feat(capture): bindable capture family — master/tracks/items/razor (M7)

Four wet capture actions route to OfflineRenderBackend (snapshot/restore
RENDER_*, 32-bit float), produce a Sample, add to the bank, persist. Pure
render_settings maps source mode to RENDER_SETTINGS and parses P_RAZOREDITS
(tested). No arrange insertion. True dry deferred to M10.

src/render_settings.h

@@ -0,0 +1,108 @@
+#pragma once
+// render_settings — the REAPER-free logic behind the M7 capture action family.
+//
+// PURE MODULE (CLAUDE.md §load-bearing split): NO REAPER types, NO SWELL, NO
+// vendor/ includes. Standard library only. The capture shell (capture.cpp) reads
+// the actual DAW state (time selection, selected tracks/items, razor strings) and
+// hands the raw values here so the three genuinely-pure, easy-to-get-wrong pieces
+// are unit-tested outside the DAW:
+//
+//   1. sourceMode -> the RENDER_SETTINGS integer bit value (wet only; M7 scope).
+//   2. a P_RAZOREDITS string -> the list of (start,end) ranges + their union bound.
+//   3. the capture-action table (id string, description, source mode, wet/dry) —
+//      the taxonomy, in one place so main.cpp iterates it instead of hand-listing.
+//
+// The RENDER_SETTINGS bit MEANINGS are transcribed verbatim from
+// reaper_plugin_functions.h line ~3041 (see kRender* constants); the CHOICE of
+// which bits each source mode sets is this module's logic and is tested.
+
+#include <string>
+#include <vector>
+
+#include "bank_model.h"  // SourceMode (pure enum)
+
+namespace reasampler {
+
+// --- RENDER_SETTINGS source/processing bits (verbatim from SDK header ~3041) --
+//
+// Only the bits M7 actually uses are named. Values are the documented bit
+// weights; the DOC of each is the SDK header's, not a guess.
+inline constexpr int kRenderMasterMix          = 0;      // (&(1|2))==0, no source bits
+inline constexpr int kRenderSelItems           = 32;     // &32   selected media items
+inline constexpr int kRenderSelItemsViaMaster  = 64;     // &64   selected media items via master
+inline constexpr int kRenderSelTracksViaMaster = 128;    // &128  selected tracks via master
+inline constexpr int kRenderRazorEdits         = 4096;   // &4096 render razor edits
+// NOTE: kRenderPreFaderStems (&8192) is NOT used in M7. REAPER offline render has
+// no true pre-FX "dry" bit. Pre-fader stems are post-FX/pre-fader-volume — an
+// approximation, not a dry capture. True pre-FX dry requires FX-bypass-around-
+// render or the M8 realtime pre-FX path; it will be designed with the M10 null
+// test. All M7 capture actions are wet-only.
+inline constexpr int kRenderSingleFile         = (4 << 16);  // items/razor -> one file
+
+// The RENDER_SETTINGS value for a given source mode. `supported` is false only
+// for SourceMode::Realtime (that is the M8 backend, not offline render).
+struct RenderSettingsChoice {
+    int  settings  = kRenderMasterMix;
+    bool supported = true;  // false => not an offline-render source in M7
+};
+
+// Maps a source mode to the wet RENDER_SETTINGS value for M7.
+// All M7 actions are wet-only (post-FX). `wetDry` is accepted but ignored for
+// the mapping — retained in CaptureRequest as the seam for future M10 dry work.
+//
+// CONFIRMED (SDK header ~3041):
+//   MasterMix / TimeSelection -> master mix (0).
+//   SelectedTracks            -> &128 selected tracks via master.
+//   SelectedItems             -> &32  | single-file (one wav, not one-per-item).
+//   RazorArea                 -> &4096| single-file.
+RenderSettingsChoice renderSettingsFor(SourceMode mode, double wetDry);
+
+// A single razor-edit area: a time range on one track (envelope GUID ignored —
+// M7 captures track-audio razor areas, not envelope lanes).
+struct RazorRange {
+    double startSeconds = 0.0;
+    double endSeconds   = 0.0;
+};
+
+// Parses ONE track's P_RAZOREDITS string (SDK header ~2899): space-separated
+// TRIPLES of <start> <end> <envGuidString>. The envelope GUID is "" (an empty
+// quoted string, i.e. the literal two chars `""`) for a track-audio area and a
+// GUID like {…} for an envelope-lane area.
+//
+// Returns only the track-audio ranges (envelope-lane triples are skipped — M7
+// renders track audio). Malformed/short trailing tokens are ignored, not fatal.
+// A range with end <= start is dropped (no negative/empty areas leak through).
+std::vector<RazorRange> parseRazorEdits(const std::string& razorString);
+
+// The union bound (min start, max end) of a set of razor ranges — the exact
+// window the offline render must cover so every area is inside the rendered file.
+// Returns {0,0} for an empty input (caller treats that as "no razor area").
+RazorRange razorUnionBounds(const std::vector<RazorRange>& ranges);
+
+// --- Capture-action taxonomy (the bindable set main.cpp registers) -----------
+//
+// One row per bindable action. All M7 rows are wet-only (post-FX). Tail is OFF
+// for every row (exact bounds); a tail-on variant is a later opt-in, YAGNI now.
+// Yields a bounded, discoverable set with NO dialogs (the tool's no-clutter ethos).
+//
+// commandString is FOREVER-STABLE (user keybindings key off it) — never change a
+// shipped value. baseName feeds the file stem (sanitized by capture_paths).
+// wetDry is retained as the M10 seam; all M7 rows set it to 1.0.
+struct CaptureActionDef {
+    const char* commandString;  // CEREBELLUM_REASAMPLER_… FOREVER-STABLE id string
+    const char* description;    // Actions-list label
+    const char* baseName;       // file-stem base for this capture
+    SourceMode  sourceMode;
+    double      wetDry;         // 1.0 (wet) for all M7 rows; seam for M10 dry
+};
+
+// The full M7 capture-action table. Iterated by main.cpp to register the family
+// and route each fired command back to its definition. Kept here (pure) so the
+// taxonomy is one testable list, not scattered registration code.
+//
+// Four wet-only rows: CAPTURE_MASTER, CAPTURE_TRACKS_WET, CAPTURE_ITEMS_WET,
+// CAPTURE_RAZOR_WET. Dry variants are deferred to M10 (null-test work) — see the
+// kRenderPreFaderStems note above for why offline dry is non-trivial.
+const std::vector<CaptureActionDef>& captureActionTable();
+
+} // namespace reasampler