[astrobyte-dev]

Studio can generate and shape sounds through canonical synth tracks, five instruments, eight serial insert effects, engine-owned modulation and local patches. P3 compositional automation now also targets 14 deliberate FX controls by fx.<instanceId>.<semanticParameter>. Reordering retains those targets; removal cleans matching lanes/routes atomically, and Undo restores them with the insert.

Base values, P3 automation and continuous Sound Lab modulation remain separate authored layers. Tidal compiles silent control events alongside music in the existing track slot, including through rests. SuperDirt delivers those controls to persistent inserts under per-lane authorization, runtime generation, node and transport guards. SC selects automation or stored base, adds modulation, and clamps before DSP mapping. Disabling either movement layer preserves the other and base; stop/expiry release automation. Knobs communicate both states using the existing tactile controls. UI and MCP use the same canonical validation, revision guards, history and persistence.

Supported composition parameters: filter cutoff/resonance; distortion drive/mix; bitcrush bits/mix; reverb size/mix; delay feedback/mix; chorus depth/mix; compressor amount; ring mix. Sensitive time/rate/frequency parameters, compressor threshold and reverb damping remain deliberately excluded. Unsupported new targets are rejected clearly.

This is a stacked draft, based on exact P3 commit 7f5971ab603c33f893071839c5880b57ed8569f1 and targeting feat/p3-composition-performance. Dependencies #5 (P3) and #4 (P2.6) remain unmerged. Do not merge this PR as native-audio accepted.

Validation on Ubuntu 24.04.4 with Node 24.14.0/npm 11.9.0:

• 256 tests passed, 3 expected Windows-only skips, 259 discovered; 55 new Sound Lab tests, including 20 additional FX automation regressions. Discovery floor 259.
• Production build and both server/Studio typechecks passed.
• Expanded P3.5A browser journey: semantic FX lanes, base editing, reorder/removal, Undo/Redo, independent layer disables, real MCP synchronization/stale/unsupported rejection, independent scene lanes, save/new/reopen/reload.
• P3, Classic, Studio, P2, System and Linux lifecycle fixture regressions passed.
• Sound Lab screenshots reviewed; historical milestone screenshots preserved. No page overflow or JS errors.
• Final diff review covered semantic ownership, scene staging/recovery, stale scheduled events, finite-event expiry, node cleanup and unchanged synth compilation. No browser scheduling loop added.

Implementation scope is complete for P3.5A's supported surface. Native acceptance remains pending: no native SC/Tidal compilation, audible synthesis/FX quality, acoustic timing, CPU/node-lifetime or Windows desktop/audio acceptance is claimed. The new SuperDirt control-event path has source/contract and fixture coverage, not native execution evidence. P2.6 remains Ubuntu Runtime Safe with Windows revalidation pending; P3 native audio/timing acceptance remains pending.

Remaining limits: synth modulation phase starts per voice; source/note/automation-curve edits during prepared performance require relaunch, while disabling/removing FX automation releases immediately. Inserts/modulation/mixer/tempo remain live. User patches live in the current project. Unknown definitions/versions retain inert authored state. No P3.5B/P4/P5 features or system/audio package changes.

Architecture, supported controls, ownership/removal semantics, evidence and exit criteria: P3.5A completion report. Machine-readable results: validation summary.