## Summary
Fixed critical performance issue where demo/poetry presets would hang for 10+ seconds due to FontStage rendering all 1438+ headline items instead of just the visible ~5 items.
## Changes
### Core Fix: ViewportFilterStage
- New pipeline stage that filters items to only those fitting in the viewport
- Reduces 1438 items → ~5 items (288x reduction) before FontStage
- Prevents expensive PIL font rendering operations on items that won't be displayed
- Located: engine/pipeline/adapters.py:348-403
### Pipeline Integration
- Updated app.py to add ViewportFilterStage before FontStage for headlines/poetry sources
- Ensures correct data flow: source → viewport_filter → font → camera → effects → display
- ViewportFilterStage depends on 'source' capability, providing pass-through filtering
### Display Protocol Enhancement
- Added is_quit_requested() and clear_quit_request() method signatures to Display protocol
- Documented as optional methods for backends supporting keyboard input
- Already implemented by pygame backend, now formally part of protocol
### Debug Infrastructure
- Added MAINLINE_DEBUG_DATAFLOW environment variable logging throughout pipeline
- Logs stage input/output types and data sizes to stderr (when flag enabled)
- Verified working: 1438 → 5 item reduction shown in debug output
### Performance Testing
- Added pytest-benchmark (v5.2.3) as dev dependency for statistical benchmarking
- Created comprehensive performance regression tests (tests/test_performance_regression.py)
- Tests verify:
- ViewportFilterStage filters 2000 items efficiently (<1ms)
- FontStage processes filtered items quickly (<50ms)
- 288x performance improvement ratio maintained
- Pipeline doesn't hang with large datasets
- All 523 tests passing, including 7 new performance tests
## Performance Impact
**Before:** FontStage renders all 1438 items per frame → 10+ second hang
**After:** FontStage renders ~5 items per frame → sub-second execution
Real-world impact: Demo preset now responsive and usable with news sources.
## Testing
- Unit tests: 523 passed, 16 skipped
- Regression tests: Catch performance degradation with large datasets
- E2E verification: Debug logging confirms correct pipeline flow
- Benchmark suite: Statistical performance tracking enabled
- Add DataType properties to SensorStage
- Fix MicSensor import issues (remove conflicting TYPE_CHECKING)
- Add numpy to main dependencies for type hints
- Fix lint errors and LSP issues in benchmark.py
- Add --hook mode to compare against saved baseline
- Add --baseline flag to save results as baseline
- Add --threshold to configure degradation threshold (default 20%)
- Add benchmark step to pre-push hook in hk.pkl
- Update AGENTS.md with hk documentation links and benchmark runner docs
- Implement pure Python Sixel encoder (no C dependency)
- Add SixelDisplay class to display.py with ANSI parsing
- Update controller._get_display() to handle sixel mode
- Add --display sixel CLI flag
- Add mise run-sixel task
- Update docs with display modes
Add typed dataclasses for tuple returns:
- types.py: HeadlineItem, FetchResult, Block dataclasses with legacy tuple converters
- fetch.py: Add type hints and HeadlineTuple type alias
Add pyright for static type checking:
- Add pyright to dependencies
- Verify type coverage with pyright (0 errors in core modules)
This enables:
- Named types instead of raw tuples (better IDE support, self-documenting)
- Type-safe APIs across modules
- Backward compatibility via to_tuple/from_tuple methods
Note: Lazy imports skipped for render.py - startup impact is minimal.
- Fix pre-existing lint errors in engine/ modules using ruff --unsafe-fixes
- Add hk.pkl with pre-commit and pre-push hooks using ruff builtin
- Configure hooks to use 'uv run' prefix for tool execution
- Update mise.toml to include hk and pkl tools
- All 73 tests pass
fix: apply ruff auto-fixes and add hk git hooks
- Fix pre-existing lint errors in engine/ modules using ruff --unsafe-fixes
- Add hk.pkl with pre-commit and pre-push hooks using ruff builtin
- Configure hooks to use 'uv run' prefix for tool execution
- Update mise.toml to include hk and pkl tools
- Use 'hk install --mise' for proper mise integration
- All 73 tests pass
