docs(product): spec Phase L L7 — capture ordering, card metadata, and selection styling

Persisted gap-preserving per-bank display order + drag-drop reorder (model change, JSON round-trip + migration), decorative bars.beats/s.ms overlay, tertiary-border selection restyle. Model work separated from draw work; forks flagged (meter source, M9 substrate overlap, drag disambiguation).

PLAN.md

@@ -372,17 +372,123 @@ work.
   state — never a pulse, per the speed constraint) as the signature surface; VST3 class UID
   unchanged. (Gated.)
 
+## L7 — capture ordering, card metadata, and selection styling (ungated, after L6)
+**Goal:** Three grid-facing improvements to the dock panel, drawn through the L1 kit in the
+settled DS-2 palette. (1) **Persisted deterministic capture order + drag-drop reorder + sparse
+placement:** each bank (and the pool) carries an explicit, persisted per-sample order, changed
+by dragging cards within the grid; a card may sit in a grid slot that leaves gaps (an empty
+first row above an occupied second row). (2) **Decorative metadata over the peaks:** each card
+overlays capture length as **bars.beats.subdivisions in the bottom-LEFT** and **seconds.ms in
+the bottom-RIGHT**, subtle/legible over the waveform in the kit's micro / value-mono type
+classes. (3) **Selection restyle:** a selected card drops the inverted accent-fill and instead
+draws the *normal* cell + an **`accent/tertiary` (pastel purple `#C2AAE8`) border**; hover,
+focus, and drag-highlight stay visually distinct. **No new capture/placement behavior** — this
+is model + layout + draw only; the "capture ≠ placement" principle is untouched.
+
+> **This is a persisted-model change, not pure layout.** Feature (1) adds an explicit
+> per-sample ordinal/slot to the persisted state and its JSON round-trip + a migration for
+> existing projects — scoped honestly below, model work separated from draw work.
+
+> **Forks for Daniel (surface before build — see CONTEXT.md §L7):**
+> - **F1 — bars.beats source.** `Sample` already carries `captureTempo` (BPM at capture) and
+>   `lengthBeats`, but **no time-signature field.** bars.beats.subdivisions needs a
+>   time-signature reference. **Recommendation: a capture-time stamp** (add `captureTimeSigNum`
+>   /`captureTimeSigDenom` to `Sample`, stamped on the capture path) so the label is stable as
+>   the project tempo/meter later changes — matching the existing `captureTempo` stamp
+>   philosophy. This adds a **capture-path stamp beyond draw work** (its own checkbox below,
+>   flagged). Alternative (live project meter at draw time) is rejected: the label would drift
+>   under the card as the project changes, and a bank sample outlives the project state it was
+>   captured under.
+> - **F2 — M9 un-deferral awareness.** M9 "slots" (capture-to-slot-N / insert-slot-N,
+>   MIDI-bindable, MPC-style) is **explicitly deferred (Daniel, 2026-07-26).** L7's sparse
+>   placement is a **partial overlap** — both need addressable grid positions. Building L7's
+>   sparse-slot model effectively lays the *position substrate* M9 would sit on, but L7 does
+>   **not** add slot-numbered capture/insert actions or MIDI bindings. Flagged so Daniel knows
+>   L7 un-defers the *coordinate model* portion of M9, not the *action* portion. If Daniel wants
+>   the slot substrate to be explicitly M9-shaped (numbered addressable slots vs. a plain
+>   gap-preserving ordinal), that is a fork to settle before the model checkbox.
+> - **F3 — drag-disambiguation rule (proposed, Daniel to confirm).** The panel already has
+>   internal bank-move/copy drag and OS drag-out. In-grid reorder must coexist. **Proposed
+>   rule:** a drag whose drop lands **within the SAME bank's own grid** = **reorder-to-slot**;
+>   a drop on **a tab / the other region's bank** = **move/copy** (as today); a drag that
+>   **leaves the client rect** = **OS drag-out** (as today). One clean precedence: leave-client
+>   wins → else other-bank wins → else same-bank-grid = reorder. See CONTEXT.md §L7.
+
+**Verify (in DAW):** capture several samples; drag a card to a new position within its bank —
+the order persists across project save/reload and Ctrl-Z restores the prior order; drag the
+first card below the second so the first row is empty — the gap holds across reload; each card
+shows bars.beats.subdivisions bottom-left and s.ms bottom-right, legible over the peaks; a
+selected card shows the normal cell with a purple (`accent/tertiary`) border — no inversion —
+and hover / focus / drag-target remain distinct; dragging a card to another bank's tab still
+moves/copies (not reorder), and dragging out of the panel still starts an OS file drag; an
+existing project (saved before L7) loads cleanly with cards in their prior insertion order.
+**Depends on:** L1 (the kit) for all draw; sequences **after L6** (both rework the same
+`bank_panel` grid). **Ungated by Phase S** (the dock panel is on dev); independent of the L3
+gate. No `capture` / `insert` behavior change; no palette/font decision re-opened.
+
+**(a) Persisted order + sparse-position model (pure, hard-tested) — model work, separate from draw:**
+- [ ] Add an explicit per-sample **display position** to the persisted bank state (gap-preserving
+  ordinal or slot coordinate — settle the shape against F2). Decide the home: `bank_model`
+  is stated untouched by `bank_book`'s wrapping — position is a **per-bank display concern**, so
+  it belongs with the bank's membership, not on `Sample`. Candidate: a per-`Bank` ordered/keyed
+  position map in `bank_book` (id → slot), leaving `bank_model` / `Sample` untouched. Settle the
+  exact carrier at build.
+- [ ] JSON round-trip for the position data (`serialize`/`deserialize` remain lossless:
+  `deserialize(serialize(x)) == x` including positions).
+- [ ] **Migration for existing projects** (old blobs with no position data): load cleanly with a
+  **default = current insertion order, densely packed** (no gaps). Spec the default explicitly so
+  a pre-L7 project is visually identical on first load post-L7.
+- [ ] **Gap semantics on insert / delete / prune** (pure, tested): a new capture takes the next
+  free slot after the last occupied one (append); a delete/remove/prune **leaves a gap** (does
+  not re-pack) so positions stay stable; define whether an empty trailing tail is trimmed.
+- [ ] **Reorder mutator** (pure): move sample `id` to target slot within its bank, gap-preserving;
+  deterministic; unit-tested.
+- [ ] Undo integration: a reorder is one Ctrl-Z (batched undo point in the actions/shell layer,
+  matching the existing bank-verb undo discipline).
+
+**(b) Reorder-drag gesture + slot hit-test (pure geometry + shell wiring):**
+- [ ] **Sparse-aware grid layout** (pure, extend `bank_grid`): map per-slot positions (with gaps)
+  to `CellRect`s — an empty slot is drawn empty (or skipped), not back-filled. Slot ↔ pixel-rect
+  math + point→slot hit-test stay pure and unit-tested (mirror `mode_switch`/`bank_grid`).
+- [ ] **Drag-disambiguation** (F3): drop within the same bank's grid = reorder-to-slot; drop on a
+  tab / other bank = move/copy (unchanged); leave client = OS drag-out (unchanged). Precedence
+  encoded in a **pure decision helper** (mirror `drag_out::decideGesture`); shell reads live
+  pointer + region + client rect and calls it.
+- [ ] Shell wiring: on a same-bank reorder drop, resolve the target slot via the pure hit-test and
+  call the reorder mutator; drop-target slot highlight during the drag (distinct from the existing
+  region/tab drop highlights).
+
+**(c) Metadata overlay (pure formatting + kit draw):**
+- [ ] **Pure formatters, unit-tested:** `bars.beats.subdivisions` from `lengthSeconds` +
+  `captureTempo` + capture-time signature (F1) and `seconds.milliseconds` from `lengthSeconds`.
+  Deterministic string output; edge cases (zero length, missing tempo → graceful blank/fallback).
+- [ ] **[FLAGGED — F1, capture-path stamp beyond draw work] Capture-time signature stamp:** add
+  `captureTimeSigNum` / `captureTimeSigDenom` to `Sample` + its JSON round-trip, stamped on the
+  capture path (read the project meter at capture). Only needed if F1 resolves to the capture-time
+  stamp (recommended). Old samples with no stamp fall back gracefully in the formatter.
+- [ ] **Kit draw:** overlay the two strings on the card — bars.beats bottom-LEFT, s.ms
+  bottom-RIGHT — via the kit `text()` in the micro / value-mono class, `text/dim` (or a subtle
+  shadowed variant for legibility over the waveform); **decorative, non-interactive** (no
+  hit-test, no hover). Respects the speed constraint (no animation).
+
+**(d) Selection restyle (tertiary border):**
+- [ ] `drawThumbnail`: a selected card draws the **normal cell fill** (Rest/Hover surface, not
+  `InteractionState::Active`) + an **`accent/tertiary` border** (pastel purple `#C2AAE8`); the
+  waveform draws in its normal accent color (drop the inverted `bg/base` wave). Focus ring, hover
+  state, and drag-target highlight stay **distinct** from the selection border (keep them
+  coherent — spec the four states' visual separation in CONTEXT.md §L7).
+
 ## Phase L — sequencing
 ```
 L1 (shared kit) ──► L2 (dock-panel layout redesign) [LANDED]
         ├─────────► L3 (VST editor + embed-strip restyle; GATED on Phase S landing on dev)
         └─────────► L4 (dock-panel button layout enhancement) [LANDED]
                             └────► L5 (dock-panel button refinements; ungated, after L4) [LANDED]
-
-Phase S (separate team, ungated): S-work builds with current drawing, adopts L1 when it lands.
+                                        └────► L6 (toolbar polish; ungated, after L5) [LANDED]
+                                                    └────► L7 (capture ordering + card metadata + selection styling; ungated, after L6)
 ```
-L1, L2, L4, and L5 have landed. L3 waits for Phase S to reach dev.
-Phase S feature work runs in parallel, ungated by Phase L.
+L1, L2, L4, L5, and L6 have landed. L7 is the next ungated dock-panel work. L3 waits for
+Phase S to reach dev. Phase S feature work runs in parallel, ungated by Phase L.
 
 ## Phase L — must-verify-before-build
 - **LICE design-kit surfaces (L1)** — `LICE_GradRect`, `LICE_RoundRect`, AA
@@ -407,6 +513,15 @@ Phase S feature work runs in parallel, ungated by Phase L.
   pure module; sourced from the registered action phrase, prefix stripped at draw time); item-move
   and track-tag action ids confirmed; active-mode read confirmed via the same
   `view().activeModeId()` the footer toggle uses.
+- **L7 model + tempo surface (L7)** — settle at L7 build/spec-review: (1) **position carrier** —
+  where the per-sample display position lives (candidate: a per-`Bank` id→slot map in `bank_book`,
+  keeping `bank_model`/`Sample` untouched per CLAUDE.md); (2) **F1 bars.beats source** — confirm
+  the capture-time signature stamp with Daniel (recommended) vs. live project meter; the stamp adds
+  a capture-path write (its own flagged checkbox); (3) **F2 M9 overlap** — confirm L7's sparse-slot
+  substrate is not mis-scoped as M9's slot *actions*; (4) **F3 drag rule** — confirm the
+  same-bank-grid = reorder / other-bank = move-copy / leave-client = OS-drag precedence. Verify the
+  REAPER meter-read API for the stamp (`TimeMap_GetTimeSigAtTime` or equivalent) against the SDK at
+  build.
 
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