Audio track velocity editing in the sequencer.

docs/ROADMAP.md

@@ -3612,6 +3612,50 @@ checks, plus rendered screenshot inspection. See [the gallery](../screenshots/RE
 
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+## Phase 110 — Continuous Audio Velocity Editing in the Sequencer
+
+### Goal
+
+Extend the sequencer's downward-expanding velocity lanes to audio tracks, with
+level editing at arbitrary timeline positions using the existing C gain
+automation, playback, persistence and history contracts.
+
+### Tasks and acceptance criteria
+
+- [x] Display a connected audio level envelope beneath audio tracks using the
+      same disclosure arrows and row layout as MIDI velocity lanes.
+- [x] Add points anywhere, independently of snap and note positions; drag caps
+      vertically to adjust gain between silence and 400%, and right-click to remove.
+- [x] Preview edits locally, cancel with Escape, and commit once per gesture
+      through the arrangement edit hook and undo/redo publication path.
+- [x] Share saved gain automation with the mixer, respecting existing Linear/Hold
+      segments and preserving interpolation mode when editing an existing point.
+- [x] Verify off-grid point creation, edits, clamping, removal, cancellation,
+      undo/redo, save/reopen and rendered audio levels in GUI integration tests.
+- [x] Capture the real audio envelope beside MIDI velocity bars, add it to the
+      complete screenshot gallery and document the workflow.
+
+### Implementation status
+
+Implemented on 2026-11-06 without engine, dependency or project-format changes.
+Audio velocity controls track gain (0–4 linear, displayed as 0–400%); it is not
+MIDI note velocity. Empty tracks, buses and tracks containing audio display the
+gain envelope; tracks containing only MIDI retain their note velocity bars.
+On mixed audio/MIDI tracks the gain envelope affects both sources, and individual
+MIDI velocities remain editable in the piano roll. Automation replaces static
+track gain and holds its first/last values beyond its endpoints. New points use
+Linear interpolation; existing Hold segments remain supported. An initial point
+therefore sets the whole track's level until further points shape the curve.
+Points stay at their timeline position during vertical drags; add/remove points
+to change timing. The existing project-wide 1024-point automation limit applies.
+Envelope edits are saved; track disclosure state remains temporary GUI state.
+
+Validation: warning-enabled CMake build, CTest checks including real FLTK
+lane gestures and comparison of rendered audio against the unautomated source,
+and inspection of the actual [audio envelope capture](../screenshots/audio-velocity-expanded.png).
+
+---
+
 ## Recommended Execution Order
 
 Reorder the phases when the audit reveals a blocking dependency. Do not mark a