Fix cross-rate Preserve splices, re-stamp on host-rate change, name the rate refusal

The splice crossfade now counts output frames and stops before the ring's far end (this also fixes a lap at matched rate). The search strides by the rate ratio. The editor takes its time base from its own decode. Same-rate output is pinned to hashes from before the change.

src/core/instrument/CLAUDE.md

@@ -178,15 +178,24 @@ voice reads SOURCE frames and emits OUTPUT frames, and `SampleData::sourceRateRa
 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`).
+  spline phase, the detected period, and the Preserve ring (`preserveWindowFrames`) with every
+  splice distance in it.
 - **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.
+  `SampleData::renderRate`), the filter solve, the live ramps, the declick, and the shifter's
+  splice crossfade (`PitchShifter::setSourceRateRatio`, which also strides the splice search to
+  a matched rate's cost). 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.
+- **That cost is asymmetric.** Nothing band-limits the read, so a file ABOVE the host rate
+  folds whatever it holds over the host's Nyquist into the audible band even at its root — the
+  aliasing a matched capture only meets when transposed up. A file BELOW the host rate is read
+  slower than one frame per frame and only images, the milder direction. Offline captures
+  render at the project rate (`shell/capture` pins `RENDER_SRATE`), so the exposed case is an
+  ingested high-rate file, or a host running below the rate a capture was made at.
 
 ### Live parameter delivery — a knob moves the note already sounding (settled 2026-07-30)