Realign code with the 2026-07-31 findings-resolution rulings

The full bullet list from Implementation card bf080d9a — both ruling
batches, including the three appended mid-session by 16ef377:

- Restore subjects compose the inverse, never nest: crossing "Undo: S"
  emits "Redo: S" and vice versa; parity, not stack depth, reads a
  legacy double prefix (GitHistoryProvider.restoreSubject).
- Git-operation failures join the one-shot failure banner tier:
  BannerCenter.GitFailureBanner (undo/redo/branchSwitch/addGit), error
  tone at failure rank merged with write one-shots by recency; the
  postLoss compromise is retired at both AppModel wirings.
- order/schema optional below the board root: append-at-end reading
  (ordered siblings first, folder-name tie-break among the order-less),
  schema reads 1, both coerce-tier logged; the root keeps its
  requirements. Ranks.resolvedOrders materializes finite ranks so
  models and placement math stay untouched; first Writer rewrite
  stamps a real rank on touch, placement against an order-less sibling
  stamps that sibling inline in the same bracket. Agent guide v10
  teaches optional keys and zero-read filing. Hostile-YAML order
  shapes become coercion tests; Fixtures/Valid/optional-keys.kanban
  replaces the four retired Malformed boards.
- .gitignore is the relocation-heal noise gate: GitignoreRules pure
  matcher (standard semantics, board-root file only), loader consults
  it once per walk so matched loose files keep the stray posture;
  seeded (.DS_Store + .*.lanework-*) at board creation and template
  instantiation, healed in when missing at open — repo-nested
  included; empty file honored, existing files never edited; the
  committer's obedience via libgit2 status is pinned by test.
- Comments crash-residue sweep gates on step ownership: HistoryStep
  derives backing from its own undo expectations, backedContent unions
  both stacks, the sweep purges per-entry only what no live step owns.
- Skip-purge decoupled (16ef377): a stale-skipped coarse step strands
  whole in NativeHistoryProvider.strandedSteps — still backing, retired
  only at session end; clean exits purge as before.
- Coarse close step named "Changes to '<card>'"; the fine body-edit
  wording never leaks onto the board menu.
- Branch-switch settle clears every open card window's fine stack on
  Save All and Discard alike; the empty fold registers no coarse step.
- Close flush awaits its covering snapshot (quiesce + one generation
  bump, 1s bound), and an explicit flush now queues behind an
  in-flight one instead of skipping — the audit-caught interleaving
  could lose a close flush permanently when the debounce fired inside
  the close sequence; regression tests force both races.
- Commit comment bullets sort chronologically by created, not UUID.
- The production-unwired CardBodyEditSession.editSessionDidChange seam
  is deleted with its seam-only tests.
- Composition-root pins: beginSession composes the committer with the
  store's own EchoLedger and binds the announcer (the miswire class).
- Deliberate 06 conformance pass over every 2026-07-31-tagged
  sentence: fixed Change-custom-key subjects (the retired named
  generic was the only producer), the unbuilt Replace attachment
  vocabulary, heal commits now authored Lanework Integrity, the config
  reader scopes identity to plain [user] sections, add-git re-runs
  detection at create (a stale mode-none could initialize inside the
  user's repo), and add-git failures answer at the form or the banner.
  Structural residue filed on the Redesign board.

2554 tests / 439 suites green.

Claude-Session: https://claude.ai/code/session_01CqjXB7ASoWtbyoGod68k97

KanbanTests/CommentWriteTests.swift

@@ -402,6 +402,33 @@ struct CommentResidueTests {
         #expect(store.heals.memo(for: .commentTrashResidue) == nil, "cleared on success")
     }
 
+    @Test("Content a live step still backs is not residue — the sweep asks the stack first")
+    func aLiveStepsBackingIsNotResidue() throws {
+        // 13-native-undo.md ▸ Interaction with the trash, 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". The gate is over
+        // *steps*, not over the coarse one by name, so the shortest way to hold a live step is the
+        // window-less delete (`deleteComment`'s `nil` window, which is the board's own stack).
+        let fixture = try WriterFixture()
+        defer { fixture.tearDown() }
+        let card = try makeCommentBoard(fixture)
+        try fixture.item(commentPath(CommentIdent.one, inCard: card), commentText())
+        try fixture.item("\(card)/comments/.trash/\(CommentIdent.two)", commentText())
+        let (store, history) = try makeStore(fixture)
+        let cardID = ItemID(rawValue: Ident.card1)
+
+        #expect(store.deleteComment(ItemID(rawValue: CommentIdent.one), inCard: cardID))
+        store.sweepCommentTrashResidue(inCard: cardID)
+
+        #expect(fixture.exists("\(card)/comments/.trash/\(CommentIdent.one)"),
+                "the delete step's undo is the move back out — this is its backing")
+        #expect(!fixture.exists("\(card)/comments/.trash/\(CommentIdent.two)"),
+                "and the entry no step names swept as before")
+
+        history.undo()
+        #expect(fixture.exists(commentPath(CommentIdent.one, inCard: card)), "so ⌘Z still has something to restore")
+    }
+
     @Test("An open with nothing to sweep rests — no bracket, no memo")
     func cleanOpenRests() throws {
         let fixture = try WriterFixture()