Land the 2026-07-31 design-ruling sweep

Uncommitted ruling prose from the pro-m1 sessions, committed as found:
trash sorts newest-first by modified stamp (no rank minting); kind-blind
trash selection; native undo in every tier with the provider following
the board; session-coarsening for card-window stacks; column-major
masonry; changed-path channel (02); window-scoped comment-thread heals;
commit-message vocabulary growth; integrity commit author; signature
passed per-commit instead of repo config; repo-state validation
tightening; comments pane defaults on; draft close-failure guard;
deferred comment-trash purge; 2.0 ships only with pro-m1 (RELEASE.md).

Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY

DESIGN/13-native-undo.md

@@ -1,13 +1,13 @@
 # Native Undo (free tier)
 
-The undo/redo substrate for the free tier (12-editions.md), filling the one gap mode:none admits (06-history-undo.md, 07-sync-collab.md): boards without git had no undo. Pro's substrate remains git (06); this doc never applies there. The design problem is not NSUndoManager itself — it is native undo over **files-are-truth**: the disk can change underneath the stack, because the app is not the only writer.
+The undo/redo substrate for **every gitless board, in every tier** (re-ruled 2026-07-31 — the provider follows the board, not the tier alone; formerly free-tier-only, which made a Pro upgrade *remove* undo from mode-none boards): the free tier binds it everywhere (any `.git` inert — 12-editions.md), and Pro binds it on mode-none boards, switching to the git provider (06-history-undo.md) where git exists. Repo-nested boards remain the one no-undo case (06's leave-strictly-alone stance). **Add-git swaps the substrate mid-session** — the commanded flip discards the in-session native stack and seeds the git trail from the root commit, the branch-switch discard-and-reseed precedent applied; a subscription lapse still never interrupts (12). The design problem is not NSUndoManager itself — it is native undo over **files-are-truth**: the disk can change underneath the stack, because the app is not the only writer.
 
 ## Rules
 
-- **One stack per board, owned by the board session.** Not per-window: every window over a board (board window, its card windows) shares the store and shares the stack. `window.undoManager` for board surfaces returns the session's manager; 06 ▸ Undo routing applies unchanged — text-editing surfaces get their session-scoped text undo, everywhere else ⌘Z/⇧⌘Z hit the board stack. Undo is board-local, exactly as git undo was.
+- **Two levels: one stack per board, one per open card window** (re-ruled 2026-07-31 — the session-coarsening model, superseding the pure one-stack rule): the **board stack** is owned by the board session and shared by board surfaces; a **card window owns its own stack** for the session it represents — every gesture issued in that window (comment post/delete/edit, body Edit sessions, style/details changes, attachment ops where undoable) registers there at fine grain, and `window.undoManager` answers with it (standard per-window AppKit scoping). Disk stays live throughout — files-first untouched; this is history granularity only. **Window close coarsens**: the session's net effect registers on the board stack as **one coarse step** ("Edit card 'Fix login'"), values-based, whose undo restores the card subtree to its session-start state — deleted comments included — and whose redo reapplies the net effect; a session with no net change registers nothing. The coarse step is transactional at apply time: staleness validation runs per component (the field-level predicate below), and any stale component skips the whole step — never a partial session revert. 06 ▸ Undo routing applies unchanged — text-editing surfaces get their session-scoped text undo above either stack.
 - **Registration at the Writer boundary.** Every app-mediated mutation already passes through the Writer as a `WriteOperation` (02-architecture.md) — that closed enum is the exact inventory of undoable operations. Each Writer call site registers the inverse operation, computed from the pre-write snapshot the store already holds: move → move back (original lane, original `order`); reorder → restore original `order`; rename → restore title; restyle → restore prior style; resize → restore prior width; Edit-session body save → restore prior body bytes; card or lane delete (⌫) → move back out of `.trash/` (lanes rejoined the trash 2026-07-29 — the recreate-from-capture inverse retires with the last destructive delete); restore-by-move → move back in; create → remove the created folder.
 - **What is not undoable** (settled): **Permanently delete** (the trash's Delete, Empty Trash) — `purgeIsUnrecoverable` stays true in base, and the existing confirmation rule (03-board-ui.md) already fires on all base boards, since none have git history: the confirm *is* the safety. **The duplicate-id remint** (01-storage-format.md — a silent scheduled heal since 2026-07-29, formerly the user-gated Repair) — heals aren't user gestures, so nothing enters the stack, and undoing one would recreate the duplicate id it exists to remove. Permanently delete matches its existing "destructive, confirmed, final" posture; the remint sits outside undo as all heals do.
-- **Coalescing follows commit granularity** (settled): one gesture, one undo step — a multi-card move is one step with a plural title; an Edit session is one step, registered at the Edit→Preview flip (the effective Save — 05-card-window.md); a styling batch is one step (03's one-gesture-one-commit rule, substrate swapped). The 06 vocabulary supplies menu titles ("Undo Move 3 Cards"), via NSUndoManager's dynamic retitling — the same naming machinery both editions use.
+- **Coalescing follows commit granularity** (settled; window scoping added 2026-07-31): one gesture, one undo step — a multi-card move is one step with a plural title; an Edit session is one step, registered at the Edit→Preview flip (the effective Save — 05-card-window.md) **on the card window's stack**, like every window gesture; the window close registers the one coarse session step on the board stack (Rules above); a styling batch is one step (03's one-gesture-one-commit rule, substrate swapped). The 06 vocabulary supplies menu titles ("Undo Move 3 Cards"), via NSUndoManager's dynamic retitling — the same naming machinery both editions use.
 - **Session-only persistence** (settled): the stack lives with the board session and dies at close/quit — standard macOS behavior. Git undo's survive-relaunch property is a Pro difference, stated honestly (12's matrix).
 - **Foreign writes never join the stack** (settled): NSUndoManager can only undo what the app mediated. An agent's or hand edit is not a step — the honest capability gap vs Pro (12's matrix). Foreign changes also do not clear the stack wholesale; collisions are handled lazily, per step, by validation:
 - **Staleness validation before every apply** (settled): an inverse operation re-checks its target against the disk — a fresh read of the target at ⌘Z time (blessed 2026-07-29: not the store snapshot, which is by construction one reload behind the app's own writes; a rapid ⌘Z run validated against the snapshot would compare pre-state and false-skip every step). **The predicate is field-level** (settled — ruled 2026-07-27): each step registers both sides of its write anyway (the before-value is the inverse; the after-value is what its write set), so validation compares the targeted field's current value against the expected after-value — nearly free, and truer to never-surprise-the-file than an existence-only check (an inverse rename must not clobber a foreign rename on a still-existing card; body steps compare bytes). Target folder gone, or the field no longer holding the step's after-value → the step is **skipped, not applied**: popped from the stack with an info-tone banner ("Undo skipped — 'Fix login' changed outside Lanework"), and ⌘Z falls through to the next step. Never apply a stale inverse on top of someone else's newer write. **Invalidation is lazy** (settled — ruled 2026-07-27): staleness is discovered at ⌘Z time, never by background pruning — the EchoLedger's foreign diffs do not eagerly drop colliding steps. The stack always looks full; with the field-level predicate a skip fires only on a genuine per-field collision, and a skipped step's banner explains itself, where eager pruning would shrink the stack invisibly mid-session.
@@ -17,7 +17,7 @@ The undo/redo substrate for the free tier (12-editions.md), filling the one gap
 
 ⌫'s undo is the move back — a delete is a move into `.trash/` (cards resettled 2026-07-28; lanes rejoined 2026-07-29), so its undo is the ordinary inverse move, returning a card to its source lane and rank, a lane to its strip position (subtree intact — it never left the folder); a restore-by-move undoes the same way in reverse. The stack and the trash never conflict — they are the same folder moves addressed by recency instead of by selection. The old lane-delete recreate-from-capture inverse is **retired** — no destructive delete remains outside a trash, so nothing needs byte capture. A **permanent delete registers no step** — the trash's Delete and Empty Trash are not undoable (Rules above), lanes and their freight included; the confirm is the safety.
 
-**Comments (post-2.0) keep the no-capture rule true** (ruled 2026-07-29): a comment delete is a move into the card's `comments/.trash/` (01-storage-format.md ▸ Enhanced schema — the materialized-trash pattern one level down), so its inverse is the ordinary move back; the comment operations (post, edit, delete) join the `WriteOperation` inventory and the move-based inverse family when the feature ships (post-undo naturally rides the same rail — exact inventory settled at the build pass). The window-close purge of `comments/.trash/` registers nothing (the permanent-delete posture), and any comment steps still on the board stack afterwards simply go stale and skip by the ordinary staleness validation — effectively window-lifetime undo for comments with zero new machinery, the one-stack-per-board rule and lazy invalidation untouched.
+**Comments keep the no-capture rule true — on the window stack** (re-ruled 2026-07-31, superseding the board-stack routing): a comment delete is a move into the card's `comments/.trash/` (01-storage-format.md ▸ Enhanced schema — the materialized-trash pattern one level down), its inverse the ordinary move back, and the step lives on the **card window's own stack** (Rules above) — the board stack never carries a granular comment step, so the old stale-after-close skip scenario cannot arise. **The purge of `comments/.trash/` defers with the coarse step** (re-ruled 2026-07-31, superseding purge-at-close): the coarse close step's undo restores deleted comments, so their backing lives as long as the step does — the purge runs when the coarse step leaves the board stack (undone-and-superseded, dropped off the end, or gone stale) or the board session ends; crash residue still sweeps at the next card-window open (the armed-then-cleared memo, unchanged). On Pro the substrate is history: the close commit nets delete-plus-purge to a removal, revert restores it, so purge rides the close flush there as before — purge timing follows the undo substrate's need.
 
 ## Out of scope