Comments join attachments on the card face — a quiet bubble-and-count chip, present-only

A card whose thread holds one comment or more now draws a second trailing chip beside the
paperclip: a secondary-tinted bubble glyph plus its count, shown only when the count is above
zero (design ruling 2026-08-09, card e729e30a). Same styling family as the attachments chip —
caption size, secondary tint, decorative and hidden outright from the accessibility tree — but
this one carries a visible count rather than staying icon-only, per the ruling's own "bubble-style
SF Symbol + count." It sits after the attachments chip at the row's trailing edge, in both the
live title row and the drag replica.

The count is a new `Card.commentCount` field the loader fills with a readdir over `comments/`'s
identity-shaped children that carry their own `index.md` — `BoardLoader.commentCount(in:)`, built
on the same `identityShapedChildren` predicate a trash entry's held-card count already uses. Never
a parse: `.draft` and `.trash/` are excluded for free, the same dot-prefixed hidden-entry skip
`CommentThread.load` documents for both, so the walk stays exactly the O(cards) shape
01-storage-format.md § Enhanced schema already commits to. Because the count rides inside the
`card: Card` parameter `CardFaceView` already takes — not a new parameter of its own — drawing the
chip costs nothing beyond a field read on an already-compared value: no new Observable read joins
the body, and the equatable gate already covers it via `Card`'s synthesized `Equatable`.

The one divergence from the comments pane's parsed count is documented rather than hidden: a
comment folder whose `index.md` exists but fails to parse is a `Stray` the thread read excludes by
opening and rejecting it, a cost this readdir does not pay. The face may then read one comment
high until that folder is fixed or removed — the trade the ruling's "cheap directory-entry count…
not a parse" asks for, over paying full parse cost on every card of every load. Every well-formed
comment, and every card with no malformed one, agrees with the pane exactly.

VoiceOver: `AccessibilityPhrases.cardValue` gains a `comments: Int` parameter, appended after
attachments and before the cut-pending phrase — the same left-to-right order the two chips draw
in, so a sighted read and a VoiceOver read never disagree about which comes first. The trashed
lane row's own call site (an opaque unit with no comments to speak of) passes `comments: 0`.

Docs: DESIGN/03-board-ui.md's card-face section describes both chips and retires the stale "closed
with no growth" sentence, honestly recording the 2026-08-09 growth (the hero banner landed hours
earlier, this chip after it) as exposure of facts the card already carries rather than a body
excerpt. DESIGN/10-accessibility.md's flattened-element sentence gains the comment count.
DESIGN/01-storage-format.md's Enhanced schema paragraph records the chip as shipped. WISHLIST #9
is marked shipped in place — not renumbered, since #10 and #11 are cross-referenced elsewhere.

Tests: CardCommentCountListingTests (BoardLoaderTests.swift) pins the readdir against a synthetic
tree — no comments/ folder, an empty one, non-identity-shaped and index-less strays excluded,
.draft/.trash/ excluded for free, agreement with CommentThread.load's parsed count in the
well-formed case, and the one documented divergence on a malformed index.md.
AccessibilityPhrasesTests covers cardValue's new parameter alone, alongside attachments, and
all three fragments together. ViewEquatableTests pins that a comment landing on a card is a gate
difference. BoardRenderPerformanceTests adds a render-cost guard: one comment added to one card
on a hosted 180-card board re-renders a handful of bodies, not the board.

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

KanbanTests/BoardRenderPerformanceTests.swift

@@ -330,6 +330,40 @@ struct BoardRenderPerformanceTests {
                 "a one-card external edit re-rendered \(edit.containers) bodies for \(laneCount) containers")
     }
 
+    /// **The comments chip's render-cost guard** (design ruling 2026-08-09, card e729e30a): a
+    /// comment landing on one card must cost this suite's card budget, not the board's — proof that
+    /// `Card.commentCount` riding inside the already-compared `card` parameter (no new
+    /// `CardFaceView` parameter, no new Observable read) actually holds under a real hosted board,
+    /// not just in the equality-gate unit tests (`ViewEquatableTests.aCommentCountChangeIsADifference`
+    /// pins the gate; this pins what the gate is *for*). Structurally `aOneCardEditIsNotAWholeBoardRebuild`,
+    /// a comment folder in place of an edited `index.md`.
+    @Test("A comment added to one card re-renders a handful of bodies, not the board")
+    func aOneCommentAddedIsNotAWholeBoardRebuild() async throws {
+        let fixture = try makeFixture()
+        defer { fixture.tearDown() }
+        let board = try host(fixture)
+        let total = laneCount * cardsPerLane
+
+        // A foreign comment arriving under exactly one card — the shape a card window's post, or an
+        // agent's own `mkdir` + `index.md`, leaves on disk.
+        try fixture.item(
+            "\(laneName(3))/\(cardName(3, 17))/comments/\(UUID().uuidString.lowercased())",
+            "---\nschema: 1\n---\nA comment.\n"
+        )
+
+        BoardRenderMetrics.reset()
+        await board.reload()
+        let commented = Cost()
+
+        print("── reload, ONE comment added — \(commented.summary)")
+
+        #expect(board.store.snapshotGeneration > 0, "the comment never landed")
+        #expect(commented.cards <= 8,
+                "one comment on one card re-rendered \(commented.cards) of \(total) card faces")
+        #expect(commented.containers <= laneCount,
+                "one comment on one card re-rendered \(commented.containers) bodies for \(laneCount) containers")
+    }
+
     @Test("Every lane re-runs on a one-card edit, and not because its gate compared unequal")
     func theLaneCostFollowsTheBoard() async throws {
         let wide = laneCount * 2