reasampler/PLAN.md

# PLAN.md — ReaSampler milestone roadmap

Living milestone roadmap for ReaSampler. Derived from CONTEXT.md's 11-step build
order; CONTEXT.md remains the authoritative spec — this file is the tickable
checklist, not a re-statement of the spec. When a point lands, doc-keeper removes
it here and appends it to `COMPLETED.md`.

**Conventions**
- One checkbox `- [ ]` = one discrete, independently-landable point.
- Each milestone opens with a **Goal** (one line) and a **Verify** criterion
  (the acceptance gate; precision invariants pulled in where one applies).
- Verify-in-DAW points require a manual REAPER run; pure points are gated by CTest.
- "See CONTEXT.md §…" points at the authoritative detail — do not duplicate it here.

---

## Milestone 0 — Transition scaffold: reaper_mpeview → ReaSampler
**Goal:** Retire the MPE scaffold and stand up the sampler's pure core in its
place, preserving the pure-core / REAPER-shell split.
**Verify:** `cmake -B build -S .` configures clean; `cmake --build build` builds
the renamed extension target and the pure-core test target; `ctest --test-dir
build` is green with the new `bank_model` + `peaks` suites present.

- [ ] Delete `src/mpe_model.{h,cpp}` and `src/mpe_view.{h,cpp}`; remove
  `tests/test_mpe_model.cpp`.
- [ ] Rename the CMake `project()` and the extension MODULE target from
  `reaper_mpeview` to `reaper_reasampler` (binary `OUTPUT_NAME` likewise);
  update `PREFIX ""` / platform SUFFIX blocks to the new target name.
- [ ] Replace the pure `mpe_model` static lib + `mpe_model_tests` executable with
  `bank_model` (pure static lib) + `bank_model_tests`; keep the CTest wiring.
- [ ] Repoint `src/main.cpp`: drop the `mpe_view.h` include and all `MpeView_*`
  calls (toggle / IsOpen / OnTimer / Cleanup); stub the extension entry so it
  loads, logs to console, and registers nothing MPE-specific. The
  `command_id` / `gaccel` / `hookcommand` registration *pattern* is preserved for
  reuse (CLAUDE.md §REAPER extension contract) — the MPE action string is removed.
- [ ] Choose and record the persistent action-id prefix for the sampler family
  (replaces `CEREBELLUM_MPEVIEW_TOGGLE`); this string is forever-stable once
  shipped (CLAUDE.md §action registration).
- [ ] Refresh `README.md` layout/next-step sections to the sampler module set.
  (Landed-work reflection is doc-keeper's; this point exists so the stale MPE
  README does not mislead the first implementer.)

> After Milestone 0, Milestones 1 and 2 below are the pure-core heart. They are
> also the near-term slice tracked in `TODO.md`.

## Milestone 1 — bank_model + JSON round-trip (pure)
**Goal:** The `Sample` metadata struct and `BankIndex` (add / remove / query /
tier moves / dedup-by-hash) with JSON serialize/deserialize to `std::string`.
CONTEXT.md §Data model, §Module architecture.
**Verify:** CTest green. Round-trip is lossless (deserialize(serialize(x)) == x)
across all fields; dedup-by-hash and tier filtering asserted; **relative paths
only** invariant enforced at the model boundary (no absolute path accepted/stored).

- [ ] Define `Sample` with the full field set (id, display name, relative path,
  source mode, source range in project time + PPQ, track GUID(s), wet/dry,
  channels, SR, length sec + beats, capture tempo, optional key, peak/RMS/LUFS,
  clip flag, tier, content hash, provenance, created ts). CONTEXT.md §Data model.
- [ ] `BankIndex`: ordered collection keyed by id; add / remove / query.
- [ ] Hash lookup for dedup-by-content-hash.
- [ ] Tier model (scratch | archive) + tier-move + tier filtering; scratch marked
  auto-prunable.
- [ ] JSON serialize/deserialize to/from `std::string`.
- [ ] Tests: full-field round-trip lossless; dedup collapses equal-hash adds;
  tier filter/move correct; relative-path invariant rejects absolute paths;
  empty-index and malformed-JSON edge cases.

## Milestone 2 — peaks (pure)
**Goal:** Compute waveform min/max bins from raw PCM, dependency-free (not
REAPER's peak API). CONTEXT.md §Module architecture, §Non-goals.
**Verify:** CTest green. Fed a known signal (full-scale sine, ramp), asserted
min/max envelope per bin matches expected within tolerance; channel count
preserved; bin count honored for arbitrary sample lengths (incl. remainder bin).

- [ ] Min/max bin computation from interleaved PCM given a target bin count.
- [ ] Multi-channel handling (per-channel envelope; no silent fold).
- [ ] Tests: sine envelope ≈ ±amplitude; ramp envelope monotonic; DC/silence →
  zero envelope; short-buffer and non-divisible-length edge cases.

---

## Milestone 3 — Offline capture spike (REAPER shell)
**Goal:** Offline-render the time-selection master mix to a wav in the project
bank folder, add a `Sample`, log it. The render-driving spike. CONTEXT.md
§REAPER API surface (offline render), Build order 3.
**Verify (in DAW):** Headless (no-dialog) render runs; file lands in the
project-relative bank folder; a `Sample` is added to the in-memory `BankIndex`.
**Bit-identical repeats:** two identical requests produce byte-identical files.
**Exact bounds:** rendered length matches the requested range (no rounding, no
added silence without an explicit tail).

- [ ] `ICaptureBackend` interface + `CaptureRequest` (source mode, time range,
  wet/dry, tail, SR/bit-depth/channels, output path). CONTEXT.md §capture.
- [ ] `OfflineRenderBackend`: drive `GetSetProjectInfo` render settings +
  `GetSetProjectInfo_String` file/pattern/format; **verify every flag against
  `vendor/reaper-sdk/sdk/reaper_plugin_functions.h`.**
- [ ] Resolve the no-dialog render command/flag on the current REAPER build
  (open question) and confirm it runs headless.
- [ ] Populate a `Sample` from the finished file; hand to `bank_model`; console-log.
- [ ] Verify bit-identical repeats and exact-bounds by hand on a known range.

## Milestone 4 — persist (index ↔ project ext state)
**Goal:** Write the `BankIndex` JSON to project ext state, reload on project open;
project-relative path resolution. CONTEXT.md §persist, §Persistence & paths.
**Verify (in DAW):** Index survives Save / Save As / close+reopen; **bank travels
with the .rpp**; **relative paths only** in the persisted index (Save As to a new
folder still resolves the bank).

- [ ] `SetProjExtState` / `GetProjExtState` under namespace `"reasampler"`.
- [ ] Bank-folder resolution from the current project path
  (`EnumProjects` / `GetProjectPathEx`); store under a project-relative subfolder.
- [ ] Reload-on-open; confirm survival across Save / Save As.

## Milestone 5 — bank_panel (docked grid)
**Goal:** Docked LICE-drawn grid: thumbnails (from `peaks`), audition,
multi-select, keyboard navigation. Reuses the docking setup from the retired
`mpe_view.cpp`. CONTEXT.md §bank_panel.
**Verify (in DAW):** Grid docks; thumbnails render from computed peaks; audition
plays selected sample; multi-select + keyboard nav work.

- [ ] Docked window + LICE grid render loop.
- [ ] Thumbnail draw from `peaks` bins.
- [ ] Audition (play selected sample) + stop.
- [ ] Multi-select + keyboard navigation.

## Milestone 6 — insert (placement)
**Goal:** "Insert selected sample at edit cursor" via `InsertMedia`. CONTEXT.md
§insert, Build order 6.
**Verify (in DAW):** Selected sample inserts at the edit cursor wrapped in
`Undo_BeginBlock2` / `Undo_EndBlock2`; conform-to-tempo is an explicit flag —
**no silent time-stretch** when off.

- [ ] `InsertMedia(path, mode)` at edit cursor (verify mode bits against SDK).
- [ ] Conform-to-project-tempo vs literal as an explicit flag (never silent).
- [ ] Undo-block wrapping.

## Milestone 7 — capture action family
**Goal:** Bindable capture actions for master / selected tracks / selected items /
razor area, each with wet-dry + tail options. CONTEXT.md §actions, Build order 7.
**Verify (in DAW):** Each action registered (bindable in Actions list), routes to
the offline backend, and honors wet/dry + tail. **Load-bearing principle:** none
auto-inserts into the arrange.

- [ ] Source resolvers: master mix, selected tracks, selected items, razor area
  (`GetSet_LoopTimeRange`, `P_RAZOREDITS`, `CountSelectedMediaItems`, etc.).
- [ ] Register each as a bindable action (`command_id`/`gaccel`/`hookcommand`).
- [ ] Wet-dry + tail options per action.
- [ ] Review gate: confirm no capture path touches the timeline.

## Milestone 8 — RealtimeRecordBackend
**Goal:** Realtime record behind the same `ICaptureBackend`, producing identical
bank entries. CONTEXT.md §capture (realtime), §Precision invariants.
**Verify (in DAW):** Hidden temp track resamples wet output; recorded file moves
into the bank; **non-destructive** — temp track removed cleanly, source routing
and user monitoring restored unchanged.

- [ ] Hidden-track resample recipe (`I_RECMODE`/`I_RECINPUT`/`I_RECARM`,
  `CSurf_OnRecord`/`CSurf_OnStop`); verify record-mode values against SDK.
- [ ] Resolve wet-master routing that does not alter user monitoring (open
  question).
- [ ] Move recorded source into bank; populate identical `Sample`; clean teardown.

## Milestone 9 — slots (MPC-style)
**Goal:** "Capture to slot N" / "insert slot N", MIDI-bindable. CONTEXT.md
Build order 9.
**Verify (in DAW):** Slot capture and slot insert fire from MIDI bindings; slot
state persists via the index.

- [ ] Slot model + slot↔sample assignment.
- [ ] "Capture to slot N" / "insert slot N" actions, MIDI-bindable.

## Milestone 10 — provenance + null-test verify action
**Goal:** Provenance (parent sample id + FX-chain snapshot) and "re-capture from
source"; ship the null-test verification action. CONTEXT.md §Precision invariants,
Build order 10.
**Verify (in DAW):** **Null test** — a dry offline capture of a range, re-inserted
at its source position, nulls to silence against the source. This action is the
tool's trust anchor and must pass.

- [ ] Provenance fields populated on resample-from-sample (parent id + FX-chain
  snapshot string).
- [ ] "Re-capture from source" action.
- [ ] Null-test verification action (capture → re-insert at source pos → assert
  silence sum).

## Milestone 11 — polish
**Goal:** Batch capture (per selected item / per razor area),
resample-and-mute-source, conform-on-insert, native OS drag-out. CONTEXT.md
Build order 11, §Non-goals (drag-out deferred to last).
**Verify (in DAW):** Each polish action works without regressing the precision
invariants; drag-out places a valid file in the OS target.

- [ ] Batch capture: per selected item / per razor area.
- [ ] Resample-and-mute-source.
- [ ] Conform-on-insert (explicit).
- [ ] Native OS drag-out (deferred final; `InsertMedia` path must already work).

---

## Open questions to resolve during build
Carried from CONTEXT.md §Open questions — keep visible until each is closed by a
landed milestone.

- **No-dialog render command/flag** on the current REAPER build. (blocks M3)
- **Realtime wet-master routing** that captures master output without altering the
  user's monitoring. (blocks M8)
- **Bank audio format:** wav bit-depth default; allow float for wavetable
  fidelity. (touches M3, informs M1 `Sample` fields)
- **Thumbnail cache:** recompute peaks vs store peak bins alongside the index.
  (touches M2/M4/M5)