[astrobyte-dev]

Bring user-owned WAVs and external input into the existing Studio sample, FX and composition workflow. My Sounds now imports/deduplicates managed audio with immutable identities and cached waveforms; Capture provides explicit input/monitoring, validated dry takes and Keep as Sample. The Sample tab adds nondestructive trim, rate-based pitch, reverse, envelopes, phrase loops and stable chops/pad mappings, with shared Undo/Redo, persistence and structured MCP operations.

This draft is intentionally stacked on feat/p3.5a-sound-lab-core at 3ea7f7b4441bdd456c83699f9a170c9e6c9a56d9. Do not merge this or its lower draft dependencies as part of this delivery. P4/P5 were not started.

Validation

• Baseline: 259 tests, 256 passed, three Windows-only skips; build, both typechecks, six browser journeys and Linux lifecycle passed before edits.
• Final: 304 tests, 301 passed, three Windows-only skips; 45 new sampling tests. Production build and both typechecks pass.
• All seven classic/Studio/P2/P3/P3.5A/P3.5B/System browser journeys and Linux runtime harness pass. Final display adjustment was followed by build/typechecks, 45 sampling tests and a repeated P3.5B journey.
• Production Studio/HTTP/storage plus actual MCP exercise import/folder filtering/dedup, shaped previews, grouped trim history, FX, fixture capture/finalize/Keep, assignment/chops/sequencing/scenes, stale write rejection and complete save/reopen. Screenshots reviewed at 1280/1440/1920.
• Security/path, destructive file mutation, audio ownership, cache/memory bounds and full diff reviewed. External originals and retained sounds are not deleted by musical Undo.

Acceptance limits

Implementation complete; native input/audio acceptance pending. Ubuntu evidence uses explicit deterministic audio fixtures, not a physical microphone or real SuperCollider/Tidal sound. Windows is unavailable. Native device/channel behavior, monitor/preview/output isolation, five-minute cutoff/finalization, sound/timing/CPU and buffer lifetime still require hardware acceptance.

All inherited gates remain open: P2.6 Windows desktop/audio; P3 native audio/timing and Windows; P3.5A native audio/timing/CPU and Windows. No system packages, kernel/apt state or native audio installation/configuration were changed.

Initial scope deliberately supports PCM16 mono/stereo WAV imports (256 MiB/15 minutes), one of two mono input channels, dry capture after gain (five minutes), track FX after Keep, playback-rate pitch and phrase retriggering. It does not offer live input FX, processed capture or elastic time stretching. Projects reference managed audio/ files; copy that directory/sidecars with projects. Missing files require exact-content relinking.

Full architecture, file inventory, test evidence, screenshots, exact exit criteria and remaining limitations: P3.5B completion report, validation JSON, task.