capture: refuse the multi-track ranged item render, silence the track's children and receives for it, and gate every exact-bounds capture on its frame count

src/shell/capture/CLAUDE.md

@@ -25,6 +25,18 @@ detail not covered there:
   resolved range (`core/capture/render_window`) and hands the answer to
   `sourceModeForScope` on `ResolvedSource`. Why, in
   `src/core/capture/CLAUDE.md`.
+- **A ranged item capture isolates TRACKS, not ITEMS.** Routing it through the
+  selected-tracks source widens what the render hears, and the two widenings are
+  answered differently. Folder children and receives are cut for the render's
+  duration (`render_isolation`) because they are tracks, and a recipe carrying
+  tracks can recompute that plan at replay time. An overlapping item on the source
+  track itself is NOT isolated: the recipe stores tracks and a range, never item
+  GUIDs, so a mute plan over items could not be replayed and the capture would stop
+  reproducing itself. Do not "fix" the second by muting items.
+- **`renderOffline` is the one seam both a fresh capture and a recipe replay
+  cross**, which is why the refusal and both transient guards live there rather
+  than in the action bodies — anything placed in `ResolveScopeSource` alone would
+  miss `RunRecaptureFromSource` entirely.
 - **FX-bypass guard ordering.** `scope_resolve` reads the M10 provenance-assembly
   inputs (track/item selection, FX-chain identity) BEFORE the FX-bypass guard
   neutralizes the in-scope chain — provenance must see the chain as it really is,
@@ -41,7 +53,8 @@ detail not covered there:
 
 - `capture` — two CONCRETE backends with deliberately different lifecycles (no shared interface — the former `ICaptureBackend` was deleted in Q-W3, T4-26: one deriver, zero polymorphic call sites): `OfflineRenderBackend` (deterministic default, synchronous) and `RealtimeRecordBackend` (async begin/tick/abort). Input: `CaptureRequest`. Output: finished file + populated `Sample` handed to `bank_model`.
 - `scope_resolve` (`shell/capture`) — scope/source resolution shared by every capture entry point (Q-W3 hoist out of `main.cpp`): razor-else-time range inference, selected-track/selected-item-owning-track collection with canonical GUIDs, and the M10 provenance-assembly inputs (read BEFORE the FX-bypass guard neutralizes the in-scope chain).
-- `render_selection` (`shell/capture`) — the transient track selection a selected-tracks render (`&128`) requires, as a stack RAII guard: REAPER prints whatever tracks are selected, so `renderOffline` makes the request's own tracks BE the selection for the render's duration and restores the user's set on every exit path. Engaged only for that source mode; a ranged item capture and re-capture-from-source both name tracks the user has not selected.
+- `render_selection` (`shell/capture`) — the transient track selection a selected-tracks render (`&128`) requires, as a stack RAII guard: REAPER prints whatever tracks are selected, so `renderOffline` makes the request's own tracks BE the selection for the render's duration and restores the user's set on every exit path. Engaged ONLY for that source mode, which leaves a stated residual: a `&32` selected-items render still prints whatever ITEMS the user has selected. Live captures are unaffected (that selection is the source), but a recipe replay of a `SelectedItems` capture renders against whatever happens to be selected then — the recipe stores tracks and a range, never item GUIDs, so this guard cannot close it. Filed in `docs/TODO.md`.
+- `render_isolation` (`shell/capture`) — the transient upstream silencing a ranged ITEM render needs, as a stack RAII guard alongside the two above: the selected-tracks source prints everything flowing INTO the track, so each direct folder child's `B_MAINSEND` and each of the track's receives' `B_MUTE` are cut for the render and restored on every exit path. Direct children only — a grandchild reaches the track through the child that owns it. The child-set walk is pure (`core/capture/track_topology`).
 - `capture_orchestrator` (`shell/capture`) — single-capture orchestration + the realtime/insert action bodies (Q-W3 hoist, T4-02): `renderOffline` (one offline render under the scope's FX-bypass guard), `captureAndIndexOne` (render + provenance stamp + bank add + tracking-ledger record, unpersisted), `RunCapture`/`RunCaptureItemAssign`, `RunCaptureRealtimeTrack`/`RunCancelRealtime` (the realtime action bodies — the in-flight state lives in `realtime_lifecycle`), and `RunInsertSelected` (the ONE deliberate exception to capture-never-places).
 - `bake_land` (`shell/capture`) — the EXTENSION's half of the resample chain: scans every open project tab for pending `rsbake_*` requests, lands the ones belonging to the project this session has loaded, and refuses the rest with `WrongProject` — one undo point for the batch, each answered over its own key inside the invoking instance's synchronous action call. It RENDERS NOTHING — the instrument already did, through its own engine in its own process, which is what makes the baked audio the sound the user approved and what keeps the voice engine out of the extension's link graph. Replace-vs-add comes from `tracking::resampleLanding`; a replace keeps the entry's id and slot and never deletes the superseded file. Hash-dedup applies on the add path only, before the disk write, matching `updateSampleInPlace`'s "an in-place refresh is not an insert". A refused index withdraws the bytes this call had just written — the self-cleanup carve-out from prune's deletion authority, stated in `prune_fs.cpp`'s header.
 - `capture_batch` (`shell/capture`) — the batch-capture family + re-capture-from-source (Q-W3 hoist, T4-02): `RunBatchCaptureItems` (one sample per selected item), `RunBatchCaptureRazor` (one sample per razor area), `RunRecaptureFromSource` (regenerate a provenanced sample from its recorded source's current state, bank-only). Every unit routes through `capture_orchestrator` so every precision invariant holds; persist is batched to one ext-state write per action.
@@ -60,3 +73,12 @@ detail not covered there:
 - `capture` and `capture_realtime_shell` deliberately share NO common interface with
   each other (the former `ICaptureBackend` was removed) — do not reintroduce one
   without a real second polymorphic call site.
+- **The selected-tracks render (`&128`) is read as emitting one file per selected
+  track** — the single-file bit is documented for item/razor sources only (SDK header
+  ~3041), and that is the whole basis for the reading; it is DAW-unverified. If it
+  holds, then since `RENDER_PATTERN` is one literal stem and success is a file-exists
+  check, N tracks would land one track's audio as a successful capture.
+  `renderOffline` refuses that shape for the RANGED ITEM capture only
+  (`render_settings::isMultiTrackRangedItemRender`). Track scope renders through the
+  same source with the same exposure and is deliberately untouched here — filed in
+  `docs/TODO.md`.