Play cross-rate captures at their own pitch and length

The voice now converts the file's rate to the host's at note-on instead of assuming they match. Stage times resolve at the host rate, the filter solves at it, and the bake follows. Same-rate renders are unchanged bit for bit.

src/core/instrument/CLAUDE.md

@@ -170,6 +170,24 @@ pitch envelope/curve (AD?) which is off by default."*
 - **S15/S16 are Tier 0–1 engine features, not Tier 2/3** — do not let the held Tier-2
   feature list (velocity layers / round-robin / filter work) drive their build shape.
 
+### Two frame domains — a capture plays at its own rate in any host
+
+A capture's file rate and the host's are independent, and the engine never resamples: the
+voice reads SOURCE frames and emits OUTPUT frames, and `SampleData::sourceRateRatio`
+(`play_params.h`) is the one conversion between them, folded into the read, the Preserve feed and
+the shifter's tap at note-on.
+
+- **Source frames:** the PCM, the loop and its crossfade, the start point, the Trigger span, the
+  spline phase, the detected period, and the Preserve ring (`preserveWindowFrames`).
+- **Output frames (the host's):** every stage time in `SampleData::play` (resolved at
+  `SampleData::renderRate`), the filter solve, the live ramps and the declick. A source-offset
+  envelope converts through `stageFitRate`, which carries the ratio.
+- **Rejected alternative: resample at load.** It would round every loop point into the host
+  domain (detuning a single-cycle loop), force the editor and the bank intrinsics through a
+  conversion at every edge, and need a band-limited resampler in the core. The cost of the
+  chosen shape is that a mismatched capture's ROOT note is interpolated like any other repitched
+  note already is.
+
 ### Live parameter delivery — a knob moves the note already sounding (settled 2026-07-30)
 
 Daniel's ruling, verbatim: *"hell no, I was going to bring that up for the other envelopes. We
@@ -325,7 +343,7 @@ anything for a trigger shape.
 
 ### `map/`
 
-- `sample_map` — the bank blob → selected capture resolve, the channel policy (downmix / dual-mono / L-R split), `InstrumentParams` (the ONE parameter set: root/loop/start overrides, keyTrack, velocity curve, `PlaySeconds`), the single override-beats-intrinsic fold (`resolveCapture`, shared by the bank and refs paths so they cannot drift), and the `SampleData` build. **Wall-clock times stored as rate-free SECONDS, resolved against the live project rate — NO hardcoded sample rates in `src/`** (Daniel's standing ruling, load-bearing). Deliberately does NOT link the voice engine: the build's product is plain `SampleData`.
+- `sample_map` — the bank blob → selected capture resolve, the channel policy (downmix / dual-mono / L-R split), `InstrumentParams` (the ONE parameter set: root/loop/start overrides, keyTrack, velocity curve, `PlaySeconds`), the single override-beats-intrinsic fold (`resolveCapture`, shared by the bank and refs paths so they cannot drift), and the `SampleData` build. **Wall-clock times stored as rate-free SECONDS, resolved against the HOST rate the voice emits at (never the WAV's own — see "Two frame domains" above) — NO hardcoded sample rates in `src/`** (Daniel's standing ruling, load-bearing). Deliberately does NOT link the voice engine: the build's product is plain `SampleData`.
 - `play_seconds` — the stored, wall-clock-SECONDS value layer (`PlaySeconds` + `AdsrSeconds` / `AhdSeconds` / `PitchEnvSeconds` / `FilterSeconds`), header-only and split from `sample_map` so a consumer that only edits those values reaches them without the bank model and the WAV codec. `resolvePlay`, which turns them into the engine's frame domain, stays with the rest of the mapping.
 - `component_state_io` (`core/instrument/map`) — the `ComponentState` envelope + params-payload binary codec (envelope v1…v11, params payload v1…v16), split out of `sample_map` (Q-W2v, T4-13 ≡ T2-07) so BOTH artifacts can link the codec without the extension pulling in the whole voice engine to serialize one preset blob — the extension's `instrument_drop` and the instrument's processor read/write the identical bytes, so the cross-artifact contract cannot drift. Payload v1…v7 are the RETIRED per-zone lists: still read, lifting by adopting zone one's capture + parameters (that first zone is what the old first-match resolve actually played, so it is also what supersedes the envelope's stored selection id). Payload v9 appends the per-voice filter tail; a v8 blob is a strict prefix of it and lifts to the off/neutral filter default. Every tail since is a strict suffix on the same discipline — v10 the staged curves, v11 the loop crossfade, v12 the velocity→pitch curve, v13 the dual Staged/Spline state (the three contours, plus hard-flag tails for the three velocity curves — their v7/v9/v12 blocks are frozen at 16 bytes/point and had no room for a per-point flag), v14 the resample bake's Hold division, v15 the master-bus limiter enable, v16 the playback rate + the baseline pitch offset. v12 also RE-TAGS the y DOMAIN of one frozen slot inside the v9 filter tail — its velocity curve reads bipolar from v12 on, unipolar before — which needs no version branch, because a pre-v12 curve's y values are already valid bipolar ones; every other filter slot, `velAmount` included, keeps its meaning.
 - `params_payload` — the PARAMS-PAYLOAD half of that codec, split from the envelope half on the axis the format already has: the payload carries its own version and grows independently, so the two version ladders are two responsibilities. An INTERNAL seam — the public entry points stay `serialize`/`deserializeComponentState`. The prose ladder and every version constant stay in `component_state_io.h`, their one home.