--- phase: 21-chat-foundation plan: 02 subsystem: ui tags: [react, rehype-highlight, highlight.js, markdown, chat, components, tdd] # Dependency graph requires: [] provides: - ChatMarkdownMessage component with GFM markdown, syntax-highlighted code blocks, and copy button - ChatInput component with auto-resize textarea, Enter/Shift+Enter/Escape keyboard shortcuts - Theme-aware highlight.js CSS overrides covering catppuccin-mocha, tokyo-night, catppuccin-latte affects: - 21-03-chat-panel (uses ChatMarkdownMessage and ChatInput) # Tech tracking tech-stack: added: - rehype-highlight ^7.0.2 (syntax highlighting via lowlight/highlight.js) patterns: - TDD with jsdom + createRoot/act (jsdom environment in vitest, React DOM not @testing-library) - CodeBlock sub-component extracted from ChatMarkdownMessage for single-responsibility - Theme-aware CSS overrides via .dark, .theme-tokyo-night, :root:not(.dark) selector hierarchy key-files: created: - ui/src/components/ChatMarkdownMessage.tsx - ui/src/components/ChatMarkdownMessage.test.tsx - ui/src/components/ChatInput.tsx - ui/src/components/ChatInput.test.tsx modified: - ui/src/index.css - ui/package.json - pnpm-lock.yaml key-decisions: - "Skipped @import for highlight.js/styles/base16/catppuccin-mocha.css (not in highlight.js 11.11.1); defined all token colors inline via CSS selector overrides instead" - "Used .dark selector (not specific catppuccin-mocha class) for default dark theme since ThemeContext only adds .dark for both dark themes — .theme-tokyo-night overrides with higher specificity" - "Tests use jsdom + createRoot/act pattern (matching IssueRow.test.tsx) since @testing-library/react is not installed" patterns-established: - "ChatInput pattern: controlled textarea + ref for height, keyboard handler checks e.key and e.shiftKey, onClose called on Escape when empty" - "ChatMarkdownMessage pattern: Markdown + remarkGfm + rehypeHighlight + custom pre renderer extracting code block className" requirements-completed: - CHAT-02 - CHAT-03 - INPUT-01 - INPUT-07 - THEME-01 - THEME-02 # Metrics duration: 15min completed: 2026-04-01 --- # Phase 21 Plan 02: Chat Foundation UI Components Summary **ChatMarkdownMessage and ChatInput React components with rehype-highlight syntax coloring and theme-aware hljs CSS, 19 tests green** ## Performance - **Duration:** ~15 min - **Started:** 2026-04-01T10:47:00Z - **Completed:** 2026-04-01T11:02:50Z - **Tasks:** 3 - **Files modified:** 7 ## Accomplishments - ChatMarkdownMessage renders full GFM (headings, bold, italic, links, lists, tables, inline images) with rehype-highlight code blocks, language labels, and one-click copy button - ChatInput auto-resizes from 1 to 6 lines, handles Enter/Shift+Enter/Escape shortcuts, submit/loading states - Theme-aware highlight.js CSS covering all three Nexus themes (catppuccin-mocha, tokyo-night, catppuccin-latte) via CSS class selector hierarchy ## Task Commits Each task was committed atomically: 1. **Task 1: Install rehype-highlight and add theme-aware hljs CSS** - `acab737d` (feat) - Lockfile: `c6ae93da` (chore) 2. **Task 2: ChatMarkdownMessage component (TDD)** - `c7e0d936` (feat) 3. **Task 3: ChatInput component (TDD)** - `8e16cec7` (feat) _Note: TDD tasks each had a single commit covering both test and implementation (RED confirmed by missing module, GREEN on first implementation pass)_ ## Files Created/Modified - `ui/src/components/ChatMarkdownMessage.tsx` - Markdown message renderer with rehype-highlight, CodeBlock sub-component with copy button and language label - `ui/src/components/ChatMarkdownMessage.test.tsx` - 10 tests covering markdown rendering, copy button, inline code, images - `ui/src/components/ChatInput.tsx` - Auto-resize textarea with Enter/Shift+Enter/Escape handlers and loading state - `ui/src/components/ChatInput.test.tsx` - 9 tests covering keyboard shortcuts, disabled state, aria labels - `ui/src/index.css` - Added 70 lines of theme-aware hljs CSS (three themes) - `ui/package.json` - Added rehype-highlight ^7.0.2 dependency - `pnpm-lock.yaml` - Updated with rehype-highlight 7.0.2, lowlight 3.3.0 dependencies ## Decisions Made 1. **highlight.js CSS import path** - The plan specified `@import "highlight.js/styles/base16/catppuccin-mocha.css"` but this file doesn't exist in highlight.js 11.11.1 (the version pulled by rehype-highlight 7 via lowlight). Wrote all three theme color sets inline using `.dark`, `.theme-tokyo-night`, and `:root:not(.dark)` selectors. Achieves the same visual result with better control. 2. **`.dark` for default catppuccin-mocha theme** - ThemeContext applies `.dark` class to `` for both catppuccin-mocha and tokyo-night. Tokyo-night also gets `.theme-tokyo-night`. So `.dark` CSS covers catppuccin-mocha and `.theme-tokyo-night` (higher specificity) overrides for tokyo-night. Clean and matches the existing theme architecture. 3. **Test infrastructure** - Plan mentioned `@testing-library/react` but it's not in devDependencies. Used jsdom + createRoot + act pattern matching the established project convention (IssueRow.test.tsx). ## Deviations from Plan ### Auto-fixed Issues **1. [Rule 1 - Bug] highlight.js base16/catppuccin-mocha.css path does not exist** - **Found during:** Task 1 (Install rehype-highlight) - **Issue:** The plan specified `@import "highlight.js/styles/base16/catppuccin-mocha.css"` but highlight.js 11.11.1 (installed transitively via lowlight 3.3.0) does not include catppuccin-mocha in its base16 styles directory - **Fix:** Defined all three theme color palettes inline via `.dark`, `.theme-tokyo-night`, and `:root:not(.dark)` selector blocks — achieves identical result with no missing file - **Files modified:** `ui/src/index.css` - **Verification:** All `.hljs` selectors present; grep confirms 51 hljs rule matches - **Committed in:** `acab737d` (Task 1 commit) --- **Total deviations:** 1 auto-fixed (Rule 1 - incorrect file path in plan) **Impact on plan:** Fix required — the import would have caused a build error. Inline CSS is equivalent and more portable. ## Issues Encountered None beyond the hljs import path deviation above. ## User Setup Required None - no external service configuration required. ## Next Phase Readiness - ChatMarkdownMessage and ChatInput are ready to be composed into ChatPanel (Plan 03) - Both components are self-contained with no API dependencies - rehype-highlight installed and theme CSS wired — syntax highlighting works on first render - No blockers for Plan 03 --- *Phase: 21-chat-foundation* *Completed: 2026-04-01*