fix(drop-fx): inject via .vstpreset + TrackFX_SetPreset (vst_chunk is REAPER-framed, raw bytes silently no-op); FX hotspot now prefix tcp.fx*/mcp.fx*/fx_*

CLAUDE.md

@@ -80,7 +80,7 @@ There is no hot-reload. Copy the built binary into REAPER's `UserPlugins/` folde
 - `tooltip` — pure tooltip placement + prefix-strip: strips the `ReaSampler:` display prefix from the registered action phrase; width clamped to the client rect.
 - `card_drag` — pure drag-gesture precedence + slot hit-test: leave-client → OS drag-out; other-bank → move/copy; same-bank → reorder / Alt-over-occupied → replace.
 - `card_meta` — pure card-metadata formatters: bars.beats.subdivisions and seconds.milliseconds; blank when the sample is unstamped.
-- `instrument_drop` — pure FX-button drop blob builder: constructs the base64-encoded vst_chunk blob needed to inject a pre-configured `reasampler_9000` instrument. All-or-nothing contract — caller rolls back via `TrackFX_Delete` on any failure.
+- `instrument_drop` — pure FX-drop payload builder: constructs a Steinberg-format `.vstpreset` image (channel-active class ID + the instrument's own component state, capture pre-selected) the shell applies via `TrackFX_SetPreset`; owns the `infoNamesFxHotspot` prefix classifier for `GetThingFromPoint` tokens. All-or-nothing contract — caller rolls back via `TrackFX_Delete` on any failure.
 - `assignment_request` — pure ingest-assign wire: typed request record carrying the drop payload from the `ingest` shell through to the VST3 bridge.
 
 **REAPER-facing shells:**
@@ -93,7 +93,7 @@ There is no hot-reload. Copy the built binary into REAPER's `UserPlugins/` folde
 - `provenance_shell` — FX-chain identity queries via `TrackFX_*`/`TakeFX_*` APIs; feeds the pure `provenance` fingerprint builder. Stamps `Sample.provenance` on capture; ambiguous/mixed cases record nothing conservatively.
 - `drag_out_win` — OS drag-out shell: Windows OLE `DoDragDrop`/`CF_HDROP`, copy-only (`DROPEFFECT_MOVE` not offered); macOS/Linux via `SWELL_InitiateDragDropOfFileList`.
 - `ingest` — ingest-through-the-bank shell on the EXTENSION side: three surfaces — (1) arrange capture→bank→assign (bindable action), (2) Media-Explorer import→bank→instrument on the selected track, (3) file drop onto the bank panel→bank only. Only surface (1) writes the `assignment_request` ext-state wire. **ingest NEVER inserts a timeline item.**
-- `instrument_drop_win` — FX-button drop shell: resolves a screen point to a track + TCP FX-button hotspot, then adds a ReaSampler 9000 instance and injects state via `TrackFX_SetNamedConfigParm` "vst_chunk". Exposes `loadInstrumentOntoTrack` (inner half, no own undo block) and `performInstrumentDrop` (wraps in its own undo block). **Never captures, never writes the bank, never inserts a timeline item.**
+- `instrument_drop_win` — FX-button drop shell: resolves a screen point to a track + FX-surface hotspot, then adds a ReaSampler 9000 instance and applies the dragged capture's state via a transient `.vstpreset` + `TrackFX_SetPreset` (the former `TrackFX_SetNamedConfigParm` "vst_chunk" write was silently unappliable for VST3). Exposes `loadInstrumentOntoTrack` (inner half, no own undo block) and `performInstrumentDrop` (wraps in its own undo block). **Never captures, never writes the bank, never inserts a timeline item.**
 - `draw_kit` — shared LICE draw shell: `fillSurface`, `drawButton`/`drawSlider`/`drawListRow`/`drawWaveform`, cached-font `text()`, full interaction-state model, double-buffer preserved. Consumes `theme` + `component_geometry`.
 - `actions` — registers the capture/placement/slot, Design View, multi-bank, and prune action families; routes each via the `command_id`/`gaccel`/`hookcommand` contract. **Every bank index verb wraps its mutation in a batched REAPER undo point (`Undo_BeginBlock2`/`EndBlock2`, `UNDO_STATE_MISCCFG`) so one bank operation is one Ctrl-Z.** The prune action (`BANK_PRUNE_FOLDER`) is **the ONLY file-deletion authority in the system**; it opens no undo point (file deletion is not REAPER-undoable).