Comments, phase 3 — search, the thread find, announcements, and a11y

Board search reaches comment bodies through a search-owned transient
index: the first live-query keystroke sweeps comments/*/index.md
off-actor (.draft and comments/.trash excluded), keystrokes re-filter
in memory, the index discards on clear — the snapshot stays O(cards).
⌘F routes by focus: the comments pane gets an app-owned find bar
spanning the whole rendered thread (next/prev cross rows with
wraparound); body and composer keep NSTextFinder; Find Next/Previous
graduate from FutureCommands. Foreign comment changes speak
path-shaped beside the announcer's ladder ("New comment on 'X'",
plural folds), narrowed by EchoLedger receipts consumed through
CommentPath.classify — and that read fixed a latent footprint bug
where a comment receipt resolved against the card's attachment
listing, read .absent, and classified the user's own write as
foreign. The pane completes its a11y story: flattened comment
elements with Edit/Delete/Reveal custom actions (un-flattening
during inline edit), phrase-table vocabulary, labeled composer and
sort control, and an audit over the open pane on a comment-seeded
fixture (runnable only where automation permission exists).

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

Kanban/UI/Board/BoardView.swift

@@ -334,11 +334,16 @@ struct BoardView: View {
         // arrivers are the card and row transitions already attached inside the lanes and the trash
         // column; this is the survivors' spring around them.
         //
-        // **Every way the query changes rides it**, which is the reason the key is the query rather
+        // **Every way the filter changes rides it**, which is the reason the key is the filter rather
         // than the transaction being wrapped at each mutation: typing, the field's Escape, the
         // board's Escape, and creation's clear (`TransientBoardState.beginPlaceholder`) all land
         // here without any of them knowing about motion.
-        .animation(Motion.contentReflow(reduced: reduceMotion), value: store.searchQuery)
+        //
+        // The *filter*, not the query, since comments joined the search's scope (04 ▸ Search, re-ruled
+        // 2026-07-29): a landed comment-index sweep widens what matches without the query changing at
+        // all, and keying on the query alone would make those cards pop in while every other arrival
+        // eased. `SearchFilter` is `Equatable` and carries the index' answer, so one key covers both.
+        .animation(Motion.contentReflow(reduced: reduceMotion), value: store.searchFilter)
     }
 
     /// The rubber band itself: a translucent accent fill with a hairline border, in strip