Transform source citations from plain text to clickable links that open
lesson videos in new tabs. Links are embedded invisibly - users see only
"Course Title - Lesson X" as clickable blue text.

Backend changes:
- Modified search_tools.py to retrieve lesson links from vector store
- Changed sources from List[str] to List[Dict] with text and optional link
- Updated QueryResponse model to accept Union[str, Dict] for compatibility

Frontend changes:
- Enhanced script.js to render <a> tags with target="_blank"
- Added source-link CSS styling with hover and focus states
- Maintained backward compatibility for string sources

Gracefully handles missing links by displaying as plain text.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Add a new chat button to the sidebar that allows users to clear the current conversation and start fresh without page reload. The button is positioned above the Courses section and matches the styling of existing sidebar elements.

Changes:
- Add NEW CHAT button to sidebar with matching uppercase styling
- Implement session cleanup on both frontend and backend
- Add /api/session/clear endpoint for proper memory management
- Auto-focus input field after clearing for better UX
- Clear chat messages and reset session state when clicked

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

- Added get_course_outline() method to VectorStore for retrieving complete course structures
- Created CourseOutlineTool with bullet-point formatted output
- Registered outline tool alongside search tool in RAGSystem
- Updated AI system prompt to return outline results without synthesis

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Combined local 2-round tool calling with remote's specific tool names
and get_course_outline method.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Removed duplicate CourseOutlineTool class that was inserted into
ToolManager during merge, causing get_tool_definitions and other
methods to be misplaced.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Add _extract_text() to safely handle empty API responses instead of
crashing with IndexError on response.content[0].text. Wrap Anthropic
API calls to catch AuthenticationError and APIError, re-raising as
RuntimeError with descriptive context for the 500 handler.

Add 25 diagnostic tests covering search tools, AI generator tool
calling, and RAG query pipeline.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

…andling

Extract _call_api() helper, execute all parallel tools before flow control,
add DIRECT_RETURN_TOOLS/MAX_TOOL_ROUNDS constants, and reorganize tests
for multi-round, parallel, and partial-failure scenarios.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Add test_api_endpoints.py with 10 tests covering /api/query, /api/courses,
  and /api/session/clear endpoints using a standalone test app to avoid
  static file mount issues
- Enhance conftest.py with shared fixtures (mock_config, mock_rag_system,
  mock_vector_store)
- Add pytest.ini_options in pyproject.toml for testpaths and pythonpath
- Add httpx dependency for FastAPI TestClient

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Set up black as a dev dependency with project configuration,
create scripts/quality.sh for running format checks and tests,
and apply black formatting across all 11 Python source files.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Add sun/moon toggle button (fixed top-right) with smooth icon rotation
- Implement complete light theme via CSS custom properties on data-theme attribute
- Prevent FOUC with inline head script that applies theme before first paint
- Respect OS prefers-color-scheme when no saved preference exists
- Persist user choice in localStorage, update on toggle and OS change
- Add color-scheme property and meta tag for native browser chrome adaptation
- Add Firefox scrollbar support (scrollbar-color) alongside WebKit pseudo-elements
- Add themed ::selection, error/success messages, source links, code blocks
- Replace all hardcoded colors with CSS variables for full theme coverage
- Add .no-transitions suppression class to prevent animations on page load
- Add Ctrl+Shift+L keyboard shortcut and dynamic aria-label on toggle button
- Ensure WCAG AA contrast ratios on all text-on-background combinations
- Document all changes in frontend-changes.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

…7504

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