Summary

• Adds 1, 2, and 4 bar hybrid clip length support using tick-based lengthTicks values.
• Derives drum sequencer and piano roll grids from clip length instead of assuming one bar.
• Uses the selected clip length for PAT loop playback by passing loopEndTick to the audio engine.
• Requires confirmation before shortening would remove or trim events outside the new clip length.

Changes

• Adds hybrid clip length helpers, grid count helpers, and length update/trim logic in the model layer.
• Adds a compact clip length control to the hybrid clip editor header.
• Extends drum sequencer rendering to 16/32/64 steps and piano roll rendering to 32/64/128 columns.
• Updates docs and Active Issue Order for Variable hybrid clip length #48.
• Adds unit tests for clip length ticks, grid derivation, shortening behavior, longer-clip events, and arrangement default instance length.

Testing

• npm run typecheck --if-present: pass
• npm run lint --if-present: pass
• npm run test --if-present: pass, 13 files / 83 tests
• npm run build --if-present: pass
• npm run dev -- --host 127.0.0.1 --port 5173: started on 5174 because 5173 was occupied; curl -I http://127.0.0.1:5174/ returned 200 OK

Notes / Limitations

• Browser-level manual checks still need user review: change a clip to 2/4 bars, add events in later bars, play the PAT loop, and confirm shortening prompts before trimming/removing out-of-range events.
• Existing arrangement clip instances keep their stored lengthTicks; newly dropped hybrid clip instances use the source clip length.
• Longer piano roll grids scroll horizontally, while the 1-bar view remains compact.

Closes #48