border-primary/50 transition-all duration-200">
-                    <Textarea
-                        ref={textareaRef}
-                        value={input}
-                        onChange={handleChange}
-                        onKeyDown={handleKeyDown}
-                        onPaste={handlePaste}
-                        placeholder={dict.chat.placeholder}
-                        disabled={isDisabled}
-                        aria-label="Chat input"
-                        className="min-h-[60px] max-h-[200px] resize-none border-0 bg-transparent px-4 py-3 text-sm focus-visible:ring-0 focus-visible:ring-offset-0 placeholder:text-muted-foreground/60 scrollbar-thin"
-                    />
-
-                    <div className="flex items-center justify-end gap-1 px-3 py-2 border-t border-border/50">
-                        <div className="flex items-center gap-1 overflow-x-hidden">
-                            <ButtonWithTooltip
-                                type="button"
-                                variant="ghost"
-                                size="sm"
-                                onClick={() => setShowHistory(true)}
-                                disabled={
-                                    isDisabled || diagramHistory.length === 0
-                                }
-                                tooltipContent={dict.chat.diagramHistory}
-                                className="h-8 w-8 p-0 text-muted-foreground hover:text-foreground"
-                            >
-                                <History className="h-4 w-4" />
-                            </ButtonWithTooltip>
-
-                            <ButtonWithTooltip
-                                type="button"
-                                variant="ghost"
-                                size="sm"
-                                onClick={() => setShowSaveDialog(true)}
-                                disabled={
-                                    isDisabled || !isRealDiagram(chartXML)
-                                }
-                                tooltipContent={dict.chat.saveDiagram}
-                                className="h-8 w-8 p-0 text-muted-foreground hover:text-foreground"
-                            >
-                                <Download className="h-4 w-4" />
-                            </ButtonWithTooltip>
-
-                            <ButtonWithTooltip
-                                type="button"
-                                variant="ghost"
-                                size="sm"
-                                onClick={triggerFileInput}
-                                disabled={isDisabled}
-                                tooltipContent={dict.chat.uploadFile}
-                                className="h-8 w-8 p-0 text-muted-foreground hover:text-foreground"
-                            >
-                                <ImageIcon className="h-4 w-4" />
-                            </ButtonWithTooltip>
-
-                            {onUrlChange && (
-                                <ButtonWithTooltip
-                                    type="button"
-                                    variant="ghost"
-                                    size="sm"
-                                    onClick={() => setShowUrlDialog(true)}
-                                    disabled={isDisabled}
-                                    tooltipContent={dict.chat.ExtractURL}
-                                    className="h-8 w-8 p-0 text-muted-foreground hover:text-foreground"
-                                >
-                                    <Link className="h-4 w-4" />
-                                </ButtonWithTooltip>
-                            )}
-
-                            <ButtonWithTooltip
-                                type="button"
-                                variant="ghost"
-                                size="sm"
-                                onClick={() => setShowSaveAsTemplate(true)}
-                                disabled={isDisabled || !input.trim()}
-                                tooltipContent={dict.templates.saveAsTemplate}
-                                className="h-8 w-8 p-0 text-muted-foreground hover:text-foreground"
-                            >
-                                <BookmarkPlus className="h-4 w-4" />
-                            </ButtonWithTooltip>
-
-                            <input
-                                type="file"
-                                ref={fileInputRef}
-                                className="hidden"
-                                onChange={handleFileChange}
-                                accept="image/png,image/jpeg,image/gif,image/webp,.svg,.pdf,application/pdf,text/*,.md,.markdown,.json,.csv,.xml,.yaml,.yml,.toml"
-                                multiple
-                                disabled={isDisabled}
-                            />
-                        </div>
-                        <ModelSelector
-                            models={models}
-                            selectedModelId={selectedModelId}
-                            onSelect={onModelSelect}
-                            onConfigure={onConfigureModels}
-                            disabled={isDisabled}
-                            showUnvalidatedModels={showUnvalidatedModels}
-                        />
-                        <div className="w-px h-5 bg-border mx-1" />
-                        {(status === "streaming" || status === "submitted") &&
-                        onStop ? (
-                            <Button
-                                type="button"
-                                onClick={onStop}
-                                size="sm"
-                                variant="destructive"
-                                className="h-8 w-8 p-0 rounded-xl shadow-sm"
-                                aria-label={dict.chat.stopGeneration}
-                            >
-                                <Square className="h-4 w-4" />
-                            </Button>
-                        ) : (
-                            <Button
-                                type="submit"
-                                disabled={
-                                    isDisabled ||
-                                    isExtractingAttachments ||
-                                    !input.trim()
-                                }
-                                size="sm"
-                                className="h-8 px-4 rounded-xl font-medium shadow-sm"
-                                aria-label={dict.chat.send}
-                            >
-                                <Send className="h-4 w-4 mr-1.5" />
-                                {dict.chat.send}
-                            </Button>
-                        )}
-                    </div>
-                </div>
-                <HistoryDialog
-                    showHistory={showHistory}
-                    onToggleHistory={setShowHistory}
-                />
-                <SaveDialog
-                    open={showSaveDialog}
-                    onOpenChange={setShowSaveDialog}
-                    onSave={(filename, format) =>
-                        saveDiagramToFile(
-                            filename,
-                            format,
-                            sessionId,
-                            dict.save.savedSuccessfully,
-                        )
-                    }
-                    // Local date as YYYY-MM-DD (toISOString would give UTC)
-                    defaultFilename={`diagram-${new Date().toLocaleDateString("sv-SE")}`}
-                />
-                {onUrlChange && (
-                    <UrlInputDialog
-                        open={showUrlDialog}
-                        onOpenChange={setShowUrlDialog}
-                        onSubmit={handleUrlExtract}
-                        isExtracting={isExtractingUrl}
-                    />
-                )}
-                <TemplateCreateDialog
-                    open={showSaveAsTemplate}
-                    onOpenChange={setShowSaveAsTemplate}
-                    onSuccess={() => {
-                        setShowSaveAsTemplate(false)
-                        // Let the template list in the lobby reload
-                        window.dispatchEvent(new Event("templatesChanged"))
-                    }}
-                    initialPrompt={input.trim()}
-                />
-            </form>
-        )
-    },
-)

components/chat/ChatLobby.tsx

@@ -1,360 +0,0 @@
-"use client"
-
-import {
-    ChevronDown,
-    ChevronUp,
-    MessageSquare,
-    Search,
-    Trash2,
-    X,
-} from "lucide-react"
-import { useEffect, useState } from "react"
-import { TemplatePanel } from "@/components/chat/TemplatePanel"
-import ExamplePanel from "@/components/chat-example-panel"
-import Image from "@/components/image-with-basepath"
-import {
-    AlertDialog,
-    AlertDialogAction,
-    AlertDialogCancel,
-    AlertDialogContent,
-    AlertDialogDescription,
-    AlertDialogFooter,
-    AlertDialogHeader,
-    AlertDialogTitle,
-} from "@/components/ui/alert-dialog"
-import { STORAGE_KEYS } from "@/lib/storage"
-import type { Template } from "@/lib/template-storage"
-
-interface SessionMetadata {
-    id: string
-    title: string
-    updatedAt: number
-    thumbnailDataUrl?: string
-}
-
-interface ChatLobbyProps {
-    sessions: SessionMetadata[]
-    onSelectSession: (id: string) => void
-    onDeleteSession?: (id: string) => void
-    setInput: (input: string) => void
-    setFiles: (files: File[]) => void
-    onSendTemplate?: (template: Template) => void
-    currentInput?: string
-    dict: {
-        sessionHistory?: {
-            recentChats?: string
-            searchPlaceholder?: string
-            noResults?: string
-            justNow?: string
-            deleteTitle?: string
-            deleteDescription?: string
-        }
-        templates?: {
-            title?: string
-            myTemplates?: string
-        }
-        examples?: {
-            quickExamples?: string
-        }
-        common: {
-            delete: string
-            cancel: string
-        }
-    }
-}
-
-// Helper to format session date
-function formatSessionDate(
-    timestamp: number,
-    dict?: { justNow?: string },
-): string {
-    const date = new Date(timestamp)
-    const now = new Date()
-    const diffMs = now.getTime() - date.getTime()
-    const diffMins = Math.floor(diffMs / (1000 * 60))
-    const diffHours = Math.floor(diffMs / (1000 * 60 * 60))
-
-    if (diffMins < 1) return dict?.justNow || "Just now"
-    if (diffMins < 60) return `${diffMins}m ago`
-    if (diffHours < 24) return `${diffHours}h ago`
-
-    return date.toLocaleDateString(undefined, {
-        month: "short",
-        day: "numeric",
-    })
-}
-
-function getPanelVisibility() {
-    if (typeof window === "undefined")
-        return { recentChats: true, myTemplates: true, quickExamples: true }
-    return {
-        recentChats:
-            localStorage.getItem(STORAGE_KEYS.showRecentChats) !== "false",
-        myTemplates:
-            localStorage.getItem(STORAGE_KEYS.showMyTemplates) !== "false",
-        quickExamples:
-            localStorage.getItem(STORAGE_KEYS.showQuickExamples) !== "false",
-    }
-}
-
-export function ChatLobby({
-    sessions,
-    onSelectSession,
-    onDeleteSession,
-    setInput,
-    setFiles,
-    onSendTemplate,
-    currentInput = "",
-    dict,
-}: ChatLobbyProps) {
-    const [templatesExpanded, setTemplatesExpanded] = useState(true)
-    const [examplesExpanded, setExamplesExpanded] = useState(true)
-    const [panelVisibility, setPanelVisibility] = useState(getPanelVisibility)
-    const [deleteDialogOpen, setDeleteDialogOpen] = useState(false)
-    const [sessionToDelete, setSessionToDelete] = useState<string | null>(null)
-    const [searchQuery, setSearchQuery] = useState("")
-
-    // Listen for panel visibility changes from settings
-    useEffect(() => {
-        const handler = () => setPanelVisibility(getPanelVisibility())
-        window.addEventListener("panelVisibilityChange", handler)
-        return () =>
-            window.removeEventListener("panelVisibilityChange", handler)
-    }, [])
-
-    const hasHistory = sessions.length > 0
-
-    if (!hasHistory) {
-        if (!panelVisibility.myTemplates && !panelVisibility.quickExamples) {
-            return null
-        }
-        return (
-            <div className="animate-fade-in">
-                {panelVisibility.myTemplates && (
-                    <TemplatePanel
-                        setInput={setInput}
-                        onSendTemplate={onSendTemplate}
-                        currentInput={currentInput}
-                    />
-                )}
-                {panelVisibility.quickExamples && (
-                    <div className={panelVisibility.myTemplates ? "mt-6" : ""}>
-                        <ExamplePanel setInput={setInput} setFiles={setFiles} />
-                    </div>
-                )}
-            </div>
-        )
-    }
-
-    // Show history + collapsible examples when there are sessions
-    return (
-        <div className="py-6 px-2 animate-fade-in">
-            {/* Recent Chats Section */}
-            {panelVisibility.recentChats && (
-                <div className="mb-6">
-                    <p className="text-xs font-medium text-muted-foreground uppercase tracking-wider px-1 mb-3">
-                        {dict.sessionHistory?.recentChats || "Recent Chats"}
-                    </p>
-                    {/* Search Bar */}
-                    <div className="relative mb-3">
-                        <Search className="absolute left-3 top-1/2 -translate-y-1/2 w-4 h-4 text-muted-foreground" />
-                        <input
-                            type="text"
-                            placeholder={
-                                dict.sessionHistory?.searchPlaceholder ||
-                                "Search chats..."
-                            }
-                            value={searchQuery}
-                            onChange={(e) => setSearchQuery(e.target.value)}
-                            className="w-full pl-9 pr-3 py-2 text-sm rounded-lg border border-border/60 bg-background focus:outline-none focus:ring-2 focus:ring-primary/30 focus:border-primary/50 transition-all"
-                        />
-                        {searchQuery && (
-                            <button
-                                type="button"
-                                onClick={() => setSearchQuery("")}
-                                className="absolute right-2 top-1/2 -translate-y-1/2 p-1 rounded hover:bg-muted transition-colors"
-                            >
-                                <X className="w-3 h-3 text-muted-foreground" />
-                            </button>
-                        )}
-                    </div>
-                    <div className="space-y-2">
-                        {sessions
-                            .filter((session) =>
-                                session.title
-                                    .toLowerCase()
-                                    .includes(searchQuery.toLowerCase()),
-                            )
-                            .map((session) => (
-                                // biome-ignore lint/a11y/useSemanticElements: Cannot use button - has nested delete button which causes hydration error
-                                <div
-                                    key={session.id}
-                                    role="button"
-                                    tabIndex={0}
-                                    className="group w-full flex items-center gap-3 p-3 rounded-xl border border-border/60 bg-card hover:bg-accent/50 hover:border-primary/30 transition-all duration-200 cursor-pointer text-left"
-                                    onClick={() => onSelectSession(session.id)}
-                                    onKeyDown={(e) => {
-                                        // Ignore keys bubbling up from the delete button
-                                        if (e.target !== e.currentTarget) return
-                                        if (
-                                            e.key === "Enter" ||
-                                            e.key === " "
-                                        ) {
-                                            e.preventDefault()
-                                            onSelectSession(session.id)
-                                        }
-                                    }}
-                                >
-                                    {session.thumbnailDataUrl ? (
-                                        <div className="w-12 h-12 shrink-0 rounded-lg border bg-white overflow-hidden">
-                                            <Image
-                                                src={session.thumbnailDataUrl}
-                                                alt=""
-                                                width={48}
-                                                height={48}
-                                                className="object-contain w-full h-full"
-                                            />
-                                        </div>
-                                    ) : (
-                                        <div className="w-12 h-12 shrink-0 rounded-lg bg-primary/10 flex items-center justify-center">
-                                            <MessageSquare className="w-5 h-5 text-primary" />
-                                        </div>
-                                    )}
-                                    <div className="min-w-0 flex-1">
-                                        <div className="text-sm font-medium truncate">
-                                            {session.title}
-                                        </div>
-                                        <div className="text-xs text-muted-foreground">
-                                            {formatSessionDate(
-                                                session.updatedAt,
-                                                dict.sessionHistory,
-                                            )}
-                                        </div>
-                                    </div>
-                                    {onDeleteSession && (
-                                        <button
-                                            type="button"
-                                            onClick={(e) => {
-                                                e.stopPropagation()
-                                                setSessionToDelete(session.id)
-                                                setDeleteDialogOpen(true)
-                                            }}
-                                            className="p-1.5 rounded-lg opacity-0 group-hover:opacity-100 text-muted-foreground hover:text-destructive hover:bg-destructive/10 transition-all"
-                                            title={dict.common.delete}
-                                        >
-                                            <Trash2 className="w-4 h-4" />
-                                        </button>
-                                    )}
-                                </div>
-                            ))}
-                        {sessions.filter((s) =>
-                            s.title
-                                .toLowerCase()
-                                .includes(searchQuery.toLowerCase()),
-                        ).length === 0 &&
-                            searchQuery && (
-                                <p className="text-sm text-muted-foreground text-center py-4">
-                                    {dict.sessionHistory?.noResults ||
-                                        "No chats found"}
-                                </p>
-                            )}
-                    </div>
-                </div>
-            )}
-
-            {/* Collapsible My Templates Section */}
-            {panelVisibility.myTemplates && (
-                <div className="border-t border-border/50 pt-4">
-                    <button
-                        type="button"
-                        onClick={() => setTemplatesExpanded(!templatesExpanded)}
-                        className="w-full flex items-center justify-between px-1 py-2 text-xs font-medium text-muted-foreground uppercase tracking-wider hover:text-foreground transition-colors"
-                    >
-                        <span>
-                            {dict.templates?.myTemplates || "My Templates"}
-                        </span>
-                        {templatesExpanded ? (
-                            <ChevronUp className="w-4 h-4" />
-                        ) : (
-                            <ChevronDown className="w-4 h-4" />
-                        )}
-                    </button>
-                    {templatesExpanded && (
-                        <div className="mt-2">
-                            <TemplatePanel
-                                setInput={setInput}
-                                onSendTemplate={onSendTemplate}
-                                currentInput={currentInput}
-                            />
-                        </div>
-                    )}
-                </div>
-            )}
-
-            {/* Collapsible Quick Examples Section */}
-            {panelVisibility.quickExamples && (
-                <div className="border-t border-border/50 pt-4">
-                    <button
-                        type="button"
-                        onClick={() => setExamplesExpanded(!examplesExpanded)}
-                        className="w-full flex items-center justify-between px-1 py-2 text-xs font-medium text-muted-foreground uppercase tracking-wider hover:text-foreground transition-colors"
-                    >
-                        <span>
-                            {dict.examples?.quickExamples || "Quick Examples"}
-                        </span>
-                        {examplesExpanded ? (
-                            <ChevronUp className="w-4 h-4" />
-                        ) : (
-                            <ChevronDown className="w-4 h-4" />
-                        )}
-                    </button>
-                    {examplesExpanded && (
-                        <div className="mt-2">
-                            <ExamplePanel
-                                setInput={setInput}
-                                setFiles={setFiles}
-                                minimal
-                            />
-                        </div>
-                    )}
-                </div>
-            )}
-
-            {/* Delete Confirmation Dialog */}
-            <AlertDialog
-                open={deleteDialogOpen}
-                onOpenChange={setDeleteDialogOpen}
-            >
-                <AlertDialogContent className="max-w-sm">
-                    <AlertDialogHeader>
-                        <AlertDialogTitle>
-                            {dict.sessionHistory?.deleteTitle ||
-                                "Delete this chat?"}
-                        </AlertDialogTitle>
-                        <AlertDialogDescription>
-                            {dict.sessionHistory?.deleteDescription ||
-                                "This will permanently delete this chat session and its diagram. This action cannot be undone."}
-                        </AlertDialogDescription>
-                    </AlertDialogHeader>
-                    <AlertDialogFooter>
-                        <AlertDialogCancel>
-                            {dict.common.cancel}
-                        </AlertDialogCancel>
-                        <AlertDialogAction
-                            onClick={() => {
-                                if (sessionToDelete && onDeleteSession) {
-                                    onDeleteSession(sessionToDelete)
-                                }
-                                setDeleteDialogOpen(false)
-                                setSessionToDelete(null)
-                            }}
-                            className="border border-red-300 bg-red-50 text-red-700 hover:bg-red-100 hover:border-red-400"
-                        >
-                            {dict.common.delete}
-                        </AlertDialogAction>
-                    </AlertDialogFooter>
-                </AlertDialogContent>
-            </AlertDialog>
-        </div>
-    )
-}

components/chat/TemplatePanel.tsx

@@ -41,7 +41,8 @@ import { TemplateEditDialog } from "./TemplateEditDialog"
 
 interface TemplatePanelProps {
     setInput: (input: string) => void
-    onSendTemplate?: (template: Template) => void
+    /** Whether it was sent */
+    onSendTemplate?: (template: Template) => Promise<boolean>
     currentInput?: string
 }
 
@@ -178,16 +179,21 @@ export function TemplatePanel({
 
     // Actually send the template
     const sendTemplate = async (template: Template) => {
-        // Increment click count only when actually sending
-        await incrementClickCount(template.id)
         if (onSendTemplate) {
-            // Increment run count and update lastUsedAt
-            await incrementRunCount(template.id)
-            // Reload to show updated stats
-            loadTemplates()
-            // Call the send callback
-            onSendTemplate(template)
+            // Sent first, while the chat is the one it was clicked in (the
+            // counts wait for storage). A run only when it was sent (not
+            // while a message is still being sent, or attachments read).
+            const sending = onSendTemplate(template)
+            // Increment click count only when actually sending
+            await incrementClickCount(template.id)
+            if (await sending) {
+                // Increment run count and update lastUsedAt
+                await incrementRunCount(template.id)
+                // Reload to show updated stats
+                loadTemplates()
+            }
         } else {
+            await incrementClickCount(template.id)
             // Fallback: just fill the input if no send callback provided
             setInput(template.prompt)
         }
@@ -333,14 +339,6 @@ export function TemplatePanel({
     if (!loading && templates.length === 0) {
         return (
             <div className="py-6 px-2 animate-fade-in">
-                <div className="text-center mb-6">
-                    <h2 className="text-lg font-semibold text-foreground mb-2">
-                        {dict.templates.title}
-                    </h2>
-                    <p className="text-sm text-muted-foreground max-w-xs mx-auto">
-                        {dict.templates.subtitle}
-                    </p>
-                </div>
                 <div className="flex flex-col items-center justify-center py-8 px-4">
                     <div className="w-16 h-16 rounded-2xl bg-primary/10 flex items-center justify-center mb-4">
                         <FileText className="w-8 h-8 text-primary/60" />

components/chat/ToolCallCard.tsx

@@ -1,267 +0,0 @@
-"use client"
-
-import { Check, ChevronDown, ChevronUp, Copy, Cpu } from "lucide-react"
-import type { Dispatch, SetStateAction } from "react"
-import { CodeBlock } from "@/components/code-block"
-import { isMxCellXmlComplete } from "@/lib/utils"
-import type { DiagramOperation, ToolPartLike } from "./types"
-
-interface ToolCallCardProps {
-    part: ToolPartLike
-    expandedTools: Record<string, boolean>
-    setExpandedTools: Dispatch<SetStateAction<Record<string, boolean>>>
-    onCopy: (callId: string, text: string, isToolCall: boolean) => void
-    copiedToolCallId: string | null
-    copyFailedToolCallId: string | null
-    dict: {
-        tools: { complete: string }
-        chat: { copied: string; failedToCopy: string; copyResponse: string }
-    }
-}
-
-function OperationsDisplay({ operations }: { operations: DiagramOperation[] }) {
-    // Streamed or invalid input can hold anything: show only what React can
-    // render (an object in place of a string would crash the whole chat)
-    const shown = operations.filter(
-        (op) => typeof (op as { operation?: unknown })?.operation === "string",
-    )
-    const text = (value: unknown) => (typeof value === "string" ? value : "")
-    return (
-        <div className="space-y-3">
-            {shown.map((op, index) => (
-                <div
-                    key={`${op.operation}-${text(op.cell_id)}-${index}`}
-                    className="rounded-lg border border-border/50 overflow-hidden bg-background/50"
-                >
-                    <div className="px-3 py-1.5 bg-muted/40 border-b border-border/30 flex items-center gap-2">
-                        <span
-                            className={`text-[10px] font-medium uppercase tracking-wide ${
-                                op.operation === "delete"
-                                    ? "text-red-600"
-                                    : op.operation === "add"
-                                      ? "text-green-600"
-                                      : "text-blue-600"
-                            }`}
-                        >
-                            {op.operation}
-                        </span>
-                        <span className="text-xs text-muted-foreground">
-                            cell_id: {text(op.cell_id)}
-                        </span>
-                    </div>
-                    {text(op.new_xml) && (
-                        <div className="px-3 py-2">
-                            <pre className="text-[11px] font-mono text-foreground/80 bg-muted/30 rounded px-2 py-1.5 overflow-x-auto whitespace-pre-wrap break-all">
-                                {text(op.new_xml)}
-                            </pre>
-                        </div>
-                    )}
-                </div>
-            ))}
-        </div>
-    )
-}
-
-export function ToolCallCard({
-    part,
-    expandedTools,
-    setExpandedTools,
-    onCopy,
-    copiedToolCallId,
-    copyFailedToolCallId,
-    dict,
-}: ToolCallCardProps) {
-    const callId = part.toolCallId
-    const { state, input, output, errorText } = part
-    // Default to expanded for all states (user can manually collapse if needed)
-    const isExpanded = expandedTools[callId] ?? true
-    const toolName = part.type?.replace("tool-", "")
-    const isCopied = copiedToolCallId === callId
-
-    const toggleExpanded = () => {
-        setExpandedTools((prev) => ({
-            ...prev,
-            [callId]: !isExpanded,
-        }))
-    }
-
-    const getToolDisplayName = (name: string) => {
-        switch (name) {
-            case "display_diagram":
-                return "Generate Diagram"
-            case "edit_diagram":
-                return "Edit Diagram"
-            case "get_shape_library":
-                return "Get Shape Library"
-            default:
-                return name
-        }
-    }
-
-    // Incomplete XML means the output hit the length limit, unless the user
-    // stopped the generation themselves. Without an input the JSON was
-    // broken (the server repairs JSON cut short by the limit).
-    const isTruncated =
-        state === "output-error" &&
-        errorText !== "Stopped by user" &&
-        (toolName === "display_diagram" || toolName === "append_diagram") &&
-        typeof input?.xml === "string" &&
-        !isMxCellXmlComplete(input.xml)
-
-    const handleCopy = () => {
-        let textToCopy = ""
-
-        if (input && typeof input === "object") {
-            if (input.xml) {
-                textToCopy = input.xml
-            } else if (input.operations && Array.isArray(input.operations)) {
-                textToCopy = JSON.stringify(input.operations, null, 2)
-            } else if (Object.keys(input).length > 0) {
-                textToCopy = JSON.stringify(input, null, 2)
-            }
-        }
-
-        if (
-            output &&
-            toolName === "get_shape_library" &&
-            typeof output === "string"
-        ) {
-            textToCopy = output
-        }
-
-        if (textToCopy) {
-            onCopy(callId, textToCopy, true)
-        }
-    }
-
-    return (
-        <div className="my-3 rounded-xl border border-border/60 bg-muted/30 overflow-hidden">
-            <div className="flex items-center justify-between px-4 py-3 bg-muted/50">
-                <div className="flex items-center gap-2">
-                    <div className="w-6 h-6 rounded-md bg-primary/10 flex items-center justify-center">
-                        <Cpu className="w-3.5 h-3.5 text-primary" />
-                    </div>
-                    <span className="text-sm font-medium text-foreground/80">
-                        {getToolDisplayName(toolName)}
-                    </span>
-                </div>
-                <div className="flex items-center gap-2">
-                    {state === "input-streaming" && (
-                        <div className="h-4 w-4 border-2 border-primary border-t-transparent rounded-full animate-spin" />
-                    )}
-                    {state === "output-available" && (
-                        <>
-                            <span className="text-xs font-medium text-green-600 bg-green-50 px-2 py-0.5 rounded-full">
-                                {dict.tools.complete}
-                            </span>
-                            {isExpanded && (
-                                <button
-                                    type="button"
-                                    onClick={handleCopy}
-                                    className="p-1 rounded hover:bg-muted transition-colors"
-                                    title={
-                                        copiedToolCallId === callId
-                                            ? dict.chat.copied
-                                            : copyFailedToolCallId === callId
-                                              ? dict.chat.failedToCopy
-                                              : dict.chat.copyResponse
-                                    }
-                                >
-                                    {isCopied ? (
-                                        <Check className="w-4 h-4 text-green-600" />
-                                    ) : (
-                                        <Copy className="w-4 h-4 text-muted-foreground" />
-                                    )}
-                                </button>
-                            )}
-                        </>
-                    )}
-                    {state === "output-error" &&
-                        (isTruncated ? (
-                            <span className="text-xs font-medium text-yellow-600 bg-yellow-50 px-2 py-0.5 rounded-full">
-                                Truncated
-                            </span>
-                        ) : (
-                            <span className="text-xs font-medium text-red-600 bg-red-50 px-2 py-0.5 rounded-full">
-                                Error
-                            </span>
-                        ))}
-                    {input && Object.keys(input).length > 0 && (
-                        <button
-                            type="button"
-                            onClick={toggleExpanded}
-                            className="p-1 rounded hover:bg-muted transition-colors"
-                        >
-                            {isExpanded ? (
-                                <ChevronUp className="w-4 h-4 text-muted-foreground" />
-                            ) : (
-                                <ChevronDown className="w-4 h-4 text-muted-foreground" />
-                            )}
-                        </button>
-                    )}
-                </div>
-            </div>
-            {input && isExpanded && (
-                <div className="px-4 py-3 border-t border-border/40 bg-muted/20">
-                    {typeof input === "object" && input.xml ? (
-                        state === "input-streaming" ||
-                        state === "input-available" ? (
-                            <pre
-                                className="text-[11px] leading-relaxed overflow-x-auto overflow-y-auto max-h-48 scrollbar-thin break-all whitespace-pre-wrap"
-                                style={{
-                                    fontFamily:
-                                        "var(--font-mono), ui-monospace, monospace",
-                                    margin: 0,
-                                    padding: 0,
-                                }}
-                            >
-                                {input.xml}
-                            </pre>
-                        ) : (
-                            <CodeBlock code={input.xml} language="xml" />
-                        )
-                    ) : typeof input === "object" &&
-                      input.operations &&
-                      Array.isArray(input.operations) ? (
-                        <OperationsDisplay operations={input.operations} />
-                    ) : typeof input === "object" &&
-                      Object.keys(input).length > 0 ? (
-                        <CodeBlock
-                            code={JSON.stringify(input, null, 2)}
-                            language="json"
-                        />
-                    ) : null}
-                </div>
-            )}
-            {/* AI SDK stores tool errors in errorText */}
-            {state === "output-error" && (errorText || output) && (
-                <div
-                    className={`px-4 py-3 border-t border-border/40 text-sm whitespace-pre-wrap break-words ${isTruncated ? "text-yellow-600" : "text-red-600"}`}
-                >
-                    {isTruncated
-                        ? "Output truncated due to length limits. Try a simpler request or increase Max Output Tokens in Settings."
-                        : (errorText ?? output)}
-                </div>
-            )}
-            {/* Show get_shape_library output on success */}
-            {output &&
-                toolName === "get_shape_library" &&
-                state === "output-available" &&
-                isExpanded && (
-                    <div className="px-4 py-3 border-t border-border/40">
-                        <div className="text-xs text-muted-foreground mb-2">
-                            Library loaded (
-                            {typeof output === "string" ? output.length : 0}{" "}
-                            chars)
-                        </div>
-                        <pre className="text-xs bg-muted/50 p-2 rounded-md overflow-auto max-h-32 whitespace-pre-wrap">
-                            {typeof output === "string"
-                                ? output.substring(0, 800) +
-                                  (output.length > 800 ? "\n..." : "")
-                                : String(output)}
-                        </pre>
-                    </div>
-                )}
-        </div>
-    )
-}

components/chat/attachments.ts

@@ -0,0 +1,77 @@
+import { MAX_FILES, MAX_FILE_SIZE as MAX_IMAGE_SIZE } from "@/lib/chat-helpers"
+import { formatMessage } from "@/lib/i18n/utils"
+import { isPdfFile, isTextFile } from "@/lib/pdf-utils"
+
+// Image formats every supported model provider accepts (SVG is read as text)
+const SUPPORTED_IMAGE_TYPES = [
+    "image/png",
+    "image/jpeg",
+    "image/gif",
+    "image/webp",
+]
+
+/** Accept list for the attachment picker */
+export const ATTACHMENT_ACCEPT =
+    "image/png,image/jpeg,image/gif,image/webp,.svg,.pdf,application/pdf,text/*,.md,.markdown,.json,.csv,.xml,.yaml,.yml,.toml"
+
+function isValidFileType(file: File): boolean {
+    return (
+        SUPPORTED_IMAGE_TYPES.includes(file.type) ||
+        isPdfFile(file) ||
+        isTextFile(file)
+    )
+}
+
+function formatFileSize(bytes: number): string {
+    const mb = bytes / 1024 / 1024
+    if (mb < 0.01) return `${(bytes / 1024).toFixed(0)}KB`
+    return `${mb.toFixed(2)}MB`
+}
+
+/** Keep the files that can be attached; describe the rest as errors */
+export function validateFiles(
+    newFiles: File[],
+    existingCount: number,
+    dict: any,
+): { validFiles: File[]; errors: string[] } {
+    const errors: string[] = []
+    const validFiles: File[] = []
+    const availableSlots = MAX_FILES - existingCount
+
+    if (availableSlots <= 0) {
+        errors.push(formatMessage(dict.errors.maxFiles, { max: MAX_FILES }))
+        return { validFiles, errors }
+    }
+
+    for (const file of newFiles) {
+        if (validFiles.length >= availableSlots) {
+            errors.push(
+                formatMessage(dict.errors.onlyMoreAllowed, {
+                    slots: availableSlots,
+                }),
+            )
+            break
+        }
+        if (!isValidFileType(file)) {
+            errors.push(
+                formatMessage(dict.errors.unsupportedType, { name: file.name }),
+            )
+            continue
+        }
+        // PDFs and text files are extracted in the browser, so only images
+        // have a size limit
+        const isExtractedFile = isPdfFile(file) || isTextFile(file)
+        if (!isExtractedFile && file.size > MAX_IMAGE_SIZE) {
+            errors.push(
+                formatMessage(dict.errors.fileExceeds, {
+                    name: file.name,
+                    size: formatFileSize(file.size),
+                    max: MAX_IMAGE_SIZE / 1024 / 1024,
+                }),
+            )
+        } else {
+            validFiles.push(file)
+        }
+    }
+    return { validFiles, errors }
+}

components/chat/chat-panel.tsx

@@ -0,0 +1,190 @@
+import {
+    ChevronDown,
+    Download,
+    MessageSquareDashed,
+    PanelRightClose,
+    Settings2,
+    SquarePen,
+} from "lucide-react"
+import { useRef } from "react"
+import { DevXmlSimulator } from "@/components/dev-xml-simulator"
+import { BrandMark } from "@/components/workspace/brand-mark"
+import { IconButton } from "@/components/workspace/icon-button"
+import { useDiagram } from "@/contexts/diagram-context"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { usePanelWidth } from "@/hooks/use-panel-width"
+import { modKey } from "@/lib/platform"
+import { cn } from "@/lib/utils"
+import {
+    PANEL_MAX_WIDTH,
+    PANEL_MIN_WIDTH,
+    useSettingsStore,
+} from "@/stores/settings-store"
+import { useUiStore } from "@/stores/ui-store"
+import { useChatEngine } from "./chat-engine"
+import { Composer } from "./composer"
+import { MessageList } from "./message-list"
+import { SessionMenu, useSessionTitle } from "./session-menu"
+import { VersionStrip } from "./version-strip"
+
+const DEBUG = process.env.NODE_ENV === "development"
+
+/** Drag handle on the panel's left edge (the panel sits on the right) */
+function ResizeHandle() {
+    const panelWidth = usePanelWidth()
+    const setPanelWidth = useSettingsStore((s) => s.setPanelWidth)
+    const startRef = useRef<{ x: number; width: number } | null>(null)
+
+    return (
+        // biome-ignore lint/a11y/useSemanticElements: a draggable handle, not a divider line
+        <div
+            role="separator"
+            aria-orientation="vertical"
+            aria-valuenow={panelWidth}
+            aria-valuemin={PANEL_MIN_WIDTH}
+            aria-valuemax={PANEL_MAX_WIDTH}
+            tabIndex={-1}
+            className="absolute top-4 -left-1.5 bottom-4 z-10 w-3 cursor-col-resize after:absolute after:inset-y-0 after:left-1/2 after:w-0.5 after:-translate-x-1/2 after:rounded-full after:bg-foreground/0 after:transition-colors hover:after:bg-foreground/15"
+            onPointerDown={(e) => {
+                e.preventDefault()
+                const panel = e.currentTarget.parentElement
+                startRef.current = {
+                    x: e.clientX,
+                    width: panel?.getBoundingClientRect().width ?? 384,
+                }
+                e.currentTarget.setPointerCapture(e.pointerId)
+            }}
+            onPointerMove={(e) => {
+                const start = startRef.current
+                if (!start) return
+                // Dragging left widens the panel
+                setPanelWidth(start.width - (e.clientX - start.x))
+            }}
+            onPointerUp={(e) => {
+                startRef.current = null
+                e.currentTarget.releasePointerCapture(e.pointerId)
+            }}
+        />
+    )
+}
+
+function EmptyThread() {
+    const dict = useDictionary()
+    return (
+        <div className="flex h-full flex-col items-center justify-center gap-2 px-8 text-center">
+            <MessageSquareDashed className="size-5 text-faint" />
+            <p className="max-w-60 text-[13px] text-muted-foreground">
+                {dict.chat.emptyThread}
+            </p>
+        </div>
+    )
+}
+
+/** The floating chat panel: header, versions, conversation, message box */
+export function ChatPanel({
+    mobile = false,
+    onOpenFile,
+}: {
+    mobile?: boolean
+    onOpenFile: () => void
+}) {
+    const dict = useDictionary()
+    const engine = useChatEngine()
+    const { loadDiagram, isDrawioReady } = useDiagram()
+    const setSaveDialogOpen = useUiStore((s) => s.setSaveDialogOpen)
+    const title = useSessionTitle()
+    const panelWidth = usePanelWidth()
+    const openSettings = useUiStore((s) => s.openSettings)
+    const setPanelOpen = useUiStore((s) => s.setPanelOpen)
+
+    return (
+        <aside
+            className={cn(
+                "flex flex-col bg-card",
+                mobile
+                    ? "absolute inset-0"
+                    : "absolute top-3 right-3 bottom-3 z-20 rounded-2xl shadow-float animate-panel-in",
+            )}
+            style={mobile ? undefined : { width: panelWidth }}
+            aria-label={dict.nav.aiChat}
+            data-testid="chat-panel"
+        >
+            <header className="flex h-[52px] shrink-0 items-center gap-1 pr-2 pl-3">
+                <BrandMark />
+                <SessionMenu onOpenFile={onOpenFile}>
+                    <button
+                        type="button"
+                        className="ml-1 flex min-w-0 items-center gap-1 rounded-lg px-1.5 py-1 hover:bg-accent"
+                        data-testid="session-title"
+                    >
+                        <span className="truncate text-[15px] font-semibold tracking-[-0.01em]">
+                            {title}
+                        </span>
+                        <ChevronDown className="size-4 shrink-0 text-faint" />
+                    </button>
+                </SessionMenu>
+                <div className="ml-auto flex items-center">
+                    {isDrawioReady && (
+                        <IconButton
+                            label={dict.workspace.export}
+                            onClick={() => setSaveDialogOpen(true)}
+                            data-testid="export-button"
+                        >
+                            <Download />
+                        </IconButton>
+                    )}
+                    <IconButton
+                        label={dict.nav.newChat}
+                        onClick={engine.newChat}
+                        disabled={engine.isBusy}
+                        data-testid="new-chat-button"
+                    >
+                        <SquarePen />
+                    </IconButton>
+                    <IconButton
+                        label={dict.nav.settings}
+                        onClick={() => openSettings()}
+                        data-testid="settings-button"
+                    >
+                        <Settings2 />
+                    </IconButton>
+                    {!mobile && (
+                        <IconButton
+                            label={dict.nav.hidePanel}
+                            shortcut={`${modKey}B`}
+                            onClick={() => setPanelOpen(false)}
+                        >
+                            <PanelRightClose />
+                        </IconButton>
+                    )}
+                </div>
+            </header>
+
+            <VersionStrip />
+
+            <div className="min-h-0 flex-1 overflow-y-auto scrollbar-thin">
+                {engine.messages.length > 0 ? <MessageList /> : <EmptyThread />}
+            </div>
+
+            {DEBUG && (
+                <DevXmlSimulator
+                    setMessages={engine.setMessages as any}
+                    onDisplayChart={(xml) => loadDiagram(xml, true)}
+                />
+            )}
+
+            <div className="shrink-0 p-2.5 pt-1">
+                <Composer
+                    placeholder={
+                        engine.messages.length > 0 &&
+                        engine.chatSelection.length === 0
+                            ? dict.chat.placeholderFollowUp
+                            : undefined
+                    }
+                />
+            </div>
+
+            {!mobile && <ResizeHandle />}
+        </aside>
+    )
+}

components/chat/compare-dialog.tsx

@@ -0,0 +1,160 @@
+import { ChevronLeft, ChevronRight, RotateCcw } from "lucide-react"
+import { useEffect, useMemo, useState } from "react"
+import {
+    Dialog,
+    DialogContent,
+    DialogDescription,
+    DialogHeader,
+    DialogTitle,
+} from "@/components/ui/dialog"
+import { useDiagram } from "@/contexts/diagram-context"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { diffDiagrams, isSameDocument } from "@/lib/diagram-diff"
+import { formatMessage } from "@/lib/i18n/utils"
+import { describeChanges } from "@/lib/version-text"
+import { useUiStore } from "@/stores/ui-store"
+import { useVersionsStore } from "@/stores/versions-store"
+import { useChatEngine } from "./chat-engine"
+import { VersionThumb } from "./tool-activity"
+
+function Sheet({
+    label,
+    svg,
+}: {
+    label: string
+    svg: string | null | undefined
+}) {
+    return (
+        <figure className="flex min-w-0 flex-1 flex-col gap-2">
+            <figcaption className="text-xs font-medium text-muted-foreground">
+                {label}
+            </figcaption>
+            <div className="sheet-light flex aspect-[16/10] items-center justify-center overflow-hidden rounded-xl border border-border bg-white p-2">
+                <VersionThumb svg={svg} className="max-h-full max-w-full" />
+            </div>
+        </figure>
+    )
+}
+
+/** A saved version next to the current canvas, with restore */
+export function CompareDialog() {
+    const dict = useDictionary()
+    const t = dict.versions
+    const engine = useChatEngine()
+    const { getVersionSvg, chartXML } = useDiagram()
+    const versionId = useUiStore((s) => s.compareVersionId)
+    const openCompare = useUiStore((s) => s.openCompare)
+    const closeCompare = useUiStore((s) => s.closeCompare)
+    const versions = useVersionsStore((s) => s.versions)
+    const [currentSvg, setCurrentSvg] = useState<string | null>(null)
+
+    const index = versions.findIndex((v) => v.id === versionId)
+    const version = index >= 0 ? versions[index] : null
+
+    // Whether the canvas is this version, on every page
+    const same = useMemo(
+        () => !version || isSameDocument(version.xml, chartXML),
+        [version, chartXML],
+    )
+    // What the canvas has changed since this version on the first page
+    // (null: nothing there)
+    const changes = useMemo(() => {
+        if (!version || same) return null
+        const { summary } = diffDiagrams(version.xml, chartXML)
+        return Object.values(summary).some((n) => n > 0) ? summary : null
+    }, [version, chartXML, same])
+
+    // The version went away (dropped as the oldest, another chat): the
+    // dialog closes, and nothing waits for its Escape
+    useEffect(() => {
+        if (versionId && !version) closeCompare()
+    }, [versionId, version, closeCompare])
+
+    // Picture of the canvas as it is now, taken again once an answer that
+    // was running is done ("" when none could be made)
+    useEffect(() => {
+        if (!versionId) return
+        let cancelled = false
+        setCurrentSvg(null)
+        getVersionSvg().then((svg) => {
+            if (!cancelled) setCurrentSvg(svg ?? "")
+        })
+        return () => {
+            cancelled = true
+        }
+    }, [versionId, engine.isBusy])
+
+    return (
+        <Dialog
+            open={!!version}
+            onOpenChange={(open) => !open && closeCompare()}
+        >
+            <DialogContent className="gap-5 sm:max-w-4xl">
+                <DialogHeader>
+                    <DialogTitle>{t.compareTitle}</DialogTitle>
+                    <DialogDescription>
+                        {!version
+                            ? ""
+                            : same
+                              ? t.isOnCanvas
+                              : changes
+                                ? `${formatMessage(t.compareSince, { n: version.number })} ${describeChanges(changes, t)}`
+                                : formatMessage(t.differsElsewhere, {
+                                      n: version.number,
+                                  })}
+                    </DialogDescription>
+                </DialogHeader>
+                {version && (
+                    <div className="flex flex-col gap-4 sm:flex-row">
+                        <Sheet
+                            label={formatMessage(t.versionLabel, {
+                                n: version.number,
+                            })}
+                            svg={version.svg}
+                        />
+                        <Sheet label={t.currentCanvas} svg={currentSvg} />
+                    </div>
+                )}
+                <div className="flex items-center gap-2">
+                    <button
+                        type="button"
+                        disabled={index <= 0}
+                        onClick={() => openCompare(versions[index - 1].id)}
+                        className="inline-flex size-8 items-center justify-center rounded-lg border border-border text-muted-foreground hover:text-foreground disabled:opacity-30"
+                        aria-label={t.previous}
+                    >
+                        <ChevronLeft className="size-4" />
+                    </button>
+                    <button
+                        type="button"
+                        disabled={index < 0 || index >= versions.length - 1}
+                        onClick={() => openCompare(versions[index + 1].id)}
+                        className="inline-flex size-8 items-center justify-center rounded-lg border border-border text-muted-foreground hover:text-foreground disabled:opacity-30"
+                        aria-label={t.next}
+                    >
+                        <ChevronRight className="size-4" />
+                    </button>
+                    <span className="text-xs text-muted-foreground tabular-nums">
+                        {index + 1} / {versions.length}
+                    </span>
+                    <button
+                        type="button"
+                        disabled={!version || same || engine.isBusy}
+                        onClick={() => {
+                            if (!version) return
+                            engine.restoreVersion(version.id)
+                            closeCompare()
+                        }}
+                        className="ml-auto inline-flex h-9 items-center gap-1.5 rounded-lg bg-primary px-3.5 text-[13px] font-medium text-primary-foreground hover:opacity-90 disabled:opacity-40"
+                        data-testid="compare-restore"
+                    >
+                        <RotateCcw className="size-4" />
+                        {formatMessage(t.restoreVersion, {
+                            n: version?.number ?? 0,
+                        })}
+                    </button>
+                </div>
+            </DialogContent>
+        </Dialog>
+    )
+}

components/chat/composer.tsx

@@ -0,0 +1,552 @@
+import {
+    ArrowUp,
+    BookMarked,
+    BookmarkPlus,
+    Globe,
+    Paperclip,
+    Plus,
+    Square,
+    SquareDashedMousePointer,
+    X,
+} from "lucide-react"
+import type React from "react"
+import {
+    useCallback,
+    useEffect,
+    useLayoutEffect,
+    useRef,
+    useState,
+} from "react"
+import { toast } from "sonner"
+import { TemplateCreateDialog } from "@/components/chat/TemplateCreateDialog"
+import { TemplatePanel } from "@/components/chat/TemplatePanel"
+import { ErrorToast } from "@/components/error-toast"
+import { FilePreviewList } from "@/components/file-preview-list"
+import { ModelSelector } from "@/components/model-selector"
+import {
+    Dialog,
+    DialogContent,
+    DialogHeader,
+    DialogTitle,
+} from "@/components/ui/dialog"
+import {
+    Popover,
+    PopoverContent,
+    PopoverTrigger,
+} from "@/components/ui/popover"
+import { UrlInputDialog } from "@/components/url-input-dialog"
+import { IconButton } from "@/components/workspace/icon-button"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { formatMessage } from "@/lib/i18n/utils"
+import { modKey } from "@/lib/platform"
+import { extractUrlContent } from "@/lib/url-utils"
+import { cn } from "@/lib/utils"
+import { useSettingsStore } from "@/stores/settings-store"
+import { useUiStore } from "@/stores/ui-store"
+import { ATTACHMENT_ACCEPT, validateFiles } from "./attachments"
+import { useChatEngine } from "./chat-engine"
+
+function showErrorToast(message: React.ReactNode) {
+    toast.custom(
+        (t) => (
+            <ErrorToast message={message} onDismiss={() => toast.dismiss(t)} />
+        ),
+        { duration: 5000 },
+    )
+}
+
+function showValidationErrors(errors: string[], dict: any) {
+    if (errors.length === 0) return
+    if (errors.length === 1) {
+        showErrorToast(
+            <span className="text-muted-foreground">{errors[0]}</span>,
+        )
+        return
+    }
+    showErrorToast(
+        <div className="flex flex-col gap-1">
+            <span className="font-medium">
+                {formatMessage(dict.errors.filesRejected, {
+                    count: errors.length,
+                })}
+            </span>
+            <ul className="list-inside list-disc text-xs text-muted-foreground">
+                {errors.slice(0, 3).map((err) => (
+                    <li key={err}>{err}</li>
+                ))}
+                {errors.length > 3 && (
+                    <li>
+                        {formatMessage(dict.errors.andMore, {
+                            count: errors.length - 3,
+                        })}
+                    </li>
+                )}
+            </ul>
+        </div>,
+    )
+}
+
+function MenuItem({
+    icon,
+    children,
+    onClick,
+    disabled,
+    disabledHint,
+}: {
+    icon: React.ReactNode
+    children: React.ReactNode
+    onClick: () => void
+    disabled?: boolean
+    /** Why the item can't be used now, shown under it while disabled */
+    disabledHint?: string
+}) {
+    return (
+        <button
+            type="button"
+            onClick={onClick}
+            disabled={disabled}
+            className="group/item flex w-full items-start gap-2.5 rounded-md px-2.5 py-2 text-left text-[13px] hover:bg-accent disabled:pointer-events-none [&_svg]:mt-px [&_svg]:size-4 [&_svg]:text-muted-foreground"
+        >
+            <span className="contents group-disabled/item:[&>svg]:opacity-40">
+                {icon}
+            </span>
+            <span className="min-w-0">
+                <span className="block group-disabled/item:opacity-40">
+                    {children}
+                </span>
+                {disabled && disabledHint && (
+                    <span className="block text-xs text-muted-foreground">
+                        {disabledHint}
+                    </span>
+                )}
+            </span>
+        </button>
+    )
+}
+
+/**
+ * The message box: text, attachments, the selected shapes, the model picker
+ * and send/stop. `variant="hero"` is the large box on the start screen.
+ */
+export function Composer({
+    variant = "panel",
+    placeholder,
+    autoFocus = false,
+}: {
+    variant?: "panel" | "hero"
+    placeholder?: string
+    autoFocus?: boolean
+}) {
+    const dict = useDictionary()
+    const engine = useChatEngine()
+    const {
+        input,
+        setInput,
+        files,
+        setFiles,
+        pdfData,
+        urlData,
+        setUrlData,
+        isBusy,
+        error,
+        chatSelection,
+        dismissSelection,
+        modelConfig,
+    } = engine
+    const sendShortcut = useSettingsStore((s) => s.sendShortcut)
+    const openSettings = useUiStore((s) => s.openSettings)
+    const focusToken = useUiStore((s) => s.focusComposerToken)
+
+    const textareaRef = useRef<HTMLTextAreaElement>(null)
+    const fileInputRef = useRef<HTMLInputElement>(null)
+    const [isDragging, setIsDragging] = useState(false)
+    const [addOpen, setAddOpen] = useState(false)
+    const [templatesOpen, setTemplatesOpen] = useState(false)
+    const [showUrlDialog, setShowUrlDialog] = useState(false)
+    const [isExtractingUrl, setIsExtractingUrl] = useState(false)
+    const [saveTemplateOpen, setSaveTemplateOpen] = useState(false)
+
+    const isHero = variant === "hero"
+    // Allow a retry when the last request failed, even mid-stream. While
+    // the chat is being left, what is typed could not be sent.
+    const isDisabled = (isBusy && !error) || engine.isLeaving
+    const canSend =
+        !isDisabled && !engine.isExtractingAttachments && !!input.trim()
+
+    const adjustHeight = useCallback(() => {
+        const textarea = textareaRef.current
+        if (!textarea) return
+        textarea.style.height = "auto"
+        textarea.style.height = `${Math.min(textarea.scrollHeight, 220)}px`
+    }, [])
+    useEffect(() => {
+        adjustHeight()
+    }, [input, adjustHeight])
+
+    // Focus requests from elsewhere (new chat, "ask AI" button, ⌘/)
+    useEffect(() => {
+        if (focusToken === 0 && !autoFocus) return
+        const timer = setTimeout(() => textareaRef.current?.focus(), 60)
+        return () => clearTimeout(timer)
+    }, [focusToken, autoFocus])
+
+    // The chat is left while the user types (browser back): the browser
+    // takes the focus from the input it disables, after this runs. It gets
+    // the focus back once enabled, unless something else took it meanwhile.
+    const refocusRef = useRef(false)
+    const isLeaving = engine.isLeaving
+    useLayoutEffect(() => {
+        if (isDisabled) {
+            if (isLeaving && document.activeElement === textareaRef.current) {
+                refocusRef.current = true
+            }
+            return
+        }
+        if (!refocusRef.current) return
+        refocusRef.current = false
+        if (document.activeElement === document.body) {
+            textareaRef.current?.focus()
+        }
+    }, [isDisabled, isLeaving])
+
+    const addFiles = (newFiles: File[]) => {
+        const { validFiles, errors } = validateFiles(
+            newFiles,
+            files.length,
+            dict,
+        )
+        showValidationErrors(errors, dict)
+        if (validFiles.length > 0) setFiles([...files, ...validFiles])
+    }
+
+    const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
+        // Enter that confirms an IME candidate must not send the message
+        if (e.nativeEvent.isComposing || e.keyCode === 229) return
+        const shouldSend =
+            sendShortcut === "enter"
+                ? e.key === "Enter" && !e.shiftKey && !e.ctrlKey && !e.metaKey
+                : (e.metaKey || e.ctrlKey) && e.key === "Enter"
+        if (shouldSend) {
+            e.preventDefault()
+            if (canSend) engine.submit()
+        }
+    }
+
+    const handlePaste = async (e: React.ClipboardEvent) => {
+        if (isDisabled) return
+        const imageItems = Array.from(e.clipboardData.items).filter((item) =>
+            item.type.startsWith("image/"),
+        )
+        if (imageItems.length === 0) return
+        const imageFiles = imageItems
+            .map((item, index) => {
+                const file = item.getAsFile()
+                if (!file) return null
+                return new File(
+                    [file],
+                    `pasted-image-${Date.now()}-${index}.${file.type.split("/")[1]}`,
+                    { type: file.type },
+                )
+            })
+            .filter((f): f is File => f !== null)
+        addFiles(imageFiles)
+    }
+
+    const handleUrlExtract = async (url: string) => {
+        setIsExtractingUrl(true)
+        // Functional updates, so a removal or send made while extracting is
+        // not overwritten when the request finishes
+        try {
+            setUrlData((prev) =>
+                new Map(prev).set(url, {
+                    url,
+                    title: url,
+                    content: "",
+                    charCount: 0,
+                    isExtracting: true,
+                }),
+            )
+            const data = await extractUrlContent(url)
+            setUrlData((prev) =>
+                prev.has(url) ? new Map(prev).set(url, data) : prev,
+            )
+            setShowUrlDialog(false)
+        } catch (err) {
+            setUrlData((prev) => {
+                const next = new Map(prev)
+                next.delete(url)
+                return next
+            })
+            showErrorToast(
+                <span className="text-muted-foreground">
+                    {err instanceof Error ? err.message : dict.url.failed}
+                </span>,
+            )
+        } finally {
+            setIsExtractingUrl(false)
+        }
+    }
+
+    const selectionLabel =
+        chatSelection.length === 1
+            ? formatMessage(dict.selection.one, {
+                  label:
+                      chatSelection[0].label ||
+                      (chatSelection[0].isEdge
+                          ? dict.selection.connector
+                          : dict.selection.shape),
+              })
+            : formatMessage(dict.selection.many, {
+                  count: chatSelection.length,
+              })
+
+    const hasChips =
+        chatSelection.length > 0 || files.length > 0 || urlData.size > 0
+
+    return (
+        <form
+            id={isHero ? "hero-chat-form" : "chat-form"}
+            onSubmit={(e) => {
+                e.preventDefault()
+                if (canSend) engine.submit()
+            }}
+            onDragOver={(e) => {
+                e.preventDefault()
+                setIsDragging(true)
+            }}
+            onDragLeave={(e) => {
+                e.preventDefault()
+                setIsDragging(false)
+            }}
+            onDrop={(e) => {
+                e.preventDefault()
+                setIsDragging(false)
+                if (!isDisabled) addFiles(Array.from(e.dataTransfer.files))
+            }}
+            className={cn(
+                "group/composer relative w-full rounded-[14px] border border-border bg-card transition-[border-color,box-shadow] duration-150",
+                "focus-within:border-foreground/20 focus-within:shadow-[0_0_0_4px_var(--accent)]",
+                isHero && "rounded-[18px] border-transparent shadow-pop",
+                isDragging &&
+                    "border-foreground/30 shadow-[0_0_0_4px_var(--marker-soft)]",
+            )}
+        >
+            {hasChips && (
+                <div className="flex flex-wrap items-center gap-1.5 px-2.5 pt-2.5">
+                    {chatSelection.length > 0 && (
+                        <span
+                            className="inline-flex max-w-full items-center gap-1.5 rounded-lg bg-marker-soft py-1 pr-1 pl-2 text-xs font-medium text-marker-ink"
+                            data-testid="selection-chip"
+                        >
+                            <SquareDashedMousePointer className="size-3.5 shrink-0" />
+                            <span className="truncate">{selectionLabel}</span>
+                            <button
+                                type="button"
+                                onClick={dismissSelection}
+                                aria-label={dict.selection.remove}
+                                className="rounded p-0.5 hover:bg-black/5 dark:hover:bg-white/10"
+                            >
+                                <X className="size-3" />
+                            </button>
+                        </span>
+                    )}
+                    {(files.length > 0 || urlData.size > 0) && (
+                        // A short window keeps room for the buttons below
+                        <div className="max-h-[min(176px,22vh)] w-full overflow-y-auto scrollbar-thin">
+                            <FilePreviewList
+                                files={files}
+                                onRemoveFile={(file) =>
+                                    setFiles(files.filter((f) => f !== file))
+                                }
+                                pdfData={pdfData}
+                                urlData={urlData}
+                                onRemoveUrl={(url) =>
+                                    setUrlData((prev) => {
+                                        const next = new Map(prev)
+                                        next.delete(url)
+                                        return next
+                                    })
+                                }
+                            />
+                        </div>
+                    )}
+                </div>
+            )}
+
+            <textarea
+                ref={textareaRef}
+                value={input}
+                onChange={(e) => setInput(e.target.value)}
+                onKeyDown={handleKeyDown}
+                onPaste={handlePaste}
+                placeholder={
+                    placeholder ??
+                    (chatSelection.length > 0
+                        ? dict.selection.placeholder
+                        : dict.chat.placeholder)
+                }
+                disabled={isDisabled}
+                aria-label={dict.chat.inputLabel}
+                data-testid="chat-input"
+                rows={isHero ? 3 : 2}
+                className={cn(
+                    // A short window keeps room for the buttons below
+                    "block max-h-[min(220px,30vh)] w-full resize-none bg-transparent text-foreground outline-none placeholder:text-faint scrollbar-thin disabled:opacity-60",
+                    isHero
+                        ? "min-h-[84px] px-[18px] pt-4 pb-1 text-[15px] leading-relaxed"
+                        : "min-h-[52px] px-3.5 pt-3 pb-1 text-sm",
+                )}
+            />
+
+            <div
+                className={cn(
+                    "flex items-center gap-0.5",
+                    isHero ? "px-2.5 pt-1 pb-2.5" : "px-1.5 pt-0.5 pb-1.5",
+                )}
+            >
+                <Popover open={addOpen} onOpenChange={setAddOpen}>
+                    <PopoverTrigger asChild>
+                        <IconButton
+                            label={dict.chat.attach}
+                            tooltipSide="top"
+                            disabled={isDisabled}
+                            data-testid="composer-add"
+                        >
+                            <Plus />
+                        </IconButton>
+                    </PopoverTrigger>
+                    <PopoverContent
+                        side="top"
+                        align="start"
+                        className="w-64 p-1"
+                    >
+                        <MenuItem
+                            icon={<Paperclip />}
+                            onClick={() => {
+                                setAddOpen(false)
+                                fileInputRef.current?.click()
+                            }}
+                        >
+                            {dict.chat.uploadFile}
+                        </MenuItem>
+                        <MenuItem
+                            icon={<Globe />}
+                            onClick={() => {
+                                setAddOpen(false)
+                                setShowUrlDialog(true)
+                            }}
+                        >
+                            {dict.chat.ExtractURL}
+                        </MenuItem>
+                        <MenuItem
+                            icon={<BookmarkPlus />}
+                            disabled={!input.trim()}
+                            disabledHint={dict.templates.saveDisabledHint}
+                            onClick={() => {
+                                setAddOpen(false)
+                                setSaveTemplateOpen(true)
+                            }}
+                        >
+                            {dict.templates.saveAsTemplate}
+                        </MenuItem>
+                    </PopoverContent>
+                </Popover>
+                <IconButton
+                    label={dict.templates.myTemplates}
+                    tooltipSide="top"
+                    disabled={isDisabled}
+                    onClick={() => setTemplatesOpen(true)}
+                >
+                    <BookMarked />
+                </IconButton>
+
+                <div className="ml-auto flex min-w-0 flex-1 items-center justify-end gap-1">
+                    <ModelSelector
+                        models={modelConfig.models}
+                        selectedModelId={modelConfig.selectedModelId}
+                        onSelect={modelConfig.setSelectedModelId}
+                        onConfigure={() => openSettings("models")}
+                        disabled={isDisabled}
+                        showUnvalidatedModels={
+                            modelConfig.showUnvalidatedModels
+                        }
+                    />
+                    {!isBusy && input.trim() && (
+                        <kbd
+                            className="hidden shrink-0 font-sans text-[11px] text-faint sm:inline"
+                            aria-hidden
+                        >
+                            {sendShortcut === "enter" ? "↵" : `${modKey}↵`}
+                        </kbd>
+                    )}
+                    {isBusy ? (
+                        <button
+                            type="button"
+                            onClick={engine.stop}
+                            aria-label={dict.chat.stopGeneration}
+                            className="inline-flex size-8 shrink-0 items-center justify-center rounded-[10px] bg-foreground text-background transition-opacity hover:opacity-85"
+                        >
+                            <Square className="size-3 fill-current" />
+                        </button>
+                    ) : (
+                        <button
+                            type="submit"
+                            disabled={!canSend}
+                            aria-label={dict.chat.send}
+                            className="inline-flex size-8 shrink-0 items-center justify-center rounded-[10px] bg-primary text-primary-foreground transition-[opacity,background-color] hover:opacity-90 disabled:bg-muted disabled:text-faint"
+                        >
+                            <ArrowUp className="size-4 stroke-[2.25]" />
+                        </button>
+                    )}
+                </div>
+            </div>
+
+            <input
+                ref={fileInputRef}
+                type="file"
+                className="hidden"
+                accept={ATTACHMENT_ACCEPT}
+                data-testid="attachment-input"
+                multiple
+                disabled={isDisabled}
+                onChange={(e) => {
+                    addFiles(Array.from(e.target.files || []))
+                    e.target.value = ""
+                }}
+            />
+
+            <UrlInputDialog
+                open={showUrlDialog}
+                onOpenChange={setShowUrlDialog}
+                onSubmit={handleUrlExtract}
+                isExtracting={isExtractingUrl}
+            />
+            <TemplateCreateDialog
+                open={saveTemplateOpen}
+                onOpenChange={setSaveTemplateOpen}
+                onSuccess={() => setSaveTemplateOpen(false)}
+                initialPrompt={input.trim()}
+            />
+            <Dialog open={templatesOpen} onOpenChange={setTemplatesOpen}>
+                <DialogContent className="flex max-h-[80vh] flex-col gap-0 p-0 sm:max-w-lg">
+                    <DialogHeader className="px-5 pt-5 pb-2">
+                        <DialogTitle>{dict.templates.myTemplates}</DialogTitle>
+                    </DialogHeader>
+                    <div className="min-h-0 flex-1 overflow-y-auto px-3 pb-3 scrollbar-thin">
+                        <TemplatePanel
+                            setInput={(value) => {
+                                setInput(value)
+                                setTemplatesOpen(false)
+                            }}
+                            currentInput={input}
+                            onSendTemplate={(template) => {
+                                setTemplatesOpen(false)
+                                return engine.sendTemplate(template.prompt)
+                            }}
+                        />
+                    </div>
+                </DialogContent>
+            </Dialog>
+        </form>
+    )
+}

components/chat/lobby-hero.tsx

@@ -0,0 +1,284 @@
+import { FileText, FileUp, History, Pencil } from "lucide-react"
+import type React from "react"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { getAssetUrl } from "@/lib/base-path"
+import { cn } from "@/lib/utils"
+import { useChatEngine } from "./chat-engine"
+import { Composer } from "./composer"
+import { SessionMenu } from "./session-menu"
+
+interface Example {
+    key: string
+    title: string
+    description: string
+    /** Picture of the result (or of the input, for "replicate" examples) */
+    image?: string
+    prompt: string
+    /** Bundled file sent with the prompt; matches the cached example */
+    file?: { path: string; name: string; type: string }
+}
+
+async function loadExampleFile(file: NonNullable<Example["file"]>) {
+    const response = await fetch(getAssetUrl(file.path))
+    const blob = await response.blob()
+    return new File([blob], file.name, { type: file.type })
+}
+
+/** One start-screen choice: a small picture, a title and one line */
+function ExampleCard({
+    onClick,
+    title,
+    description,
+    picture,
+    plain,
+    testId,
+}: {
+    onClick: () => void
+    title: string
+    description: string
+    picture: React.ReactNode
+    /** An icon on a tinted tile instead of a diagram on paper */
+    plain?: boolean
+    testId?: string
+}) {
+    return (
+        <button
+            type="button"
+            onClick={onClick}
+            className="group/example flex min-w-0 items-center gap-2.5 rounded-xl border border-border bg-card p-1.5 pr-2.5 text-left transition-colors hover:border-foreground/25"
+            data-testid={testId}
+        >
+            <span
+                className={cn(
+                    "flex h-12 w-16 shrink-0 items-center justify-center overflow-hidden rounded-lg",
+                    plain ? "bg-muted" : "sheet-light bg-white",
+                )}
+            >
+                {picture}
+            </span>
+            <span className="min-w-0 flex-1">
+                <span className="line-clamp-2 text-[13px] leading-snug font-medium text-foreground">
+                    {title}
+                </span>
+                <span className="mt-0.5 block truncate text-xs text-muted-foreground">
+                    {description}
+                </span>
+            </span>
+        </button>
+    )
+}
+
+/**
+ * Start screen over an empty canvas: one large message box and the cached
+ * examples (they answer instantly without calling a model).
+ */
+export function LobbyHero({
+    onDrawYourself,
+    onOpenFile,
+    compact = false,
+}: {
+    onDrawYourself: () => void
+    onOpenFile: () => void
+    /** Phone layout: no example pictures, tighter spacing */
+    compact?: boolean
+}) {
+    const dict = useDictionary()
+    const t = dict.lobby
+    const engine = useChatEngine()
+
+    // Prompts and file names must stay as they are: cached responses match them
+    const examples: Example[] = [
+        {
+            key: "paper",
+            title: dict.examples.paperToDiagram,
+            description: dict.examples.paperDescription,
+            prompt: "Summarize this paper as a diagram",
+            file: {
+                path: "/chain-of-thought.txt",
+                name: "chain-of-thought.txt",
+                type: "text/plain",
+            },
+        },
+        {
+            key: "animated",
+            title: dict.examples.animatedDiagram,
+            description: dict.examples.animatedDescription,
+            image: "/animated_connectors.svg",
+            prompt: "Give me a **animated connector** diagram of transformer's architecture",
+        },
+        {
+            key: "aws",
+            title: dict.examples.awsArchitecture,
+            description: dict.examples.awsDescription,
+            image: "/aws_demo.svg",
+            prompt: "Replicate this in aws style",
+            file: {
+                path: "/architecture.png",
+                name: "architecture.png",
+                type: "image/png",
+            },
+        },
+        {
+            key: "flowchart",
+            title: dict.examples.replicateFlowchart,
+            description: dict.examples.replicateDescription,
+            image: "/example.png",
+            prompt: "Replicate this flowchart.",
+            file: {
+                path: "/example.png",
+                name: "example.png",
+                type: "image/png",
+            },
+        },
+        {
+            key: "cat",
+            title: dict.examples.creativeDrawing,
+            description: dict.examples.creativeDescription,
+            image: "/cat_demo.svg",
+            prompt: "Draw a cat for me",
+        },
+    ]
+
+    const pickExample = async (example: Example) => {
+        engine.setInput(example.prompt)
+        if (!example.file) {
+            engine.setFiles([])
+            return
+        }
+        try {
+            engine.setFiles([await loadExampleFile(example.file)])
+        } catch (error) {
+            console.error(dict.errors.failedToLoadExample, error)
+        }
+    }
+
+    return (
+        <div
+            className={cn(
+                "mx-auto w-full",
+                compact ? "max-w-xl px-4 py-8" : "max-w-[720px] px-6 py-10",
+            )}
+            data-testid="lobby-hero"
+        >
+            <h1
+                className={cn(
+                    "text-center font-semibold tracking-[-0.025em] text-foreground",
+                    compact
+                        ? "text-[26px] leading-tight"
+                        : "text-[34px] leading-[1.15]",
+                )}
+            >
+                {t.title}
+            </h1>
+            <p
+                className={cn(
+                    "mx-auto mt-2.5 max-w-[34em] text-center text-muted-foreground",
+                    compact ? "mb-5 text-[13px]" : "mb-6 text-[14.5px]",
+                )}
+            >
+                {t.lede}
+            </p>
+
+            <Composer
+                variant="hero"
+                autoFocus={!compact}
+                placeholder={t.placeholder}
+            />
+
+            <div
+                className={cn(
+                    "mt-5 grid gap-2",
+                    compact ? "grid-cols-1" : "grid-cols-3",
+                )}
+            >
+                {examples.map((example) =>
+                    compact ? (
+                        <button
+                            key={example.key}
+                            type="button"
+                            onClick={() => pickExample(example)}
+                            className="flex items-center gap-3 rounded-xl border border-border bg-card px-3 py-2.5 text-left hover:border-foreground/25"
+                        >
+                            <span className="min-w-0 flex-1">
+                                <span className="block truncate text-[13px] font-medium">
+                                    {example.title}
+                                </span>
+                                <span className="block truncate text-xs text-muted-foreground">
+                                    {example.description}
+                                </span>
+                            </span>
+                        </button>
+                    ) : (
+                        <ExampleCard
+                            key={example.key}
+                            onClick={() => pickExample(example)}
+                            title={example.title}
+                            description={example.description}
+                            testId={`example-${example.key}`}
+                            picture={
+                                example.image ? (
+                                    // biome-ignore lint/performance/noImgElement: static preview
+                                    <img
+                                        src={getAssetUrl(example.image)}
+                                        alt=""
+                                        className="max-h-10 max-w-[56px] object-contain transition-transform duration-300 group-hover/example:scale-[1.06]"
+                                    />
+                                ) : (
+                                    <FileText className="size-5 text-muted-foreground" />
+                                )
+                            }
+                            plain={!example.image}
+                        />
+                    ),
+                )}
+                {!compact && (
+                    <ExampleCard
+                        onClick={onOpenFile}
+                        title={dict.workspace.openFile}
+                        description={t.openFileHint}
+                        picture={
+                            <FileUp className="size-5 text-muted-foreground" />
+                        }
+                        plain
+                    />
+                )}
+            </div>
+            <p className="mt-3 text-center text-xs text-faint">
+                {dict.examples.cachedNote}
+            </p>
+
+            <div className="mt-6 flex flex-wrap items-center justify-center gap-x-5 gap-y-2 text-[13px] text-muted-foreground">
+                {engine.sessions.length > 0 && (
+                    <SessionMenu align="center" onOpenFile={onOpenFile}>
+                        <button
+                            type="button"
+                            className="inline-flex items-center gap-1.5 hover:text-foreground"
+                        >
+                            <History className="size-4" />
+                            {t.recent}
+                        </button>
+                    </SessionMenu>
+                )}
+                {compact && (
+                    <button
+                        type="button"
+                        onClick={onOpenFile}
+                        className="inline-flex items-center gap-1.5 hover:text-foreground"
+                    >
+                        <FileUp className="size-4" />
+                        {dict.workspace.openFile}
+                    </button>
+                )}
+                <button
+                    type="button"
+                    onClick={onDrawYourself}
+                    className="inline-flex items-center gap-1.5 hover:text-foreground"
+                    data-testid="draw-yourself"
+                >
+                    <Pencil className="size-4" />
+                    {t.drawYourself}
+                </button>
+            </div>
+        </div>
+    )
+}

components/chat/message-list.tsx

@@ -0,0 +1,640 @@
+import type { UIMessage } from "ai"
+import {
+    AlertCircle,
+    BookmarkPlus,
+    Check,
+    ChevronDown,
+    Copy,
+    FileCode,
+    FileText,
+    Link,
+    Pencil,
+    RotateCcw,
+    ThumbsDown,
+    ThumbsUp,
+} from "lucide-react"
+import { useEffect, useRef, useState } from "react"
+import ReactMarkdown from "react-markdown"
+import { toast } from "sonner"
+import {
+    Reasoning,
+    ReasoningContent,
+    ReasoningTrigger,
+} from "@/components/ai-elements/reasoning"
+import { Shimmer } from "@/components/ai-elements/shimmer"
+import { TemplateCreateDialog } from "@/components/chat/TemplateCreateDialog"
+import type { ToolPartLike } from "@/components/chat/types"
+import { ValidationCard } from "@/components/chat/ValidationCard"
+import Image from "@/components/image-with-basepath"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { getApiEndpoint } from "@/lib/base-path"
+import { useCopy } from "@/lib/clipboard"
+import { cn } from "@/lib/utils"
+import { useUiStore } from "@/stores/ui-store"
+import { useChatEngine } from "./chat-engine"
+import {
+    getMessageTextContent,
+    getUserOriginalText,
+    splitTextIntoFileSections,
+    type TextSection,
+} from "./message-text"
+import { ToolActivity } from "./tool-activity"
+
+function ActionButton({
+    label,
+    onClick,
+    active,
+    children,
+}: {
+    label: string
+    onClick: () => void
+    active?: boolean
+    children: React.ReactNode
+}) {
+    return (
+        <button
+            type="button"
+            onClick={onClick}
+            title={label}
+            aria-label={label}
+            className={cn(
+                "inline-flex size-7 items-center justify-center rounded-lg text-faint transition-colors hover:bg-accent hover:text-foreground [&_svg]:size-3.5",
+                active && "text-foreground",
+            )}
+        >
+            {children}
+        </button>
+    )
+}
+
+/** Copies a message's text, with a short "copied" state */
+function CopyButton({ text }: { text: string }) {
+    const dict = useDictionary()
+    const { copied, copy } = useCopy(() =>
+        toast.error(dict.chat.failedToCopyDetail),
+    )
+    return (
+        <ActionButton
+            label={copied ? dict.chat.copied : dict.chat.copyResponse}
+            onClick={() => copy(text)}
+        >
+            {copied ? <Check /> : <Copy />}
+        </ActionButton>
+    )
+}
+
+function AttachedSection({ section }: { section: TextSection }) {
+    const [open, setOpen] = useState(false)
+    const dict = useDictionary()
+    const Icon =
+        section.fileType === "pdf"
+            ? FileText
+            : section.fileType === "url"
+              ? Link
+              : FileCode
+    const chars =
+        section.charCount && section.charCount >= 1000
+            ? `${(section.charCount / 1000).toFixed(1)}k`
+            : section.charCount
+    return (
+        <div className="overflow-hidden rounded-lg border border-border bg-card">
+            <button
+                type="button"
+                onClick={(e) => {
+                    e.stopPropagation()
+                    setOpen((v) => !v)
+                }}
+                className="flex w-full items-center gap-2 px-2.5 py-1.5 text-left hover:bg-accent"
+            >
+                <Icon className="size-4 shrink-0 text-muted-foreground" />
+                <span className="min-w-0 flex-1 truncate text-xs font-medium text-foreground">
+                    {section.filename}
+                </span>
+                <span className="shrink-0 text-[11px] text-faint">
+                    {chars} {dict.file.chars}
+                </span>
+                <ChevronDown
+                    className={cn(
+                        "size-3.5 shrink-0 text-muted-foreground transition-transform",
+                        open && "rotate-180",
+                    )}
+                />
+            </button>
+            {open && (
+                <pre className="max-h-48 overflow-y-auto whitespace-pre-wrap border-t border-border px-2.5 py-2 text-xs text-muted-foreground scrollbar-thin">
+                    {section.content}
+                </pre>
+            )}
+        </div>
+    )
+}
+
+function MessageText({ text }: { text: string }) {
+    const sections = splitTextIntoFileSections(text)
+    return (
+        <div className="space-y-2">
+            {sections.map((section, index) =>
+                section.type === "text" ? (
+                    <div
+                        key={index}
+                        className={cn(
+                            "prose prose-sm max-w-none break-words text-[14px] leading-relaxed text-foreground [&>*:first-child]:mt-0 [&>*:last-child]:mb-0",
+                            "prose-p:my-1.5 prose-pre:bg-surface-2 prose-pre:text-foreground prose-code:before:content-none prose-code:after:content-none dark:prose-invert",
+                        )}
+                    >
+                        <ReactMarkdown>{section.content}</ReactMarkdown>
+                    </div>
+                ) : (
+                    <AttachedSection key={index} section={section} />
+                ),
+            )}
+        </div>
+    )
+}
+
+function UserMessage({
+    message,
+    index,
+    isLast,
+}: {
+    message: UIMessage
+    index: number
+    isLast: boolean
+}) {
+    const dict = useDictionary()
+    const engine = useChatEngine()
+    const [editing, setEditing] = useState(false)
+    const [editText, setEditText] = useState("")
+    const [saveTemplate, setSaveTemplate] = useState(false)
+    const textareaRef = useRef<HTMLTextAreaElement>(null)
+    const text = getMessageTextContent(message)
+    const canEdit = isLast && !engine.isBusy
+
+    useEffect(() => {
+        if (editing) textareaRef.current?.focus()
+    }, [editing])
+
+    const startEdit = () => {
+        if (!canEdit) return
+        setEditText(getUserOriginalText(message))
+        setEditing(true)
+    }
+    const submitEdit = async () => {
+        if (!editText.trim()) return
+        // Kept open, with its text, when it could not go now
+        if (await engine.editMessage(index, editText.trim())) setEditing(false)
+    }
+
+    if (editing) {
+        return (
+            <div className="ml-6 flex flex-col gap-2">
+                <textarea
+                    ref={textareaRef}
+                    value={editText}
+                    onChange={(e) => setEditText(e.target.value)}
+                    rows={Math.min(editText.split("\n").length + 1, 6)}
+                    onKeyDown={(e) => {
+                        if (e.key === "Escape") setEditing(false)
+                        else if (
+                            e.key === "Enter" &&
+                            (e.metaKey || e.ctrlKey)
+                        ) {
+                            e.preventDefault()
+                            submitEdit()
+                        }
+                    }}
+                    className="w-full resize-none rounded-xl border border-foreground/20 bg-card px-3 py-2.5 text-sm outline-none focus:shadow-[0_0_0_4px_var(--accent)]"
+                />
+                <div className="flex justify-end gap-2">
+                    <button
+                        type="button"
+                        onClick={() => setEditing(false)}
+                        className="h-7 rounded-lg px-3 text-xs text-muted-foreground hover:bg-accent hover:text-foreground"
+                    >
+                        {dict.common.cancel}
+                    </button>
+                    <button
+                        type="button"
+                        onClick={submitEdit}
+                        disabled={!editText.trim()}
+                        className="h-7 rounded-lg bg-primary px-3 text-xs font-medium text-primary-foreground disabled:opacity-40"
+                    >
+                        {dict.chat.saveAndSubmit}
+                    </button>
+                </div>
+            </div>
+        )
+    }
+
+    const images = (message.parts ?? []).filter((p) => p.type === "file") as {
+        url: string
+    }[]
+
+    return (
+        <div className="group/message flex items-start justify-end gap-1">
+            <div className="mt-1 flex shrink-0 items-center transition-opacity [@media(hover:hover)]:opacity-0 group-hover/message:opacity-100 focus-within:opacity-100">
+                {canEdit && (
+                    <ActionButton
+                        label={dict.chat.editMessage}
+                        onClick={startEdit}
+                    >
+                        <Pencil />
+                    </ActionButton>
+                )}
+                <CopyButton text={text} />
+                <ActionButton
+                    label={dict.templates.saveAsTemplate}
+                    onClick={() => setSaveTemplate(true)}
+                >
+                    <BookmarkPlus />
+                </ActionButton>
+            </div>
+            <div
+                className={cn(
+                    "min-w-0 max-w-[85%] rounded-2xl rounded-br-md bg-secondary px-3.5 py-2.5",
+                    canEdit &&
+                        "cursor-pointer transition-colors hover:bg-interactive-active",
+                )}
+                role={canEdit ? "button" : undefined}
+                tabIndex={canEdit ? 0 : undefined}
+                onClick={(e) => {
+                    // Not for a link or an attachment's toggle inside, nor
+                    // when text was selected to copy it
+                    const target = e.target as Element
+                    if (target.closest("a, button")) return
+                    if (window.getSelection()?.toString()) return
+                    startEdit()
+                }}
+                onKeyDown={(e) => {
+                    if (e.target !== e.currentTarget) return
+                    if (canEdit && (e.key === "Enter" || e.key === " ")) {
+                        e.preventDefault()
+                        startEdit()
+                    }
+                }}
+                title={canEdit ? dict.chat.clickToEdit : undefined}
+            >
+                {images.length > 0 && (
+                    <div className="mb-2 flex flex-wrap gap-1.5">
+                        {images.map((image, i) => (
+                            <Image
+                                key={i}
+                                src={image.url}
+                                width={96}
+                                height={72}
+                                alt={dict.chat.attachedImage}
+                                className="h-[72px] w-24 rounded-lg border border-border bg-white object-cover"
+                            />
+                        ))}
+                    </div>
+                )}
+                {text && <MessageText text={text} />}
+            </div>
+            {saveTemplate && (
+                <TemplateCreateDialog
+                    open
+                    onOpenChange={(open) => !open && setSaveTemplate(false)}
+                    onSuccess={() => setSaveTemplate(false)}
+                    initialPrompt={getUserOriginalText(message)}
+                />
+            )}
+        </div>
+    )
+}
+
+function AssistantMessage({
+    message,
+    index,
+    isLastMessage,
+    isLastAssistant,
+}: {
+    message: UIMessage
+    index: number
+    isLastMessage: boolean
+    isLastAssistant: boolean
+}) {
+    const dict = useDictionary()
+    // The thinking header in the page language
+    const thinkingMessage = (isStreaming: boolean, duration?: number) => {
+        if (isStreaming || duration === 0) {
+            return <Shimmer duration={1}>{dict.reasoning.thinking}</Shimmer>
+        }
+        if (duration === undefined) return <p>{dict.reasoning.thoughtBrief}</p>
+        return (
+            <p>
+                {duration === 1
+                    ? dict.reasoning.thoughtForOne
+                    : dict.reasoning.thoughtFor.replace(
+                          "{duration}",
+                          String(duration),
+                      )}
+            </p>
+        )
+    }
+    const engine = useChatEngine()
+    const [feedback, setFeedback] = useState<"good" | "bad" | null>(null)
+    const isRestored = engine.loadedMessageIdsRef.current.has(message.id)
+    const parts = message.parts ?? []
+    const isCachedExample = parts.some((p: any) =>
+        p.toolCallId?.startsWith("cached-"),
+    )
+    const text = getMessageTextContent(message)
+
+    const submitFeedback = async (value: "good" | "bad") => {
+        if (feedback === value) {
+            setFeedback(null)
+            return
+        }
+        setFeedback(value)
+        try {
+            await fetch(getApiEndpoint("/api/log-feedback"), {
+                method: "POST",
+                headers: { "Content-Type": "application/json" },
+                body: JSON.stringify({
+                    messageId: message.id,
+                    feedback: value,
+                    sessionId: engine.langfuseSessionId,
+                }),
+            })
+        } catch (error) {
+            console.error("Failed to log feedback:", error)
+            toast.error(dict.errors.failedToRecordFeedback)
+            setFeedback(null)
+        }
+    }
+
+    // Text parts with nothing shown between them render together (a step
+    // boundary of an automatic retry shows nothing); tools render in place
+    const blocks: {
+        kind: "text" | "tool" | "reasoning"
+        index: number
+        texts: string[]
+    }[] = []
+    parts.forEach((part, partIndex) => {
+        if (part.type === "reasoning")
+            blocks.push({ kind: "reasoning", index: partIndex, texts: [] })
+        else if (part.type?.startsWith("tool-"))
+            blocks.push({ kind: "tool", index: partIndex, texts: [] })
+        else if (part.type === "text") {
+            const text = (part as { text: string }).text
+            const last = blocks[blocks.length - 1]
+            if (last?.kind === "text") last.texts.push(text)
+            else blocks.push({ kind: "text", index: partIndex, texts: [text] })
+        }
+    })
+
+    return (
+        <div className="group/message space-y-2.5">
+            {blocks.map((block) => {
+                const part = parts[block.index]
+                if (block.kind === "reasoning") {
+                    const isStreamingReasoning =
+                        engine.status === "streaming" &&
+                        isLastMessage &&
+                        block.index === parts.length - 1
+                    return (
+                        <Reasoning
+                            key={`r-${block.index}`}
+                            className="w-full"
+                            isStreaming={isStreamingReasoning}
+                            defaultOpen={!isRestored}
+                        >
+                            <ReasoningTrigger
+                                getThinkingMessage={thinkingMessage}
+                            />
+                            <ReasoningContent>
+                                {(part as { text: string }).text}
+                            </ReasoningContent>
+                        </Reasoning>
+                    )
+                }
+                if (block.kind === "tool") {
+                    const toolPart = part as unknown as ToolPartLike
+                    const validationState =
+                        engine.validationStates[toolPart.toolCallId]
+                    return (
+                        <div key={`t-${block.index}`} className="space-y-2">
+                            <ToolActivity
+                                part={toolPart}
+                                isLastMessage={isLastMessage}
+                            />
+                            {toolPart.type === "tool-display_diagram" &&
+                                validationState && (
+                                    <ValidationCard
+                                        state={validationState}
+                                        onImproveWithSuggestions={
+                                            engine.improveWithSuggestions
+                                        }
+                                    />
+                                )}
+                        </div>
+                    )
+                }
+                const run = block.texts.join("\n")
+                if (!run.trim()) return null
+                return <MessageText key={`x-${block.index}`} text={run} />
+            })}
+
+            {!(engine.isBusy && isLastMessage) && (
+                <div className="-ml-1.5 flex items-center transition-opacity [@media(hover:hover)]:opacity-0 group-hover/message:opacity-100 focus-within:opacity-100">
+                    {text && <CopyButton text={text} />}
+                    {isLastAssistant && !isCachedExample && (
+                        <ActionButton
+                            label={dict.chat.regenerate}
+                            onClick={() => engine.regenerate(index)}
+                        >
+                            <RotateCcw />
+                        </ActionButton>
+                    )}
+                    <ActionButton
+                        label={dict.chat.goodResponse}
+                        active={feedback === "good"}
+                        onClick={() => submitFeedback("good")}
+                    >
+                        <ThumbsUp
+                            className={cn(
+                                feedback === "good" && "fill-current",
+                            )}
+                        />
+                    </ActionButton>
+                    <ActionButton
+                        label={dict.chat.badResponse}
+                        active={feedback === "bad"}
+                        onClick={() => submitFeedback("bad")}
+                    >
+                        <ThumbsDown
+                            className={cn(feedback === "bad" && "fill-current")}
+                        />
+                    </ActionButton>
+                </div>
+            )}
+        </div>
+    )
+}
+
+/**
+ * A failed request: what to do in the text color, the provider's own words
+ * below it, and the action that can fix it first
+ */
+function ErrorNotice({
+    text,
+    openModelConfig,
+    onOpenModelConfig,
+    onRetry,
+}: {
+    text: string
+    openModelConfig: boolean
+    onOpenModelConfig: () => void
+    onRetry?: () => void
+}) {
+    const dict = useDictionary()
+    // Provider errors are "hint\n\nprovider message"
+    const split = text.indexOf("\n\n")
+    const headline = split >= 0 ? text.slice(0, split) : text
+    const detail = split >= 0 ? text.slice(split + 2).trim() : ""
+    const button =
+        "inline-flex h-7 items-center gap-1 rounded-lg px-2.5 text-xs font-medium"
+    return (
+        <div
+            role="alert"
+            className="rounded-xl border border-destructive/25 bg-destructive/5 px-3.5 py-3 text-[13px]"
+        >
+            <div className="flex items-start gap-2.5">
+                <AlertCircle className="mt-0.5 size-4 shrink-0 text-destructive" />
+                <div className="min-w-0 flex-1">
+                    <p className="whitespace-pre-line break-words font-medium text-foreground">
+                        {headline}
+                    </p>
+                    {detail && (
+                        <p className="mt-1 whitespace-pre-line break-words text-xs text-muted-foreground">
+                            {detail}
+                        </p>
+                    )}
+                    {(openModelConfig || onRetry) && (
+                        <div className="mt-2.5 flex flex-wrap gap-2">
+                            {openModelConfig && (
+                                <button
+                                    type="button"
+                                    onClick={onOpenModelConfig}
+                                    className={cn(
+                                        button,
+                                        "bg-primary text-primary-foreground hover:opacity-90",
+                                    )}
+                                >
+                                    {dict.errors.llm.openModelSettings}
+                                </button>
+                            )}
+                            {onRetry && (
+                                <button
+                                    type="button"
+                                    onClick={onRetry}
+                                    className={cn(
+                                        button,
+                                        "border border-border bg-card text-foreground hover:bg-accent",
+                                    )}
+                                    data-testid="retry-button"
+                                >
+                                    <RotateCcw className="size-3.5" />
+                                    {dict.chat.retry}
+                                </button>
+                            )}
+                        </div>
+                    )}
+                </div>
+            </div>
+        </div>
+    )
+}
+
+export function MessageList() {
+    const dict = useDictionary()
+    const openSettings = useUiStore((s) => s.openSettings)
+    const engine = useChatEngine()
+    const { messages } = engine
+    const endRef = useRef<HTMLDivElement>(null)
+    const prevCountRef = useRef(0)
+    const throttleRef = useRef<ReturnType<typeof setTimeout> | null>(null)
+
+    // Keep the newest message in view; jump instantly on bulk loads
+    useEffect(() => {
+        if (!endRef.current || messages.length === 0) return
+        const prev = prevCountRef.current
+        prevCountRef.current = messages.length
+        if (prev === 0 || messages.length - prev > 1) {
+            endRef.current.scrollIntoView({ behavior: "instant", block: "end" })
+            return
+        }
+        if (!throttleRef.current) {
+            endRef.current.scrollIntoView({ behavior: "smooth", block: "end" })
+            throttleRef.current = setTimeout(() => {
+                throttleRef.current = null
+                endRef.current?.scrollIntoView({
+                    behavior: "smooth",
+                    block: "end",
+                })
+            }, 150)
+        }
+    }, [messages])
+
+    const lastAssistantIndex = messages
+        .map((m) => m.role)
+        .lastIndexOf("assistant")
+    const lastUserIndex = messages.map((m) => m.role).lastIndexOf("user")
+
+    return (
+        <div className="space-y-4 px-4 pt-4 pb-2">
+            {messages.map((message, index) => {
+                const isRestored = engine.loadedMessageIdsRef.current.has(
+                    message.id,
+                )
+                return (
+                    <div
+                        key={message.id}
+                        className={cn(!isRestored && "animate-message-in")}
+                    >
+                        {message.role === "user" ? (
+                            <UserMessage
+                                message={message}
+                                index={index}
+                                isLast={index === lastUserIndex}
+                            />
+                        ) : message.role === "assistant" ? (
+                            <AssistantMessage
+                                message={message}
+                                index={index}
+                                isLastMessage={index === messages.length - 1}
+                                isLastAssistant={index === lastAssistantIndex}
+                            />
+                        ) : (
+                            <ErrorNotice
+                                text={getMessageTextContent(message)}
+                                openModelConfig={
+                                    !!(
+                                        message.metadata as
+                                            | { openModelConfig?: boolean }
+                                            | undefined
+                                    )?.openModelConfig
+                                }
+                                onOpenModelConfig={() => openSettings("models")}
+                                onRetry={
+                                    index === messages.length - 1 &&
+                                    !engine.isBusy &&
+                                    lastUserIndex >= 0
+                                        ? engine.retryLastMessage
+                                        : undefined
+                                }
+                            />
+                        )}
+                    </div>
+                )
+            })}
+            {engine.status === "submitted" &&
+                messages[messages.length - 1]?.role === "user" && (
+                    <div className="px-1 text-[13px]" aria-live="polite">
+                        <Shimmer as="span">{dict.reasoning.thinking}</Shimmer>
+                    </div>
+                )}
+            <div ref={endRef} />
+        </div>
+    )
+}

components/chat/message-text.ts

@@ -0,0 +1,64 @@
+import type { UIMessage } from "ai"
+
+/** A run of plain text, or an attached file / URL whose text was inlined */
+export interface TextSection {
+    type: "text" | "file" | "url"
+    content: string
+    filename?: string
+    charCount?: number
+    fileType?: "pdf" | "text" | "url"
+}
+
+// Matches the [PDF: ...], [File: ...] and [URL: ...] sections appended to the user's text
+export const APPENDED_FILE_SECTIONS_PATTERN =
+    /\n\n\[(PDF|File|URL):\s*[^\]]+\]\n[\s\S]*$/
+
+export function splitTextIntoFileSections(text: string): TextSection[] {
+    const sections: TextSection[] = []
+    const filePattern =
+        /\[(PDF|File|URL):\s*([^\]]+)\]\n([\s\S]*?)(?=\n\n\[(PDF|File|URL):|$)/g
+    let lastIndex = 0
+    let match: RegExpExecArray | null
+
+    while ((match = filePattern.exec(text)) !== null) {
+        const beforeText = text.slice(lastIndex, match.index).trim()
+        if (beforeText) sections.push({ type: "text", content: beforeText })
+
+        const sectionType = match[1].toLowerCase()
+        const fileType =
+            sectionType === "pdf"
+                ? "pdf"
+                : sectionType === "url"
+                  ? "url"
+                  : "text"
+        const content = match[3].trim()
+        sections.push({
+            type: sectionType === "url" ? "url" : "file",
+            content,
+            filename: match[2].trim(),
+            charCount: content.length,
+            fileType,
+        })
+        lastIndex = match.index + match[0].length
+    }
+
+    const remainingText = text.slice(lastIndex).trim()
+    if (remainingText) sections.push({ type: "text", content: remainingText })
+    if (sections.length === 0) sections.push({ type: "text", content: text })
+    return sections
+}
+
+export function getMessageTextContent(message: UIMessage): string {
+    if (!message.parts) return ""
+    return message.parts
+        .filter((part) => part.type === "text")
+        .map((part) => (part as { text: string }).text)
+        .join("\n")
+}
+
+/** Only the user's typed text, without appended file content */
+export function getUserOriginalText(message: UIMessage): string {
+    return getMessageTextContent(message)
+        .replace(APPENDED_FILE_SECTIONS_PATTERN, "")
+        .trim()
+}

components/chat/session-menu.tsx

@@ -0,0 +1,295 @@
+import { FileUp, Pencil, Plus, Search, Trash2 } from "lucide-react"
+import { useParams } from "next/navigation"
+import { useEffect, useRef, useState } from "react"
+import {
+    AlertDialog,
+    AlertDialogAction,
+    AlertDialogCancel,
+    AlertDialogContent,
+    AlertDialogDescription,
+    AlertDialogFooter,
+    AlertDialogHeader,
+    AlertDialogTitle,
+} from "@/components/ui/alert-dialog"
+import {
+    Popover,
+    PopoverContent,
+    PopoverTrigger,
+} from "@/components/ui/popover"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { formatRelativeTime } from "@/lib/relative-time"
+import { cn } from "@/lib/utils"
+import { useChatEngine } from "./chat-engine"
+
+/** Title shown for a session, with the default "New Chat" localized */
+export function useSessionTitle(): string {
+    const dict = useDictionary()
+    const { currentTitle } = useChatEngine()
+    return !currentTitle || currentTitle === "New Chat"
+        ? dict.workspace.untitled
+        : currentTitle
+}
+
+/**
+ * Popover listing saved diagrams: rename the current one, switch, delete,
+ * start a new one or open a file.
+ */
+export function SessionMenu({
+    children,
+    align = "start",
+    onOpenFile,
+}: {
+    children: React.ReactNode
+    align?: "start" | "center" | "end"
+    onOpenFile: () => void
+}) {
+    const dict = useDictionary()
+    const t = dict.sessionHistory
+    const params = useParams<{ lang: string }>()
+    const engine = useChatEngine()
+    const [open, setOpen] = useState(false)
+    const title = useSessionTitle()
+    const [query, setQuery] = useState("")
+    const [renaming, setRenaming] = useState(false)
+    const [draftTitle, setDraftTitle] = useState("")
+    const [toDelete, setToDelete] = useState<string | null>(null)
+    const renameRef = useRef<HTMLInputElement>(null)
+
+    useEffect(() => {
+        if (!open) {
+            setRenaming(false)
+            setQuery("")
+        }
+    }, [open])
+    useEffect(() => {
+        if (renaming) renameRef.current?.select()
+    }, [renaming])
+
+    // The title as the list shows it
+    const shownTitle = (title: string) =>
+        title === "New Chat" ? dict.workspace.untitled : title
+    const sessions = engine.sessions.filter((s) =>
+        shownTitle(s.title).toLowerCase().includes(query.trim().toLowerCase()),
+    )
+
+    const commitRename = async () => {
+        const next = draftTitle.trim()
+        setRenaming(false)
+        if (next && next !== title) await engine.renameSession(next)
+    }
+
+    return (
+        <>
+            <Popover open={open} onOpenChange={setOpen}>
+                <PopoverTrigger asChild>{children}</PopoverTrigger>
+                <PopoverContent
+                    align={align}
+                    className="flex max-h-[min(560px,80vh)] w-[340px] flex-col overflow-hidden rounded-xl p-0 shadow-pop"
+                >
+                    <div className="border-b border-border p-3">
+                        {renaming ? (
+                            <input
+                                ref={renameRef}
+                                value={draftTitle}
+                                onChange={(e) => setDraftTitle(e.target.value)}
+                                onBlur={commitRename}
+                                onKeyDown={(e) => {
+                                    // Enter that picks an IME candidate
+                                    // (Safari: keyCode 229)
+                                    if (
+                                        e.nativeEvent.isComposing ||
+                                        e.keyCode === 229
+                                    ) {
+                                        return
+                                    }
+                                    if (e.key === "Enter") commitRename()
+                                    if (e.key === "Escape") setRenaming(false)
+                                }}
+                                maxLength={100}
+                                aria-label={t.rename}
+                                className="h-8 w-full rounded-lg border border-foreground/20 bg-card px-2.5 text-[13px] font-medium outline-none"
+                            />
+                        ) : (
+                            <button
+                                type="button"
+                                onClick={() => {
+                                    setDraftTitle(title)
+                                    setRenaming(true)
+                                }}
+                                className="group/rename flex h-8 w-full items-center gap-2 rounded-lg px-2.5 text-left hover:bg-accent"
+                                data-testid="rename-session"
+                            >
+                                <span className="min-w-0 flex-1 truncate text-[13px] font-medium">
+                                    {title}
+                                </span>
+                                <Pencil className="size-3.5 shrink-0 text-muted-foreground" />
+                            </button>
+                        )}
+                        <div className="mt-2 flex gap-1.5">
+                            <button
+                                type="button"
+                                disabled={engine.isBusy}
+                                onClick={() => {
+                                    setOpen(false)
+                                    engine.newChat()
+                                }}
+                                className="flex h-8 flex-1 items-center justify-center gap-1.5 rounded-lg bg-primary text-xs font-medium text-primary-foreground hover:opacity-90 disabled:opacity-40"
+                            >
+                                <Plus className="size-3.5" />
+                                {dict.nav.newChat}
+                            </button>
+                            <button
+                                type="button"
+                                disabled={engine.isBusy}
+                                onClick={() => {
+                                    setOpen(false)
+                                    onOpenFile()
+                                }}
+                                className="flex h-8 flex-1 items-center justify-center gap-1.5 rounded-lg border border-border text-xs text-muted-foreground hover:text-foreground disabled:opacity-40"
+                            >
+                                <FileUp className="size-3.5" />
+                                {dict.workspace.openFile}
+                            </button>
+                        </div>
+                    </div>
+
+                    {engine.sessions.length > 0 && (
+                        <div className="px-3 pt-3">
+                            <div className="relative">
+                                <Search className="pointer-events-none absolute top-1/2 left-2.5 size-3.5 -translate-y-1/2 text-faint" />
+                                <input
+                                    value={query}
+                                    onChange={(e) => setQuery(e.target.value)}
+                                    placeholder={t.searchPlaceholder}
+                                    className="h-8 w-full rounded-lg bg-muted pr-2.5 pl-8 text-[13px] outline-none placeholder:text-faint"
+                                />
+                            </div>
+                        </div>
+                    )}
+
+                    <div className="min-h-0 flex-1 overflow-y-auto p-1.5 scrollbar-thin">
+                        {engine.sessions.length === 0 ? (
+                            <p className="px-3 py-6 text-center text-xs text-muted-foreground">
+                                {t.empty}
+                            </p>
+                        ) : sessions.length === 0 ? (
+                            <p className="px-3 py-6 text-center text-xs text-muted-foreground">
+                                {t.noResults}
+                            </p>
+                        ) : (
+                            sessions.map((session) => {
+                                const isCurrent =
+                                    session.id === engine.currentSessionId
+                                // The answer being written must stay in its
+                                // own chat
+                                const locked = engine.isBusy && !isCurrent
+                                const choose = () => {
+                                    if (locked) return
+                                    setOpen(false)
+                                    if (!isCurrent) {
+                                        engine.selectSession(session.id)
+                                    }
+                                }
+                                return (
+                                    // biome-ignore lint/a11y/useSemanticElements: contains the delete button
+                                    <div
+                                        key={session.id}
+                                        role="button"
+                                        tabIndex={locked ? -1 : 0}
+                                        aria-disabled={locked || undefined}
+                                        title={locked ? t.busyHint : undefined}
+                                        onClick={choose}
+                                        onKeyDown={(e) => {
+                                            if (e.target !== e.currentTarget)
+                                                return
+                                            if (
+                                                e.key === "Enter" ||
+                                                e.key === " "
+                                            ) {
+                                                e.preventDefault()
+                                                choose()
+                                            }
+                                        }}
+                                        className={cn(
+                                            "group/session flex cursor-pointer items-center gap-2.5 rounded-lg p-1.5 hover:bg-accent",
+                                            isCurrent && "bg-accent",
+                                            locked &&
+                                                "cursor-not-allowed opacity-50 hover:bg-transparent",
+                                        )}
+                                    >
+                                        <span className="sheet-light flex h-9 w-12 shrink-0 items-center justify-center overflow-hidden rounded-md border border-border bg-white">
+                                            {session.thumbnailDataUrl && (
+                                                // biome-ignore lint/performance/noImgElement: data URL thumbnail
+                                                <img
+                                                    src={
+                                                        session.thumbnailDataUrl
+                                                    }
+                                                    alt=""
+                                                    className="max-h-8 max-w-11 object-contain"
+                                                />
+                                            )}
+                                        </span>
+                                        <span className="min-w-0 flex-1">
+                                            <span className="block truncate text-[13px] text-foreground">
+                                                {shownTitle(session.title)}
+                                            </span>
+                                            <span className="block text-[11px] text-faint">
+                                                {formatRelativeTime(
+                                                    session.updatedAt,
+                                                    params.lang,
+                                                    t.justNow,
+                                                )}
+                                            </span>
+                                        </span>
+                                        <button
+                                            type="button"
+                                            disabled={
+                                                isCurrent && engine.isBusy
+                                            }
+                                            onClick={(e) => {
+                                                e.stopPropagation()
+                                                setToDelete(session.id)
+                                            }}
+                                            aria-label={t.deleteTitle}
+                                            className="inline-flex size-7 shrink-0 items-center justify-center rounded-md text-faint [@media(hover:hover)]:opacity-0 hover:bg-destructive/10 hover:text-destructive group-hover/session:opacity-100 focus-visible:opacity-100"
+                                        >
+                                            <Trash2 className="size-3.5" />
+                                        </button>
+                                    </div>
+                                )
+                            })
+                        )}
+                    </div>
+                </PopoverContent>
+            </Popover>
+
+            <AlertDialog
+                open={!!toDelete}
+                onOpenChange={(o) => !o && setToDelete(null)}
+            >
+                <AlertDialogContent>
+                    <AlertDialogHeader>
+                        <AlertDialogTitle>{t.deleteTitle}</AlertDialogTitle>
+                        <AlertDialogDescription>
+                            {t.deleteDescription}
+                        </AlertDialogDescription>
+                    </AlertDialogHeader>
+                    <AlertDialogFooter>
+                        <AlertDialogCancel>
+                            {dict.common.cancel}
+                        </AlertDialogCancel>
+                        <AlertDialogAction
+                            className="bg-destructive text-white hover:bg-destructive/90"
+                            onClick={() => {
+                                if (toDelete) engine.deleteSession(toDelete)
+                                setToDelete(null)
+                            }}
+                        >
+                            {dict.common.delete}
+                        </AlertDialogAction>
+                    </AlertDialogFooter>
+                </AlertDialogContent>
+            </AlertDialog>
+        </>
+    )
+}

components/chat/tool-activity.tsx

@@ -0,0 +1,531 @@
+import {
+    AlertCircle,
+    Check,
+    ChevronDown,
+    Code2,
+    Copy,
+    Library,
+    PenTool,
+    Redo2,
+    RotateCcw,
+    Undo2,
+} from "lucide-react"
+import { useState } from "react"
+import { Shimmer } from "@/components/ai-elements/shimmer"
+import { CodeBlock } from "@/components/code-block"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { useCopy } from "@/lib/clipboard"
+import { formatMessage } from "@/lib/i18n/utils"
+import { cn, isMxCellXmlComplete } from "@/lib/utils"
+import { describeChanges, describeTotals } from "@/lib/version-text"
+import { useUiStore } from "@/stores/ui-store"
+import { type DiagramVersion, useVersionsStore } from "@/stores/versions-store"
+import { useChatEngine } from "./chat-engine"
+import type { DiagramOperation, ToolPartLike } from "./types"
+
+export function ToolInputDetails({ part }: { part: ToolPartLike }) {
+    const { input, state } = part
+    if (!input || typeof input !== "object") return null
+    if (typeof input.xml === "string" && input.xml) {
+        // Plain text while streaming; highlighting re-runs on every chunk
+        return state === "input-streaming" || state === "input-available" ? (
+            <pre className="max-h-48 overflow-auto whitespace-pre-wrap break-all font-mono text-[11px] leading-relaxed text-muted-foreground scrollbar-thin">
+                {input.xml}
+            </pre>
+        ) : (
+            <CodeBlock code={input.xml} language="xml" />
+        )
+    }
+    if (Array.isArray(input.operations)) {
+        // Streamed or invalid input can hold anything: show only what React
+        // can render (an object in place of a string would crash the chat)
+        const shown = (input.operations as DiagramOperation[]).filter(
+            (op) =>
+                typeof (op as { operation?: unknown })?.operation === "string",
+        )
+        const text = (value: unknown) =>
+            typeof value === "string" ? value : ""
+        return (
+            <div className="space-y-2">
+                {shown.map((op, index) => (
+                    <div
+                        key={`${op.operation}-${text(op.cell_id)}-${index}`}
+                        className="overflow-hidden rounded-lg border border-border bg-card"
+                    >
+                        <div className="flex items-center gap-2 border-b border-border px-2.5 py-1 text-[11px]">
+                            <span className="font-medium text-foreground">
+                                {op.operation}
+                            </span>
+                            <span className="text-muted-foreground">
+                                {text(op.cell_id)}
+                            </span>
+                        </div>
+                        {text(op.new_xml) && (
+                            <pre className="overflow-x-auto whitespace-pre-wrap break-all px-2.5 py-1.5 font-mono text-[11px] text-muted-foreground">
+                                {text(op.new_xml)}
+                            </pre>
+                        )}
+                    </div>
+                ))}
+            </div>
+        )
+    }
+    if (Object.keys(input).length === 0) return null
+    return <CodeBlock code={JSON.stringify(input, null, 2)} language="json" />
+}
+
+function toolText(part: ToolPartLike): string {
+    const { input } = part
+    if (!input || typeof input !== "object") return ""
+    if (typeof input.xml === "string" && input.xml) return input.xml
+    if (Array.isArray(input.operations)) {
+        return JSON.stringify(input.operations, null, 2)
+    }
+    return JSON.stringify(input, null, 2)
+}
+
+/** Picture of a version (SVG data URL), or what stands in for it */
+export function VersionThumb({
+    svg,
+    dimmed,
+    className,
+}: {
+    /** undefined or null: still being made; "": none could be made */
+    svg: string | null | undefined
+    dimmed?: boolean
+    className?: string
+}) {
+    const t = useDictionary().versions
+    if (svg) {
+        return (
+            // biome-ignore lint/performance/noImgElement: data URL thumbnail
+            <img
+                src={svg}
+                alt=""
+                className={cn(
+                    "object-contain transition-opacity",
+                    dimmed && "opacity-40",
+                    className,
+                )}
+            />
+        )
+    }
+    if (svg === "") {
+        return <span className="text-xs text-faint">{t.noPreview}</span>
+    }
+    return (
+        <Shimmer as="span" className="text-xs">
+            {t.rendering}
+        </Shimmer>
+    )
+}
+
+/**
+ * Card for one diagram version produced by a tool call. The latest shows
+ * its picture; older ones fold into one row (the picture opens Compare).
+ */
+function VersionCard({
+    part,
+    version,
+    isLatest,
+}: {
+    part: ToolPartLike
+    version: DiagramVersion
+    isLatest: boolean
+}) {
+    const dict = useDictionary()
+    const t = dict.versions
+    const engine = useChatEngine()
+    const undoneVersionId = useVersionsStore((s) => s.undoneVersionId)
+    const onCanvasVersionId = useVersionsStore((s) => s.onCanvasVersionId)
+    const openCompare = useUiStore((s) => s.openCompare)
+    const [showCode, setShowCode] = useState(false)
+    const { copied, copy } = useCopy()
+
+    const isUndone = undoneVersionId === version.id
+    const isOnCanvas = onCanvasVersionId === version.id
+    const isEdit = part.type === "tool-edit_diagram"
+    // Undo/redo belongs to the newest change while it is (or was) on the
+    // canvas; after an older version was restored, this one is restored too
+    const canUndo =
+        isLatest && version.beforeXml !== undefined && (isOnCanvas || isUndone)
+    const title = isUndone ? t.undone : isEdit ? t.edited : t.created
+    const summary = version.fromScratch
+        ? describeTotals(version.summary, t)
+        : describeChanges(version.summary, t)
+    const badge = (
+        <span
+            className={cn(
+                "shrink-0 rounded-md px-1.5 py-0.5 text-[11px] font-semibold tabular-nums",
+                isOnCanvas
+                    ? "bg-marker-soft text-marker-ink"
+                    : "bg-muted text-muted-foreground",
+            )}
+        >
+            v{version.number}
+        </span>
+    )
+    const actionClass =
+        "inline-flex h-7 shrink-0 items-center gap-1 rounded-lg px-2 text-xs text-muted-foreground hover:bg-accent hover:text-foreground disabled:opacity-40"
+    const restoreButton = (
+        <button
+            type="button"
+            disabled={engine.isBusy || isOnCanvas}
+            onClick={() => engine.restoreVersion(version.id)}
+            className={actionClass}
+            data-testid="version-restore"
+        >
+            <RotateCcw className="size-3.5" />
+            {formatMessage(t.restoreVersion, { n: version.number })}
+        </button>
+    )
+
+    // What the AI wrote, on every card (main showed it on every tool call)
+    const codeButton = (
+        <button
+            type="button"
+            onClick={() => setShowCode((v) => !v)}
+            aria-label={showCode ? t.hideCode : t.showCode}
+            title={showCode ? t.hideCode : t.showCode}
+            className="inline-flex size-7 shrink-0 items-center justify-center rounded-lg text-muted-foreground hover:bg-accent hover:text-foreground"
+        >
+            <Code2 className="size-4" />
+        </button>
+    )
+    const codePanel = showCode && (
+        <div className="relative border-t border-border bg-surface-1 px-3 py-2.5">
+            <button
+                type="button"
+                onClick={() => copy(toolText(part))}
+                className="absolute top-2 right-2 z-10 inline-flex size-7 items-center justify-center rounded-lg bg-card text-muted-foreground shadow-float hover:text-foreground"
+                aria-label={dict.chat.copyResponse}
+            >
+                {copied ? (
+                    <Check className="size-3.5" />
+                ) : (
+                    <Copy className="size-3.5" />
+                )}
+            </button>
+            <ToolInputDetails part={part} />
+        </div>
+    )
+
+    if (!isLatest) {
+        return (
+            <div
+                className="overflow-hidden rounded-xl border border-border bg-card"
+                data-testid="version-card"
+                data-tool-state={part.state}
+            >
+                <div className="flex items-center gap-2.5 p-1.5 pr-2">
+                    <button
+                        type="button"
+                        onClick={() => openCompare(version.id)}
+                        className="sheet-light flex h-9 w-14 shrink-0 items-center justify-center overflow-hidden rounded-md border border-border bg-white hover:border-foreground/30"
+                        aria-label={t.compare}
+                        title={t.compare}
+                    >
+                        <VersionThumb
+                            svg={version.svg}
+                            className="max-h-8 max-w-[52px]"
+                        />
+                    </button>
+                    {badge}
+                    <div className="min-w-0 flex-1" title={summary}>
+                        <div className="truncate text-[13px] text-foreground">
+                            {title}
+                        </div>
+                        <div className="truncate text-xs text-muted-foreground">
+                            {summary}
+                        </div>
+                    </div>
+                    {codeButton}
+                    {restoreButton}
+                </div>
+                {codePanel}
+            </div>
+        )
+    }
+
+    return (
+        <div
+            className={cn(
+                "overflow-hidden rounded-xl border border-border bg-card",
+                isOnCanvas && "border-foreground/15",
+            )}
+            data-testid="version-card"
+            data-tool-state={part.state}
+        >
+            <button
+                type="button"
+                onClick={() => openCompare(version.id)}
+                className="group/thumb sheet-light relative flex h-24 w-full items-center justify-center border-b border-border bg-white"
+                aria-label={t.compare}
+            >
+                <VersionThumb
+                    svg={version.svg}
+                    dimmed={isUndone}
+                    className="max-h-20 max-w-[88%]"
+                />
+                <span className="absolute right-2 bottom-2 rounded-md bg-black/60 px-1.5 py-0.5 text-[11px] text-white opacity-0 transition-opacity group-hover/thumb:opacity-100">
+                    {t.compare}
+                </span>
+            </button>
+            <div className="flex items-center gap-2.5 px-3 py-2.5">
+                {badge}
+                <div className="min-w-0 flex-1" title={summary}>
+                    <div className="truncate text-[13px] font-medium text-foreground">
+                        {title}
+                    </div>
+                    <div className="line-clamp-2 text-xs text-muted-foreground">
+                        {summary}
+                    </div>
+                </div>
+                {codeButton}
+                {canUndo ? (
+                    <button
+                        type="button"
+                        disabled={engine.isBusy}
+                        onClick={() => engine.undoVersion(version.id)}
+                        className={actionClass}
+                        data-testid="version-undo"
+                    >
+                        {isUndone ? (
+                            <Redo2 className="size-3.5" />
+                        ) : (
+                            <Undo2 className="size-3.5" />
+                        )}
+                        {isUndone ? t.redo : t.undo}
+                    </button>
+                ) : (
+                    restoreButton
+                )}
+            </div>
+            {codePanel}
+        </div>
+    )
+}
+
+/** Compact row for tool calls that are running, failed or produced no version */
+function ToolRow({
+    part,
+    icon,
+    label,
+    tone = "default",
+    detail,
+}: {
+    part: ToolPartLike
+    icon: React.ReactNode
+    label: React.ReactNode
+    tone?: "default" | "error" | "warning"
+    detail?: string
+}) {
+    const dict = useDictionary()
+    const [open, setOpen] = useState(false)
+    const { copied, copy } = useCopy()
+    const hasInput = !!part.input && Object.keys(part.input).length > 0
+    return (
+        <div
+            className={cn(
+                "overflow-hidden rounded-xl border border-border bg-card",
+                tone === "error" && "border-destructive/25",
+            )}
+            data-testid="tool-row"
+            data-tool-name={part.type?.replace("tool-", "")}
+            data-tool-state={part.state}
+        >
+            <button
+                type="button"
+                onClick={() => setOpen((v) => !v)}
+                disabled={!hasInput && !detail}
+                className="flex w-full items-center gap-2.5 px-3 py-2.5 text-left"
+            >
+                <span
+                    className={cn(
+                        "inline-flex size-7 shrink-0 items-center justify-center rounded-lg bg-muted text-muted-foreground [&_svg]:size-4",
+                        tone === "error" &&
+                            "bg-destructive/10 text-destructive",
+                        tone === "warning" && "bg-marker-soft text-marker-ink",
+                    )}
+                >
+                    {icon}
+                </span>
+                <span className="min-w-0 flex-1 truncate text-[13px] text-foreground">
+                    {label}
+                </span>
+                {(hasInput || detail) && (
+                    <ChevronDown
+                        className={cn(
+                            "size-4 shrink-0 text-muted-foreground transition-transform",
+                            open && "rotate-180",
+                        )}
+                    />
+                )}
+            </button>
+            {open && (
+                <div
+                    className={cn(
+                        "relative space-y-2 border-t border-border bg-surface-1 px-3 py-2.5",
+                        hasInput && "pr-11",
+                    )}
+                >
+                    {hasInput && (
+                        <button
+                            type="button"
+                            onClick={() => copy(toolText(part))}
+                            className="absolute top-2 right-2 z-10 inline-flex size-7 items-center justify-center rounded-lg bg-card text-muted-foreground shadow-float hover:text-foreground"
+                            aria-label={dict.chat.copyResponse}
+                        >
+                            {copied ? (
+                                <Check className="size-3.5" />
+                            ) : (
+                                <Copy className="size-3.5" />
+                            )}
+                        </button>
+                    )}
+                    {detail && (
+                        <p
+                            className={cn(
+                                "whitespace-pre-wrap break-words text-xs",
+                                tone === "error"
+                                    ? "text-destructive"
+                                    : "text-muted-foreground",
+                            )}
+                        >
+                            {detail}
+                        </p>
+                    )}
+                    {hasInput && <ToolInputDetails part={part} />}
+                </div>
+            )}
+        </div>
+    )
+}
+
+export function ToolActivity({
+    part,
+    isLastMessage,
+}: {
+    part: ToolPartLike
+    isLastMessage: boolean
+}) {
+    const dict = useDictionary()
+    const t = dict.versions
+    const engine = useChatEngine()
+    const versions = useVersionsStore((s) => s.versions)
+    const toolName = part.type?.replace("tool-", "")
+    const { state, errorText, output } = part
+
+    const versionIndex = versions.findIndex(
+        (v) => v.toolCallId === part.toolCallId,
+    )
+    if (state === "output-available" && versionIndex >= 0) {
+        return (
+            <VersionCard
+                part={part}
+                version={versions[versionIndex]}
+                isLatest={versionIndex === versions.length - 1}
+            />
+        )
+    }
+
+    // The answer ended before the call did (stopped, network error)
+    const running = isLastMessage && engine.isBusy
+
+    if (toolName === "get_shape_library" && state !== "output-error") {
+        const isDone = state === "output-available"
+        return (
+            <ToolRow
+                part={part}
+                icon={<Library />}
+                label={
+                    isDone ? (
+                        t.libraryLoaded
+                    ) : running ? (
+                        <Shimmer as="span">{t.loadingLibrary}</Shimmer>
+                    ) : (
+                        t.stopped
+                    )
+                }
+                detail={
+                    isDone && typeof output === "string"
+                        ? `${output.slice(0, 600)}${output.length > 600 ? "…" : ""}`
+                        : undefined
+                }
+            />
+        )
+    }
+
+    // Stop turns a call still streaming into "Stopped by user" (right
+    // away, or when the answer has ended for one not on screen yet): one
+    // left like this was cut off (a closed connection, an error, a closed
+    // tab)
+    if (state === "input-streaming" || state === "input-available") {
+        const failed = !running && !(isLastMessage && engine.stoppedRef.current)
+        return (
+            <ToolRow
+                part={part}
+                icon={running ? <PenTool /> : <AlertCircle />}
+                tone={failed ? "error" : "default"}
+                label={
+                    running ? (
+                        <Shimmer as="span">
+                            {toolName === "edit_diagram"
+                                ? t.editing
+                                : t.drawing}
+                        </Shimmer>
+                    ) : failed ? (
+                        t.failed
+                    ) : (
+                        t.stopped
+                    )
+                }
+            />
+        )
+    }
+
+    if (state === "output-error") {
+        const stopped = errorText === "Stopped by user"
+        // Incomplete XML means the output hit the length limit. Without an
+        // input the JSON was broken (the server repairs JSON cut short by
+        // the limit).
+        const truncated =
+            !stopped &&
+            (toolName === "display_diagram" || toolName === "append_diagram") &&
+            typeof part.input?.xml === "string" &&
+            !isMxCellXmlComplete(part.input.xml)
+        return (
+            <ToolRow
+                part={part}
+                icon={<AlertCircle />}
+                tone={stopped ? "default" : truncated ? "warning" : "error"}
+                label={
+                    stopped
+                        ? t.stopped
+                        : truncated
+                          ? dict.tools.truncated
+                          : isLastMessage && engine.isBusy
+                            ? t.failedRetrying
+                            : t.failed
+                }
+                detail={
+                    stopped
+                        ? undefined
+                        : truncated
+                          ? t.truncatedHint
+                          : (errorText ??
+                            (typeof output === "string" ? output : ""))
+                }
+            />
+        )
+    }
+
+    // Finished without a version (sessions saved before versions existed)
+    return (
+        <ToolRow
+            part={part}
+            icon={<PenTool />}
+            label={toolName === "edit_diagram" ? t.edited : t.created}
+        />
+    )
+}

components/chat/use-diagram-streaming.ts

@@ -0,0 +1,231 @@
+"use client"
+
+import type { UIMessage } from "ai"
+import type { RefObject } from "react"
+import { useCallback, useEffect, useRef } from "react"
+import type { DiagramOperation, ToolPartLike } from "@/components/chat/types"
+import { useDiagram } from "@/contexts/diagram-context"
+import {
+    convertToLegalXml,
+    extractCompleteMxCells,
+    replaceNodes,
+} from "@/lib/utils"
+import { applyDiagramOperations } from "@/packages/mcp-server/src/diagram-operations.ts"
+import { BLANK_MXFILE } from "@/packages/mcp-server/src/pages.ts"
+
+// Helper to extract complete operations from streaming input
+function getCompleteOperations(
+    operations: DiagramOperation[] | undefined,
+): DiagramOperation[] {
+    if (!operations || !Array.isArray(operations)) return []
+    return operations.filter(
+        (op) =>
+            op &&
+            typeof op.operation === "string" &&
+            ["update", "add", "delete"].includes(op.operation) &&
+            typeof op.cell_id === "string" &&
+            op.cell_id.length > 0 &&
+            (op.operation === "delete" || typeof op.new_xml === "string"),
+    )
+}
+
+interface UseDiagramStreamingParams {
+    messages: UIMessage[]
+    processedToolCallsRef: RefObject<Set<string>>
+    editDiagramOriginalXmlRef: RefObject<Map<string, string>>
+    loadedMessageIdsRef: RefObject<Set<string>>
+}
+
+/**
+ * Draws AI tool output onto the canvas while it streams, as a preview that
+ * is not recorded in undo history.
+ *
+ * display_diagram: the complete mxCells written so far. edit_diagram: the
+ * complete operations applied to the diagram from before the call. The tool
+ * handler validates and commits the final result. Runs in the chat engine
+ * so streaming continues while the chat panel is collapsed.
+ */
+export function useDiagramStreaming({
+    messages,
+    processedToolCallsRef,
+    editDiagramOriginalXmlRef,
+    loadedMessageIdsRef,
+}: UseDiagramStreamingParams) {
+    const { chartXML, chartXMLRef, loadDiagram } = useDiagram()
+    const previousXML = useRef<string>("")
+    // Last processed XML per toolCallId, to skip redundant work while streaming
+    const lastProcessedXmlRef = useRef<Map<string, string>>(new Map())
+
+    // Reset when messages become empty (new chat or session switch), so
+    // cached examples work again after starting a new session
+    useEffect(() => {
+        if (messages.length === 0) {
+            previousXML.current = ""
+            lastProcessedXmlRef.current.clear()
+            processedToolCallsRef.current.clear()
+            editDiagramOriginalXmlRef.current.clear()
+        }
+    }, [messages.length, processedToolCallsRef, editDiagramOriginalXmlRef])
+
+    // Streaming preview of display_diagram: draw the complete cells written
+    // so far. The tool handler validates and loads the final diagram.
+    const handleDisplayChart = useCallback(
+        (xml: string) => {
+            const completeCells = extractCompleteMxCells(xml || "")
+            if (!completeCells) return
+            const convertedXml = convertToLegalXml(completeCells)
+            if (convertedXml === previousXML.current) return
+
+            // Skip this update while the cells written so far don't parse
+            const testDoc = new DOMParser().parseFromString(
+                `<root>${convertedXml}</root>`,
+                "text/xml",
+            )
+            if (testDoc.querySelector("parsererror")) return
+
+            try {
+                // Replace the first page's cells so other pages stay intact.
+                // An empty canvas gets a default mxfile to put the cells in.
+                const baseXML = chartXML || BLANK_MXFILE
+                const replacedXML = replaceNodes(baseXML, convertedXml)
+                previousXML.current = convertedXml
+                loadDiagram(replacedXML, true, "preview")
+            } catch (error) {
+                console.error("Error processing XML:", error)
+            }
+        },
+        [chartXML, loadDiagram],
+    )
+
+    useEffect(() => {
+        // Only the last message can still be streaming
+        const message = messages[messages.length - 1]
+        if (!message?.parts) return
+
+        // Messages restored from a saved session were applied before it was
+        // saved; the saved diagram is authoritative, so don't replay them
+        if (loadedMessageIdsRef.current.has(message.id)) return
+
+        // The diagram without streamed previews, as loaded last: the tool
+        // handler's result of an earlier edit is there before the chartXML
+        // state catches up. Undoing a failed edit's preview below changes it
+        // too, and an edit streaming right after must start from the undone
+        // diagram.
+        let baseXml = chartXMLRef.current
+
+        for (const part of message.parts) {
+            if (
+                part.type !== "tool-display_diagram" &&
+                part.type !== "tool-edit_diagram"
+            ) {
+                continue
+            }
+            const { toolCallId, state, input } = part as ToolPartLike
+
+            // Failed or stopped: if the original XML is still stored, the
+            // tool handler never ran (invalid JSON, or the user pressed
+            // stop), so undo the streamed preview here. Invalid JSON leaves
+            // no input, so check this first.
+            if (state === "output-error") {
+                const originalXml =
+                    editDiagramOriginalXmlRef.current.get(toolCallId)
+                if (originalXml) {
+                    editDiagramOriginalXmlRef.current.delete(toolCallId)
+                    loadDiagram(originalXml, true, "revert")
+                    baseXml = originalXml
+                }
+                continue
+            }
+
+            // Input complete, or the tool handler, a stop or an error took
+            // the call already: the tool handler loads the checked diagram.
+            // The messages update at most every 150 ms (useChat throttle in
+            // the chat engine), so they can still show the call streaming
+            // after that.
+            if (
+                state !== "input-streaming" ||
+                processedToolCallsRef.current.has(toolCallId)
+            ) {
+                processedToolCallsRef.current.add(toolCallId)
+                lastProcessedXmlRef.current.delete(toolCallId)
+                lastProcessedXmlRef.current.delete(`${toolCallId}-result`)
+                lastProcessedXmlRef.current.delete(`${toolCallId}-ops`)
+                continue
+            }
+
+            if (part.type === "tool-display_diagram") {
+                const xml = input?.xml as string | undefined
+                // Skip if XML hasn't changed since last processing
+                if (!xml || lastProcessedXmlRef.current.get(toolCallId) === xml)
+                    continue
+                // Keep the diagram from before the preview, to undo it on a
+                // stop or an error
+                if (!editDiagramOriginalXmlRef.current.has(toolCallId)) {
+                    editDiagramOriginalXmlRef.current.set(
+                        toolCallId,
+                        baseXml || BLANK_MXFILE,
+                    )
+                }
+                handleDisplayChart(xml)
+                lastProcessedXmlRef.current.set(toolCallId, xml)
+                continue
+            }
+
+            // edit_diagram: apply operations incrementally for a preview.
+            // editDiagramOriginalXmlRef is shared with the tool handler.
+            if (!input?.operations) continue
+            const completeOps = getCompleteOperations(
+                input.operations as DiagramOperation[],
+            )
+            if (completeOps.length === 0) continue
+
+            // Capture the original XML when streaming starts
+            if (!editDiagramOriginalXmlRef.current.has(toolCallId)) {
+                if (!baseXml) {
+                    console.warn(
+                        "[edit_diagram streaming] No chart XML available",
+                    )
+                    continue
+                }
+                editDiagramOriginalXmlRef.current.set(toolCallId, baseXml)
+            }
+            const originalXml =
+                editDiagramOriginalXmlRef.current.get(toolCallId)
+            if (!originalXml) continue
+
+            // The last operation's XML may still be streaming: it applies
+            // once it parses, so compare results, not the number of
+            // operations. Skip if nothing changed since the last preview.
+            const resultKey = `${toolCallId}-result`
+            const opsKey = `${toolCallId}-ops`
+            const ops = JSON.stringify(completeOps)
+            if (lastProcessedXmlRef.current.get(opsKey) === ops) continue
+            lastProcessedXmlRef.current.set(opsKey, ops)
+            try {
+                const { result } = applyDiagramOperations(
+                    originalXml,
+                    completeOps,
+                )
+                if (lastProcessedXmlRef.current.get(resultKey) === result) {
+                    continue
+                }
+                // Load the full document so other pages stay intact
+                loadDiagram(result, true, "preview")
+                lastProcessedXmlRef.current.set(resultKey, result)
+            } catch (e) {
+                console.warn(
+                    "[edit_diagram streaming] Operation failed:",
+                    e instanceof Error ? e.message : e,
+                )
+            }
+        }
+    }, [
+        messages,
+        handleDisplayChart,
+        chartXMLRef,
+        loadDiagram,
+        processedToolCallsRef,
+        editDiagramOriginalXmlRef,
+        loadedMessageIdsRef,
+    ])
+}

components/chat/use-versions.ts

@@ -0,0 +1,183 @@
+import type { RefObject } from "react"
+import { useEffect, useRef } from "react"
+import { toast } from "sonner"
+import { useDiagram } from "@/contexts/diagram-context"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { diffDiagrams, isSameDocument } from "@/lib/diagram-diff"
+import { clearHighlights, highlightCells } from "@/lib/drawio/editor-bridge"
+import { formatMessage } from "@/lib/i18n/utils"
+import { BLANK_MXFILE } from "@/packages/mcp-server/src/pages.ts"
+import { useVersionsStore } from "@/stores/versions-store"
+
+interface UseVersionsParams {
+    /** Index of the user message whose turn is running */
+    currentTurnRef: RefObject<number>
+    isBusy: boolean
+    /** Live busy state, for the restore toast's Undo that runs later */
+    isTurnActive: () => boolean
+    /** Changes when another chat comes on screen */
+    getChatGeneration: () => number
+}
+
+/**
+ * Turns every committed AI change into a version (card in the chat), marks
+ * the changed shapes on the canvas, and restores or undoes versions.
+ */
+export function useVersions({
+    currentTurnRef,
+    isBusy,
+    isTurnActive,
+    getChatGeneration,
+}: UseVersionsParams) {
+    const dict = useDictionary()
+    // chartXML changes with hand edits, undo and loads; the ref is the
+    // document on the canvas now
+    const {
+        loadDiagram,
+        getVersionSvg,
+        setCommitHandler,
+        chartXML,
+        chartXMLRef,
+    } = useDiagram()
+    // A restore commits too; that path must not add a version
+    const restoringRef = useRef(false)
+
+    // Registered once: re-registering on every render would leave a gap
+    // (effect cleanups run before the streaming hook commits). The handler
+    // only reads refs and stable functions.
+    useEffect(() => {
+        setCommitHandler(({ beforeXml, afterXml, toolCallId }) => {
+            if (restoringRef.current) return
+            const { summary, touchedIds, fromScratch } = diffDiagrams(
+                beforeXml,
+                afterXml,
+            )
+            const id = useVersionsStore.getState().addVersion({
+                xml: afterXml,
+                beforeXml,
+                turnIndex: currentTurnRef.current,
+                toolCallId,
+                summary,
+                fromScratch,
+            })
+            // Mark what changed, unless the whole diagram is new
+            if (!fromScratch) {
+                setTimeout(() => {
+                    const marker = getComputedStyle(document.documentElement)
+                        .getPropertyValue("--marker")
+                        .trim()
+                    highlightCells(touchedIds, marker || "#ffd84d")
+                }, 60)
+            }
+            // The picture is of the canvas: take it right away, before a
+            // newer version can be on it; once one is, this one gets none
+            // rather than the newer one's
+            const isNewest = () =>
+                useVersionsStore.getState().versions.at(-1)?.id === id
+            setTimeout(async () => {
+                const svg = isNewest() ? await getVersionSvg() : null
+                useVersionsStore
+                    .getState()
+                    .updateVersion(id, { svg: svg && isNewest() ? svg : "" })
+            }, 0)
+        })
+        return () => setCommitHandler(null)
+    }, [])
+
+    // A version is on the canvas (or its change undone) while the canvas
+    // holds that XML. Hand edits, Ctrl+Z or a new page end it, with an
+    // external draw.io too; Ctrl+Z or redo can also bring the latest version
+    // (or the diagram before it) back. Checked once an answer is done: its
+    // previews change the canvas on the way.
+    useEffect(() => {
+        if (isBusy || isTurnActive() || !chartXML) return
+        const store = useVersionsStore.getState()
+        const id = store.onCanvasVersionId ?? store.undoneVersionId
+        const version = store.versions.find((v) => v.id === id)
+        if (version) {
+            const shown =
+                id === store.onCanvasVersionId
+                    ? version.xml
+                    : version.beforeXml || BLANK_MXFILE
+            if (isSameDocument(shown, chartXML)) return
+            // Its Undo would also take the changes made since away
+            toast.dismiss("version-restored")
+        }
+        const latest = store.versions.at(-1)
+        if (latest && isSameDocument(latest.xml, chartXML)) {
+            store.setOnCanvas(latest.id)
+        } else if (
+            latest?.beforeXml !== undefined &&
+            isSameDocument(latest.beforeXml || BLANK_MXFILE, chartXML)
+        ) {
+            store.setUndone(latest.id)
+        } else {
+            store.clearCanvasFlags()
+        }
+    }, [chartXML, isBusy])
+
+    const apply = (xml: string) => {
+        restoringRef.current = true
+        try {
+            loadDiagram(xml, true, "commit")
+        } finally {
+            restoringRef.current = false
+        }
+        clearHighlights()
+    }
+
+    const restoreVersion = (versionId: string) => {
+        if (isTurnActive()) return
+        const store = useVersionsStore.getState()
+        const index = store.versions.findIndex((v) => v.id === versionId)
+        if (index < 0) return
+        // The canvas before the restore, to go back to it: a multi-page
+        // document is loaded in full, which Ctrl+Z cannot undo
+        const before = chartXMLRef.current
+        const wasOnCanvas = store.onCanvasVersionId
+        const wasUndone = store.undoneVersionId
+        const generation = getChatGeneration()
+        apply(store.versions[index].xml)
+        store.setOnCanvas(versionId)
+        toast.success(
+            formatMessage(dict.versions.restoredVersion, {
+                n: store.versions[index].number,
+            }),
+            {
+                id: "version-restored",
+                duration: 8000,
+                action: {
+                    label: dict.versions.undoRestore,
+                    onClick: () => {
+                        // Another chat is on screen, or an answer is
+                        // changing the canvas: the old canvas is not theirs
+                        if (!before || isTurnActive()) return
+                        if (getChatGeneration() !== generation) return
+                        apply(before)
+                        const now = useVersionsStore.getState()
+                        if (wasUndone) now.setUndone(wasUndone)
+                        else if (wasOnCanvas) now.setOnCanvas(wasOnCanvas)
+                    },
+                },
+            },
+        )
+    }
+
+    /** Undo the change of the latest version, or redo it when undone */
+    const undoVersion = (versionId: string) => {
+        if (isTurnActive()) return
+        const store = useVersionsStore.getState()
+        const version = store.versions.find((v) => v.id === versionId)
+        if (!version) return
+        if (store.undoneVersionId === versionId) {
+            apply(version.xml)
+            store.setOnCanvas(versionId)
+            return
+        }
+        if (version.beforeXml === undefined) return
+        apply(version.beforeXml || BLANK_MXFILE)
+        store.setUndone(versionId)
+    }
+
+    return { restoreVersion, undoVersion }
+}

components/chat/version-strip.tsx

@@ -0,0 +1,91 @@
+import { useEffect, useRef } from "react"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { cn } from "@/lib/utils"
+import { useUiStore } from "@/stores/ui-store"
+import { useVersionsStore } from "@/stores/versions-store"
+import { useChatEngine } from "./chat-engine"
+
+/** Row of version thumbnails under the panel header; click to compare */
+export function VersionStrip() {
+    const dict = useDictionary()
+    const versions = useVersionsStore((s) => s.versions)
+    const onCanvasVersionId = useVersionsStore((s) => s.onCanvasVersionId)
+    const openCompare = useUiStore((s) => s.openCompare)
+    const engine = useChatEngine()
+    const scrollRef = useRef<HTMLDivElement>(null)
+
+    // Keep the newest version in view
+    useEffect(() => {
+        const el = scrollRef.current
+        if (el) el.scrollTo({ left: el.scrollWidth, behavior: "smooth" })
+    }, [versions.length])
+
+    // Versions with no card in the chat: saved by older app versions, from
+    // a turn that was retried, or drawn by a call that then failed its
+    // screenshot check (a call still running gets its card when done)
+    const hasCardless = versions.some(
+        (v) =>
+            !v.toolCallId ||
+            !engine.messages.some((m) =>
+                m.parts?.some((p) => {
+                    const part = p as { toolCallId?: string; state?: string }
+                    return (
+                        part.toolCallId === v.toolCallId &&
+                        part.state !== "output-error"
+                    )
+                }),
+            ),
+    )
+    // One version with a card: the strip adds nothing to it
+    if (versions.length < 2 && !hasCardless) return null
+
+    return (
+        <div className="flex items-center gap-2 border-b border-border px-3.5 pt-1 pb-3">
+            <span className="shrink-0 text-xs text-muted-foreground">
+                {dict.versions.strip}
+            </span>
+            <div
+                ref={scrollRef}
+                className="flex min-w-0 flex-1 gap-1.5 overflow-x-auto p-1 scrollbar-thin"
+            >
+                {versions.map((version) => {
+                    const isCurrent = version.id === onCanvasVersionId
+                    return (
+                        <button
+                            key={version.id}
+                            type="button"
+                            onClick={() => openCompare(version.id)}
+                            title={`v${version.number}${version.id === onCanvasVersionId ? ` · ${dict.versions.currentCanvas}` : ""}`}
+                            className={cn(
+                                "sheet-light relative flex h-12 w-[72px] shrink-0 items-center justify-center overflow-hidden rounded-lg border border-border bg-white transition-colors hover:border-foreground/30",
+                                // An outline with a gap reads on the white
+                                // picture in both themes
+                                isCurrent &&
+                                    "outline-2 outline-offset-2 outline-foreground",
+                            )}
+                            data-testid="version-thumb"
+                        >
+                            {version.svg && (
+                                // biome-ignore lint/performance/noImgElement: data URL thumbnail
+                                <img
+                                    src={version.svg}
+                                    alt=""
+                                    className="max-h-9 max-w-[62px] object-contain"
+                                />
+                            )}
+                            <span
+                                className={cn(
+                                    "absolute bottom-0.5 left-1 text-[10px] font-medium tabular-nums text-neutral-500",
+                                    isCurrent &&
+                                        "font-semibold text-neutral-900",
+                                )}
+                            >
+                                v{version.number}
+                            </span>
+                        </button>
+                    )
+                })}
+            </div>
+        </div>
+    )
+}

components/history-dialog.tsx

@@ -1,114 +0,0 @@
-"use client"
-
-import { useState } from "react"
-import Image from "@/components/image-with-basepath"
-import { Button } from "@/components/ui/button"
-import {
-    Dialog,
-    DialogContent,
-    DialogDescription,
-    DialogFooter,
-    DialogHeader,
-    DialogTitle,
-} from "@/components/ui/dialog"
-import { useDiagram } from "@/contexts/diagram-context"
-import { useDictionary } from "@/hooks/use-dictionary"
-import { formatMessage } from "@/lib/i18n/utils"
-
-interface HistoryDialogProps {
-    showHistory: boolean
-    onToggleHistory: (show: boolean) => void
-}
-
-export function HistoryDialog({
-    showHistory,
-    onToggleHistory,
-}: HistoryDialogProps) {
-    const dict = useDictionary()
-    const { loadDiagram: onDisplayChart, diagramHistory } = useDiagram()
-    const [selectedIndex, setSelectedIndex] = useState<number | null>(null)
-
-    const handleClose = () => {
-        setSelectedIndex(null)
-        onToggleHistory(false)
-    }
-
-    const handleConfirmRestore = () => {
-        if (selectedIndex !== null) {
-            // Skip validation for trusted history snapshots
-            onDisplayChart(diagramHistory[selectedIndex].xml, true)
-            handleClose()
-        }
-    }
-
-    return (
-        <Dialog open={showHistory} onOpenChange={onToggleHistory}>
-            <DialogContent className="max-w-3xl max-h-[80vh] overflow-y-auto scrollbar-thin">
-                <DialogHeader>
-                    <DialogTitle>{dict.history.title}</DialogTitle>
-                    <DialogDescription>
-                        {dict.history.description}
-                    </DialogDescription>
-                </DialogHeader>
-
-                {diagramHistory.length === 0 ? (
-                    <div className="text-center p-4 text-gray-500">
-                        {dict.history.noHistory}
-                    </div>
-                ) : (
-                    <div className="grid grid-cols-2 md:grid-cols-3 gap-4 py-4">
-                        {diagramHistory.map((item, index) => (
-                            <div
-                                key={index}
-                                className={`border rounded-md p-2 cursor-pointer hover:border-primary transition-colors ${
-                                    selectedIndex === index
-                                        ? "border-primary ring-2 ring-primary"
-                                        : ""
-                                }`}
-                                onClick={() => setSelectedIndex(index)}
-                            >
-                                <div className="aspect-video bg-white rounded overflow-hidden flex items-center justify-center">
-                                    <Image
-                                        src={item.svg}
-                                        alt={`${dict.history.version} ${index + 1}`}
-                                        width={200}
-                                        height={100}
-                                        className="object-contain w-full h-full p-1"
-                                    />
-                                </div>
-                                <div className="text-xs text-center mt-1 text-gray-500">
-                                    {dict.history.version} {index + 1}
-                                </div>
-                            </div>
-                        ))}
-                    </div>
-                )}
-
-                <DialogFooter>
-                    {selectedIndex !== null ? (
-                        <>
-                            <div className="flex-1 text-sm text-muted-foreground">
-                                {formatMessage(dict.history.restoreTo, {
-                                    version: selectedIndex + 1,
-                                })}
-                            </div>
-                            <Button
-                                variant="outline"
-                                onClick={() => setSelectedIndex(null)}
-                            >
-                                {dict.common.cancel}
-                            </Button>
-                            <Button onClick={handleConfirmRestore}>
-                                {dict.common.confirm}
-                            </Button>
-                        </>
-                    ) : (
-                        <Button variant="outline" onClick={handleClose}>
-                            {dict.common.close}
-                        </Button>
-                    )}
-                </DialogFooter>
-            </DialogContent>
-        </Dialog>
-    )
-}

components/model-config-dialog.tsx

@@ -41,13 +41,6 @@ import {
     CommandItem,
     CommandList,
 } from "@/components/ui/command"
-import {
-    Dialog,
-    DialogContent,
-    DialogDescription,
-    DialogHeader,
-    DialogTitle,
-} from "@/components/ui/dialog"
 import { Input } from "@/components/ui/input"
 import { Label } from "@/components/ui/label"
 import {
@@ -80,7 +73,6 @@ import { cn } from "@/lib/utils"
 
 interface ModelConfigDialogProps {
     open: boolean
-    onOpenChange: (open: boolean) => void
     modelConfig: UseModelConfigReturn
 }
 
@@ -103,7 +95,7 @@ function ConfigSection({
             <div className="flex items-center justify-between">
                 <div className="flex items-center gap-2">
                     <Icon className="h-4 w-4 text-muted-foreground" />
-                    <span className="text-xs font-medium text-muted-foreground uppercase tracking-wider">
+                    <span className="text-xs font-medium text-muted-foreground">
                         {title}
                     </span>
                 </div>
@@ -123,9 +115,28 @@ function ConfigCard({ children }: { children: React.ReactNode }) {
     )
 }
 
+/** A Bedrock API key or an access key pair, and a region */
+function hasBedrockCredentials(p: ProviderConfig): boolean {
+    return (
+        (!!p.apiKey || (!!p.awsAccessKeyId && !!p.awsSecretAccessKey)) &&
+        !!p.awsRegion
+    )
+}
+
+/** Providers as last saved (the model config is saved on every change) */
+function savedProviders(): ProviderConfig[] {
+    try {
+        const stored = localStorage.getItem(STORAGE_KEYS.modelConfigs)
+        return stored
+            ? (JSON.parse(stored) as { providers: ProviderConfig[] }).providers
+            : []
+    } catch {
+        return []
+    }
+}
+
 export function ModelConfigDialog({
     open,
-    onOpenChange,
     modelConfig,
 }: ModelConfigDialogProps) {
     const dict = useDictionary()
@@ -192,10 +203,22 @@ export function ModelConfigDialog({
     // Number of the latest Test click: only that test may reset the busy
     // state when its credentials changed meanwhile
     const validationRunRef = useRef(0)
+    // Set when this view goes away (settings closed or on another tab): its
+    // config no longer follows edits, the saved one does
+    const closedRef = useRef(false)
+    useEffect(() => {
+        closedRef.current = false
+        return () => {
+            closedRef.current = true
+        }
+    }, [])
+    // The providers as they are now: once this view is gone, as saved
+    const providersNow = () =>
+        closedRef.current ? savedProviders() : configRef.current.providers
     // A model list or test result belongs to the credentials it was asked
     // with; they can change meanwhile, here or in another tab
     const credentialsOf = (providerId: string) => {
-        const p = configRef.current.providers.find((x) => x.id === providerId)
+        const p = providersNow().find((x) => x.id === providerId)
         return JSON.stringify([
             p?.provider,
             p?.apiKey,
@@ -266,7 +289,9 @@ export function ModelConfigDialog({
                 const hints = dict.errors.llm as Record<string, string>
                 setFetchModelsError(
                     [hints[data.code], data.error].filter(Boolean).join(" ") ||
-                        `Request failed (${response.status})`,
+                        formatMessage(dict.modelConfig.requestFailed, {
+                            status: response.status,
+                        }),
                 )
             }
         } catch {
@@ -355,7 +380,7 @@ export function ModelConfigDialog({
         if (!selectedProviderId || !selectedProvider) return false
         // Prevent duplicate model IDs
         if (existingModelIds.includes(modelId)) {
-            setDuplicateError(`Model "${modelId}" already exists`)
+            setDuplicateError(dict.modelConfig.modelIdExists)
             return false
         }
         setDuplicateError("")
@@ -388,13 +413,7 @@ export function ModelConfigDialog({
         const isOllama = selectedProvider.provider === "ollama"
         const isVertexAI = selectedProvider.provider === "vertexai"
         if (isBedrock) {
-            if (
-                !selectedProvider.awsAccessKeyId ||
-                !selectedProvider.awsSecretAccessKey ||
-                !selectedProvider.awsRegion
-            ) {
-                return
-            }
+            if (!hasBedrockCredentials(selectedProvider)) return
         } else if (isVertexAI) {
             // Vertex AI requires vertexApiKey for Express Mode
             if (!selectedProvider.vertexApiKey) {
@@ -406,7 +425,7 @@ export function ModelConfigDialog({
 
         // Need at least one model to validate
         if (selectedProvider.models.length === 0) {
-            setValidationError("Add at least one model to validate")
+            setValidationError(dict.modelConfig.addModelFirst)
             setValidationStatus("error")
             return
         }
@@ -485,14 +504,17 @@ export function ModelConfigDialog({
                                       .filter(Boolean)
                                       .join(" ") ||
                                   (response.ok
-                                      ? "Validation failed"
-                                      : `Request failed (${response.status})`),
+                                      ? dict.modelConfig.validationError
+                                      : formatMessage(
+                                            dict.modelConfig.requestFailed,
+                                            { status: response.status },
+                                        )),
                               validationWarning: undefined,
                           }
                 } catch {
                     update = {
                         validated: false,
-                        validationError: "Network error",
+                        validationError: dict.errors.networkError,
                         validationWarning: undefined,
                     }
                 }
@@ -511,7 +533,7 @@ export function ModelConfigDialog({
                     return
                 }
                 // So did this model's id: the result is for the old one
-                const current = configRef.current.providers
+                const current = providersNow()
                     .find((p) => p.id === selectedProviderId)
                     ?.models.find((m) => m.id === model.id)
                 if (current?.modelId !== model.modelId) {
@@ -565,7 +587,11 @@ export function ModelConfigDialog({
             }, 1500)
         } else {
             setValidationStatus("error")
-            setValidationError(`${errorCount} model(s) failed validation`)
+            setValidationError(
+                formatMessage(dict.modelConfig.validationFailedCount, {
+                    count: errorCount,
+                }),
+            )
         }
     }, [
         selectedProvider,
@@ -682,27 +708,13 @@ export function ModelConfigDialog({
     }
 
     return (
-        <Dialog open={open} onOpenChange={onOpenChange}>
-            <DialogContent className="sm:max-w-4xl h-[80vh] max-h-[800px] overflow-hidden flex flex-col gap-0 p-0">
-                {/* Header */}
-                <DialogHeader className="px-6 pt-6 pb-4 shrink-0">
-                    <DialogTitle className="flex items-center gap-3">
-                        <div className="p-2 rounded-xl bg-surface-2">
-                            <Server className="h-5 w-5 text-primary" />
-                        </div>
-                        {dict.modelConfig?.title || "AI Model Configuration"}
-                    </DialogTitle>
-                    <DialogDescription className="mt-1">
-                        {dict.modelConfig?.description ||
-                            "Configure multiple AI providers and models for your workspace"}
-                    </DialogDescription>
-                </DialogHeader>
-
-                <div className="flex flex-1 min-h-0 overflow-hidden border-t border-border-subtle">
+        <>
+            <div className="flex min-h-0 flex-1 flex-col">
+                <div className="flex flex-1 min-h-0 overflow-hidden">
                     {/* Provider List (Left Sidebar) */}
                     <div className="w-60 shrink-0 flex flex-col bg-surface-1/50 border-r border-border-subtle">
                         <div className="px-4 py-3">
-                            <span className="text-xs font-medium text-muted-foreground uppercase tracking-wider">
+                            <span className="text-xs font-medium text-muted-foreground">
                                 {dict.modelConfig.providers}
                             </span>
                         </div>
@@ -898,6 +910,7 @@ export function ModelConfigDialog({
                                                 awsRegion={
                                                     selectedProvider.awsRegion
                                                 }
+                                                bedrockApiKey
                                                 onChange={(field, value) =>
                                                     handleProviderUpdate(
                                                         field,
@@ -914,9 +927,9 @@ export function ModelConfigDialog({
                                                     selectedProvider.provider ===
                                                     "bedrock"
                                                         ? renderTestButton(
-                                                              !!selectedProvider.awsAccessKeyId &&
-                                                                  !!selectedProvider.awsSecretAccessKey &&
-                                                                  !!selectedProvider.awsRegion,
+                                                              hasBedrockCredentials(
+                                                                  selectedProvider,
+                                                              ),
                                                           )
                                                         : selectedProvider.provider ===
                                                             "edgeone"
@@ -1413,7 +1426,7 @@ export function ModelConfigDialog({
                                                                                 model.id,
                                                                             )
                                                                         }
-                                                                        aria-label={`Delete ${model.modelId}`}
+                                                                        aria-label={`${dict.common.delete} ${model.modelId}`}
                                                                     >
                                                                         <X className="h-4 w-4" />
                                                                     </Button>
@@ -1474,10 +1487,14 @@ export function ModelConfigDialog({
                                     <Server className="h-8 w-8 text-muted-foreground" />
                                 </div>
                                 <h3 className="font-semibold text-lg tracking-tight mb-1">
-                                    {dict.modelConfig.configureProviders}
+                                    {config.providers.length === 0
+                                        ? dict.modelConfig.noProvidersTitle
+                                        : dict.modelConfig.configureProviders}
                                 </h3>
                                 <p className="text-sm text-muted-foreground max-w-xs">
-                                    {dict.modelConfig.selectProviderHint}
+                                    {config.providers.length === 0
+                                        ? dict.modelConfig.noProvidersHint
+                                        : dict.modelConfig.selectProviderHint}
                                 </p>
                             </div>
                         )}
@@ -1508,7 +1525,7 @@ export function ModelConfigDialog({
                         </p>
                     </div>
                 </div>
-            </DialogContent>
+            </div>
 
             {/* Delete Confirmation Dialog */}
             <AlertDialog
@@ -1588,6 +1605,6 @@ export function ModelConfigDialog({
                     </AlertDialogFooter>
                 </AlertDialogContent>
             </AlertDialog>
-        </Dialog>
+        </>
     )
 }

components/model-selector.tsx

@@ -26,6 +26,7 @@ import {
     ModelSelectorTrigger,
 } from "@/components/ai-elements/model-selector"
 import { ButtonWithTooltip } from "@/components/button-with-tooltip"
+import { ProviderLogo } from "@/components/provider-logo"
 import { useDictionary } from "@/hooks/use-dictionary"
 import {
     type FlattenedModel,
@@ -66,6 +67,26 @@ function groupModelsByProvider(
     return groups
 }
 
+/**
+ * The model id without the provider or region prefix that the logo already
+ * shows: "nvidia/nemotron-3-ultra" and "global.anthropic.claude-opus-5-5"
+ * become "nemotron-3-ultra" and "claude-opus-5-5". The full id is in the
+ * tooltip and the list.
+ */
+export function shortModelName(id: string): string {
+    const name = id.slice(id.lastIndexOf("/") + 1)
+    const short = name.replace(
+        /^(?:(?:global|us|eu|apac|jp|au|ca|us-gov)\.)?[a-z][a-z0-9-]*\.(?=[a-z])/i,
+        "",
+    )
+    // Ids like "deepseek.r1-v1:0" name the vendor only in the prefix: drop
+    // just the region
+    if (!short || /^[a-z]\d/i.test(short)) {
+        return name.replace(/^(?:global|us|eu|apac|jp|au|ca|us-gov)\./i, "")
+    }
+    return short
+}
+
 export function ModelSelector({
     models,
     selectedModelId,
@@ -158,7 +179,7 @@ export function ModelSelector({
     }, [])
 
     return (
-        <div ref={wrapperRef} className="min-w-0 max-w-48">
+        <div ref={wrapperRef} className="min-w-0 max-w-44">
             <ModelSelectorRoot open={open} onOpenChange={setOpen}>
                 <ModelSelectorTrigger asChild>
                     <ButtonWithTooltip
@@ -167,18 +188,26 @@ export function ModelSelector({
                         size="sm"
                         disabled={disabled}
                         className={cn(
-                            "h-8 min-w-0 max-w-full shrink overflow-hidden gap-1.5 px-2 transition-[padding,background-color] duration-150 ease-in-out hover:bg-accent",
+                            "h-8 min-w-0 max-w-full shrink overflow-hidden gap-1.5 px-2 font-normal text-muted-foreground transition-[padding,background-color] duration-150 ease-in-out hover:bg-accent hover:text-foreground",
                             !showLabel && "px-1.5 justify-center",
                         )}
                         // accessibility: expose label to screen readers
                         aria-label={tooltipContent}
+                        data-testid="model-selector"
                     >
-                        <Bot className="h-4 w-4 flex-shrink-0 text-muted-foreground" />
+                        {selectedModel ? (
+                            <ProviderLogo
+                                provider={selectedModel.provider}
+                                className="size-3.5 flex-shrink-0 opacity-80"
+                            />
+                        ) : (
+                            <Bot className="h-4 w-4 flex-shrink-0" />
+                        )}
                         {/* show/hide visible label based on measured width */}
                         {showLabel ? (
                             <span className="min-w-0 truncate text-xs">
                                 {selectedModel
-                                    ? selectedModel.modelId
+                                    ? shortModelName(selectedModel.modelId)
                                     : dict.modelConfig.default}
                             </span>
                         ) : (

components/provider-credentials-fields.tsx

@@ -53,6 +53,9 @@ interface ProviderCredentialsFieldsProps {
     name?: string
     baseUrl?: string
     awsRegion?: string
+    // Bedrock: also offer an API key (the user dialog; the admin panel
+    // stores access keys only)
+    bedrockApiKey?: boolean
     disabled?: boolean
     // Update a plain text field
     onChange: (field: "name" | "baseUrl" | "awsRegion", value: string) => void
@@ -72,6 +75,7 @@ export function ProviderCredentialsFields({
     name,
     baseUrl,
     awsRegion,
+    bedrockApiKey,
     disabled,
     onChange,
     renderSecret,
@@ -112,6 +116,26 @@ export function ProviderCredentialsFields({
 
             {provider === "bedrock" ? (
                 <>
+                    {/* Bedrock API key: used instead of the access keys */}
+                    {bedrockApiKey && (
+                        <div className="space-y-2">
+                            <Label
+                                htmlFor="bedrock-api-key"
+                                className="text-xs font-medium flex items-center gap-1.5"
+                            >
+                                <Key className="h-3.5 w-3.5 text-muted-foreground" />
+                                {dict.modelConfig.bedrockApiKey}
+                            </Label>
+                            {renderSecret({
+                                field: "apiKey",
+                                id: "bedrock-api-key",
+                            })}
+                            <p className="text-xs text-muted-foreground">
+                                {dict.modelConfig.bedrockApiKeyHint}
+                            </p>
+                        </div>
+                    )}
+
                     {/* AWS Access Key ID */}
                     <div className="space-y-2">
                         <Label

components/reset-warning-modal.tsx

@@ -1,50 +0,0 @@
-"use client"
-
-import { Button } from "@/components/ui/button"
-import {
-    Dialog,
-    DialogContent,
-    DialogDescription,
-    DialogFooter,
-    DialogHeader,
-    DialogTitle,
-} from "@/components/ui/dialog"
-import { useDictionary } from "@/hooks/use-dictionary"
-
-interface ResetWarningModalProps {
-    open: boolean
-    onOpenChange: (open: boolean) => void
-    onClear: () => void
-}
-
-export function ResetWarningModal({
-    open,
-    onOpenChange,
-    onClear,
-}: ResetWarningModalProps) {
-    const dict = useDictionary()
-
-    return (
-        <Dialog open={open} onOpenChange={onOpenChange}>
-            <DialogContent>
-                <DialogHeader>
-                    <DialogTitle>{dict.dialogs.clearTitle}</DialogTitle>
-                    <DialogDescription>
-                        {dict.dialogs.clearDescription}
-                    </DialogDescription>
-                </DialogHeader>
-                <DialogFooter>
-                    <Button
-                        variant="outline"
-                        onClick={() => onOpenChange(false)}
-                    >
-                        {dict.common.cancel}
-                    </Button>
-                    <Button variant="destructive" onClick={onClear}>
-                        {dict.dialogs.clearEverything}
-                    </Button>
-                </DialogFooter>
-            </DialogContent>
-        </Dialog>
-    )
-}

components/save-dialog.tsx

@@ -1,6 +1,6 @@
 "use client"
 
-import { useEffect, useState } from "react"
+import { useEffect, useRef, useState } from "react"
 import { Button } from "@/components/ui/button"
 import {
     Dialog,
@@ -10,15 +10,8 @@ import {
     DialogHeader,
     DialogTitle,
 } from "@/components/ui/dialog"
-import { Input } from "@/components/ui/input"
-import {
-    Select,
-    SelectContent,
-    SelectItem,
-    SelectTrigger,
-    SelectValue,
-} from "@/components/ui/select"
 import { useDictionary } from "@/hooks/use-dictionary"
+import { cn } from "@/lib/utils"
 
 export type ExportFormat = "drawio" | "png" | "svg" | "xmlsvg"
 
@@ -39,10 +32,12 @@ export function SaveDialog({
     const [filename, setFilename] = useState(defaultFilename)
     const [format, setFormat] = useState<ExportFormat>("drawio")
 
+    // The default name each time the dialog opens; a chat title that comes
+    // while it is open (the chat is saved meanwhile) keeps what was typed
+    const wasOpenRef = useRef(false)
     useEffect(() => {
-        if (open) {
-            setFilename(defaultFilename)
-        }
+        if (open && !wasOpenRef.current) setFilename(defaultFilename)
+        wasOpenRef.current = open
     }, [open, defaultFilename])
 
     const handleSave = () => {
@@ -52,6 +47,8 @@ export function SaveDialog({
     }
 
     const handleKeyDown = (e: React.KeyboardEvent) => {
+        // Enter that picks an IME candidate (Safari: keyCode 229)
+        if (e.nativeEvent.isComposing || e.keyCode === 229) return
         if (e.key === "Enter") {
             e.preventDefault()
             handleSave()
@@ -62,21 +59,25 @@ export function SaveDialog({
         {
             value: "drawio" as const,
             label: dict.save.formats.drawio,
+            hint: dict.save.hints.drawio,
             extension: ".drawio",
         },
         {
             value: "png" as const,
             label: dict.save.formats.png,
+            hint: dict.save.hints.png,
             extension: ".png",
         },
         {
             value: "svg" as const,
             label: dict.save.formats.svg,
+            hint: dict.save.hints.svg,
             extension: ".svg",
         },
         {
             value: "xmlsvg" as const,
             label: dict.save.formats.xmlsvg,
+            hint: dict.save.hints.xmlsvg,
             extension: ".drawio.svg",
         },
     ]
@@ -85,7 +86,7 @@ export function SaveDialog({
 
     return (
         <Dialog open={open} onOpenChange={onOpenChange}>
-            <DialogContent className="sm:max-w-md">
+            <DialogContent className="sm:max-w-lg">
                 <DialogHeader>
                     <DialogTitle>{dict.save.title}</DialogTitle>
                     <DialogDescription>
@@ -93,44 +94,54 @@ export function SaveDialog({
                     </DialogDescription>
                 </DialogHeader>
                 <div className="space-y-4">
-                    <div className="space-y-2">
-                        <label className="text-sm font-medium">
-                            {dict.save.format}
-                        </label>
-                        <Select
-                            value={format}
-                            onValueChange={(v) => setFormat(v as ExportFormat)}
-                        >
-                            <SelectTrigger>
-                                <SelectValue />
-                            </SelectTrigger>
-                            <SelectContent>
-                                {FORMAT_OPTIONS.map((opt) => (
-                                    <SelectItem
-                                        key={opt.value}
-                                        value={opt.value}
-                                    >
-                                        {opt.label}
-                                    </SelectItem>
-                                ))}
-                            </SelectContent>
-                        </Select>
+                    <div
+                        role="radiogroup"
+                        aria-label={dict.save.format}
+                        className="grid grid-cols-2 gap-2"
+                    >
+                        {FORMAT_OPTIONS.map((opt) => (
+                            // biome-ignore lint/a11y/useSemanticElements: styled radio tile
+                            <button
+                                key={opt.value}
+                                type="button"
+                                role="radio"
+                                aria-checked={format === opt.value}
+                                onClick={() => setFormat(opt.value)}
+                                className={cn(
+                                    "rounded-lg border border-border p-3 text-left transition-colors hover:border-foreground/30",
+                                    format === opt.value &&
+                                        "border-foreground bg-accent",
+                                )}
+                            >
+                                <span className="block text-[13px] font-medium text-foreground">
+                                    {opt.label}
+                                </span>
+                                <span className="mt-0.5 block text-xs text-muted-foreground">
+                                    {opt.hint}
+                                </span>
+                            </button>
+                        ))}
                     </div>
                     <div className="space-y-2">
-                        <label className="text-sm font-medium">
+                        <label
+                            htmlFor="export-filename"
+                            className="text-sm font-medium"
+                        >
                             {dict.save.filename}
                         </label>
-                        <div className="flex items-stretch">
-                            <Input
+                        {/* One field: the name, then its extension */}
+                        <div className="flex h-9 items-center overflow-hidden rounded-md border border-input focus-within:ring-2 focus-within:ring-ring/40">
+                            <input
+                                id="export-filename"
                                 value={filename}
                                 onChange={(e) => setFilename(e.target.value)}
                                 onKeyDown={handleKeyDown}
                                 placeholder={dict.save.filenamePlaceholder}
                                 autoFocus
                                 onFocus={(e) => e.target.select()}
-                                className="rounded-r-none border-r-0 focus-visible:z-10"
+                                className="h-full min-w-0 flex-1 bg-transparent px-3 text-sm outline-none"
                             />
-                            <span className="inline-flex items-center px-3 rounded-r-md border border-l-0 border-input bg-muted text-sm text-muted-foreground font-mono">
+                            <span className="shrink-0 pr-3 text-sm text-muted-foreground">
                                 {currentFormat?.extension || ".drawio"}
                             </span>
                         </div>
@@ -143,7 +154,9 @@ export function SaveDialog({
                     >
                         {dict.common.cancel}
                     </Button>
-                    <Button onClick={handleSave}>{dict.common.save}</Button>
+                    <Button onClick={handleSave}>
+                        {dict.workspace.export}
+                    </Button>
                 </DialogFooter>
             </DialogContent>
         </Dialog>

components/ui/resizable.tsx

@@ -1,56 +0,0 @@
-"use client"
-
-import * as React from "react"
-import { GripVerticalIcon } from "lucide-react"
-import * as ResizablePrimitive from "react-resizable-panels"
-
-import { cn } from "@/lib/utils"
-
-function ResizablePanelGroup({
-  className,
-  ...props
-}: React.ComponentProps<typeof ResizablePrimitive.PanelGroup>) {
-  return (
-    <ResizablePrimitive.PanelGroup
-      data-slot="resizable-panel-group"
-      className={cn(
-        "flex h-full w-full data-[panel-group-direction=vertical]:flex-col",
-        className
-      )}
-      {...props}
-    />
-  )
-}
-
-function ResizablePanel({
-  ...props
-}: React.ComponentProps<typeof ResizablePrimitive.Panel>) {
-  return <ResizablePrimitive.Panel data-slot="resizable-panel" {...props} />
-}
-
-function ResizableHandle({
-  withHandle,
-  className,
-  ...props
-}: React.ComponentProps<typeof ResizablePrimitive.PanelResizeHandle> & {
-  withHandle?: boolean
-}) {
-  return (
-    <ResizablePrimitive.PanelResizeHandle
-      data-slot="resizable-handle"
-      className={cn(
-        "bg-border focus-visible:ring-ring relative flex w-px items-center justify-center after:absolute after:inset-y-0 after:left-1/2 after:w-1 after:-translate-x-1/2 focus-visible:ring-1 focus-visible:ring-offset-1 focus-visible:outline-hidden data-[panel-group-direction=vertical]:h-px data-[panel-group-direction=vertical]:w-full data-[panel-group-direction=vertical]:after:left-0 data-[panel-group-direction=vertical]:after:h-1 data-[panel-group-direction=vertical]:after:w-full data-[panel-group-direction=vertical]:after:translate-x-0 data-[panel-group-direction=vertical]:after:-translate-y-1/2 [&[data-panel-group-direction=vertical]>div]:rotate-90",
-        className
-      )}
-      {...props}
-    >
-      {withHandle && (
-        <div className="bg-border z-10 flex h-4 w-3 items-center justify-center rounded-xs border">
-          <GripVerticalIcon className="size-2.5" />
-        </div>
-      )}
-    </ResizablePrimitive.PanelResizeHandle>
-  )
-}
-
-export { ResizablePanelGroup, ResizablePanel, ResizableHandle }

components/workspace/app-toaster.tsx

@@ -0,0 +1,28 @@
+"use client"
+
+import { Toaster } from "sonner"
+import { useSettingsStore } from "@/stores/settings-store"
+
+/** The single toast container, mounted once at the root */
+export function AppToaster() {
+    const isDark = useSettingsStore((s) => s.isDark)
+    return (
+        <Toaster
+            position="bottom-center"
+            // Show stacked toasts in full, so a later one never covers the
+            // button of an earlier one (e.g. "Continue without saving")
+            expand
+            theme={isDark ? "dark" : "light"}
+            offset={{ bottom: 20 }}
+            mobileOffset={{ bottom: 72 }}
+            toastOptions={{
+                duration: 2500,
+                style: { maxWidth: "480px" },
+                classNames: {
+                    toast: "!rounded-xl !border-border !bg-card !text-foreground !shadow-pop",
+                    description: "!text-muted-foreground",
+                },
+            }}
+        />
+    )
+}

components/workspace/brand-mark.tsx

@@ -0,0 +1,29 @@
+"use client"
+
+import { getAssetUrl } from "@/lib/base-path"
+import { cn } from "@/lib/utils"
+
+/** The app icon in a rounded tile; the white variant is used in dark mode */
+export function BrandMark({ className }: { className?: string }) {
+    return (
+        <span
+            className={cn(
+                "relative inline-flex size-7 shrink-0 items-center justify-center overflow-hidden rounded-lg bg-card",
+                className,
+            )}
+        >
+            {/* biome-ignore lint/performance/noImgElement: tiny static icon */}
+            <img
+                src={getAssetUrl("/favicon-192x192.png")}
+                alt=""
+                className="size-full object-contain dark:hidden"
+            />
+            {/* biome-ignore lint/performance/noImgElement: tiny static icon */}
+            <img
+                src={getAssetUrl("/favicon-white.svg")}
+                alt=""
+                className="hidden size-5 object-contain dark:block"
+            />
+        </span>
+    )
+}

components/workspace/icon-button.tsx

@@ -0,0 +1,80 @@
+"use client"
+
+import type React from "react"
+import { forwardRef } from "react"
+import {
+    Tooltip,
+    TooltipContent,
+    TooltipTrigger,
+} from "@/components/ui/tooltip"
+import { cn } from "@/lib/utils"
+
+interface IconButtonProps extends React.ComponentProps<"button"> {
+    label: string
+    /** Shown next to the label in the tooltip, e.g. "⌘B" */
+    shortcut?: string
+    active?: boolean
+    tooltipSide?: "top" | "bottom" | "left" | "right"
+    size?: "sm" | "md"
+}
+
+/** Square icon button with a tooltip; the tooltip text is also its label */
+export const IconButton = forwardRef<HTMLButtonElement, IconButtonProps>(
+    function IconButton(
+        {
+            label,
+            shortcut,
+            active = false,
+            tooltipSide = "bottom",
+            size = "md",
+            className,
+            children,
+            ...props
+        },
+        ref,
+    ) {
+        return (
+            <Tooltip>
+                <TooltipTrigger asChild>
+                    <button
+                        ref={ref}
+                        type="button"
+                        aria-label={label}
+                        aria-pressed={active || undefined}
+                        className={cn(
+                            "inline-flex shrink-0 items-center justify-center rounded-lg text-muted-foreground transition-colors",
+                            "hover:bg-accent hover:text-foreground",
+                            "focus-visible:outline-2 focus-visible:outline-offset-1 focus-visible:outline-ring",
+                            "disabled:pointer-events-none disabled:opacity-35",
+                            "[&_svg]:size-4 [&_svg]:stroke-[1.75]",
+                            size === "md" ? "size-8" : "size-7",
+                            // A tinted tile: solid ink is for the main action
+                            active &&
+                                "bg-interactive-active text-foreground hover:bg-interactive-active [&_svg]:stroke-2",
+                            className,
+                        )}
+                        {...props}
+                    >
+                        {children}
+                    </button>
+                </TooltipTrigger>
+                <TooltipContent
+                    side={tooltipSide}
+                    className="flex items-center gap-2"
+                >
+                    {label}
+                    {shortcut && (
+                        <kbd className="font-sans text-[11px] opacity-60">
+                            {shortcut}
+                        </kbd>
+                    )}
+                </TooltipContent>
+            </Tooltip>
+        )
+    },
+)
+
+/** Thin vertical divider between toolbar groups */
+export function ToolbarDivider() {
+    return <span className="mx-1 h-5 w-px shrink-0 bg-border" aria-hidden />
+}

components/workspace/workspace.tsx

@@ -0,0 +1,403 @@
+"use client"
+
+import { MessageSquare, PanelRightOpen, Settings2, Shapes } from "lucide-react"
+import { usePathname, useRouter } from "next/navigation"
+import { useEffect, useRef, useState } from "react"
+import { CanvasStage } from "@/components/canvas/canvas-stage"
+import {
+    ChatEngineProvider,
+    useChatEngine,
+} from "@/components/chat/chat-engine"
+import { ChatPanel } from "@/components/chat/chat-panel"
+import { CompareDialog } from "@/components/chat/compare-dialog"
+import { LobbyHero } from "@/components/chat/lobby-hero"
+import { SaveDialog } from "@/components/save-dialog"
+import { SettingsDialog } from "@/components/settings-dialog"
+import { BrandMark } from "@/components/workspace/brand-mark"
+import { IconButton } from "@/components/workspace/icon-button"
+import { useDiagram } from "@/contexts/diagram-context"
+import { useDictionary } from "@/hooks/use-dictionary"
+import { usePanelWidth } from "@/hooks/use-panel-width"
+import { setAppShortcutHandler } from "@/lib/drawio/editor-bridge"
+import { i18n, type Locale } from "@/lib/i18n/config"
+import { modKey } from "@/lib/platform"
+import { STORAGE_KEYS } from "@/lib/storage"
+import { cn, isRealDiagram } from "@/lib/utils"
+import { useSettingsStore } from "@/stores/settings-store"
+import { useUiStore } from "@/stores/ui-store"
+import { useVersionsStore } from "@/stores/versions-store"
+
+/** File types the "Open .drawio file" picker accepts */
+const DIAGRAM_FILE_ACCEPT = ".drawio,.xml,.svg,application/xml,image/svg+xml"
+
+const MOBILE_BREAKPOINT = 768
+// Gap between the floating panel and the window edge
+const PANEL_GAP = 12
+
+function useIsMobile() {
+    const [isMobile, setIsMobile] = useState(false)
+    useEffect(() => {
+        const query = window.matchMedia(
+            `(max-width: ${MOBILE_BREAKPOINT - 1}px)`,
+        )
+        const update = () => setIsMobile(query.matches)
+        update()
+        query.addEventListener("change", update)
+        return () => query.removeEventListener("change", update)
+    }, [])
+    return isMobile
+}
+
+/** Restore the language picked last time (the URL may say otherwise) */
+function useSavedLocale() {
+    const router = useRouter()
+    const pathname = usePathname()
+    useEffect(() => {
+        const saved = localStorage.getItem(STORAGE_KEYS.locale)
+        if (!saved || !i18n.locales.includes(saved as Locale)) return
+        const parts = pathname.split("/").filter(Boolean)
+        if (parts[0] === saved) return
+        parts[0] = saved
+        const { search, hash } = window.location
+        router.replace(`/${parts.join("/")}${search}${hash}`)
+    }, [])
+}
+
+/** The diagram's title as a file name, or diagram-YYYY-MM-DD without one */
+export function exportFilename(title: string | null): string {
+    const name = (title && title !== "New Chat" ? title : "")
+        .replace(/[\\/:*?"<>|]+/g, "-")
+        .replace(/\s+/g, " ")
+        .trim()
+        .slice(0, 80)
+    // Local date (toISOString would give UTC)
+    return name || `diagram-${new Date().toLocaleDateString("sv-SE")}`
+}
+
+/** App name and settings button above the start screen */
+function StartBar({
+    className,
+    nameClassName,
+}: {
+    className: string
+    nameClassName: string
+}) {
+    const dict = useDictionary()
+    const openSettings = useUiStore((s) => s.openSettings)
+    return (
+        <div className={className}>
+            <BrandMark className="size-6" />
+            <span
+                className={cn(
+                    "text-[13px] font-semibold tracking-[-0.01em]",
+                    nameClassName,
+                )}
+            >
+                Next AI Draw.io
+            </span>
+            <IconButton
+                label={dict.nav.settings}
+                onClick={() => openSettings()}
+                data-testid="settings-button"
+            >
+                <Settings2 />
+            </IconButton>
+        </div>
+    )
+}
+
+/** The whole editor: canvas, chat panel, dialogs */
+export function Workspace() {
+    const hydrate = useSettingsStore((s) => s.hydrate)
+    useEffect(() => {
+        hydrate()
+    }, [hydrate])
+    useSavedLocale()
+
+    return (
+        <ChatEngineProvider>
+            <WorkspaceLayout />
+        </ChatEngineProvider>
+    )
+}
+
+function WorkspaceLayout() {
+    const dict = useDictionary()
+    const engine = useChatEngine()
+    const { chartXML, saveDiagramToFile } = useDiagram()
+    const isMobile = useIsMobile()
+    const panelWidth = usePanelWidth()
+    const {
+        panelOpen,
+        togglePanel,
+        setPanelOpen,
+        mobileView,
+        setMobileView,
+        focusComposer,
+        saveDialogOpen,
+        setSaveDialogOpen,
+    } = useUiStore()
+    const heroDismissed = useUiStore((s) => s.heroDismissed)
+    const setHeroDismissed = useUiStore((s) => s.setHeroDismissed)
+    const fileInputRef = useRef<HTMLInputElement>(null)
+
+    // Start screen: nothing said and nothing drawn yet. A new chat brings
+    // it back, an opened file or saved chat puts it away (the chat engine).
+    const showHero =
+        engine.isRestored &&
+        engine.messages.length === 0 &&
+        !engine.isResending &&
+        !isRealDiagram(chartXML) &&
+        !heroDismissed
+
+    // Phones: show the canvas while the AI draws and when a new version
+    // lands, so the result is visible; the chat tab gets a dot meanwhile
+    const isBusy = engine.isBusy
+    const versionCount = useVersionsStore((s) => s.versions.length)
+    const [chatUnread, setChatUnread] = useState(false)
+    const lastVersionCountRef = useRef(versionCount)
+    useEffect(() => {
+        if (isMobile && isBusy) setMobileView("canvas")
+    }, [isMobile, isBusy, setMobileView])
+    useEffect(() => {
+        const grew = versionCount > lastVersionCountRef.current
+        lastVersionCountRef.current = versionCount
+        if (isMobile && grew && engine.isRestored) {
+            setMobileView("canvas")
+            setChatUnread(true)
+        }
+    }, [versionCount, isMobile, engine.isRestored, setMobileView])
+    useEffect(() => {
+        if (mobileView === "chat") setChatUnread(false)
+    }, [mobileView])
+
+    // ⌘B toggles the panel; ⌘/ asks the AI about the selection
+    useEffect(() => {
+        const handle = (event: KeyboardEvent) => {
+            if (!(event.metaKey || event.ctrlKey)) return false
+            // ⌘⇧B stays with the browser (Chrome's bookmarks bar)
+            if (!event.shiftKey && (event.key === "b" || event.key === "B")) {
+                if (isMobile) return false
+                togglePanel()
+                return true
+            }
+            if (event.key === "/") {
+                setHeroDismissed(true)
+                focusComposer()
+                return true
+            }
+            return false
+        }
+        const onKeyDown = (event: KeyboardEvent) => {
+            if (handle(event)) event.preventDefault()
+        }
+        // draw.io takes focus when it (re)loads, e.g. after a language
+        // switch; Escape typed there must still close our dialogs.
+        // ⌘B stays with draw.io in the canvas (bold, and ⇧ for to back).
+        const handleInFrame = (event: KeyboardEvent) => {
+            if (event.key === "b" || event.key === "B") return false
+            if (event.key === "Escape") {
+                const ui = useUiStore.getState()
+                if (
+                    ui.settingsOpen ||
+                    ui.compareVersionId ||
+                    ui.saveDialogOpen
+                ) {
+                    ui.setSettingsOpen(false)
+                    ui.closeCompare()
+                    ui.setSaveDialogOpen(false)
+                    return true
+                }
+            }
+            return handle(event)
+        }
+        window.addEventListener("keydown", onKeyDown)
+        setAppShortcutHandler(handleInFrame)
+        return () => {
+            window.removeEventListener("keydown", onKeyDown)
+            setAppShortcutHandler(null)
+        }
+    }, [isMobile, togglePanel, focusComposer])
+
+    const openFile = () => fileInputRef.current?.click()
+    const dismissHero = () => {
+        setHeroDismissed(true)
+        setPanelOpen(true)
+    }
+
+    const panelVisible = !isMobile && !showHero && panelOpen
+    // The canvas edge slides with the panel as it opens or closes; a window
+    // resize or a dragged panel edge moves it at once. Set in the render
+    // that changes the edge, so the transition applies to that change.
+    const [sliding, setSliding] = useState(false)
+    const [lastPanelVisible, setLastPanelVisible] = useState(panelVisible)
+    if (lastPanelVisible !== panelVisible) {
+        setLastPanelVisible(panelVisible)
+        setSliding(true)
+    }
+    useEffect(() => {
+        if (!sliding) return
+        const timer = setTimeout(() => setSliding(false), 400)
+        return () => clearTimeout(timer)
+    }, [sliding])
+    // The panel floats on the right; the canvas ends where it begins
+    const canvasRight = panelVisible ? panelWidth + PANEL_GAP * 2 : 0
+
+    return (
+        <div
+            className="fixed inset-0 overflow-hidden bg-canvas"
+            data-testid="workspace"
+        >
+            {/* One canvas for both layouts: a new one would reload draw.io
+                and lose its undo history */}
+            <div className="absolute inset-0 flex flex-col">
+                <div className="relative min-h-0 flex-1">
+                    <CanvasStage
+                        className={
+                            isMobile
+                                ? cn(
+                                      "inset-0",
+                                      mobileView !== "canvas" && "invisible",
+                                  )
+                                : cn(
+                                      "inset-y-0 left-0",
+                                      sliding &&
+                                          "transition-[right] duration-300 ease-[var(--ease-out)]",
+                                  )
+                        }
+                        style={isMobile ? undefined : { right: canvasRight }}
+                        hideOverlays={!isMobile && showHero}
+                    />
+                    {isMobile ? (
+                        mobileView === "chat" &&
+                        (showHero ? (
+                            <div className="absolute inset-0 overflow-y-auto bg-canvas">
+                                <StartBar
+                                    className="flex items-center gap-2 px-4 pt-3"
+                                    nameClassName="mr-auto"
+                                />
+                                <LobbyHero
+                                    compact
+                                    onOpenFile={openFile}
+                                    onDrawYourself={() => {
+                                        setHeroDismissed(true)
+                                        setMobileView("canvas")
+                                    }}
+                                />
+                            </div>
+                        ) : (
+                            <ChatPanel mobile onOpenFile={openFile} />
+                        ))
+                    ) : (
+                        <>
+                            {panelVisible && (
+                                <ChatPanel onOpenFile={openFile} />
+                            )}
+
+                            {/* Below draw.io's toolbar (50 px), whose
+                                right-hand buttons it would cover */}
+                            {!showHero && !panelOpen && (
+                                <div className="absolute top-[60px] right-3 z-20 flex items-center gap-1 rounded-xl bg-card p-1 shadow-float animate-fade-in">
+                                    <BrandMark className="mx-0.5 size-6" />
+                                    <IconButton
+                                        label={dict.nav.showPanel}
+                                        shortcut={`${modKey}B`}
+                                        onClick={() => setPanelOpen(true)}
+                                        data-testid="show-panel"
+                                    >
+                                        <PanelRightOpen />
+                                    </IconButton>
+                                </div>
+                            )}
+
+                            {showHero && (
+                                <>
+                                    <div className="absolute inset-0 z-10 overflow-y-auto bg-canvas">
+                                        <div className="flex min-h-full items-center">
+                                            <LobbyHero
+                                                onOpenFile={openFile}
+                                                onDrawYourself={dismissHero}
+                                            />
+                                        </div>
+                                    </div>
+                                    <StartBar
+                                        className="absolute top-3 left-3 z-20 flex items-center gap-1.5 rounded-xl bg-card py-1 pr-1 pl-1.5 shadow-float"
+                                        nameClassName="pr-1"
+                                    />
+                                </>
+                            )}
+                        </>
+                    )}
+                </div>
+                {isMobile && (
+                    <nav className="flex shrink-0 items-center justify-center gap-1 border-t border-border bg-card px-3 pt-1.5 pb-[max(6px,env(safe-area-inset-bottom))]">
+                        {(
+                            [
+                                {
+                                    view: "canvas",
+                                    label: dict.workspace.mobileCanvas,
+                                    icon: <Shapes />,
+                                },
+                                {
+                                    view: "chat",
+                                    label: dict.workspace.mobileChat,
+                                    icon: <MessageSquare />,
+                                },
+                            ] as const
+                        ).map((item) => (
+                            <button
+                                key={item.view}
+                                type="button"
+                                onClick={() => setMobileView(item.view)}
+                                aria-pressed={mobileView === item.view}
+                                className={cn(
+                                    "flex h-10 flex-1 items-center justify-center gap-2 rounded-xl text-[13px] text-muted-foreground [&_svg]:size-4",
+                                    mobileView === item.view &&
+                                        "bg-accent font-medium text-foreground",
+                                )}
+                            >
+                                {item.icon}
+                                {item.label}
+                                {item.view === "chat" &&
+                                    (isBusy || chatUnread) &&
+                                    mobileView !== "chat" && (
+                                        <span className="size-1.5 rounded-full bg-marker" />
+                                    )}
+                            </button>
+                        ))}
+                    </nav>
+                )}
+            </div>
+
+            <input
+                ref={fileInputRef}
+                type="file"
+                accept={DIAGRAM_FILE_ACCEPT}
+                className="hidden"
+                onChange={(event) => {
+                    // The opened diagram hides the start screen; a file
+                    // that is not one leaves it
+                    const file = event.target.files?.[0]
+                    if (file) engine.openDiagramFile(file)
+                    event.target.value = ""
+                }}
+            />
+
+            <SettingsDialog />
+            <CompareDialog />
+            <SaveDialog
+                open={saveDialogOpen}
+                onOpenChange={setSaveDialogOpen}
+                onSave={(filename, format) =>
+                    saveDiagramToFile(
+                        filename,
+                        format,
+                        engine.langfuseSessionId,
+                        dict.save.savedSuccessfully,
+                    )
+                }
+                defaultFilename={exportFilename(engine.currentTitle)}
+            />
+        </div>
+    )
+}