refactor(capture): expose offline tail as docked-panel toggle

Replace the ...-with-tail variant actions with a pure tail_control module +
a docked-panel footer toggle (Off/Auto/Manual) read by CAPTURE_ITEM/TRACK.
Default None (byte-identical); Manual fixed 2s, in-memory session lifetime.
Tail mechanism unchanged; retired the variant ids.

CMakeLists.txt

@@ -96,6 +96,18 @@ add_library(render_settings STATIC src/render_settings.cpp)
 target_include_directories(render_settings PUBLIC src)
 target_link_libraries(render_settings PUBLIC bank_model)
 
+# ---------------------------------------------------------------------------
+# 2f') Pure tail_control library — NO REAPER, NO SWELL. The docked bank_panel's
+#      tail-mode toggle logic (T1 exposure): TailSetting state, cycle order
+#      (None->Auto->Manual->None), the manual-length clamp to the 8 s cap, and the
+#      toggle label text. Split out so the toggle's cycle/clamp/label is unit-tested
+#      outside the DAW; the bank_panel footer that draws it + routes clicks is
+#      DAW-verified. Depends on render_settings for the pure TailMode enum + caps.
+# ---------------------------------------------------------------------------
+add_library(tail_control STATIC src/tail_control.cpp)
+target_include_directories(tail_control PUBLIC src)
+target_link_libraries(tail_control PUBLIC render_settings)
+
 # ---------------------------------------------------------------------------
 # 2g) Pure realtime_record library — NO REAPER, NO SWELL. The M8 realtime-record
 #     logic: capture scope + FX-tap point -> I_RECMODE / I_RECMODE_FLAGS values,
@@ -148,6 +160,10 @@ add_executable(render_settings_tests tests/test_render_settings.cpp)
 target_link_libraries(render_settings_tests PRIVATE render_settings)
 add_test(NAME render_settings_tests COMMAND render_settings_tests)
 
+add_executable(tail_control_tests tests/test_tail_control.cpp)
+target_link_libraries(tail_control_tests PRIVATE tail_control)
+add_test(NAME tail_control_tests COMMAND tail_control_tests)
+
 add_executable(realtime_record_tests tests/test_realtime_record.cpp)
 target_link_libraries(realtime_record_tests PRIVATE realtime_record)
 add_test(NAME realtime_record_tests COMMAND realtime_record_tests)
@@ -183,7 +199,7 @@ add_library(reaper_reasampler MODULE
     src/track_guid.cpp
     src/actions.cpp
 )
-target_link_libraries(reaper_reasampler PRIVATE bank_model capture_paths peaks bank_grid mode_switch view_mode_model insert_plan render_settings realtime_record)
+target_link_libraries(reaper_reasampler PRIVATE bank_model capture_paths peaks bank_grid mode_switch view_mode_model insert_plan render_settings tail_control realtime_record)
 target_include_directories(reaper_reasampler PRIVATE ${SDK_INC} ${WDL_INC})
 set_target_properties(reaper_reasampler PROPERTIES PREFIX "" OUTPUT_NAME "reaper_reasampler")
 

docs/product/capture-tail.md

@@ -384,14 +384,18 @@ Neither is in scope now; both are single-constant seams so promotion is cheap.
   trailing edge, and the tail is appended after `ENDPOS`. But a range that itself
   ends in near-silence before a loud transient is the edge case to check the trim
   doesn't over-eat.)
-- **Auto as the action default?** Should the two shipped capture actions
-  (`CAPTURE_ITEM` / `CAPTURE_TRACK`, currently all TailMode::None
-  per `render_settings.cpp §captureActionTable`) flip to Auto tail by default once
-  this ships, or should tail be a separate action variant / a modifier? Product call
-  for Daniel. **Leaning:** a per-action-family toggle or a paired "…​with tail"
-  variant rather than silently changing the existing actions' behavior — the current
-  exact-bounds default is a documented contract and some captures (chops, wavetable
-  grabs) want no tail. Not blocking the offline implementation; the request-level
-  contract (three tail states) is independent of which action sets which.
+- **Auto as the action default? — DECIDED (2026-07-23).** The two shipped capture
+  actions (`CAPTURE_ITEM` / `CAPTURE_TRACK`) stay `TailMode::None` by default; the
+  tail mode is exposed as a **settings toggle in the docked bank panel** (None / Auto
+  / Manual — the footer strip, `bank_panel.cpp` + pure `tail_control`), and the plain
+  capture actions READ that toggle when building the `CaptureRequest`. Chosen over the
+  earlier "…with tail" paired-action lean: one toggle covers all three states without
+  doubling the action count, and the exact-bounds contract still holds because the
+  toggle defaults to None. The setting is an extension-session setting (default None;
+  persists across project loads and panel open/close within a REAPER session; resets to
+  None only on extension unload — i.e. fresh REAPER session; project persistence across
+  REAPER restarts is a follow-on). Manual ships a fixed 2 s default; a
+  fine-adjust affordance (+/- click zones or scroll) is a follow-on. The verify /
+  null-test capture still always runs `TailMode::None` regardless of the toggle.
 - **Realtime tail sequencing.** Confirmed a **follow-on** to the offline tail — do
   not block offline on it. Filed as a separate PLAN point.

src/bank_panel.cpp

@@ -42,6 +42,7 @@
 #include "mode_switch.h"
 #include "peaks.h"
 #include "persist.h"
+#include "tail_control.h"  // TailSetting, cycleTailMode, tailToggleLabel (pure)
 #include "view.h"  // applyMode — the D2/D4 mode-activation entrypoint the switch fires
 
 // SWELL / LICE. On macOS/Linux SWELL is provided by the host (SWELL_PROVIDED_BY_APP);
@@ -134,6 +135,20 @@ const LICE_pixel kColSegBorder     = LICE_RGBA(70, 70, 76, 255);   // segment di
 const COLORREF kRgbSegText       = RGB(170, 170, 176);  // inactive label
 const COLORREF kRgbSegActiveText = RGB(220, 235, 228);  // active label
 
+// --- Tail-mode footer (T1 exposure) -------------------------------------------
+// A fixed-height strip at the BOTTOM of the client area holding the tail-mode
+// toggle ("Tail: Off / Auto / Manual"). Clicking anywhere in it cycles the mode
+// (None -> Auto -> Manual -> None). Display/settings only: it mutates the panel's
+// in-memory tail setting the plain capture actions read — NEVER the project/bank/
+// arrange. The cycle/label logic is the pure tail_control module; only the draw +
+// click routing is here. The grid viewport is shortened by this strip's height so
+// cells never draw under it.
+constexpr int kFooterHeight = 26;  // px; fixed strip at the bottom
+
+const LICE_pixel kColFooterBg     = LICE_RGBA(20, 20, 22, 255);   // footer strip fill
+const LICE_pixel kColFooterBorder = LICE_RGBA(70, 70, 76, 255);   // top divider
+const COLORREF   kRgbFooterText   = RGB(190, 205, 198);           // toggle label
+
 // --- Panel state --------------------------------------------------------------
 
 // A computed thumbnail: the per-channel envelope at a known width. Held in the
@@ -173,6 +188,12 @@ struct PanelState {
     // clear the selection rather than risk indices pointing past the new count.
     int selItemCount = 0;
 
+    // --- Tail-mode toggle (T1 exposure) ---------------------------------------
+    // The current tail setting the plain capture actions read (bankPanelTailSetting).
+    // Default None (exact bounds). In-memory only — resets on panel teardown; project
+    // persistence is a noted follow-on. Mutated ONLY by a click in the footer strip.
+    TailSetting tail;
+
     // --- Audition preview (Wave B) --------------------------------------------
     //
     // The stock preview register we hand to PlayPreview/StopPreview. Its cs/mutex
@@ -424,6 +445,45 @@ void drawModeSwitch(LICE_IBitmap* bmp, int w) {
     }
 }
 
+// The tail-toggle footer rect for a client of width `w` and height `h`: the
+// full-width strip of fixed height pinned to the BOTTOM. A RECT (not HeaderRect)
+// since the whole strip is one hit target — a click anywhere in it cycles the mode.
+// Shared by paint and click routing so both agree on the band. Degenerate (empty)
+// when the client is too short to host it above the header.
+RECT panelFooter(int w, int h) {
+    RECT rc{};
+    rc.left = 0;
+    rc.right = w;
+    rc.top = h - kFooterHeight;
+    rc.bottom = h;
+    // Clamp so the footer never rides up into (or above) the header band on a very
+    // short panel — it collapses to empty rather than overlapping the mode switch.
+    if (rc.top < kHeaderHeight) rc.top = rc.bottom;  // empty: top == bottom
+    return rc;
+}
+
+// Draws the tail-mode toggle into the footer strip: a filled band, a top divider,
+// and the current mode's label ("Tail: Off / Auto / Manual") from the pure
+// tail_control module. READ-ONLY: reads g_panel.tail; the click handler mutates it.
+void drawTailFooter(LICE_IBitmap* bmp, int w, int h) {
+    const RECT f = panelFooter(w, h);
+    if (f.top >= f.bottom) return;  // no room — skip (short panel)
+
+    LICE_FillRect(bmp, f.left, f.top, w, kFooterHeight, kColFooterBg, 1.0f, 0);
+    // Top divider so the strip reads as distinct from the grid above it.
+    LICE_Line(bmp, f.left, f.top, f.right, f.top, kColFooterBorder, 1.0f, 0, false);
+
+    HDC dc = bmp->getDC();
+    if (!dc) return;
+    const std::string label = tailToggleLabel(g_panel.tail);
+    RECT rc = f;
+    rc.left += 8;  // small left pad so the label is not flush against the edge
+    SetTextColor(dc, kRgbFooterText);
+    SetBkMode(dc, TRANSPARENT);
+    DrawText(dc, label.c_str(), -1, &rc,
+             DT_LEFT | DT_VCENTER | DT_SINGLELINE | DT_END_ELLIPSIS);
+}
+
 // The cell rects for the panel's CURRENT client width and bank size, translated
 // DOWN by the header height so the grid sits below the mode switch. Both paint and
 // mouse hit-testing call this so they share identical geometry (no drift between
@@ -469,11 +529,15 @@ void paintPanel(HWND hwnd, HDC hdc) {
         // Draw each cell's thumbnail. Inner drawable width == cell width - inset;
         // compute the envelope at the cell's inner column count so bins map 1:1.
         const int binWidth = kGrid.cellWidth - 4;
+        // Cells must not draw under the footer strip: the visible grid stops at the
+        // footer top (or the client bottom when the panel is too short for a footer).
+        const RECT footer = panelFooter(w, h);
+        const int gridBottom = footer.top < footer.bottom ? footer.top : h;
         for (std::size_t i = 0; i < rects.size(); ++i) {
             const CellRect& rect = rects[i];
-            // Skip cells entirely below the viewport (Wave A has no scroll; this
-            // just avoids computing thumbnails that cannot be seen).
-            if (rect.y >= h) continue;
+            // Skip cells entirely below the visible grid area (Wave A has no scroll;
+            // this just avoids computing thumbnails that cannot be seen).
+            if (rect.y >= gridBottom) continue;
             const int idx = static_cast<int>(i);
             const bool selected = g_panel.selection.contains(idx);
             const bool focused = g_panel.selection.focus == idx;
@@ -482,9 +546,10 @@ void paintPanel(HWND hwnd, HDC hdc) {
         }
     }
 
-    // The mode switch draws LAST so its header band overlays the top of the grid /
-    // empty-state area regardless of which branch ran above.
+    // The mode switch and tail footer draw LAST so their bands overlay the top/bottom
+    // of the grid / empty-state area regardless of which branch ran above.
     drawModeSwitch(&bmp, w);
+    drawTailFooter(&bmp, w, h);
 
     BitBlt(hdc, 0, 0, w, h, bmp.getDC(), 0, 0, SRCCOPY);
 }
@@ -675,6 +740,23 @@ void handleClick(int x, int y) {
         }
     }
 
+    // Tail-mode footer: a click anywhere in the bottom strip cycles the tail mode
+    // (None -> Auto -> Manual -> None) and repaints. Settings-only — it mutates the
+    // panel's in-memory tail setting the capture actions read, and NOTHING in the
+    // project/bank/arrange. Checked before the grid so a footer click never selects.
+    {
+        RECT cr{};
+        GetClientRect(g_panel.hwnd, &cr);
+        const int w = cr.right - cr.left;
+        const int h = cr.bottom - cr.top;
+        const RECT f = panelFooter(w, h);
+        if (f.top < f.bottom && x >= f.left && x < f.right && y >= f.top && y < f.bottom) {
+            g_panel.tail.mode = cycleTailMode(g_panel.tail.mode);
+            invalidatePanel();
+            return;  // footer click consumed; do NOT fall through to grid selection
+        }
+    }
+
     const std::vector<CellRect> rects = panelRects();
     const int hit = hitTestCell(x, y, rects);
     const int count = bankItemCount();
@@ -906,6 +988,17 @@ void bankPanelRefresh() {
         InvalidateRect(g_panel.hwnd, nullptr, FALSE);
 }
 
+TailSetting bankPanelTailSetting() {
+    // In-memory for the extension's lifetime (g_panel is static): the toggle's mode
+    // survives panel open/close and bank changes, and resets to the default None only
+    // on extension unload. Persistence across project reload is a noted follow-on.
+    // manualMs is clamped here so a caller always receives a within-cap length, even
+    // if a future fine-adjust UI stored an over-cap value.
+    TailSetting s = g_panel.tail;
+    s.manualMs = clampManualMs(s.manualMs);
+    return s;
+}
+
 void bankPanelShutdown() {
     closePanel();              // stops audition + destroys the window
     deinitPreview();           // destroy the preview lock (after the last stop)

src/bank_panel.h

@@ -13,6 +13,8 @@
 #include <string>
 #include <vector>
 
+#include "tail_control.h"  // TailSetting — the panel's tail-mode toggle state
+
 namespace reasampler {
 
 class ReaSamplerSession;
@@ -48,6 +50,17 @@ std::vector<std::string> bankPanelSelectedSampleIds();
 // reflected without the panel diffing the bank itself.
 void bankPanelRefresh();
 
+// The panel's current tail-mode setting (mode + Manual length), read by the plain
+// CAPTURE_ITEM / CAPTURE_TRACK actions when building a CaptureRequest so a capture
+// applies whatever the panel toggle is set to. Default None (exact bounds) — a
+// capture with no explicit choice stays byte-identical to today. Extension-session
+// setting: persists across project loads and panel open/close within a REAPER session;
+// resets to None only when the extension unloads (fresh REAPER session). Project
+// persistence across REAPER restarts is a noted follow-on.
+// Safe to call before the panel has ever opened (returns the default). READ of panel
+// state only; the toggle is mutated by a click inside the panel, never here.
+TailSetting bankPanelTailSetting();
+
 // Tears the panel down on extension unload: destroys the window and releases any
 // cached thumbnails / PCM handles. Mirror of bankPanelInit; safe if never opened.
 void bankPanelShutdown();

src/main.cpp

@@ -69,12 +69,17 @@ static std::vector<gaccel_register_t>  g_captureAccels;
 //   * CAPTURE_MASTER and CAPTURE_MASTER_REALTIME — the master offline scope and the
 //     master realtime action are REMOVED (capture is now item + track only; realtime
 //     taps the selected track). Their shipped ids are retired so old keybindings clear.
+//   * CAPTURE_ITEM_TAIL and CAPTURE_TRACK_TAIL — the former per-action tail variants
+//     are REMOVED; tail is now a panel-setting toggle, not a paired action. Retired so
+//     old keybindings clear.
 static const char* const kRetiredCaptureCmdStrings[] = {
     "CEREBELLUM_REASAMPLER_CAPTURE_TRACKS_WET",
     "CEREBELLUM_REASAMPLER_CAPTURE_ITEMS_WET",
     "CEREBELLUM_REASAMPLER_CAPTURE_RAZOR_WET",
     "CEREBELLUM_REASAMPLER_CAPTURE_MASTER",
     "CEREBELLUM_REASAMPLER_CAPTURE_MASTER_REALTIME",
+    "CEREBELLUM_REASAMPLER_CAPTURE_ITEM_TAIL",
+    "CEREBELLUM_REASAMPLER_CAPTURE_TRACK_TAIL",
 };
 
 // Command id for "ReaSampler: toggle bank panel" (M5). FOREVER-STABLE string.
@@ -505,13 +510,19 @@ static void RunCapture(const reasampler::CaptureActionDef& def)
         return;
     }
 
+    // The tail mode is a PANEL SETTING (docked bank panel's toggle), not a per-action
+    // variant: the plain capture actions apply whatever the panel is set to. Default
+    // is None (exact bounds / byte-identical to today) until the user opts in via the
+    // toggle. tailMs is meaningful only for Manual and is pre-clamped by the panel.
+    const reasampler::TailSetting tail = reasampler::bankPanelTailSetting();
+
     reasampler::CaptureRequest req;
     req.sourceMode   = reasampler::sourceModeForScope(def.scope);
     req.startSeconds = src.startSeconds;    // exact bounds — no rounding
     req.endSeconds   = src.endSeconds;
     req.wetDry       = 1.0;                 // wet post the FX left enabled by the scope
-    req.tailMode     = def.tailMode;        // None (exact bounds) or Auto ("…with tail" variant)
-    req.tailMs       = 0.0;                 // Manual-only; no Manual action yet (future config/UI)
+    req.tailMode     = tail.mode;           // None / Auto / Manual, from the panel toggle
+    req.tailMs       = tail.manualMs;       // Manual-only (clamped); ignored for None/Auto
     req.sampleRate   = 0;                   // follow project rate
     req.channelCount = 2;
     req.bitDepth     = reasampler::WavBitDepth::Float32;  // deterministic, no dither

src/render_settings.cpp

@@ -179,38 +179,25 @@ RazorRange razorUnionBounds(const std::vector<RazorRange>& ranges) {
 }
 
 const std::vector<CaptureActionDef>& captureActionTable() {
-    // Built once (function-local static): two SCOPE actions x two tail variants.
-    // The None rows are exact bounds (byte-identical to today); the …_TAIL rows are
-    // the paired TailMode::Auto "…with tail" variants (Daniel's lean over silently
-    // flipping the exact-bounds default — spec §Open questions). Ids are FOREVER-
-    // STABLE — never edit a shipped string. Each action infers its range
-    // (razor-else-time) at fire time and enforces its FX-scope invariant via
-    // fxBypassPlanFor. The M7 CAPTURE_TRACKS_WET / CAPTURE_ITEMS_WET /
-    // CAPTURE_RAZOR_WET ids are RETIRED (mirror-unregistered in main.cpp); the
-    // CAPTURE_MASTER scope action is REMOVED (its id is likewise mirror-
-    // unregistered) — to capture the master you render a track.
+    // Built once (function-local static): two SCOPE actions, item + track. Both
+    // exact bounds by default; the tail mode a capture applies is read from the
+    // docked-panel setting at fire time (tail_control + bank_panel), so tail is NOT
+    // a per-action variant. Ids are FOREVER-STABLE — never edit a shipped string.
+    // Each action infers its range (razor-else-time) at fire time and enforces its
+    // FX-scope invariant via fxBypassPlanFor. The M7 CAPTURE_TRACKS_WET /
+    // CAPTURE_ITEMS_WET / CAPTURE_RAZOR_WET ids are RETIRED (mirror-unregistered in
+    // main.cpp); the CAPTURE_MASTER scope action is REMOVED (its id is likewise
+    // mirror-unregistered) — to capture the master you render a track.
     static const std::vector<CaptureActionDef> table = {
-        // Item scope, exact bounds — item/take FX only.
+        // Item scope — item/take FX only.
         {"CEREBELLUM_REASAMPLER_CAPTURE_ITEM",
          "ReaSampler: capture selected item(s)", "item",
-         CaptureScope::Item, TailMode::None},
+         CaptureScope::Item},
 
-        // Track scope, exact bounds — item FX + the track's own FX.
+        // Track scope — item FX + the track's own FX.
         {"CEREBELLUM_REASAMPLER_CAPTURE_TRACK",
          "ReaSampler: capture selected track(s)", "track",
-         CaptureScope::Track, TailMode::None},
-
-        // Item scope with Auto tail — captures the take-FX decay past the range end,
-        // trimmed to -72 dB. NEW forever-stable id.
-        {"CEREBELLUM_REASAMPLER_CAPTURE_ITEM_TAIL",
-         "ReaSampler: capture selected item(s) with tail", "item",
-         CaptureScope::Item, TailMode::Auto},
-
-        // Track scope with Auto tail — captures the track's own reverb/delay decay
-        // past the range end, trimmed to -72 dB. NEW forever-stable id.
-        {"CEREBELLUM_REASAMPLER_CAPTURE_TRACK_TAIL",
-         "ReaSampler: capture selected track(s) with tail", "track",
-         CaptureScope::Track, TailMode::Auto},
+         CaptureScope::Track},
     };
     return table;
 }

src/render_settings.h

@@ -89,7 +89,7 @@ double autoTrimEndRatio();
 //   None   — exact bounds, no tail. Byte-identical to the pre-tail capture. The
 //            default and the ONLY mode for null-test / verify captures.
 //   Auto   — generous 8 s tail then trim trailing silence to -72 dB (surgical
-//            normalize). The user-facing "…with tail" default.
+//            normalize). The user-facing tail-on option (panel toggle).
 //   Manual — a fixed tail length (clamped to the 8 s cap), no trim.
 enum class TailMode {
     None,
@@ -213,13 +213,11 @@ RazorRange razorUnionBounds(const std::vector<RazorRange>& ranges);
 
 // --- Capture-action taxonomy (the bindable set main.cpp registers) -----------
 //
-// One row per bindable SCOPE action. Two scopes (item / track), each in two tail
-// variants: an exact-bounds row (TailMode::None) and a paired "…with tail" row
-// (TailMode::Auto). The range each captures (razor-else-time) is inferred at fire
-// time, not a mode. The tail variants are additive — the None rows keep their
-// documented exact-bounds contract byte-for-byte; the Auto variants are a separate
-// opt-in action rather than a silent default flip (Daniel's lean, spec §Open
-// questions). Bounded, discoverable, NO dialogs (the tool's no-clutter ethos).
+// One row per bindable SCOPE action: item and track. The range each captures
+// (razor-else-time) is inferred at fire time, not a mode. TAIL is NOT a per-action
+// variant — the tail MODE (None/Auto/Manual) is a panel SETTING the capture reads
+// at fire time (see tail_control + bank_panel), so a single pair of actions covers
+// every tail state. Bounded, discoverable, 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).
@@ -228,17 +226,16 @@ struct CaptureActionDef {
     const char*  description;    // Actions-list label
     const char*  baseName;       // file-stem base for this capture
     CaptureScope scope;          // FX scope (item / track)
-    TailMode     tailMode;       // None (exact bounds) or Auto ("…with tail")
 };
 
 // The 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 rows: CAPTURE_ITEM / CAPTURE_TRACK (exact bounds, TailMode::None) plus the
-// paired CAPTURE_ITEM_TAIL / CAPTURE_TRACK_TAIL variants (TailMode::Auto). There is
-// no master capture — to capture the master you render a track. Razor is an inferred
-// range, not a mode, and each scope enforces its FX-scope invariant via fxBypassPlanFor.
+// Two rows: CAPTURE_ITEM / CAPTURE_TRACK. There is no master capture — to capture
+// the master you render a track. Razor is an inferred range, not a mode, and each
+// scope enforces its FX-scope invariant via fxBypassPlanFor. The tail mode each
+// capture applies is read from the docked-panel setting, not baked into the row.
 const std::vector<CaptureActionDef>& captureActionTable();
 
 } // namespace reasampler

src/tail_control.cpp

@@ -0,0 +1,33 @@
+// tail_control — pure implementation. See tail_control.h. NO REAPER / SWELL / vendor.
+
+#include "tail_control.h"
+
+#include <algorithm>
+
+namespace reasampler {
+
+TailMode cycleTailMode(TailMode current) {
+    switch (current) {
+        case TailMode::None:   return TailMode::Auto;
+        case TailMode::Auto:   return TailMode::Manual;
+        case TailMode::Manual: return TailMode::None;
+    }
+    return TailMode::None;  // unreachable for a valid enum; fail to the safe default
+}
+
+double clampManualMs(double manualMs) {
+    // Same runaway guard the pure tailRenderSettingsFor applies to Manual: floor a
+    // negative request to 0, cap at the 8 s ceiling.
+    return std::clamp(manualMs, 0.0, kMaxTailMs);
+}
+
+std::string tailToggleLabel(const TailSetting& setting) {
+    switch (setting.mode) {
+        case TailMode::None:   return "Tail: Off";
+        case TailMode::Auto:   return "Tail: Auto";
+        case TailMode::Manual: return "Tail: Manual";
+    }
+    return "Tail: Off";  // unreachable for a valid enum; fail to the safe default
+}
+
+} // namespace reasampler

src/tail_control.h

@@ -0,0 +1,49 @@
+#pragma once
+// tail_control — the REAPER-free logic behind the docked bank_panel's tail-mode
+// toggle. The panel shell (bank_panel.cpp) owns the SWELL window, LICE drawing, and
+// click hit-testing; what is NOT DAW-bound — the cycle order, the manual-length
+// clamp, and the toggle's label text — lives here so it is unit-tested outside the
+// DAW (CLAUDE.md §load-bearing split). Mirror of bank_grid / mode_switch.
+//
+// PURE MODULE: NO REAPER types, NO SWELL, NO vendor/ includes. Standard library
+// only (plus render_settings for the pure TailMode enum). Builds and unit-tests
+// without REAPER.
+
+#include <string>
+
+#include "render_settings.h"  // TailMode (pure enum) — the three-state tail contract
+
+namespace reasampler {
+
+// The Manual-mode starting length. 2 s is a musically useful default tail (a bar of
+// reverb throw at a moderate tempo) that is well under the 8 s cap. A fine-adjust UI
+// (+/- click zones or scroll) is a noted follow-on; this pass ships a fixed default.
+inline constexpr double kDefaultManualTailMs = 2000.0;
+
+// The panel's current tail setting: the mode plus the length used ONLY when the
+// mode is Manual. Held as in-memory panel/session state (bank_panel.cpp), default
+// None so a capture with no explicit choice stays exact-bounds / byte-identical to
+// today. `manualMs` is a stored default a future fine-adjust UI can tune; it is
+// clamped to the 8 s cap (kMaxTailMs) before it ever reaches a CaptureRequest.
+struct TailSetting {
+    TailMode mode     = TailMode::None;
+    double   manualMs = kDefaultManualTailMs;
+};
+
+// Cycles the tail mode: None -> Auto -> Manual -> None. Pure so the wrap order is
+// pinned by a test and the panel's click handler owns no enum arithmetic of its own.
+// An out-of-range value (unreachable for a valid enum) cycles back to None.
+TailMode cycleTailMode(TailMode current);
+
+// The effective manual length a Manual capture uses: `manualMs` clamped to
+// [0, kMaxTailMs] (the runaway guard the pure tailRenderSettingsFor also applies).
+// Exposed so the panel can show the clamped value and main.cpp hands a pre-clamped
+// tailMs into the CaptureRequest. Meaningful only for TailMode::Manual.
+double clampManualMs(double manualMs);
+
+// The toggle's label for a setting, e.g. "Tail: Off", "Tail: Auto", "Tail: Manual".
+// (Manual omits the length here — the panel is unobtrusive; a length readout can be
+// added with the fine-adjust follow-on.) Pure so the exact strings are test-pinned.
+std::string tailToggleLabel(const TailSetting& setting);
+
+} // namespace reasampler

tests/test_render_settings.cpp

@@ -216,17 +216,16 @@ static void testTrackScopeKeepsSelfBypassesAncestorsAndMaster() {
     CHECK(p.bypassMaster);         // no master FX
 }
 
-// --- captureActionTable: the scope x tail-variant taxonomy -------------------
+// --- captureActionTable: the scope taxonomy ----------------------------------
 
-static void testTableHasScopeAndTailVariants() {
+static void testTableHasBothScopes() {
     const auto& table = captureActionTable();
-    // Four rows: item/track x (None exact-bounds, Auto "…with tail"). No master scope.
-    CHECK(table.size() == 4);
+    // Two rows: item + track. No master scope, and NO tail variants — tail is a
+    // panel setting the capture reads at fire time, not a per-action row.
+    CHECK(table.size() == 2);
 
     std::set<std::string> ids;
-    // Count each (scope, tailMode) pairing so we assert the FULL matrix is present,
-    // not merely that some item + some track row exist.
-    int itemNone = 0, itemAuto = 0, trackNone = 0, trackAuto = 0;
+    int item = 0, track = 0;
     for (const auto& def : table) {
         // Every id is a non-empty CEREBELLUM_REASAMPLER_ string and is UNIQUE
         // (duplicate ids would collide on registration).
@@ -235,38 +234,26 @@ static void testTableHasScopeAndTailVariants() {
         CHECK(ids.insert(id).second);  // false if duplicate
         // Every scope resolves to a supported offline source.
         CHECK(renderSettingsFor(sourceModeForScope(def.scope), 1.0).supported);
-        // Tail variants only ever ship None or Auto (Manual has no dedicated action yet).
-        CHECK(def.tailMode == TailMode::None || def.tailMode == TailMode::Auto);
 
-        if (def.scope == CaptureScope::Item  && def.tailMode == TailMode::None) ++itemNone;
-        if (def.scope == CaptureScope::Item  && def.tailMode == TailMode::Auto) ++itemAuto;
-        if (def.scope == CaptureScope::Track && def.tailMode == TailMode::None) ++trackNone;
-        if (def.scope == CaptureScope::Track && def.tailMode == TailMode::Auto) ++trackAuto;
+        if (def.scope == CaptureScope::Item)  ++item;
+        if (def.scope == CaptureScope::Track) ++track;
     }
-    // Exactly one row per (scope, tail) cell — the full 2x2 matrix, no dupes/gaps.
-    CHECK(itemNone == 1);
-    CHECK(itemAuto == 1);
-    CHECK(trackNone == 1);
-    CHECK(trackAuto == 1);
+    // Exactly one row per scope — no dupes, no gaps, no tail variants.
+    CHECK(item == 1);
+    CHECK(track == 1);
 }
 
-static void testTailVariantIdsAreDistinctFromExactRows() {
-    // The …_TAIL variants must be NEW forever-stable ids, not a rename of the exact
-    // rows (renaming would break shipped keybindings on the exact-bounds actions).
+static void testScopeActionIdsAreTheShippedStrings() {
+    // Pin the shipped CAPTURE_ITEM / CAPTURE_TRACK ids so a future edit that silently
+    // changes them (breaking user keybindings) fails the gate.
     const auto& table = captureActionTable();
-    std::string itemNoneId, itemAutoId, trackNoneId, trackAutoId;
+    std::string itemId, trackId;
     for (const auto& def : table) {
-        if (def.scope == CaptureScope::Item  && def.tailMode == TailMode::None) itemNoneId  = def.commandString;
-        if (def.scope == CaptureScope::Item  && def.tailMode == TailMode::Auto) itemAutoId  = def.commandString;
-        if (def.scope == CaptureScope::Track && def.tailMode == TailMode::None) trackNoneId = def.commandString;
-        if (def.scope == CaptureScope::Track && def.tailMode == TailMode::Auto) trackAutoId = def.commandString;
+        if (def.scope == CaptureScope::Item)  itemId  = def.commandString;
+        if (def.scope == CaptureScope::Track) trackId = def.commandString;
     }
-    // The exact-bounds ids are the shipped CAPTURE_ITEM / CAPTURE_TRACK strings —
-    // pin them so a future edit that silently changes them fails the gate.
-    CHECK(itemNoneId  == "CEREBELLUM_REASAMPLER_CAPTURE_ITEM");
-    CHECK(trackNoneId == "CEREBELLUM_REASAMPLER_CAPTURE_TRACK");
-    CHECK(itemAutoId  == "CEREBELLUM_REASAMPLER_CAPTURE_ITEM_TAIL");
-    CHECK(trackAutoId == "CEREBELLUM_REASAMPLER_CAPTURE_TRACK_TAIL");
+    CHECK(itemId  == "CEREBELLUM_REASAMPLER_CAPTURE_ITEM");
+    CHECK(trackId == "CEREBELLUM_REASAMPLER_CAPTURE_TRACK");
 }
 
 int main() {
@@ -289,8 +276,8 @@ int main() {
     testRangeInference();
     testItemScopeBypassesEverythingButTake();
     testTrackScopeKeepsSelfBypassesAncestorsAndMaster();
-    testTableHasScopeAndTailVariants();
-    testTailVariantIdsAreDistinctFromExactRows();
+    testTableHasBothScopes();
+    testScopeActionIdsAreTheShippedStrings();
 
     if (g_fail == 0) std::printf("render_settings: all tests passed\n");
     else             std::printf("render_settings: %d CHECK(s) FAILED\n", g_fail);

tests/test_tail_control.cpp

@@ -0,0 +1,83 @@
+// Standalone tests for reasampler::tail_control — no REAPER, no framework. Covers
+// the pure pieces behind the docked panel's tail-mode toggle: the cycle order
+// (None -> Auto -> Manual -> None), the manual-length clamp to the 8 s cap, and the
+// toggle label text. The drawing / click hit-testing is DAW-verified in bank_panel.
+
+#include "../src/tail_control.h"
+
+#include <cstdio>
+#include <string>
+
+using namespace reasampler;
+
+static int g_fail = 0;
+#define CHECK(cond) do { if(!(cond)) { \
+    std::printf("FAIL line %d: %s\n", __LINE__, #cond); ++g_fail; } } while(0)
+
+// --- cycleTailMode: the toggle order ------------------------------------------
+
+static void testCycleOrderIsNoneAutoManualNone() {
+    // None -> Auto -> Manual -> None, wrapping. The click handler relies on exactly
+    // this order; a reorder (e.g. skipping Manual) would fail here.
+    CHECK(cycleTailMode(TailMode::None)   == TailMode::Auto);
+    CHECK(cycleTailMode(TailMode::Auto)   == TailMode::Manual);
+    CHECK(cycleTailMode(TailMode::Manual) == TailMode::None);
+}
+
+static void testCycleThreeStepsReturnsToStart() {
+    // Three cycles from any state land back on that state (a full lap of the 3-cycle).
+    TailMode m = TailMode::None;
+    m = cycleTailMode(m);
+    m = cycleTailMode(m);
+    m = cycleTailMode(m);
+    CHECK(m == TailMode::None);
+}
+
+// --- clampManualMs: the runaway guard -----------------------------------------
+
+static void testManualClampInRangeIsUnchanged() {
+    // A value inside [0, kMaxTailMs] passes through untouched.
+    CHECK(clampManualMs(kDefaultManualTailMs) == kDefaultManualTailMs);
+    CHECK(clampManualMs(0.0) == 0.0);
+    CHECK(clampManualMs(kMaxTailMs) == kMaxTailMs);
+}
+
+static void testManualClampCapsAtEightSeconds() {
+    // Over the 8 s cap clamps to kMaxTailMs; negative floors to 0. This mirrors the
+    // clamp in tailRenderSettingsFor, so the panel and the render agree on the bound.
+    CHECK(clampManualMs(kMaxTailMs + 5000.0) == kMaxTailMs);
+    CHECK(clampManualMs(-100.0) == 0.0);
+}
+
+// --- tailToggleLabel: the exact strings the panel draws -----------------------
+
+static void testLabelStringsPerMode() {
+    TailSetting off;   off.mode   = TailMode::None;
+    TailSetting autoM; autoM.mode = TailMode::Auto;
+    TailSetting man;   man.mode   = TailMode::Manual;
+    CHECK(tailToggleLabel(off)   == "Tail: Off");
+    CHECK(tailToggleLabel(autoM) == "Tail: Auto");
+    CHECK(tailToggleLabel(man)   == "Tail: Manual");
+}
+
+static void testDefaultSettingIsOff() {
+    // The zero-value setting is None (Off) with the 2 s manual default — the safe
+    // default the panel starts in so captures stay exact-bounds until opt-in.
+    TailSetting s;
+    CHECK(s.mode == TailMode::None);
+    CHECK(s.manualMs == kDefaultManualTailMs);
+    CHECK(tailToggleLabel(s) == "Tail: Off");
+}
+
+int main() {
+    testCycleOrderIsNoneAutoManualNone();
+    testCycleThreeStepsReturnsToStart();
+    testManualClampInRangeIsUnchanged();
+    testManualClampCapsAtEightSeconds();
+    testLabelStringsPerMode();
+    testDefaultSettingIsOff();
+
+    if (g_fail == 0) std::printf("tail_control: all tests passed\n");
+    else             std::printf("tail_control: %d CHECK(s) FAILED\n", g_fail);
+    return g_fail == 0 ? 0 : 1;
+}