chore: bump version to 0.4.1

The hasValidDiagramXml filter was deleting valid messages that had minor
XML issues. Error handling in handleDisplayChart now catches all errors,
so filtering is no longer needed - invalid XML just won't load the diagram
but the conversation is preserved.

README.md

@@ -207,7 +207,7 @@ All providers except AWS Bedrock and OpenRouter support custom endpoints.
 
 **Model Requirements**: This task requires strong model capabilities for generating long-form text with strict formatting constraints (draw.io XML). Recommended models include Claude Sonnet 4.5, GPT-5.1, Gemini 3 Pro, and DeepSeek V3.2/R1.
 
-Note that `claude` series has trained on draw.io diagrams with cloud architecture logos like AWS, Azue, GCP. So if you want to create cloud architecture diagrams, this is the best choice.
+Note that `claude` series has trained on draw.io diagrams with cloud architecture logos like AWS, Azure, GCP. So if you want to create cloud architecture diagrams, this is the best choice.
 
 
 ## How It Works

app/api/chat/route.ts

@@ -202,6 +202,9 @@ async function handleChatRequest(req: Request): Promise<Response> {
         modelId: req.headers.get("x-ai-model"),
     }
 
+    // Read minimal style preference from header
+    const minimalStyle = req.headers.get("x-minimal-style") === "true"
+
     // Get AI model with optional client overrides
     const { model, providerOptions, headers, modelId } =
         getAIModel(clientOverrides)
@@ -213,7 +216,7 @@ async function handleChatRequest(req: Request): Promise<Response> {
     )
 
     // Get the appropriate system prompt based on model (extended for Opus/Haiku 4.5)
-    const systemMessage = getSystemPrompt(modelId)
+    const systemMessage = getSystemPrompt(modelId, minimalStyle)
 
     // Extract file parts (images) from the last message
     const fileParts =
@@ -367,36 +370,32 @@ ${userInputText}
         tools: {
             // Client-side tool that will be executed on the client
             display_diagram: {
-                description: `Display a diagram on draw.io. Pass the XML content inside <root> tags.
+                description: `Display a diagram on draw.io. Pass ONLY the mxCell elements - wrapper tags and root cells are added automatically.
 
 VALIDATION RULES (XML will be rejected if violated):
-1. All mxCell elements must be DIRECT children of <root> - never nested
-2. Every mxCell needs a unique id
-3. Every mxCell (except id="0") needs a valid parent attribute
-4. Edge source/target must reference existing cell IDs
-5. Escape special chars in values: &lt; &gt; &amp; &quot;
-6. Always start with: <mxCell id="0"/><mxCell id="1" parent="0"/>
+1. Generate ONLY mxCell elements - NO wrapper tags (<mxfile>, <mxGraphModel>, <root>)
+2. Do NOT include root cells (id="0" or id="1") - they are added automatically
+3. All mxCell elements must be siblings - never nested
+4. Every mxCell needs a unique id (start from "2")
+5. Every mxCell needs a valid parent attribute (use "1" for top-level)
+6. Escape special chars in values: &lt; &gt; &amp; &quot;
 
-Example with swimlanes and edges (note: all mxCells are siblings):
-<root>
-  <mxCell id="0"/>
-  <mxCell id="1" parent="0"/>
-  <mxCell id="lane1" value="Frontend" style="swimlane;" vertex="1" parent="1">
-    <mxGeometry x="40" y="40" width="200" height="200" as="geometry"/>
-  </mxCell>
-  <mxCell id="step1" value="Step 1" style="rounded=1;" vertex="1" parent="lane1">
-    <mxGeometry x="20" y="60" width="160" height="40" as="geometry"/>
-  </mxCell>
-  <mxCell id="lane2" value="Backend" style="swimlane;" vertex="1" parent="1">
-    <mxGeometry x="280" y="40" width="200" height="200" as="geometry"/>
-  </mxCell>
-  <mxCell id="step2" value="Step 2" style="rounded=1;" vertex="1" parent="lane2">
-    <mxGeometry x="20" y="60" width="160" height="40" as="geometry"/>
-  </mxCell>
-  <mxCell id="edge1" style="edgeStyle=orthogonalEdgeStyle;endArrow=classic;" edge="1" parent="1" source="step1" target="step2">
-    <mxGeometry relative="1" as="geometry"/>
-  </mxCell>
-</root>
+Example (generate ONLY this - no wrapper tags):
+<mxCell id="lane1" value="Frontend" style="swimlane;" vertex="1" parent="1">
+  <mxGeometry x="40" y="40" width="200" height="200" as="geometry"/>
+</mxCell>
+<mxCell id="step1" value="Step 1" style="rounded=1;" vertex="1" parent="lane1">
+  <mxGeometry x="20" y="60" width="160" height="40" as="geometry"/>
+</mxCell>
+<mxCell id="lane2" value="Backend" style="swimlane;" vertex="1" parent="1">
+  <mxGeometry x="280" y="40" width="200" height="200" as="geometry"/>
+</mxCell>
+<mxCell id="step2" value="Step 2" style="rounded=1;" vertex="1" parent="lane2">
+  <mxGeometry x="20" y="60" width="160" height="40" as="geometry"/>
+</mxCell>
+<mxCell id="edge1" style="edgeStyle=orthogonalEdgeStyle;endArrow=classic;" edge="1" parent="1" source="step1" target="step2">
+  <mxGeometry relative="1" as="geometry"/>
+</mxCell>
 
 Notes:
 - For AWS diagrams, use **AWS 2025 icons**.
@@ -444,9 +443,9 @@ IMPORTANT: Keep edits concise:
 WHEN TO USE: Only call this tool after display_diagram was truncated (you'll see an error message about truncation).
 
 CRITICAL INSTRUCTIONS:
-1. Do NOT start with <mxGraphModel>, <root>, or <mxCell id="0"> - they already exist in the partial
+1. Do NOT include any wrapper tags - just continue the mxCell elements
 2. Continue from EXACTLY where your previous output stopped
-3. End with the closing </root> tag to complete the diagram
+3. Complete the remaining mxCell elements
 4. If still truncated, call append_diagram again with the next fragment
 
 Example: If previous output ended with '<mxCell id="x" style="rounded=1', continue with ';" vertex="1">...' and complete the remaining elements.`,

app/api/chat/xml_guide.md

@@ -81,16 +81,15 @@ Contains the actual diagram data.
 
 ## Root Cell Container: `<root>`
 
-Contains all the cells in the diagram.
+Contains all the cells in the diagram. **Note:** When generating diagrams, you only need to provide the mxCell elements - the root container and root cells (id="0", id="1") are added automatically.
 
-**Example:**
+**Internal structure (auto-generated):**
 
 ```xml
 <root>
-<mxCell id="0"/>
-<mxCell id="1" parent="0"/>
-
-  <!-- Other cells go here -->
+  <mxCell id="0"/>           <!-- Auto-added -->
+  <mxCell id="1" parent="0"/> <!-- Auto-added -->
+  <!-- Your mxCell elements go here (start from id="2") -->
 </root>
 ```
 
@@ -203,15 +202,15 @@ Draw.io files contain two special cells that are always present:
 1.  **Root Cell** (id = "0"): The parent of all cells
 2.  **Default Parent Cell** (id = "1", parent = "0"): The default layer and parent for most cells
 
-## Tips for Manually Creating Draw.io XML
+## Tips for Creating Draw.io XML
 
-1.  Start with the basic structure (`mxfile`, `diagram`, `mxGraphModel`, `root`)
-2.  Always include the two special cells (id = "0" and id = "1")
+1.  **Generate ONLY mxCell elements** - wrapper tags and root cells (id="0", id="1") are added automatically
+2.  Start IDs from "2" (id="0" and id="1" are reserved for root cells)
 3.  Assign unique and sequential IDs to all cells
-4.  Define parent relationships correctly
+4.  Define parent relationships correctly (use parent="1" for top-level shapes)
 5.  Use `mxGeometry` elements to position shapes
 6.  For connectors, specify `source` and `target` attributes
-7.  **CRITICAL: All mxCell elements must be DIRECT children of `<root>`. NEVER nest mxCell inside another mxCell.**
+7.  **CRITICAL: All mxCell elements must be siblings. NEVER nest mxCell inside another mxCell.**
 
 ## Common Patterns
 

components/chat-input.tsx

@@ -17,7 +17,13 @@ import { HistoryDialog } from "@/components/history-dialog"
 import { ResetWarningModal } from "@/components/reset-warning-modal"
 import { SaveDialog } from "@/components/save-dialog"
 import { Button } from "@/components/ui/button"
+import { Switch } from "@/components/ui/switch"
 import { Textarea } from "@/components/ui/textarea"
+import {
+    Tooltip,
+    TooltipContent,
+    TooltipTrigger,
+} from "@/components/ui/tooltip"
 import { useDiagram } from "@/contexts/diagram-context"
 import { isPdfFile, isTextFile } from "@/lib/pdf-utils"
 import { FilePreviewList } from "./file-preview-list"
@@ -129,6 +135,8 @@ interface ChatInputProps {
     onToggleHistory?: (show: boolean) => void
     sessionId?: string
     error?: Error | null
+    minimalStyle?: boolean
+    onMinimalStyleChange?: (value: boolean) => void
 }
 
 export function ChatInput({
@@ -144,6 +152,8 @@ export function ChatInput({
     onToggleHistory = () => {},
     sessionId,
     error = null,
+    minimalStyle = false,
+    onMinimalStyleChange = () => {},
 }: ChatInputProps) {
     const { diagramHistory, saveDiagramToFile } = useDiagram()
     const textareaRef = useRef<HTMLTextAreaElement>(null)
@@ -343,6 +353,32 @@ export function ChatInput({
                             showHistory={showHistory}
                             onToggleHistory={onToggleHistory}
                         />
+
+                        <Tooltip>
+                            <TooltipTrigger asChild>
+                                <div className="flex items-center gap-1.5">
+                                    <Switch
+                                        id="minimal-style"
+                                        checked={minimalStyle}
+                                        onCheckedChange={onMinimalStyleChange}
+                                        className="scale-75"
+                                    />
+                                    <label
+                                        htmlFor="minimal-style"
+                                        className={`text-xs cursor-pointer select-none ${
+                                            minimalStyle
+                                                ? "text-primary font-medium"
+                                                : "text-muted-foreground"
+                                        }`}
+                                    >
+                                        {minimalStyle ? "Minimal" : "Styled"}
+                                    </label>
+                                </div>
+                            </TooltipTrigger>
+                            <TooltipContent side="top">
+                                Use minimal for faster generation (no colors)
+                            </TooltipContent>
+                        </Tooltip>
                     </div>
 
                     {/* Right actions */}

components/chat-message-display.tsx

@@ -29,7 +29,12 @@ import {
     ReasoningTrigger,
 } from "@/components/ai-elements/reasoning"
 import { ScrollArea } from "@/components/ui/scroll-area"
-import { convertToLegalXml, replaceNodes, validateAndFixXml } from "@/lib/utils"
+import {
+    convertToLegalXml,
+    isMxCellXmlComplete,
+    replaceNodes,
+    validateAndFixXml,
+} from "@/lib/utils"
 import ExamplePanel from "./chat-example-panel"
 import { CodeBlock } from "./code-block"
 
@@ -188,6 +193,14 @@ export function ChatMessageDisplay({
     const messagesEndRef = useRef<HTMLDivElement>(null)
     const previousXML = useRef<string>("")
     const processedToolCalls = processedToolCallsRef
+    // Track the last processed XML per toolCallId to skip redundant processing during streaming
+    const lastProcessedXmlRef = useRef<Map<string, string>>(new Map())
+    // Debounce streaming diagram updates - store pending XML and timeout
+    const pendingXmlRef = useRef<string | null>(null)
+    const debounceTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(
+        null,
+    )
+    const STREAMING_DEBOUNCE_MS = 150 // Only update diagram every 150ms during streaming
     const [expandedTools, setExpandedTools] = useState<Record<string, boolean>>(
         {},
     )
@@ -279,24 +292,31 @@ export function ChatMessageDisplay({
 
     const handleDisplayChart = useCallback(
         (xml: string, showToast = false) => {
+            console.time("perf:handleDisplayChart")
             const currentXml = xml || ""
             const convertedXml = convertToLegalXml(currentXml)
             if (convertedXml !== previousXML.current) {
                 // Parse and validate XML BEFORE calling replaceNodes
+                console.time("perf:DOMParser")
                 const parser = new DOMParser()
                 const testDoc = parser.parseFromString(convertedXml, "text/xml")
+                console.timeEnd("perf:DOMParser")
                 const parseError = testDoc.querySelector("parsererror")
 
                 if (parseError) {
-                    console.error(
-                        "[ChatMessageDisplay] Malformed XML detected - skipping update",
-                    )
-                    // Only show toast if this is the final XML (not during streaming)
+                    // Use console.warn instead of console.error to avoid triggering
+                    // Next.js dev mode error overlay for expected streaming states
+                    // (partial XML during streaming is normal and will be fixed by subsequent updates)
                     if (showToast) {
+                        // Only log as error and show toast if this is the final XML
+                        console.error(
+                            "[ChatMessageDisplay] Malformed XML detected in final output",
+                        )
                         toast.error(
                             "AI generated invalid diagram XML. Please try regenerating.",
                         )
                     }
+                    console.timeEnd("perf:handleDisplayChart")
                     return // Skip this update
                 }
 
@@ -306,10 +326,14 @@ export function ChatMessageDisplay({
                     const baseXML =
                         chartXML ||
                         `<mxfile><diagram name="Page-1" id="page-1"><mxGraphModel><root><mxCell id="0"/><mxCell id="1" parent="0"/></root></mxGraphModel></diagram></mxfile>`
+                    console.time("perf:replaceNodes")
                     const replacedXML = replaceNodes(baseXML, convertedXml)
+                    console.timeEnd("perf:replaceNodes")
 
                     // Validate and auto-fix the XML
+                    console.time("perf:validateAndFixXml")
                     const validation = validateAndFixXml(replacedXML)
+                    console.timeEnd("perf:validateAndFixXml")
                     if (validation.valid) {
                         previousXML.current = convertedXml
                         // Use fixed XML if available, otherwise use original
@@ -346,6 +370,9 @@ export function ChatMessageDisplay({
                         )
                     }
                 }
+                console.timeEnd("perf:handleDisplayChart")
+            } else {
+                console.timeEnd("perf:handleDisplayChart")
             }
         },
         [chartXML, onDisplayChart],
@@ -364,7 +391,17 @@ export function ChatMessageDisplay({
     }, [editingMessageId])
 
     useEffect(() => {
-        messages.forEach((message) => {
+        console.time("perf:message-display-useEffect")
+        let processedCount = 0
+        let skippedCount = 0
+        let debouncedCount = 0
+
+        // Only process the last message for streaming performance
+        // Previous messages are already processed and won't change
+        const messagesToProcess =
+            messages.length > 0 ? [messages[messages.length - 1]] : []
+
+        messagesToProcess.forEach((message) => {
             if (message.parts) {
                 message.parts.forEach((part) => {
                     if (part.type?.startsWith("tool-")) {
@@ -383,25 +420,82 @@ export function ChatMessageDisplay({
                             input?.xml
                         ) {
                             const xml = input.xml as string
+
+                            // Skip if XML hasn't changed since last processing
+                            const lastXml =
+                                lastProcessedXmlRef.current.get(toolCallId)
+                            if (lastXml === xml) {
+                                skippedCount++
+                                return // Skip redundant processing
+                            }
+
                             if (
                                 state === "input-streaming" ||
                                 state === "input-available"
                             ) {
-                                // During streaming, don't show toast (XML may be incomplete)
-                                handleDisplayChart(xml, false)
+                                // Debounce streaming updates - queue the XML and process after delay
+                                pendingXmlRef.current = xml
+
+                                if (!debounceTimeoutRef.current) {
+                                    // No pending timeout - set one up
+                                    debounceTimeoutRef.current = setTimeout(
+                                        () => {
+                                            const pendingXml =
+                                                pendingXmlRef.current
+                                            debounceTimeoutRef.current = null
+                                            pendingXmlRef.current = null
+                                            if (pendingXml) {
+                                                console.log(
+                                                    "perf:debounced-handleDisplayChart executing",
+                                                )
+                                                handleDisplayChart(
+                                                    pendingXml,
+                                                    false,
+                                                )
+                                                lastProcessedXmlRef.current.set(
+                                                    toolCallId,
+                                                    pendingXml,
+                                                )
+                                            }
+                                        },
+                                        STREAMING_DEBOUNCE_MS,
+                                    )
+                                }
+                                debouncedCount++
                             } else if (
                                 state === "output-available" &&
                                 !processedToolCalls.current.has(toolCallId)
                             ) {
+                                // Final output - process immediately (clear any pending debounce)
+                                if (debounceTimeoutRef.current) {
+                                    clearTimeout(debounceTimeoutRef.current)
+                                    debounceTimeoutRef.current = null
+                                    pendingXmlRef.current = null
+                                }
                                 // Show toast only if final XML is malformed
                                 handleDisplayChart(xml, true)
                                 processedToolCalls.current.add(toolCallId)
+                                // Clean up the ref entry - tool is complete, no longer needed
+                                lastProcessedXmlRef.current.delete(toolCallId)
+                                processedCount++
                             }
                         }
                     }
                 })
             }
         })
+        console.log(
+            `perf:message-display-useEffect processed=${processedCount} skipped=${skippedCount} debounced=${debouncedCount}`,
+        )
+        console.timeEnd("perf:message-display-useEffect")
+
+        // Cleanup: clear any pending debounce timeout on unmount
+        return () => {
+            if (debounceTimeoutRef.current) {
+                clearTimeout(debounceTimeoutRef.current)
+                debounceTimeoutRef.current = null
+            }
+        }
     }, [messages, handleDisplayChart])
 
     const renderToolPart = (part: ToolPartLike) => {
@@ -457,8 +551,7 @@ export function ChatMessageDisplay({
                                 const isTruncated =
                                     (toolName === "display_diagram" ||
                                         toolName === "append_diagram") &&
-                                    (!input?.xml ||
-                                        !input.xml.includes("</root>"))
+                                    !isMxCellXmlComplete(input?.xml)
                                 return isTruncated ? (
                                     <span className="text-xs font-medium text-yellow-600 bg-yellow-50 px-2 py-0.5 rounded-full">
                                         Truncated
@@ -507,7 +600,7 @@ export function ChatMessageDisplay({
                         const isTruncated =
                             (toolName === "display_diagram" ||
                                 toolName === "append_diagram") &&
-                            (!input?.xml || !input.xml.includes("</root>"))
+                            !isMxCellXmlComplete(input?.xml)
                         return (
                             <div
                                 className={`px-4 py-3 border-t border-border/40 text-sm ${isTruncated ? "text-yellow-600" : "text-red-600"}`}

components/chat-panel.tsx

@@ -26,7 +26,7 @@ import { findCachedResponse } from "@/lib/cached-responses"
 import { isPdfFile, isTextFile } from "@/lib/pdf-utils"
 import { type FileData, useFileProcessor } from "@/lib/use-file-processor"
 import { useQuotaManager } from "@/lib/use-quota-manager"
-import { formatXML, wrapWithMxFile } from "@/lib/utils"
+import { formatXML, isMxCellXmlComplete, wrapWithMxFile } from "@/lib/utils"
 import { ChatMessageDisplay } from "./chat-message-display"
 
 // localStorage keys for persistence
@@ -40,6 +40,7 @@ interface MessagePart {
     type: string
     state?: string
     toolName?: string
+    input?: { xml?: string; [key: string]: unknown }
     [key: string]: unknown
 }
 
@@ -145,6 +146,7 @@ export default function ChatPanel({
     const [dailyTokenLimit, setDailyTokenLimit] = useState(0)
     const [tpmLimit, setTpmLimit] = useState(0)
     const [showNewChatDialog, setShowNewChatDialog] = useState(false)
+    const [minimalStyle, setMinimalStyle] = useState(false)
 
     // Check config on mount
     useEffect(() => {
@@ -200,6 +202,15 @@ export default function ChatPanel({
     // Persist processed tool call IDs so collapsing the chat doesn't replay old tool outputs
     const processedToolCallsRef = useRef<Set<string>>(new Set())
 
+    // Debounce timeout for localStorage writes (prevents blocking during streaming)
+    const localStorageDebounceRef = useRef<ReturnType<
+        typeof setTimeout
+    > | null>(null)
+    const xmlStorageDebounceRef = useRef<ReturnType<typeof setTimeout> | null>(
+        null,
+    )
+    const LOCAL_STORAGE_DEBOUNCE_MS = 1000 // Save at most once per second
+
     const {
         messages,
         sendMessage,
@@ -222,9 +233,16 @@ export default function ChatPanel({
             if (toolCall.toolName === "display_diagram") {
                 const { xml } = toolCall.input as { xml: string }
 
-                // Check if XML is truncated (missing </root> indicates incomplete output)
-                const isTruncated =
-                    !xml.includes("</root>") && !xml.trim().endsWith("/>")
+                // DEBUG: Log raw input to diagnose false truncation detection
+                console.log(
+                    "[display_diagram] XML ending (last 100 chars):",
+                    xml.slice(-100),
+                )
+                console.log("[display_diagram] XML length:", xml.length)
+
+                // Check if XML is truncated (incomplete mxCell indicates truncated output)
+                const isTruncated = !isMxCellXmlComplete(xml)
+                console.log("[display_diagram] isTruncated:", isTruncated)
 
                 if (isTruncated) {
                     // Store the partial XML for continuation via append_diagram
@@ -244,9 +262,9 @@ ${partialEnding}
 \`\`\`
 
 NEXT STEP: Call append_diagram with the continuation XML.
-- Do NOT start with <mxGraphModel>, <root>, or <mxCell id="0"> (they already exist)
+- Do NOT include wrapper tags or root cells (id="0", id="1")
 - Start from EXACTLY where you stopped
-- End with the closing </root> tag to complete the diagram`,
+- Complete all remaining mxCell elements`,
                     })
                     return
                 }
@@ -376,17 +394,21 @@ Please retry with an adjusted search pattern or use display_diagram if retries a
                 const { xml } = toolCall.input as { xml: string }
 
                 // Detect if LLM incorrectly started fresh instead of continuing
+                // LLM should only output bare mxCells now, so wrapper tags indicate error
+                const trimmed = xml.trim()
                 const isFreshStart =
-                    xml.trim().startsWith("<mxGraphModel") ||
-                    xml.trim().startsWith("<root") ||
-                    xml.trim().startsWith('<mxCell id="0"')
+                    trimmed.startsWith("<mxGraphModel") ||
+                    trimmed.startsWith("<root") ||
+                    trimmed.startsWith("<mxfile") ||
+                    trimmed.startsWith('<mxCell id="0"') ||
+                    trimmed.startsWith('<mxCell id="1"')
 
                 if (isFreshStart) {
                     addToolOutput({
                         tool: "append_diagram",
                         toolCallId: toolCall.toolCallId,
                         state: "output-error",
-                        errorText: `ERROR: You started fresh with wrapper tags. Do NOT include <mxGraphModel>, <root>, or <mxCell id="0">.
+                        errorText: `ERROR: You started fresh with wrapper tags. Do NOT include wrapper tags or root cells (id="0", id="1").
 
 Continue from EXACTLY where the partial ended:
 \`\`\`
@@ -401,8 +423,8 @@ Start your continuation with the NEXT character after where it stopped.`,
                 // Append to accumulated XML
                 partialXmlRef.current += xml
 
-                // Check if XML is now complete
-                const isComplete = partialXmlRef.current.includes("</root>")
+                // Check if XML is now complete (last mxCell is complete)
+                const isComplete = isMxCellXmlComplete(partialXmlRef.current)
 
                 if (isComplete) {
                     // Wrap and display the complete diagram
@@ -439,7 +461,7 @@ Please use display_diagram with corrected XML.`,
                         tool: "append_diagram",
                         toolCallId: toolCall.toolCallId,
                         state: "output-error",
-                        errorText: `XML still incomplete (missing </root>). Call append_diagram again to continue.
+                        errorText: `XML still incomplete (mxCell not closed). Call append_diagram again to continue.
 
 Current ending:
 \`\`\`
@@ -501,6 +523,10 @@ Continue from EXACTLY where you stopped.`,
                 | Record<string, unknown>
                 | undefined
 
+            // DEBUG: Log finish reason to diagnose truncation
+            console.log("[onFinish] finishReason:", metadata?.finishReason)
+            console.log("[onFinish] metadata:", metadata)
+
             if (metadata) {
                 // Use Number.isFinite to guard against NaN (typeof NaN === 'number' is true)
                 const inputTokens = Number.isFinite(metadata.inputTokens)
@@ -606,6 +632,10 @@ Continue from EXACTLY where you stopped.`,
             }
         } catch (error) {
             console.error("Failed to restore from localStorage:", error)
+            // On complete failure, clear storage to allow recovery
+            localStorage.removeItem(STORAGE_MESSAGES_KEY)
+            localStorage.removeItem(STORAGE_XML_SNAPSHOTS_KEY)
+            toast.error("Session data was corrupted. Starting fresh.")
         }
     }, [setMessages])
 
@@ -650,32 +680,71 @@ Continue from EXACTLY where you stopped.`,
         }, 500)
     }, [isDrawioReady, onDisplayChart])
 
-    // Save messages to localStorage whenever they change
+    // Save messages to localStorage whenever they change (debounced to prevent blocking during streaming)
     useEffect(() => {
         if (!hasRestoredRef.current) return
-        try {
-            localStorage.setItem(STORAGE_MESSAGES_KEY, JSON.stringify(messages))
-        } catch (error) {
-            console.error("Failed to save messages to localStorage:", error)
+
+        // Clear any pending save
+        if (localStorageDebounceRef.current) {
+            clearTimeout(localStorageDebounceRef.current)
+        }
+
+        // Debounce: save after 1 second of no changes
+        localStorageDebounceRef.current = setTimeout(() => {
+            try {
+                console.time("perf:localStorage-messages")
+                localStorage.setItem(
+                    STORAGE_MESSAGES_KEY,
+                    JSON.stringify(messages),
+                )
+                console.timeEnd("perf:localStorage-messages")
+            } catch (error) {
+                console.error("Failed to save messages to localStorage:", error)
+            }
+        }, LOCAL_STORAGE_DEBOUNCE_MS)
+
+        // Cleanup on unmount
+        return () => {
+            if (localStorageDebounceRef.current) {
+                clearTimeout(localStorageDebounceRef.current)
+            }
         }
     }, [messages])
 
-    // Save diagram XML to localStorage whenever it changes
+    // Save diagram XML to localStorage whenever it changes (debounced)
     useEffect(() => {
         if (!canSaveDiagram) return
-        if (chartXML && chartXML.length > 300) {
+        if (!chartXML || chartXML.length <= 300) return
+
+        // Clear any pending save
+        if (xmlStorageDebounceRef.current) {
+            clearTimeout(xmlStorageDebounceRef.current)
+        }
+
+        // Debounce: save after 1 second of no changes
+        xmlStorageDebounceRef.current = setTimeout(() => {
+            console.time("perf:localStorage-xml")
             localStorage.setItem(STORAGE_DIAGRAM_XML_KEY, chartXML)
+            console.timeEnd("perf:localStorage-xml")
+        }, LOCAL_STORAGE_DEBOUNCE_MS)
+
+        return () => {
+            if (xmlStorageDebounceRef.current) {
+                clearTimeout(xmlStorageDebounceRef.current)
+            }
         }
     }, [chartXML, canSaveDiagram])
 
     // Save XML snapshots to localStorage whenever they change
     const saveXmlSnapshots = useCallback(() => {
         try {
+            console.time("perf:localStorage-snapshots")
             const snapshotsArray = Array.from(xmlSnapshotsRef.current.entries())
             localStorage.setItem(
                 STORAGE_XML_SNAPSHOTS_KEY,
                 JSON.stringify(snapshotsArray),
             )
+            console.timeEnd("perf:localStorage-snapshots")
         } catch (error) {
             console.error(
                 "Failed to save XML snapshots to localStorage:",
@@ -932,6 +1001,9 @@ Continue from EXACTLY where you stopped.`,
                         }),
                         ...(config.aiModel && { "x-ai-model": config.aiModel }),
                     }),
+                    ...(minimalStyle && {
+                        "x-minimal-style": "true",
+                    }),
                 },
             },
         )
@@ -1117,6 +1189,7 @@ Continue from EXACTLY where you stopped.`,
                     style: {
                         maxWidth: "480px",
                     },
+                    duration: 2000,
                 }}
             />
             {/* Header */}
@@ -1246,6 +1319,8 @@ Continue from EXACTLY where you stopped.`,
                     onToggleHistory={setShowHistory}
                     sessionId={sessionId}
                     error={error}
+                    minimalStyle={minimalStyle}
+                    onMinimalStyleChange={setMinimalStyle}
                 />
             </footer>
 

contexts/diagram-context.tsx

@@ -86,16 +86,20 @@ export function DiagramProvider({ children }: { children: React.ReactNode }) {
         chart: string,
         skipValidation?: boolean,
     ): string | null => {
+        console.time("perf:loadDiagram")
         let xmlToLoad = chart
 
         // Validate XML structure before loading (unless skipped for internal use)
         if (!skipValidation) {
+            console.time("perf:loadDiagram-validation")
             const validation = validateAndFixXml(chart)
+            console.timeEnd("perf:loadDiagram-validation")
             if (!validation.valid) {
                 console.warn(
                     "[loadDiagram] Validation error:",
                     validation.error,
                 )
+                console.timeEnd("perf:loadDiagram")
                 return validation.error
             }
             // Use fixed XML if auto-fix was applied
@@ -112,11 +116,14 @@ export function DiagramProvider({ children }: { children: React.ReactNode }) {
         setChartXML(xmlToLoad)
 
         if (drawioRef.current) {
+            console.time("perf:drawio-iframe-load")
             drawioRef.current.load({
                 xml: xmlToLoad,
             })
+            console.timeEnd("perf:drawio-iframe-load")
         }
 
+        console.timeEnd("perf:loadDiagram")
         return null
     }
 
@@ -138,14 +145,20 @@ export function DiagramProvider({ children }: { children: React.ReactNode }) {
         setLatestSvg(data.data)
 
         // Only add to history if this was a user-initiated export
+        // Limit to 20 entries to prevent memory leaks during long sessions
+        const MAX_HISTORY_SIZE = 20
         if (expectHistoryExportRef.current) {
-            setDiagramHistory((prev) => [
-                ...prev,
-                {
-                    svg: data.data,
-                    xml: extractedXML,
-                },
-            ])
+            setDiagramHistory((prev) => {
+                const newHistory = [
+                    ...prev,
+                    {
+                        svg: data.data,
+                        xml: extractedXML,
+                    },
+                ]
+                // Keep only the last MAX_HISTORY_SIZE entries (circular buffer)
+                return newHistory.slice(-MAX_HISTORY_SIZE)
+            })
             expectHistoryExportRef.current = false
         }
 

lib/cached-responses.ts

@@ -9,12 +9,7 @@ export const CACHED_EXAMPLE_RESPONSES: CachedResponse[] = [
         promptText:
             "Give me a **animated connector** diagram of transformer's architecture",
         hasImage: false,
-        xml: `<root>
-  <mxCell id="0"/>
-  <mxCell id="1" parent="0"/>
-
-
-  <mxCell id="title" value="Transformer Architecture" style="text;html=1;strokeColor=none;fillColor=none;align=center;verticalAlign=middle;whiteSpace=wrap;rounded=0;fontSize=20;fontStyle=1;" vertex="1" parent="1">
+        xml: `<mxCell id="title" value="Transformer Architecture" style="text;html=1;strokeColor=none;fillColor=none;align=center;verticalAlign=middle;whiteSpace=wrap;rounded=0;fontSize=20;fontStyle=1;" vertex="1" parent="1">
     <mxGeometry x="300" y="20" width="250" height="30" as="geometry"/>
   </mxCell>
 
@@ -254,18 +249,12 @@ export const CACHED_EXAMPLE_RESPONSES: CachedResponse[] = [
 
   <mxCell id="output_label" value="Outputs&#xa;(shifted right)" style="text;html=1;strokeColor=none;fillColor=none;align=center;verticalAlign=middle;whiteSpace=wrap;rounded=0;fontSize=12;fontStyle=1;" vertex="1" parent="1">
     <mxGeometry x="660" y="530" width="100" height="30" as="geometry"/>
-  </mxCell>
-</root>`,
+  </mxCell>`,
     },
     {
         promptText: "Replicate this in aws style",
         hasImage: true,
-        xml: `<root>
-  <mxCell id="0"/>
-  <mxCell id="1" parent="0"/>
-
-
-  <mxCell id="2" value="AWS" style="sketch=0;outlineConnect=0;gradientColor=none;html=1;whiteSpace=wrap;fontSize=12;fontStyle=0;container=1;pointerEvents=0;collapsible=0;recursiveResize=0;shape=mxgraph.aws4.group;grIcon=mxgraph.aws4.group_aws_cloud;strokeColor=#232F3E;fillColor=none;verticalAlign=top;align=left;spacingLeft=30;fontColor=#232F3E;dashed=0;rounded=1;arcSize=5;" vertex="1" parent="1">
+        xml: `<mxCell id="2" value="AWS" style="sketch=0;outlineConnect=0;gradientColor=none;html=1;whiteSpace=wrap;fontSize=12;fontStyle=0;container=1;pointerEvents=0;collapsible=0;recursiveResize=0;shape=mxgraph.aws4.group;grIcon=mxgraph.aws4.group_aws_cloud;strokeColor=#232F3E;fillColor=none;verticalAlign=top;align=left;spacingLeft=30;fontColor=#232F3E;dashed=0;rounded=1;arcSize=5;" vertex="1" parent="1">
     <mxGeometry x="340" y="40" width="880" height="520" as="geometry"/>
   </mxCell>
 
@@ -324,18 +313,12 @@ export const CACHED_EXAMPLE_RESPONSES: CachedResponse[] = [
       <mxPoint x="700" y="350" as="sourcePoint"/>
       <mxPoint x="750" y="300" as="targetPoint"/>
     </mxGeometry>
-  </mxCell>
-</root>`,
+  </mxCell>`,
     },
     {
         promptText: "Replicate this flowchart.",
         hasImage: true,
-        xml: `<root>
-  <mxCell id="0"/>
-  <mxCell id="1" parent="0"/>
-
-
-  <mxCell id="2" value="Lamp doesn't work" style="rounded=1;whiteSpace=wrap;html=1;fillColor=#ffcccc;strokeColor=#000000;strokeWidth=2;fontSize=18;fontStyle=0;" vertex="1" parent="1">
+        xml: `<mxCell id="2" value="Lamp doesn't work" style="rounded=1;whiteSpace=wrap;html=1;fillColor=#ffcccc;strokeColor=#000000;strokeWidth=2;fontSize=18;fontStyle=0;" vertex="1" parent="1">
     <mxGeometry x="140" y="40" width="180" height="60" as="geometry"/>
   </mxCell>
 
@@ -391,16 +374,12 @@ export const CACHED_EXAMPLE_RESPONSES: CachedResponse[] = [
 
   <mxCell id="12" value="Repair lamp" style="rounded=1;whiteSpace=wrap;html=1;fillColor=#99ff99;strokeColor=#000000;strokeWidth=2;fontSize=18;fontStyle=0;" vertex="1" parent="1">
     <mxGeometry x="130" y="650" width="200" height="60" as="geometry"/>
-  </mxCell>
-</root>`,
+  </mxCell>`,
     },
     {
         promptText: "Summarize this paper as a diagram",
         hasImage: true,
-        xml: `            <root>
-                <mxCell id="0" />
-                <mxCell id="1" parent="0" />
-                <mxCell id="title_bg" parent="1"
+        xml: `<mxCell id="title_bg" parent="1"
                     style="rounded=1;whiteSpace=wrap;html=1;fillColor=#1a237e;strokeColor=none;arcSize=8;"
                     value="" vertex="1">
                     <mxGeometry height="80" width="720" x="40" y="20" as="geometry" />
@@ -751,18 +730,12 @@ export const CACHED_EXAMPLE_RESPONSES: CachedResponse[] = [
                     value="Foundational technique for modern LLM reasoning - inspired many follow-up works including Self-Consistency, Tree-of-Thought, etc."
                     vertex="1">
                     <mxGeometry height="55" width="230" x="530" y="600" as="geometry" />
-                </mxCell>
-            </root>`,
+                </mxCell>`,
     },
     {
         promptText: "Draw a cat for me",
         hasImage: false,
-        xml: `<root>
-  <mxCell id="0"/>
-  <mxCell id="1" parent="0"/>
-
-
-  <mxCell id="2" value="" style="ellipse;whiteSpace=wrap;html=1;aspect=fixed;fillColor=#FFE6CC;strokeColor=#000000;strokeWidth=2;" vertex="1" parent="1">
+        xml: `<mxCell id="2" value="" style="ellipse;whiteSpace=wrap;html=1;aspect=fixed;fillColor=#FFE6CC;strokeColor=#000000;strokeWidth=2;" vertex="1" parent="1">
     <mxGeometry x="300" y="150" width="120" height="120" as="geometry"/>
   </mxCell>
 
@@ -902,9 +875,7 @@ export const CACHED_EXAMPLE_RESPONSES: CachedResponse[] = [
         <mxPoint x="235" y="290"/>
       </Array>
     </mxGeometry>
-  </mxCell>
-
-</root>`,
+  </mxCell>`,
     },
 ]
 

lib/system-prompts.ts

@@ -104,22 +104,21 @@ When using edit_diagram tool:
 
 ## Draw.io XML Structure Reference
 
-Basic structure:
+**IMPORTANT:** You only generate the mxCell elements. The wrapper structure and root cells (id="0", id="1") are added automatically.
+
+Example - generate ONLY this:
 \`\`\`xml
-<mxGraphModel>
-  <root>
-    <mxCell id="0"/>
-    <mxCell id="1" parent="0"/>
-  </root>
-</mxGraphModel>
+<mxCell id="2" value="Label" style="rounded=1;" vertex="1" parent="1">
+  <mxGeometry x="100" y="100" width="120" height="60" as="geometry"/>
+</mxCell>
 \`\`\`
-Note: All other mxCell elements go as siblings after id="1".
 
 CRITICAL RULES:
-1. Always include the two root cells: <mxCell id="0"/> and <mxCell id="1" parent="0"/>
-2. ALL mxCell elements must be DIRECT children of <root> - NEVER nest mxCell inside another mxCell
-3. Use unique sequential IDs for all cells (start from "2" for user content)
-4. Set parent="1" for top-level shapes, or parent="<container-id>" for grouped elements
+1. Generate ONLY mxCell elements - NO wrapper tags (<mxfile>, <mxGraphModel>, <root>)
+2. Do NOT include root cells (id="0" or id="1") - they are added automatically
+3. ALL mxCell elements must be siblings - NEVER nest mxCell inside another mxCell
+4. Use unique sequential IDs starting from "2"
+5. Set parent="1" for top-level shapes, or parent="<container-id>" for grouped elements
 
 Shape (vertex) example:
 \`\`\`xml
@@ -133,12 +132,90 @@ Connector (edge) example:
 <mxCell id="3" style="endArrow=classic;html=1;" edge="1" parent="1" source="2" target="4">
   <mxGeometry relative="1" as="geometry"/>
 </mxCell>
+
+### Edge Routing Rules:
+When creating edges/connectors, you MUST follow these rules to avoid overlapping lines:
+
+**Rule 1: NEVER let multiple edges share the same path**
+- If two edges connect the same pair of nodes, they MUST exit/enter at DIFFERENT positions
+- Use exitY=0.3 for first edge, exitY=0.7 for second edge (NOT both 0.5)
+
+**Rule 2: For bidirectional connections (A↔B), use OPPOSITE sides**
+- A→B: exit from RIGHT side of A (exitX=1), enter LEFT side of B (entryX=0)
+- B→A: exit from LEFT side of B (exitX=0), enter RIGHT side of A (entryX=1)
+
+**Rule 3: Always specify exitX, exitY, entryX, entryY explicitly**
+- Every edge MUST have these 4 attributes set in the style
+- Example: style="edgeStyle=orthogonalEdgeStyle;exitX=1;exitY=0.3;entryX=0;entryY=0.3;endArrow=classic;"
+
+**Rule 4: Route edges AROUND intermediate shapes (obstacle avoidance) - CRITICAL!**
+- Before creating an edge, identify ALL shapes positioned between source and target
+- If any shape is in the direct path, you MUST use waypoints to route around it
+- For DIAGONAL connections: route along the PERIMETER (outside edge) of the diagram, NOT through the middle
+- Add 20-30px clearance from shape boundaries when calculating waypoint positions
+- Route ABOVE (lower y), BELOW (higher y), or to the SIDE of obstacles
+- NEVER draw a line that visually crosses over another shape's bounding box
+
+**Rule 5: Plan layout strategically BEFORE generating XML**
+- Organize shapes into visual layers/zones (columns or rows) based on diagram flow
+- Space shapes 150-200px apart to create clear routing channels for edges
+- Mentally trace each edge: "What shapes are between source and target?"
+- Prefer layouts where edges naturally flow in one direction (left-to-right or top-to-bottom)
+
+**Rule 6: Use multiple waypoints for complex routing**
+- One waypoint is often not enough - use 2-3 waypoints to create proper L-shaped or U-shaped paths
+- Each direction change needs a waypoint (corner point)
+- Waypoints should form clear horizontal/vertical segments (orthogonal routing)
+- Calculate positions by: (1) identify obstacle boundaries, (2) add 20-30px margin
+
+**Rule 7: Choose NATURAL connection points based on flow direction**
+- NEVER use corner connections (e.g., entryX=1,entryY=1) - they look unnatural
+- For TOP-TO-BOTTOM flow: exit from bottom (exitY=1), enter from top (entryY=0)
+- For LEFT-TO-RIGHT flow: exit from right (exitX=1), enter from left (entryX=0)
+- For DIAGONAL connections: use the side closest to the target, not corners
+- Example: Node below-right of source → exit from bottom (exitY=1) OR right (exitX=1), not corner
+
+**Before generating XML, mentally verify:**
+1. "Do any edges cross over shapes that aren't their source/target?" → If yes, add waypoints
+2. "Do any two edges share the same path?" → If yes, adjust exit/entry points
+3. "Are any connection points at corners (both X and Y are 0 or 1)?" → If yes, use edge centers instead
+4. "Could I rearrange shapes to reduce edge crossings?" → If yes, revise layout
+
+
 \`\`\`
 
+`
+
+// Style instructions - only included when minimalStyle is false
+const STYLE_INSTRUCTIONS = `
 Common styles:
 - Shapes: rounded=1 (rounded corners), fillColor=#hex, strokeColor=#hex
 - Edges: endArrow=classic/block/open/none, startArrow=none/classic, curved=1, edgeStyle=orthogonalEdgeStyle
 - Text: fontSize=14, fontStyle=1 (bold), align=center/left/right
+`
+
+// Minimal style instruction - skip styling and focus on layout (prepended to prompt for emphasis)
+const MINIMAL_STYLE_INSTRUCTION = `
+## ⚠️ MINIMAL STYLE MODE ACTIVE ⚠️
+
+### No Styling - Plain Black/White Only
+- NO fillColor, NO strokeColor, NO rounded, NO fontSize, NO fontStyle
+- NO color attributes (no hex colors like #ff69b4)
+- Style: "whiteSpace=wrap;html=1;" for shapes, "html=1;endArrow=classic;" for edges
+- IGNORE all color/style examples below
+
+### Container/Group Shapes - MUST be Transparent
+- For container shapes (boxes that contain other shapes): use "fillColor=none;" to make background transparent
+- This prevents containers from covering child elements
+- Example: style="whiteSpace=wrap;html=1;fillColor=none;" for container rectangles
+
+### Focus on Layout Quality
+Since we skip styling, STRICTLY follow the "Edge Routing Rules" section below:
+- SPACING: Minimum 50px gap between all elements
+- NO OVERLAPS: Elements and edges must never overlap
+- Follow ALL 7 Edge Routing Rules for arrow positioning
+- Use waypoints to route edges AROUND obstacles
+- Use different exitY/entryY values for multiple edges between same nodes
 
 `
 
@@ -151,34 +228,30 @@ const EXTENDED_ADDITIONS = `
 ### display_diagram Details
 
 **VALIDATION RULES** (XML will be rejected if violated):
-1. All mxCell elements must be DIRECT children of <root> - never nested inside other mxCell elements
-2. Every mxCell needs a unique id attribute
-3. Every mxCell (except id="0") needs a valid parent attribute referencing an existing cell
-4. Edge source/target attributes must reference existing cell IDs
-5. Escape special characters in values: &lt; for <, &gt; for >, &amp; for &, &quot; for "
-6. Always start with the two root cells: <mxCell id="0"/><mxCell id="1" parent="0"/>
+1. Generate ONLY mxCell elements - wrapper tags and root cells are added automatically
+2. All mxCell elements must be siblings - never nested inside other mxCell elements
+3. Every mxCell needs a unique id attribute (start from "2")
+4. Every mxCell needs a valid parent attribute (use "1" for top-level, or container-id for grouped)
+5. Edge source/target attributes must reference existing cell IDs
+6. Escape special characters in values: &lt; for <, &gt; for >, &amp; for &, &quot; for "
 
-**Example with swimlanes and edges** (note: all mxCells are siblings under <root>):
+**Example with swimlanes and edges** (generate ONLY this - no wrapper tags):
 \`\`\`xml
-<root>
-  <mxCell id="0"/>
-  <mxCell id="1" parent="0"/>
-  <mxCell id="lane1" value="Frontend" style="swimlane;" vertex="1" parent="1">
-    <mxGeometry x="40" y="40" width="200" height="200" as="geometry"/>
-  </mxCell>
-  <mxCell id="step1" value="Step 1" style="rounded=1;" vertex="1" parent="lane1">
-    <mxGeometry x="20" y="60" width="160" height="40" as="geometry"/>
-  </mxCell>
-  <mxCell id="lane2" value="Backend" style="swimlane;" vertex="1" parent="1">
-    <mxGeometry x="280" y="40" width="200" height="200" as="geometry"/>
-  </mxCell>
-  <mxCell id="step2" value="Step 2" style="rounded=1;" vertex="1" parent="lane2">
-    <mxGeometry x="20" y="60" width="160" height="40" as="geometry"/>
-  </mxCell>
-  <mxCell id="edge1" style="edgeStyle=orthogonalEdgeStyle;endArrow=classic;" edge="1" parent="1" source="step1" target="step2">
-    <mxGeometry relative="1" as="geometry"/>
-  </mxCell>
-</root>
+<mxCell id="lane1" value="Frontend" style="swimlane;" vertex="1" parent="1">
+  <mxGeometry x="40" y="40" width="200" height="200" as="geometry"/>
+</mxCell>
+<mxCell id="step1" value="Step 1" style="rounded=1;" vertex="1" parent="lane1">
+  <mxGeometry x="20" y="60" width="160" height="40" as="geometry"/>
+</mxCell>
+<mxCell id="lane2" value="Backend" style="swimlane;" vertex="1" parent="1">
+  <mxGeometry x="280" y="40" width="200" height="200" as="geometry"/>
+</mxCell>
+<mxCell id="step2" value="Step 2" style="rounded=1;" vertex="1" parent="lane2">
+  <mxGeometry x="20" y="60" width="160" height="40" as="geometry"/>
+</mxCell>
+<mxCell id="edge1" style="edgeStyle=orthogonalEdgeStyle;endArrow=classic;" edge="1" parent="1" source="step1" target="step2">
+  <mxGeometry relative="1" as="geometry"/>
+</mxCell>
 \`\`\`
 
 ### append_diagram Details
@@ -186,9 +259,9 @@ const EXTENDED_ADDITIONS = `
 **WHEN TO USE:** Only call this tool when display_diagram output was truncated (you'll see an error message about truncation).
 
 **CRITICAL RULES:**
-1. Do NOT start with <mxGraphModel>, <root>, or <mxCell id="0"> - they already exist in the partial
+1. Do NOT include any wrapper tags - just continue the mxCell elements
 2. Continue from EXACTLY where your previous output stopped
-3. End with the closing </root> tag to complete the diagram
+3. Complete the remaining mxCell elements
 4. If still truncated, call append_diagram again with the next fragment
 
 **Example:** If previous output ended with \`<mxCell id="x" style="rounded=1\`, continue with \`;" vertex="1">...\` and complete the remaining elements.
@@ -262,53 +335,6 @@ If edit_diagram fails with "pattern not found":
 
 
 
-### Edge Routing Rules:
-When creating edges/connectors, you MUST follow these rules to avoid overlapping lines:
-
-**Rule 1: NEVER let multiple edges share the same path**
-- If two edges connect the same pair of nodes, they MUST exit/enter at DIFFERENT positions
-- Use exitY=0.3 for first edge, exitY=0.7 for second edge (NOT both 0.5)
-
-**Rule 2: For bidirectional connections (A↔B), use OPPOSITE sides**
-- A→B: exit from RIGHT side of A (exitX=1), enter LEFT side of B (entryX=0)
-- B→A: exit from LEFT side of B (exitX=0), enter RIGHT side of A (entryX=1)
-
-**Rule 3: Always specify exitX, exitY, entryX, entryY explicitly**
-- Every edge MUST have these 4 attributes set in the style
-- Example: style="edgeStyle=orthogonalEdgeStyle;exitX=1;exitY=0.3;entryX=0;entryY=0.3;endArrow=classic;"
-
-**Rule 4: Route edges AROUND intermediate shapes (obstacle avoidance) - CRITICAL!**
-- Before creating an edge, identify ALL shapes positioned between source and target
-- If any shape is in the direct path, you MUST use waypoints to route around it
-- For DIAGONAL connections: route along the PERIMETER (outside edge) of the diagram, NOT through the middle
-- Add 20-30px clearance from shape boundaries when calculating waypoint positions
-- Route ABOVE (lower y), BELOW (higher y), or to the SIDE of obstacles
-- NEVER draw a line that visually crosses over another shape's bounding box
-
-**Rule 5: Plan layout strategically BEFORE generating XML**
-- Organize shapes into visual layers/zones (columns or rows) based on diagram flow
-- Space shapes 150-200px apart to create clear routing channels for edges
-- Mentally trace each edge: "What shapes are between source and target?"
-- Prefer layouts where edges naturally flow in one direction (left-to-right or top-to-bottom)
-
-**Rule 6: Use multiple waypoints for complex routing**
-- One waypoint is often not enough - use 2-3 waypoints to create proper L-shaped or U-shaped paths
-- Each direction change needs a waypoint (corner point)
-- Waypoints should form clear horizontal/vertical segments (orthogonal routing)
-- Calculate positions by: (1) identify obstacle boundaries, (2) add 20-30px margin
-
-**Rule 7: Choose NATURAL connection points based on flow direction**
-- NEVER use corner connections (e.g., entryX=1,entryY=1) - they look unnatural
-- For TOP-TO-BOTTOM flow: exit from bottom (exitY=1), enter from top (entryY=0)
-- For LEFT-TO-RIGHT flow: exit from right (exitX=1), enter from left (entryX=0)
-- For DIAGONAL connections: use the side closest to the target, not corners
-- Example: Node below-right of source → exit from bottom (exitY=1) OR right (exitX=1), not corner
-
-**Before generating XML, mentally verify:**
-1. "Do any edges cross over shapes that aren't their source/target?" → If yes, add waypoints
-2. "Do any two edges share the same path?" → If yes, adjust exit/entry points
-3. "Are any connection points at corners (both X and Y are 0 or 1)?" → If yes, use edge centers instead
-4. "Could I rearrange shapes to reduce edge crossings?" → If yes, revise layout
 
 ## Edge Examples
 
@@ -362,12 +388,16 @@ const EXTENDED_PROMPT_MODEL_PATTERNS = [
 ]
 
 /**
- * Get the appropriate system prompt based on the model ID
+ * Get the appropriate system prompt based on the model ID and style preference
  * Uses extended prompt for Opus 4.5 and Haiku 4.5 which have 4000 token cache minimum
  * @param modelId - The AI model ID from environment
+ * @param minimalStyle - If true, removes style instructions to save tokens
  * @returns The system prompt string
  */
-export function getSystemPrompt(modelId?: string): string {
+export function getSystemPrompt(
+    modelId?: string,
+    minimalStyle?: boolean,
+): string {
     const modelName = modelId || "AI"
 
     let prompt: string
@@ -388,5 +418,15 @@ export function getSystemPrompt(modelId?: string): string {
         prompt = DEFAULT_SYSTEM_PROMPT
     }
 
+    // Add style instructions based on preference
+    // Minimal style: prepend instruction at START (more prominent)
+    // Normal style: append at end
+    if (minimalStyle) {
+        console.log(`[System Prompt] Minimal style mode ENABLED`)
+        prompt = MINIMAL_STYLE_INSTRUCTION + prompt
+    } else {
+        prompt += STYLE_INSTRUCTIONS
+    }
+
     return prompt.replace("{{MODEL_NAME}}", modelName)
 }

lib/utils.ts

@@ -29,6 +29,38 @@ const STRUCTURAL_ATTRS = [
 /** Valid XML entity names */
 const VALID_ENTITIES = new Set(["lt", "gt", "amp", "quot", "apos"])
 
+// ============================================================================
+// mxCell XML Helpers
+// ============================================================================
+
+/**
+ * Check if mxCell XML output is complete (not truncated).
+ * Complete XML ends with a self-closing tag (/>) or closing mxCell tag.
+ * Also handles function-calling wrapper tags that may be incorrectly included.
+ * @param xml - The XML string to check (can be undefined/null)
+ * @returns true if XML appears complete, false if truncated or empty
+ */
+export function isMxCellXmlComplete(xml: string | undefined | null): boolean {
+    let trimmed = xml?.trim() || ""
+    if (!trimmed) return false
+
+    // Strip Anthropic function-calling wrapper tags if present
+    // These can leak into tool input due to AI SDK parsing issues
+    // Use loop because tags are nested: </mxCell></mxParameter></invoke>
+    let prev = ""
+    while (prev !== trimmed) {
+        prev = trimmed
+        trimmed = trimmed
+            .replace(/<\/mxParameter>\s*$/i, "")
+            .replace(/<\/invoke>\s*$/i, "")
+            .replace(/<\/antml:parameter>\s*$/i, "")
+            .replace(/<\/antml:invoke>\s*$/i, "")
+            .trim()
+    }
+
+    return trimmed.endsWith("/>") || trimmed.endsWith("</mxCell>")
+}
+
 // ============================================================================
 // XML Parsing Helpers
 // ============================================================================
@@ -182,6 +214,13 @@ export function convertToLegalXml(xmlString: string): string {
             )
         }
 
+        // Fix unescaped & characters in attribute values (but not valid entities)
+        // This prevents DOMParser from failing on content like "semantic & missing-step"
+        cellContent = cellContent.replace(
+            /&(?!(?:lt|gt|amp|quot|apos|#[0-9]+|#x[0-9a-fA-F]+);)/g,
+            "&amp;",
+        )
+
         // Indent each line of the matched block for readability.
         const formatted = cellContent
             .split("\n")
@@ -197,13 +236,17 @@ export function convertToLegalXml(xmlString: string): string {
 
 /**
  * Wrap XML content with the full mxfile structure required by draw.io.
- * Handles cases where XML is just <root>, <mxGraphModel>, or already has <mxfile>.
- * @param xml - The XML string (may be partial or complete)
- * @returns Full mxfile-wrapped XML string
+ * Always adds root cells (id="0" and id="1") automatically.
+ * If input already contains root cells, they are removed to avoid duplication.
+ * LLM should only generate mxCell elements starting from id="2".
+ * @param xml - The XML string (bare mxCells, <root>, <mxGraphModel>, or full <mxfile>)
+ * @returns Full mxfile-wrapped XML string with root cells included
  */
 export function wrapWithMxFile(xml: string): string {
-    if (!xml) {
-        return `<mxfile><diagram name="Page-1" id="page-1"><mxGraphModel><root><mxCell id="0"/><mxCell id="1" parent="0"/></root></mxGraphModel></diagram></mxfile>`
+    const ROOT_CELLS = '<mxCell id="0"/><mxCell id="1" parent="0"/>'
+
+    if (!xml || !xml.trim()) {
+        return `<mxfile><diagram name="Page-1" id="page-1"><mxGraphModel><root>${ROOT_CELLS}</root></mxGraphModel></diagram></mxfile>`
     }
 
     // Already has full structure
@@ -216,9 +259,20 @@ export function wrapWithMxFile(xml: string): string {
         return `<mxfile><diagram name="Page-1" id="page-1">${xml}</diagram></mxfile>`
     }
 
-    // Just <root> content - extract inner content and wrap fully
-    const rootContent = xml.replace(/<\/?root>/g, "").trim()
-    return `<mxfile><diagram name="Page-1" id="page-1"><mxGraphModel><root>${rootContent}</root></mxGraphModel></diagram></mxfile>`
+    // Has <root> wrapper - extract inner content
+    let content = xml
+    if (xml.includes("<root>")) {
+        content = xml.replace(/<\/?root>/g, "").trim()
+    }
+
+    // Remove any existing root cells from content (LLM shouldn't include them, but handle it gracefully)
+    // Use flexible patterns that match both self-closing (/>) and non-self-closing (></mxCell>) formats
+    content = content
+        .replace(/<mxCell[^>]*\bid=["']0["'][^>]*(?:\/>|><\/mxCell>)/g, "")
+        .replace(/<mxCell[^>]*\bid=["']1["'][^>]*(?:\/>|><\/mxCell>)/g, "")
+        .trim()
+
+    return `<mxfile><diagram name="Page-1" id="page-1"><mxGraphModel><root>${ROOT_CELLS}${content}</root></mxGraphModel></diagram></mxfile>`
 }
 
 /**
@@ -769,6 +823,8 @@ function checkNestedMxCells(xml: string): string | null {
  * @returns null if valid, error message string if invalid
  */
 export function validateMxCellStructure(xml: string): string | null {
+    console.time("perf:validateMxCellStructure")
+    console.log(`perf:validateMxCellStructure XML size: ${xml.length} bytes`)
     // Size check for performance
     if (xml.length > MAX_XML_SIZE) {
         console.warn(
@@ -778,10 +834,18 @@ export function validateMxCellStructure(xml: string): string | null {
 
     // 0. First use DOM parser to catch syntax errors (most accurate)
     try {
+        console.time("perf:validate-DOMParser")
         const parser = new DOMParser()
         const doc = parser.parseFromString(xml, "text/xml")
+        console.timeEnd("perf:validate-DOMParser")
         const parseError = doc.querySelector("parsererror")
         if (parseError) {
+            const actualError = parseError.textContent || "Unknown parse error"
+            console.log(
+                "[validateMxCellStructure] DOMParser error:",
+                actualError,
+            )
+            console.timeEnd("perf:validateMxCellStructure")
             return `Invalid XML: The XML contains syntax errors (likely unescaped special characters like <, >, & in attribute values). Please escape special characters: use &lt; for <, &gt; for >, &amp; for &, &quot; for ". Regenerate the diagram with properly escaped values.`
         }
 
@@ -790,6 +854,7 @@ export function validateMxCellStructure(xml: string): string | null {
         for (const cell of allCells) {
             if (cell.parentElement?.tagName === "mxCell") {
                 const id = cell.getAttribute("id") || "unknown"
+                console.timeEnd("perf:validateMxCellStructure")
                 return `Invalid XML: Found nested mxCell (id="${id}"). Cells should be siblings, not nested inside other mxCell elements.`
             }
         }
@@ -803,12 +868,18 @@ export function validateMxCellStructure(xml: string): string | null {
 
     // 1. Check for CDATA wrapper (invalid at document root)
     if (/^\s*<!\[CDATA\[/.test(xml)) {
+        console.timeEnd("perf:validateMxCellStructure")
         return "Invalid XML: XML is wrapped in CDATA section - remove <![CDATA[ from start and ]]> from end"
     }
 
     // 2. Check for duplicate structural attributes
+    console.time("perf:checkDuplicateAttributes")
     const dupAttrError = checkDuplicateAttributes(xml)
-    if (dupAttrError) return dupAttrError
+    console.timeEnd("perf:checkDuplicateAttributes")
+    if (dupAttrError) {
+        console.timeEnd("perf:validateMxCellStructure")
+        return dupAttrError
+    }
 
     // 3. Check for unescaped < in attribute values
     const attrValuePattern = /=\s*"([^"]*)"/g
@@ -816,44 +887,67 @@ export function validateMxCellStructure(xml: string): string | null {
     while ((attrValMatch = attrValuePattern.exec(xml)) !== null) {
         const value = attrValMatch[1]
         if (/</.test(value) && !/&lt;/.test(value)) {
+            console.timeEnd("perf:validateMxCellStructure")
             return "Invalid XML: Unescaped < character in attribute values. Replace < with &lt;"
         }
     }
 
     // 4. Check for duplicate IDs
+    console.time("perf:checkDuplicateIds")
     const dupIdError = checkDuplicateIds(xml)
-    if (dupIdError) return dupIdError
+    console.timeEnd("perf:checkDuplicateIds")
+    if (dupIdError) {
+        console.timeEnd("perf:validateMxCellStructure")
+        return dupIdError
+    }
 
     // 5. Check for tag mismatches
+    console.time("perf:checkTagMismatches")
     const tagMismatchError = checkTagMismatches(xml)
-    if (tagMismatchError) return tagMismatchError
+    console.timeEnd("perf:checkTagMismatches")
+    if (tagMismatchError) {
+        console.timeEnd("perf:validateMxCellStructure")
+        return tagMismatchError
+    }
 
     // 6. Check invalid character references
     const charRefError = checkCharacterReferences(xml)
-    if (charRefError) return charRefError
+    if (charRefError) {
+        console.timeEnd("perf:validateMxCellStructure")
+        return charRefError
+    }
 
     // 7. Check for invalid comment syntax (-- inside comments)
     const commentPattern = /<!--([\s\S]*?)-->/g
     let commentMatch
     while ((commentMatch = commentPattern.exec(xml)) !== null) {
         if (/--/.test(commentMatch[1])) {
+            console.timeEnd("perf:validateMxCellStructure")
             return "Invalid XML: Comment contains -- (double hyphen) which is not allowed"
         }
     }
 
     // 8. Check for unescaped entity references and invalid entity names
     const entityError = checkEntityReferences(xml)
-    if (entityError) return entityError
+    if (entityError) {
+        console.timeEnd("perf:validateMxCellStructure")
+        return entityError
+    }
 
     // 9. Check for empty id attributes on mxCell
     if (/<mxCell[^>]*\sid\s*=\s*["']\s*["'][^>]*>/g.test(xml)) {
+        console.timeEnd("perf:validateMxCellStructure")
         return "Invalid XML: Found mxCell element(s) with empty id attribute"
     }
 
     // 10. Check for nested mxCell tags
     const nestedCellError = checkNestedMxCells(xml)
-    if (nestedCellError) return nestedCellError
+    if (nestedCellError) {
+        console.timeEnd("perf:validateMxCellStructure")
+        return nestedCellError
+    }
 
+    console.timeEnd("perf:validateMxCellStructure")
     return null
 }
 
@@ -1057,12 +1151,56 @@ export function autoFixXml(xml: string): { fixed: string; fixes: string[] } {
     // This handles both opening and closing tags
     const hasCellTags = /<\/?Cell[\s>]/i.test(fixed)
     if (hasCellTags) {
+        console.log("[autoFixXml] Step 8: Found <Cell> tags to fix")
+        const beforeFix = fixed
         fixed = fixed.replace(/<Cell(\s)/gi, "<mxCell$1")
         fixed = fixed.replace(/<Cell>/gi, "<mxCell>")
         fixed = fixed.replace(/<\/Cell>/gi, "</mxCell>")
+        if (beforeFix !== fixed) {
+            console.log("[autoFixXml] Step 8: Fixed <Cell> tags")
+        }
         fixes.push("Fixed <Cell> tags to <mxCell>")
     }
 
+    // 8b. Remove non-draw.io tags (LLM sometimes includes Claude's function calling XML)
+    // Valid draw.io tags: mxfile, diagram, mxGraphModel, root, mxCell, mxGeometry, mxPoint, Array, Object
+    const validDrawioTags = new Set([
+        "mxfile",
+        "diagram",
+        "mxGraphModel",
+        "root",
+        "mxCell",
+        "mxGeometry",
+        "mxPoint",
+        "Array",
+        "Object",
+        "mxRectangle",
+    ])
+    const foreignTagPattern = /<\/?([a-zA-Z][a-zA-Z0-9_]*)[^>]*>/g
+    let foreignMatch
+    const foreignTags = new Set<string>()
+    while ((foreignMatch = foreignTagPattern.exec(fixed)) !== null) {
+        const tagName = foreignMatch[1]
+        if (!validDrawioTags.has(tagName)) {
+            foreignTags.add(tagName)
+        }
+    }
+    if (foreignTags.size > 0) {
+        console.log(
+            "[autoFixXml] Step 8b: Found foreign tags:",
+            Array.from(foreignTags),
+        )
+        for (const tag of foreignTags) {
+            // Remove opening tags (with or without attributes)
+            fixed = fixed.replace(new RegExp(`<${tag}[^>]*>`, "gi"), "")
+            // Remove closing tags
+            fixed = fixed.replace(new RegExp(`</${tag}>`, "gi"), "")
+        }
+        fixes.push(
+            `Removed foreign tags: ${Array.from(foreignTags).join(", ")}`,
+        )
+    }
+
     // 9. Fix common closing tag typos
     const tagTypos = [
         { wrong: /<\/mxElement>/gi, right: "</mxCell>", name: "</mxElement>" },
@@ -1128,6 +1266,98 @@ export function autoFixXml(xml: string): { fixed: string; fixes: string[] } {
         }
     }
 
+    // 10b. Remove extra closing tags (more closes than opens)
+    // Need to properly count self-closing tags (they don't need closing tags)
+    const tagCounts = new Map<
+        string,
+        { opens: number; closes: number; selfClosing: number }
+    >()
+    // Match full tags to detect self-closing by checking if ends with />
+    const fullTagPattern = /<(\/?[a-zA-Z][a-zA-Z0-9]*)[^>]*>/g
+    let tagCountMatch
+    while ((tagCountMatch = fullTagPattern.exec(fixed)) !== null) {
+        const fullMatch = tagCountMatch[0] // e.g., "<mxCell .../>" or "</mxCell>"
+        const tagPart = tagCountMatch[1] // e.g., "mxCell" or "/mxCell"
+        const isClosing = tagPart.startsWith("/")
+        const isSelfClosing = fullMatch.endsWith("/>")
+        const tagName = isClosing ? tagPart.slice(1) : tagPart
+
+        let counts = tagCounts.get(tagName)
+        if (!counts) {
+            counts = { opens: 0, closes: 0, selfClosing: 0 }
+            tagCounts.set(tagName, counts)
+        }
+        if (isClosing) {
+            counts.closes++
+        } else if (isSelfClosing) {
+            counts.selfClosing++
+        } else {
+            counts.opens++
+        }
+    }
+
+    // Log tag counts for debugging
+    for (const [tagName, counts] of tagCounts) {
+        if (
+            tagName === "mxCell" ||
+            tagName === "mxGeometry" ||
+            counts.opens !== counts.closes
+        ) {
+            console.log(
+                `[autoFixXml] Step 10b: ${tagName} - opens: ${counts.opens}, closes: ${counts.closes}, selfClosing: ${counts.selfClosing}`,
+            )
+        }
+    }
+
+    // Find tags with extra closing tags (self-closing tags are balanced, don't need closing)
+    for (const [tagName, counts] of tagCounts) {
+        const extraCloses = counts.closes - counts.opens // Only compare opens vs closes (self-closing are balanced)
+        if (extraCloses > 0) {
+            console.log(
+                `[autoFixXml] Step 10b: ${tagName} has ${counts.opens} opens, ${counts.closes} closes, removing ${extraCloses} extra`,
+            )
+            // Remove extra closing tags from the end
+            let removed = 0
+            const closeTagPattern = new RegExp(`</${tagName}>`, "g")
+            const matches = [...fixed.matchAll(closeTagPattern)]
+            // Remove from the end (last occurrences are likely the extras)
+            for (
+                let i = matches.length - 1;
+                i >= 0 && removed < extraCloses;
+                i--
+            ) {
+                const match = matches[i]
+                const idx = match.index ?? 0
+                fixed = fixed.slice(0, idx) + fixed.slice(idx + match[0].length)
+                removed++
+            }
+            if (removed > 0) {
+                console.log(
+                    `[autoFixXml] Step 10b: Removed ${removed} extra </${tagName}>`,
+                )
+                fixes.push(
+                    `Removed ${removed} extra </${tagName}> closing tag(s)`,
+                )
+            }
+        }
+    }
+
+    // 10c. Remove trailing garbage after last XML tag (e.g., stray backslashes, text)
+    // Find the last valid closing tag or self-closing tag
+    const closingTagPattern = /<\/[a-zA-Z][a-zA-Z0-9]*>|\/>/g
+    let lastValidTagEnd = -1
+    let closingMatch
+    while ((closingMatch = closingTagPattern.exec(fixed)) !== null) {
+        lastValidTagEnd = closingMatch.index + closingMatch[0].length
+    }
+    if (lastValidTagEnd > 0 && lastValidTagEnd < fixed.length) {
+        const trailing = fixed.slice(lastValidTagEnd).trim()
+        if (trailing) {
+            fixed = fixed.slice(0, lastValidTagEnd)
+            fixes.push("Removed trailing garbage after last XML tag")
+        }
+    }
+
     // 11. Fix nested mxCell by flattening
     // Pattern A: <mxCell id="X">...<mxCell id="X">...</mxCell></mxCell> (duplicate ID)
     // Pattern B: <mxCell id="X">...<mxCell id="Y">...</mxCell></mxCell> (different ID - true nesting)
@@ -1337,16 +1567,26 @@ export function validateAndFixXml(xml: string): {
 
     // Try to fix
     const { fixed, fixes } = autoFixXml(xml)
+    console.log("[validateAndFixXml] Fixes applied:", fixes)
 
     // Validate the fixed version
     error = validateMxCellStructure(fixed)
+    if (error) {
+        console.log("[validateAndFixXml] Still invalid after fix:", error)
+    }
 
     if (!error) {
         return { valid: true, error: null, fixed, fixes }
     }
 
-    // Still invalid after fixes
-    return { valid: false, error, fixed: null, fixes }
+    // Still invalid after fixes - but return the partially fixed XML
+    // so we can see what was fixed and what error remains
+    return {
+        valid: false,
+        error,
+        fixed: fixes.length > 0 ? fixed : null,
+        fixes,
+    }
 }
 
 export function extractDiagramXML(xml_svg_string: string): string {

package.json

@@ -1,6 +1,6 @@
 {
     "name": "next-ai-draw-io",
-    "version": "0.4.0",
+    "version": "0.4.1",
     "license": "Apache-2.0",
     "private": true,
     "scripts": {