docs: record Ξ-W2-T1, the resample bake chain, and file its two deferrals

docs/TODO.md

@@ -270,6 +270,60 @@ decode; sounding voices are still destroyed across it, with no ghost-resurrectio
 a pre-v10 blob still lifts; and `getLatencySamples()` still derives from persisted state rather
 than from a transient the deactivate cleared.
 
+## `Sample::sourceMode` has no value meaning "produced by the instrument"
+
+**Context (what shipped — Ξ-W2-T1, resample-bake-chain).** A resample bake's landed
+`Sample` entry (`bake_land.cpp`) never sets `sourceMode`; it is left at the struct
+default (`SourceMode::MasterMix`) rather than recording that the entry's audio came
+from the instrument's own offline render, not from a capture backend.
+
+**The wart.** A baked capture is indistinguishable, by `sourceMode`, from a master-mix
+render — the bank has no way to tell "this file was produced by ReaSampler 9000" from
+"this file was rendered off the master bus."
+
+**Intended fix.** Add a `SourceMode` value for instrument-produced audio and set it at
+the one landing site.
+
+**The constraint the fix MUST handle.** `bank_model.cpp`'s deserializer rejects any
+`sourceMode` value outside `MasterMix(0)..Realtime(5)` by failing the whole bank
+blob's parse (`parseSample` returns `false`), not just that one field — so appending a
+new enumerator is a forward-incompatible bank-format change: an older extension build
+reading a newer project's bank would refuse to load it entirely. This needs its own
+decision (a version-gated field, or accepting the compatibility cost) rather than a
+one-line enum append.
+
+**Priority / risk.** Low / deferred. Logged at Ξ-W2-T1's review rather than folded in.
+
+**Done looks like.** A baked capture's `sourceMode` reads as instrument-produced, and
+the compatibility question (how an older build reads a bank containing the new value)
+is answered rather than left to fail closed by accident.
+
+## `instrument_bake` doubles peak memory on the WAV build
+
+**Context (what shipped — Ξ-W2-T1, resample-bake-chain).** `runBake` (`instrument_bake.cpp`)
+copies the render's interleaved `float` buffer (`BakeAudio::interleaved`, `AudioSample
+= float`) into a `std::vector<double>` before handing it to `buildFloat32Wav`, which
+takes doubles and narrows back to float for the bank's 32-bit-float WAV contract.
+
+**The wart.** The copy roughly doubles peak memory for the bake — an 8-byte double
+holding a value that started and ends as a 4-byte float — for the duration of the WAV
+build on a large bake.
+
+**Intended fix.** Either give `buildFloat32Wav` (or a sibling entry point) a
+`float`-input overload so the bake path narrows nothing it doesn't already own in
+`float`, or narrow lazily during the WAV build instead of pre-copying the whole
+buffer.
+
+**The constraint the fix MUST handle.** `buildFloat32Wav`'s `double` parameter is
+shared with every other caller in `core/capture/wav_codec`; a fix must not change
+those callers' contract or add a second WAV-building code path to maintain.
+
+**Priority / risk.** Low / deferred. Logged at Ξ-W2-T1's review; correctness is
+unaffected, only peak memory on a large bake.
+
+**Done looks like.** A bake's peak memory no longer includes a full double-precision
+copy of the rendered buffer, with `buildFloat32Wav`'s other callers unchanged.
+
 ## The deck layout rework — SPECCED, and the original shape SUPERSEDED
 
 **Status (2026-08-01): no longer a deferral. The design notes Daniel owed this entry have