Scope sample-remove (B5) and prune (Phase R) into the plan

Adds the two missing removal capabilities: sample-level remove (Phase B
point B5, index-only) and the prune file-lifecycle path (new Phase R, the
sole file-deleting op), resolving the dangling capture/prune reference.
Adds CONTEXT.md spec, PLAN.md points, and a product note; surfaces forks
R-A..R-E for decision.

PLAN.md

@@ -118,23 +118,34 @@ landed milestone.
 > spec. Product framing: `docs/product/design-view.md` §Two-canvas direction. When a
 > point lands, doc-keeper moves it to `COMPLETED.md`.
 >
-> **D2-W1 (pure lane extension) and D2-W2 (shell: lane application + new-content detection) have landed** — see `COMPLETED.md`.
+> **D2-W1 (pure lane extension), D2-W2 (shell: lane application + new-content
+> detection), and D2-W3-A (lane minting + item→lane assignment + persist
+> round-trip) have landed** — see `COMPLETED.md`.
 
-## D2-W3 — actions, persist wiring, panel UI
-**Goal:** Any new lane/mode-management actions, the persist slice serializing the
-lane-ownership index alongside the membership index, and any panel UI indicator.
+## D2-W3-B — two-canvas actions + panel UI indicators
+**Goal:** Any new lane/mode-management actions (bindable in the Actions list), and
+any panel UI indicator for lane/mode state. The persist slice and the
+lane-ownership index round-trip were completed in D2-W3-A; this wave closes the
+remaining UI and action surface.
 See CONTEXT.md §Two-canvas sub-phase (Module architecture — persistence).
-**Verify (in DAW):** The lane-ownership index survives Save / Save As / reopen
-(rides in the `"reasampler"` `view_state` alongside the membership index);
-lane/mode-management actions are registered and bindable.
-**Depends on:** D2-W2.
+**Verify (in DAW):** Lane/mode-management actions are registered and bindable in
+the Actions list; the panel UI indicator reflects the current lane/mode state.
+**Depends on:** D2-W3-A.
 
 - [ ] Any new lane/mode-management actions (`command_id`/`gaccel`/`hookcommand`);
   bindable in the Actions list.
-- [ ] Persist slice: serialize/deserialize the lane-ownership index in the
-  `"reasampler"` `view_state` section, alongside the membership index.
 - [ ] Any panel UI indicator for lane/mode state.
 
+**D2-W3-A code-review polish (fold into this wave):**
+- [ ] Simplify the redundant per-mint `I_NUMFIXEDLANES` re-read in `view.cpp`
+  (`applyMintPlan`): a single grow-and-track pass removes the second
+  `GetMediaTrackInfo_Value` call inside the mint loop.
+- [ ] Optional shared item-read helper to remove duplicated `itemGuid`/`itemLaneName`
+  read logic between `view.cpp` and `bank_panel.cpp`.
+- [ ] Optional defensive note/check in `reconcileManagedLanes` for the edge case
+  where a managed lane name encodes an unregistered mode id (log and skip rather
+  than silently record an orphaned ownership entry).
+
 ---
 
 # Phase B — Multi-bank (parallel to the M0–M11 capture roadmap and Phase D)
@@ -254,6 +265,34 @@ and product notes → *Fork 5 — settled*.)
   index-only and reversible). **Verify the drag hit-test doesn't collide with the M5
   grid's multi-select drag.**
 
+## B5 — sample-remove (the missing sample-level verb)
+**Goal:** Drop an individual `Sample`'s index entry from a bank or the pool —
+the sample-level companion to move/copy/evacuate/delete-bank. Index-only,
+non-destructive to the file; exposes the `BankIndex::remove` primitive that
+`bank_model` already has (wires it, does not add it). CONTEXT.md §Sample removal.
+Product framing + open forks: `docs/product/removal-and-prune.md` §Sample-remove.
+**Verify (in DAW):** Remove drops the selected sample's entry from the target
+bank; a same-hash entry in another bank is untouched (no cross-bank dedup);
+pool *contents* are removable while pool-container privileges hold; removing the
+last index reference to a file leaves that file on disk (orphaned until prune —
+never deleted by remove); non-destructive (index + ext-state only, no file, no
+timeline item).
+**Depends on:** B1, B2, B3 (action set), B4 (panel affordance).
+
+- [ ] Surface `BankIndex::remove` through `bank_book`: remove a `Sample` from a
+  bank's index; pool contents removable, pool-container privileges unchanged.
+- [ ] "Remove selected sample(s)" action (`command_id`/`gaccel`/`hookcommand`),
+  MIDI-bindable; carries a `scope: this-bank | all-banks` seam (fork R-A — default
+  this-bank until Daniel settles).
+- [ ] `bank_panel` remove affordance on the current selection (reuse M5 selection
+  model, as move/copy do).
+- [ ] Confirm-on-last-reference guardrail: remove that orphans a file (no other
+  bank references it) confirms, naming the orphaned-until-prune consequence;
+  remove of a still-referenced sample does not confirm.
+- [ ] Tests: remove drops the target entry; same-hash entry in another bank
+  survives; remove-from-pool allowed; last-reference remove leaves an orphan (file
+  untouched); non-destructive (no file/timeline mutation).
+
 ## Phase B open questions
 All five forks settled by Daniel (2026-07-23): persistence key = fold pool into `banks`,
 retire legacy key (1a); delete drops members + add evacuate verb (2); move is the
@@ -265,3 +304,102 @@ ready to scope into implementation waves. One polish detail remains:
 - **Active-bank indicator placement** — per-region headers vs. single header readout
   vs. lit-tab. "Unmistakable" is settled; only placement is open. Polish detail.
   (touches B4)
+
+- **B5 sample-remove forks (NEW, unsettled — need Daniel):** **R-A** — remove scope
+  (this-bank | all-banks | both); spec-of-record is this-bank-primary with a
+  scope-parameter seam. **R-B** — undo model for `"reasampler"` ext-state index
+  mutations (affects *all* of Phase B, surfaced by remove; move/copy/evacuate/
+  delete-bank/remove are not on REAPER Ctrl-Z as specced). Lean: a single-snapshot
+  ReaSampler-internal "undo last bank change." Both in `docs/product/removal-and-prune.md`.
+
+---
+
+# Phase R — Reclaim (file lifecycle: the prune path)
+
+> **New pillar, own lettered namespace.** Prune is the file-lifecycle path the
+> capture and multi-bank specs forward-reference throughout ("files persist on disk
+> until prune") but that had no phase, module, or point. It is the **only** operation
+> in ReaSampler that deletes bytes off disk. Namespaced **`R` (Reclaim)** alongside
+> `M`/`D`/`B` because it is a distinct pillar — it serves *every* orphan-producing
+> path (delete-bank, sample-remove B5, potentially M10 re-capture), not just
+> Multi-bank, and it carries a new risk class (file deletion) with its own
+> invariants. Authoritative spec: **CONTEXT.md §Prune — file-lifecycle spec**.
+> Product framing + phase-placement justification + forks:
+> `docs/product/removal-and-prune.md` §Prune. When a point lands, doc-keeper moves it
+> to `COMPLETED.md`.
+>
+> **Boundary (load-bearing):** *remove creates orphans; prune reclaims them.* No
+> operation other than prune deletes a file; prune deletes only files no index
+> references. A bank op that deletes a file is still a bug.
+>
+> **Depends on:** B1, B2 (needs the multi-bank book to union the referenced-set
+> across all banks) and B5 conceptually (sample-remove is a primary orphan-producer,
+> so remove-then-prune is the coherent pair — mirror of evacuate-then-delete). Does
+> **not** depend on the B3/B4 UI.
+
+## R1 — prune-reconcile core (pure)
+**Goal:** REAPER-free, filesystem-free reconciler — given the set of files present
+in the bank folder and the set of files referenced by the book (unioned across all
+banks, pool included), compute the orphan set. The mirror of
+`ViewModeModel::reconcile(liveGuids)`, one level down (files instead of GUIDs).
+CONTEXT.md §Prune (Module architecture — pure).
+**Verify:** CTest green. **Prune null test:** a folder whose every file is
+referenced deletes nothing; prune returns exactly `present − referenced` and
+nothing else. Referenced-set unioned across every bank (a file referenced by any
+bank — including via a copy — is never an orphan).
+
+- [ ] Prune-reconcile pure function: `(present, referenced) → orphans`, referenced
+  unioned across the whole book (copies keep a file alive).
+- [ ] Tests: prune null test (all-referenced → empty); orphan = present−referenced;
+  a copied file referenced by a second bank survives; empty folder / empty book edge
+  cases.
+
+## R2 — prune shell + persist wiring (filesystem I/O, thin)
+**Goal:** Enumerate the current project bank folder (M4 project-relative resolution),
+supply the referenced-set (and, per fork R-D, the owned-file set) from the session,
+feed the pure core, and produce a dry-run manifest. No deletion in this wave — the
+report path only. CONTEXT.md §Prune (persist / prune shell).
+**Verify (in DAW):** Dry-run reports the orphan count + reclaimed size (+ file list
+for a small set) against the resolved current bank folder; resolves paths the same
+way the index does (survives a Save-As relocation); deletes nothing.
+**Depends on:** R1, B1, B2.
+
+- [ ] Prune shell: enumerate the resolved current bank folder; feed the pure core.
+- [ ] Session supplies the referenced-set (union across the book); resolve the bank
+  folder via the M4 project-relative machinery.
+- [ ] Dry-run manifest: orphan count + reclaimed size (+ files for a small set);
+  **no deletion in this wave.**
+
+## R3 — deletion + action (the destructive step, guarded)
+**Goal:** The confirmed deletion step and the bindable "Prune bank folder" action:
+dry-run-first, confirm-with-manifest, then reclaim the orphan set — via OS trash if
+portably available (fork R-C), else unlink. CONTEXT.md §Prune (guardrails, API).
+**Verify (in DAW):** "Prune bank folder" reports first, deletes only on explicit
+confirm, and reclaims exactly the orphan set — never a referenced file, never a
+hand-dropped non-bank file; the referenced/owned-set safety holds; non-bank and
+capture invariants untouched.
+**Depends on:** R2. **Forks R-C / R-D / R-E must be settled before this wave.**
+
+- [ ] "Prune bank folder" action (`command_id`/`gaccel`/`hookcommand`),
+  dry-run-first, confirm-to-delete.
+- [ ] Deletion mechanism (fork R-C): OS trash if a portable move-to-trash is
+  verified available, else unlink with the dry-run/confirm guardrail. **Verify the
+  platform move-to-trash surface before use.**
+- [ ] Orphan attribution (fork R-D): reclaim only the bank system's own leavings,
+  not hand-dropped folder files (owned-file manifest per the lean — see below).
+- [ ] Trigger (fork R-E): manual-primary; optional "…and prune now" offered at the
+  delete-bank confirmation; **no** background sweep.
+
+## Phase R open questions (unsettled — need Daniel)
+- **Fork R-C — deletion mechanism (OS trash vs. unlink).** Lean: trash if portably
+  available (recoverable), else unlink with strong dry-run/confirm. Needs Daniel +
+  a platform to-verify (SWELL / per-platform trash APIs).
+- **Fork R-D — orphan attribution (owned-file manifest vs. index-diff vs.
+  folder-sweep).** Lean: **owned-file manifest**. **Design-the-seam call:** the
+  manifest is cheap to maintain from capture onward but a backfill cliff to
+  reconstruct later — so **start tracking owned files as part of capture / Phase B
+  now, even though prune ships in Phase R.** Folder-sweep rejected as unsafe (deletes
+  hand-dropped files). Needs Daniel (touches the persisted shape + ideally lands
+  earlier than R3).
+- **Fork R-E — trigger (manual-only vs. offer-on-orphaning vs. periodic).** Lean:
+  manual-primary + optional delete-time "prune now"; no background sweep. Needs Daniel.