## Problem
Two audits of the repository (a workflow of finder, dedup and per-file verifier agents, run on 2026-10-11 against 1f4141e and again against 07f3e3c after a first round of refactoring) found dead code and features that were more machinery than the app needs: an Electron configuration-preset system with its own settings window, three copies of the about page, a hand-written `.env` parser, an "extended" system prompt nobody selected, two data migrations for formats from 2025-12 and 2026-01, a server-side example cache, type-to-confirm provider deletion, 81 unused dictionary keys, wrapper components around single call sites, and a long tail of unused exports, props, options and tests.
## Change
Every item below was either approved one by one or covered by "fix all of the others".
- **Electron:** the configuration-preset system is gone (settings window, preload, IPC, menu entry, dev watcher); `config-manager.ts` keeps only `userLocale`; `.env` files are parsed with `dotenv`. Entitlements file and a duplicate CI workflow removed; `test.yml` gets a type check and concurrency.
- **Server:** no extended prompt, no example cache, no `ENABLE_HISTORY_XML_REPLACE`, no message metadata or `hasConfig`; the connection test is one shared helper; EdgeOne loses its mock branch and model aliases; `DEBUG_LLM_PAYLOAD` logs message structure instead of payloads; Langfuse scoring helper; `apiKeyEnv` arrays kept and documented in `env.example` and the provider docs.
- **Pages:** one about page per language from a single component (old `/cn` and `/ja` URLs redirect with 308); layout uses `hasLocale`; the GitHub icon is a local component instead of `react-icons`; Cloudflare deploys without an R2 cache by default.
- **Chat and canvas:** the legacy `diagramHistory` conversion, the localStorage chat migration and the templates storage are gone; `chat-engine` reads the diagram through the context's refs; the diagram context has one tagged export path (`requestTaggedExport` / `fetchDiagramXml`); the screenshot check uses fetch + JSON and `generateText` with `Output.object`; `load-diagram` accepts `<svg:svg>` and strips the XML prolog.
- **Settings UI:** `model-selector` inlines its Dialog, Command and Tooltip; `ai-elements/model-selector`, `button-with-tooltip`, `error-toast` removed; no type-to-confirm, no footer, no `bedrockApiKey`; `use-model-config` loses the old-format migration; one reasoning component; the shimmer is CSS (no `motion`, no `@radix-ui/react-use-controllable-state`); 81 dictionary keys removed in all four languages.
- **MCP server:** `registerTool` / `ok` / `fail` replace per-tool try/catch; `syncFromBrowser`, `commitDocument`, `describePages`; the hand-written XML syntax check, unused result fields, `pickPageSelector`, `expandStyles` and the `host` attribute handling are gone; tests get a shared `setup.ts` and drive the server through the SDK client.
- **Prompt:** the web app's style rules come from the MCP drawing guide (`styleRules`), byte-identical to before.
- **Tests:** shared e2e helpers (`openApp`, `sse`, `toolCallEvents`, `chunkedReplies`); placeholder specs dropped; `settings-review-fixes` split by topic; unit tests use `vi.stubEnv`.
- **Dependencies removed:** `@xmldom/xmldom`, `remark-gfm`, `@anthropic-ai/tokenizer`, `@testing-library/user-event`, `concurrently`, `wait-on`, `eslint`, `eslint-config-next`, `@vitest/coverage-v8`, `shx`, `motion`, `@radix-ui/react-use-controllable-state`, `react-icons`.
Source lines: 74,983 before, 67,418 after (excluding lockfiles).
The last commit merges #984 (the canvas shell). Where the shell, the classic page or their tests depend on a wire format or signature this branch had changed, main's version wins (export fields of the poll response, `addHistory` signature); where main only extended code this branch restructured, main's change is carried into the new structure (`start_session`, `get_selection`, `prepareNewDiagram`, the diagram context's `requestExport`).
## Testing
- `tsc --noEmit` for the web app, `packages/mcp-server`, its shell and `electron`: clean
- `biome ci`: 0 errors (37 pre-existing warnings)
- Root `vitest run`: 719 passed; `packages/mcp-server` `vitest run`: 372 passed
- `next build`: clean
- Playwright, whole web suite on the dev server (4 workers): 280 tests, 279 passed; `language.spec.ts` "a stale offer to switch without saving does nothing once a message is being sent" failed under parallel load and passed alone, as it does on main
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.
* Modernize Input Field Scrollbar Design #536
* Added Input Field Scrollbar Design #536
* The edit mode for the user scroller already looks good, so there’s no need to change it. The scrollbar-thin class only makes the scrollbar smaller compared to when it’s not present, so it isn’t needed.
---------
Co-authored-by: Biki Kalita <[email protected]>
* feat(session): add chat session history with IndexedDB storage
- Add session-storage.ts with IndexedDB wrapper using idb library
- Add use-session-manager.ts hook for session state management
- Add session-history-dropdown.tsx for session selection UI
- Integrate session system into chat-panel.tsx
- Auto-generate session titles from first user message
- Auto-save sessions on message completion
- Support session switching, deletion, and creation
- Migrate existing localStorage data to IndexedDB
- Add i18n translations for session history UI
* feat(session): improve history dropdown and persist diagram history
- Add time-based grouping (Today, Yesterday, This Week, Earlier)
- Add thumbnail previews using Next.js Image component
- Add staggered entrance animations with fade-in effects
- Improve active session indicator with left border accent
- Fix scrolling by using native overflow instead of ScrollArea
- Persist diagram version history to IndexedDB sessions
- Remove redundant diagram XML from localStorage
- Add i18n strings for time group labels (en, ja, zh)
* fix(session): prevent data loss on theme change and tab close
- Add isDrawioReady effect to restore diagram after DrawIO remount
- Add visibilitychange handler to save session when page becomes hidden
- Fix missing currentSessionId in saveCurrentSession dependency array
- Remove unused sanitizeMessages import from use-session-manager
* fix(session): fix diagram save and migration data loss bugs
- Add diagramHistory to save effect dependency array so diagram-only
edits trigger saves (previously only message changes did)
- Destructure stable sessionManager values to prevent unnecessary
effect re-runs on every render
- Add try-catch wrapper around debounced async save operation
- Make saveSession() return boolean to indicate success/failure
- Verify IndexedDB write succeeded before deleting localStorage data
during migration (prevents data loss if write silently fails)
- Keep localStorage data for retry if migration fails instead of
marking as complete anyway
* refactor(session): extract helpers to reduce code duplication
- Add syncUIWithSession helper to consolidate 4 duplicate UI sync blocks
- Add buildSessionData helper to consolidate 4 duplicate save logic blocks
- Remove unused saveTimeoutRef and its cleanup effect
- Net reduction of ~80 lines of duplicate code
* style(ui): improve history dropdown and delete dialog styling
- Change destructive color from coral to muted rose for refined look
- Make session history panel taller (400px fixed height)
- Fix popover alignment to prevent truncation
- Style delete button with soft red outline instead of solid fill
- Make delete dialog more compact (max-w-sm)
* fix(session): reset refs on new chat and show recent sessions
- Fix cached example diagrams not displaying after creating new session
- Reset previousXML, lastProcessedXmlRef and processedToolCalls when
messages become empty (new chat or session switch)
- Add recent chats section in empty chat state with collapsible examples
- Pass sessions and onSelectSession to ChatMessageDisplay
- Add loadedMessageIdsRef to skip animations on session restore
- Add debug console.log for diagram processing flow
* feat(session): add search bar and improve history UI
- Remove session history dropdown, use main panel instead
- Add search bar to filter history chats by title
- Show minutes (Xm ago) instead of "Just now" for recent sessions
- Scroll to top when switching to new/empty chat
- Remove title truncation limit for better searchability
- Remove debug console.log statements
* refactor: remove redundant code and fix nested button hydration error
- Remove unused 'sessions' from deleteSession dependency array
- Remove unused 'switchedTo' variable and simplify return type
- Remove unused 'restoredMessageIdsRef' (always empty)
- Fix nested button hydration error by using div with role=button
- Simplify handleDeleteSession callback
* fix(session): fix migration bug, improve metadata perf, truncate titles
- Fix migration retry loop when localStorage has empty array
- Use cursor-based iteration for getAllSessionMetadata
- Truncate session titles to 100 chars with ellipsis
* refactor: remove dead code and extract diagram length constant
- Remove unused exports: getAllSessions, createNewSession, updateSessionTitle
- Remove write-only CURRENT_SESSION_KEY and all localStorage calls
- Remove dead messagesEndRef and unused scroll effect
- Extract magic number 300 to MIN_REAL_DIAGRAM_LENGTH constant
- Add isRealDiagram() helper function for semantic clarity
- Add CSS design system tokens (surfaces, borders, animations) to globals.css
- Update dialog.tsx with rounded-2xl, shadow-dialog, refined close button
- Enhance input.tsx with rounded-xl and refined focus states
- Refactor settings-dialog with SettingItem pattern and consistent control sizing
- Refactor model-config-dialog with ConfigSection/ConfigCard helpers
- Replace emerald-* classes with success design tokens
- Remove unused ValidationButton component and scrollState
- Add Biome as formatter and linter (replaces Prettier)
- Configure Husky + lint-staged for pre-commit hooks
- Add VS Code settings for format on save
- Ignore components/ui/ (shadcn generated code)
- Remove semicolons, use 4-space indent
- Reformat all files to new style
* feat: add markdown rendering for chat messages
- Add react-markdown and @tailwindcss/typography for markdown support
- Use prose styling for assistant message formatting
- Fix Radix ScrollArea viewport horizontal overflow issue
- Add CSS fix for viewport width constraint
* feat: add resizable chat panel
- Replace fixed width layout with react-resizable-panels
- Chat panel can be resized by dragging the handle
- Panel is collapsible with min 15% and max 50% width
- Ctrl+B keyboard shortcut still works for toggle
- Switch from Geist to Plus Jakarta Sans (body) and JetBrains Mono (code)
- Add visual diff display for edit_diagram tool showing search/replace pairs
- Update color palette to clean modern OKLCH-based scheme
- Improve chat message display with better styling and animations
- Add syntax-highlighted code blocks for XML/JSON output
- Improve scrollbar and shadow utilities
Dayuan Jiang