Every comment-trash purge kneels to the ownership gate — the container-whole retirement retires

Claude-Session: https://claude.ai/code/session_014PtZdPwqZuqEDLc6wZMtEy

DESIGN/13-native-undo.md

@@ -17,7 +17,7 @@ The undo/redo substrate for **every board without app-managed git, in every tier
 
 ⌫'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 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lives as long as the step does — the purge runs when the coarse step leaves the board stack **cleanly** — undone-and-superseded, or dropped off the end — or when the board session ends; **a stale-skipped step's backing instead survives to board-session end** (ruled 2026-07-31, decoupling skip from purge): the skip banner says nothing was applied, and an irreversible purge riding that gesture would be surprise loss — the skip is exactly when the user may want to inspect what the collision left; crash residue still sweeps at the next card-window open — **and residue is defined by the purge-deferral condition itself** (ruled 2026-07-31): `comments/.trash/` content referenced by a live coarse step on the board stack is a step's backing, not residue — the open-time sweep consults the stack and skips owned content, re-arming when the owning step leaves the stack (which is exactly when the deferred purge wanted to run; one condition, two consumers). Reopening a window can therefore never destroy its prior session's undo backing. Unowned content sweeps as before, armed-then-cleared like every heal memo. 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.
+**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 **cleanly** — undone-and-superseded, or dropped off the end — or when the board session ends; **a stale-skipped step's backing instead survives to board-session end** (ruled 2026-07-31, decoupling skip from purge): the skip banner says nothing was applied, and an irreversible purge riding that gesture would be surprise loss — the skip is exactly when the user may want to inspect what the collision left; crash residue still sweeps at the next card-window open — **and residue is defined by the purge-deferral condition itself** (ruled 2026-07-31): `comments/.trash/` content referenced by a live coarse step on the board stack is a step's backing, not residue — the open-time sweep consults the stack and skips owned content, re-arming when the owning step leaves the stack (which is exactly when the deferred purge wanted to run; one condition, two consumers). Reopening a window can therefore never destroy its prior session's undo backing. Unowned content sweeps as before, armed-then-cleared like every heal memo. **Every purge of `comments/.trash/` is per-entry behind the ownership gate** (ruled 2026-08-06 — the container-whole retirement purge retires): a step's retirement and a no-step close remove only entries no live step still backs — the same `backedContent` inventory the sweep consults, making it one condition, *three* consumers. The container-whole purge assumed one owning step per card's comment trash, and two sessions over the same card broke it: the second step's retirement — or a mere reopen-and-close that registered nothing — emptied the first step's backing out from under it, silently killing an undo the stack still promised. Under the gate a purge cannot stale a live step by construction; an entry that outlives its owner is collected by whichever consumer runs next (the next retirement, close, open-time sweep, or session end — convergence, not a leak). One carve-out: **an open card window is itself an owner of its card's comment trash** — a retirement firing while the card's window is open defers its purge to that window's close, because entries deleted in the live session are backed by the window's fine steps, which the board-stack inventory cannot see; the close then settles by the same gate (its coarse step becomes the owner, or the no-step close purges the unowned). 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