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/08-agent-integration.md

@@ -17,7 +17,7 @@ The app silently maintains a `CLAUDE.md` in every board — a condensed, agent-f
 
 - Creating cards (mkdir UUID, write `index.md`, ordering rules) — plain UTF-8, no BOM, preserving each file's existing line endings (01-storage-format.md's encoding contract).
 - Moving between lanes (folder move), reordering (gapped ranks, only touch the moved item).
-- Deletes — move the card **or lane** folder into `<root>/.trash/` (top position; never delete a folder outright unless permanence is meant); colors/icons.
+- Deletes — move the card **or lane** folder into `<root>/.trash/` and restamp `modified` (the trash sorts newest-first by that stamp — re-ruled 2026-07-31, no rank to mint; never delete a folder outright unless permanence is meant); colors/icons.
 - **`kind`** — common schema, written at creation of every object: include `kind: lane` / `kind: card` when creating anything (`kind: board` at board root), and stamp `kind: lane` when trashing a lane that lacks it. The *value* is what tells a trashed lane from a card inside the flat `.trash/` (01-storage-format.md ▸ Deletion); the app backfills a missing key on touch (01 ▸ Validation and healing), so omitting it is healable, never fatal.
 - **Attachments** (the `attachments/` convention, importing files) — including the rule that **card files belong in `attachments/`**: a loose file written beside `index.md` will be relocated there by the app with a notice (01-storage-format.md's loose-file carve-out), so agents should put it there in the first place — and the card-level **`attachments` claimed name**: `attachments` inside a card folder is the app's (the card's file folder); never create a *file* by that name.
 - **`modified-by` self-stamping** — stamp files you write; re-stamp every write *and every move* (the app clears it on its own writes; a bare folder move leaves the card unstamped); self-commit instead when you need exact authorship.