Ξ-W2-T1: the resample bake chain — instrument renders, extension banks, one click re-points and resets

src/shell/instrument/CLAUDE.md

@@ -83,8 +83,12 @@ declared ahead of the instrument slots at that member in `reasampler_processor.h
 
 **Non-goals / guardrails.**
 - The instrument never captures and never inserts into the arrange. Playback is a
-  read-only act over the bank. Any instrument path that captures, places a timeline
-  item, or writes back into the bank is a bug.
+  read-only act over the bank. Any instrument path that places a timeline item, or that
+  writes bank state itself, is a bug. **The resample bake is not an exception to that
+  and does not widen it:** the instrument RENDERS its own sound and REQUESTS a landing;
+  the extension is what captures the file into the bank and writes the index. The
+  instrument's whole outbound surface is one prefix-guarded request key plus one action
+  id — see `instrument_bake` and `reaper_bridge` below.
 - The instrument never ingests. Capture, import, and drop-ingest are *extension*
   acts; the instrument only reads and plays. A drop onto the editor window (if ever
   shipped) is relayed to the extension as an ingest request — the instrument never
@@ -99,17 +103,26 @@ declared ahead of the instrument slots at that member in `reasampler_processor.h
 
 ## Modules
 
-- `reaper_bridge` — READ-ONLY bank consumer: receives bank snapshots from the extension and exposes them as a read-only view. **Never writes to the extension's bank** — this is a load-bearing invariant; no mutation path exists in this module. **pS-usage:** gains `writeUsageExtState` (prefix-guarded — accepts only `rsusage_`-prefixed keys, refuses all others) so the processor can publish usage without weakening the read-only-bank invariant.
+- `reaper_bridge` — READ-ONLY bank consumer: receives bank snapshots from the extension and exposes them as a read-only view. **Never writes to the extension's bank** — this is a load-bearing invariant; no mutation path exists in this module. It owns TWO prefix-guarded ext-state write entry points, `writeUsageExtState` (`rsusage_`) and `writeBakeExtState` (`rsbake_`), each refusing every other key; neither weakens the read-only-*bank* invariant, because neither payload is bank state and `banks`/`view`/`tail`/`assign` stay structurally unwritable. It also owns the bake crossing — `extensionActionAvailable` / `invokeExtensionAction` (`NamedCommandLookup` + `Main_OnCommandEx` against `getReaperParent(3)`, the instance's OWN project tab, never the focused one) and `projectTempoBpm`.
 - `reasampler_processor` (`shell/instrument/`: `reasampler_processor.cpp` lifecycle + `process()`, `processor_state.cpp` component-state I/O + UI-thread parameter accessors, `processor_reload.cpp` the off-audio-thread `reloadInstrument`/publish family — Q-W2v, T4-12 split; `process()` and its per-block work stay ONE TU on purpose, no cross-TU call on the per-sample path) — VST3 `SingleComponentEffect` shell: declares event-input bus + **permanently stereo** output (GA fix: dynamic mono↔stereo bus renegotiation deleted; `ChannelMode` is now decode-only), marshals MIDI note-on/off into the VoiceEngine, renders audio; owns off-audio-thread `reloadInstrument` + atomic pointer swap so `process()` does no allocation, no file I/O, no bridge calls. The instance state is `{loaded capture id, one InstrumentParams}`, and `reloadInstrument` resolves + decodes exactly that one capture into the `SampleData` the engine plays. **Self-contained playback (pS):** `ComponentState` v10 adds a `SampleRefs` table — per referenced sample, a project-relative path + decode intrinsics (root, loop, channels, displayName); `reloadInstrument` decodes directly from `SampleRefs`, bank-free (plays with the extension absent). The bank/bridge is a browser source: loading a capture copies its reference in; the reopen-heal timer + poll-to-play apparatus are removed. `retireIdleDrain()` retires fully-idle drain snapshots on the UI-timer cadence. Voice-param edits (`setVoiceCount`/`setVoiceMode`/`setMonoTrigger`) rebuild the engine from the already-decoded `SampleData` via the drain-slot swap — no bank re-read, no WAV re-decode, no audible cut to ringing tails. **FB1:** applies the post-mixer `masterGainLinear` (from `ComponentState` v8) as a per-sample ramp over the summed output — no zipper noise. **GA v9:** `channelModeExplicit_` flag persisted; `channelModeFor()` auto-defaults the mode from the loaded capture's channel count when the flag is not set. **pS:** `ComponentState` bumped v9→v10 (`SampleRefs` table); pre-v10 blobs lift to empty refs and re-save self-contained. **pS-usage:** publishes instance usage (held `SampleRefs` paths) to `rsusage_<instanceGuid>` at the tail of `reloadInstrument` (off audio thread) via `reaper_bridge::writeUsageExtState`; `ComponentState` bumped v10→**v11** (`instanceGuid` field); pre-v11 blobs mint guid on first publish.
 - `reasampler_editor` — VST3 `IPlugView` LICE editor shell: hosts a LICE-drawn child window; the Sample face is home and Browse is a modal picker over it. Split on the Sample face's BAND axis, mirroring the pure `sample_bands` allocator: `editor_session` (session/bridge state, caches, commit-and-reload), `editor_controls` (the ONE `faceLayout` band resolve every paint and hit-test path shares, the node-drag bounds, the value labels, and the per-instance controls the parameter set does not carry — the parameter-set binding itself is the pure `core/instrument/ui/deck_values` module this only adapts int ids onto), `editor_models` (the orthogonal half: which stored struct each transient editor selection names — the staged-envelope pack/unpack, the drawn contour, and the three velocity curves), then matching paint and input sets — `editor_paint`/`editor_input` (dispatch + drag router + hover dispatch), `_chrome`, `_waveform`, `_deck` — plus the two band-independent surfaces (`_browse` for the modal picker, `_curve` for the velocity-curve popup) and `editor_platform` (IPlugView/Win32 window plumbing). Shared internals in `editor_internal.h`, no TU of its own. Drop-onto-editor ingest is NOT shipped (deferred).
 - `reasampler_embed` — implements `IReaperUIEmbedInterface` so the instrument draws inline in the TCP/MCP without a plugin-owned HWND; delegates layout to `embed_strip`. A read-only readout: the loaded capture across the keyboard span with its root marked, plus the activity level. It takes no mouse input (there is nothing on the strip to select).
 - `editor_stroke` — the editor's LICE side of the analytic stroker: builds a coverage mask with the pure `core/ui/stroke_aa` and blends it into the bitmap ONCE, writing straight to the bitmap's bits (the arithmetic matches LICE's own mode-0 combine, so a stroke composites identically to every other kit draw). Every radial and spline stroke on the editor routes through `strokeArcAA` / `strokePolylineAA` / `strokeLineAA`. Holds the draw-thread-only scratch mask and arc point list — reuse, not a hidden dependency: threading a canvas through the eight paint sites would grow those signatures to carry an allocation detail. Deliberately does NOT touch `shell/panel/draw_kit`: the waveform stroke, the docked bank panel and the browse cards are out of this seam's blast radius.
+- `instrument_bake` — the instrument's half of the resample chain, on the UI thread: render the dialed sound through the pure `core/instrument/bake` modules, stage the WAV OUTSIDE the bank folder, publish one `rsbake_<guid>` request, invoke the extension's landing action SYNCHRONOUSLY, read the outcome back over the same key, then adopt + reset in one act. Two stack-RAII guards mirror `FxBypassGuard`'s discipline: the staged file and the request key are both cleared on every exit path, so a failed bake leaves no temp, no bank entry and no parameter reset. `bakeAvailable` is the affordance's paint gate.
 - `vst_entry` — VST3 entry point: `GetPluginFactory` export, class registration, channel-forked class UIDs.
 - `editor_internal.h` — INTERNAL shared helpers for the `reasampler_editor` TU family, included only by the editor's own shell TUs (`editor_session` / `editor_controls` / `editor_paint_*` / `editor_input_*` / `editor_platform`), never a public seam: the `Rect`↔kit adapters, small draw primitives (knob face / title band), label helpers, and the velocity-curve box derivation — the helpers more than one band TU needs. The deck's control ids, group ids and group composition are the pure `deck_groups` module's, not this file's. The piano-strip and root-key draws live in `editor_paint_chrome`, their only consumer, not here.
 - `reasampler_vst.h` — shared identity constants for the ReaSampler VST3 instrument (Phase S): the plugin's class UID (the channel-selected `Steinberg::FUID`, built from the FOREVER-FROZEN macros in `core/wire/reasampler_uid.h`), vendor name/URL/email, so the processor, factory, and editor agree. A class UID is FOREVER-STABLE once shipped — minted once, never regenerated. *(Newly authored per this dispatch's brief — no existing root-CLAUDE.md bullet; verified by reading `src/shell/instrument/reasampler_vst.h` directly.)*
 
 ## Gotchas
 
+- **The bake click only ARMS; the editor's sync tick runs it.** Calling
+  `Main_OnCommandEx` inline from `WM_LBUTTONDOWN` would run the extension's whole landing
+  nested inside a mouse handler with `SetCapture` held, while the invoked action re-points
+  the very instance whose frame is on the stack. Deferring by one tick is same-thread and
+  in-instance — it is NOT a cross-process poller/nonce handshake, and it must not grow into
+  one.
+- The bake's availability probe runs on the SAME tick that paints the button, so the
+  control can never be enabled on one tick and refuse on the next.
 - `editor_internal.h` is include-only — it has no TU of its own and must never become
   a public seam; only the `reasampler_editor` band-axis TUs include it.
 - **The editor window class carries `CS_DBLCLKS`, which REPLACES the second button-down of