Phase 34: add snap grids, MIDI velocity editing and track instrument menus

docs/MIDI.md

@@ -167,3 +167,15 @@ Do not unload/replace modules during playback; candidate plans are prepared off
 the callback and old instances are reclaimed on the control thread. Missing
 references remain inspectable without loading; failed GUI preparation retains
 the current project. Save a backup for applications limited to v11 or earlier.
+
+## Phase 34 note dynamics and clip editing
+
+Double-click a MIDI clip to open its piano roll. The Note velocity slider and
+fixed Velocity lane edit individual notes from 1 to 127, preserving timing,
+pitch and channel. Chord notes at the same start can be selected individually in
+the keys before editing their highlighted bar. Completed gestures are undoable
+and save in the existing note velocity field. Velocity is not a separate dB
+volume stage: the built-in sine scales amplitude, while plugins choose their
+own patch-dependent response. The track header instrument dropdown reuses saved
+project instruments or opens explicit loading; bus tracks cannot host instruments.
+See WORKSPACE.md for grid/snap divisions, filters and control behavior.

docs/RELEASE_NOTES.md

@@ -68,3 +68,9 @@ previews. New MIDI/audio track commands are undoable and prepare candidates
 before adoption. The default window is 1280 × 800, minimum 1220 × 720.
 No dependency or project-format change. See WORKSPACE.md and the new
 `modern-session.xtc` example; existing engine/plugin limitations still apply.
+
+Phase 34 adds a sequencer grid/Snap dropdown, absolute grid snapping for moves
+and trims, MIDI double-click editing, a piano velocity lane/slider and per-track
+instrument dropdowns. Snap preferences are UI state; velocity and instrument
+bindings use the existing v12 format. No new dependency or engine feature is
+required. See WORKSPACE.md for supported divisions, controller semantics and limits.

docs/ROADMAP.md

@@ -960,6 +960,35 @@ See WORKSPACE.md for the workflow, tests and limits.
 
 ---
 
+## Phase 34 — Grid, Clip Editing and Track Instrument Controls
+
+### Goal
+Expose common DAW editing actions directly in the flat workspace: selectable
+snap, MIDI clip double-click, individual note velocity and track instruments.
+
+### Tasks and acceptance criteria
+- [x] Draw bar/beat/subdivision grid lines and expose a sequencer Snap dropdown.
+- [x] Offer Off, straight, triplet, half-note and bar divisions; synchronize the existing snap menu.
+- [x] Snap clip moves and both trim edges to absolute grid positions, including off-grid clips.
+- [x] Open the selected MIDI clip's piano roll on left-button double-click without moving it.
+- [x] Add a fixed velocity lane and selected-note slider with 1..127 validation and one undo step per edit.
+- [x] Keep coincident chord notes individually editable and preserve timing/pitch/channel.
+- [x] Add a dropdown to every non-bus track for built-in sine, project instruments and explicit plugin loading.
+- [x] Preserve track identity through reorder, undo, clear and project reload; retain candidate failure rollback.
+- [x] Keep controls flat, retain current project format and verify builds, GUI regressions and releases.
+
+### Implementation status
+Implemented in the C++ GUI over existing C model APIs. Snap preferences are
+session UI state; note velocity and track instruments already persist in v12.
+The project instrument list is built from existing assignments, with Load plugin
+for other trusted binaries; automatic disk scanning is not introduced.
+At low zoom the visual grid coarsens for readability while snap remains exact to
+the selected tick division. Off uses pointer/model tick precision. MIDI velocity
+is a performance value, not a per-note dB gain stage; third-party instrument
+patches control its audible response. See WORKSPACE.md and MIDI.md.
+
+---
+
 ## Recommended Execution Order
 
 Reorder the phases when the audit reveals a blocking dependency. Do not mark a phase complete merely because code exists: its acceptance criteria must be demonstrated by builds, tests, or documented manual verification.

docs/USER_MANUAL.md

@@ -206,3 +206,8 @@ The flat workspace puts New MIDI/audio track, WAV import and instrument loading
 in a persistent sidebar, with a musical transport display and selected-track
 overview. See [WORKSPACE.md](WORKSPACE.md) for shortcuts and workflow. Open
 `modern-session.xtc` in the installed examples for an original four-track arrangement.
+
+Phase 34: use the sequencer Snap dropdown for straight/triplet/bar grids or Off.
+Double-click MIDI clips to edit notes, then use the Velocity lane or selected-note
+slider for dynamics. Each non-bus track header has an instrument dropdown offering
+built-in sine, project instruments and explicit plugin loading. See WORKSPACE.md.

docs/WORKSPACE.md

@@ -55,3 +55,47 @@ and workflow tests cover the retained commands. A modern presentation does not
 add commercial-DAW features: detachable/resizable docks, mixer channel strips,
 automatic plugin scanning, custom plugin editors and new audio/MIDI features
 remain outside this phase. Existing plugin and engine limits still apply.
+
+## Phase 34 editing controls
+
+The **Snap** dropdown above the sequencer selects Off, 1/32, 1/16 triplet,
+1/16, 1/8 triplet, 1/8, 1/4, 1/2 or one bar. Existing View/Snap commands update
+the same preference. Bar lines are strongest, beats medium, subdivisions subtle.
+At low zoom closely spaced lines are coarsened to at least six pixels; snapping
+still uses the selected division. Clip moves and trim boundaries snap to the
+nearest absolute grid position (halfway rounds forward), including clips that
+start off the grid. Off removes musical quantization; pointer resolution and
+integer model ticks still apply. Invalid trims retain the original clip.
+Snap is a UI preference, not a project edit or a saved project setting.
+
+Double-click a MIDI clip with the left mouse button to open its piano roll.
+The clip is selected and the click does not move/trim it. Audio/silent clips
+retain their existing selection/drag behavior. The piano roll also has a Snap
+dropdown for its existing note grid; sequencer and piano snap remain independent.
+
+The piano roll has a fixed **Velocity** lane beneath the keys and a **Note
+velocity** slider. Select a note, then drag its bar vertically or release the
+slider at a value from 1 to 127. Only that note changes; pitch, timing, length,
+channel and other notes stay intact. One completed drag/slider edit is one undo
+step; Escape cancels a lane drag. For chord notes sharing a start time, select
+the desired note in the keys first; its highlighted velocity bar and slider
+remain individually editable. Horizontal scrolling aligns the lane with note
+starts; vertical scrolling moves the keys while the lane stays available.
+Filters apply to lane visibility and selection. Values save with existing note
+metadata and affect built-in synthesis; plugin patches determine velocity response.
+This is MIDI velocity, not a per-note audio gain or loudness meter.
+
+Every ordinary track header has an instrument dropdown. Choose **Built-in sine**,
+an instrument already assigned elsewhere in the project, or **Load plugin...**
+for a trusted CLAP/VST2/VST3 binary. Entries show the format and plugin label.
+Each assignment creates an independent track instance, selects that track for
+live MIDI and remains undoable; clear/reorder/reopen use stable track IDs. Bus
+tracks show their bus label instead. Cancel or failed preparation restores the
+model's selection in the dropdown. The list is project-local, not a scanner or
+installed-plugin database. Existing mono/default-configuration host limits apply.
+Instrument changes stop/reprepare playback and are refused while recording.
+
+Verification includes off-grid move/trim, snap Off, dropdown labels, double-click,
+coincident notes, per-note slider/lane edits, invalid velocities, undo/reload and
+instrument reuse/clear/reorder for all three fixture formats. Manual checks use
+the original modern-session example and the flat sequencer/piano windows.