feat(prior-art): edit-time record-sync nudge — the sync class (#2708)

A snippet recorded AT the exact file being edited is not a reuse
suggestion — it IS the record of the file being changed. The write-path
hint now renders those as their own SYNC class: 'snippet #N records this
file — updating the record is part of the edit (update_snippet /
verify_snippet)'. Nearby and semantic hits stay the reuse menu.

The two classes dedup on separate per-session channels (exclude_ids vs
exclude_sync_ids, .ids vs .sync.ids in the hook), so a reuse hint shown
early in a session can no longer silence the record-sync nudge when the
recorded file itself is edited later. Sync surfacing is measured under
its own note_usage source (write_path_sync) — its pull-through rate is
the scoreboard for whether edit-time sync actually happens, per decision
#2707 (no forge connection; records stay current in the session that has
the context). Plugin 0.1.31.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

plugin/skills/reusing-code/SKILL.md

@@ -41,6 +41,14 @@ through recall/auto-inject; this skill is the active reflex around that.
   it before you go any further. Either it's the helper you were about to
   duplicate — reuse it and drop yours — or it isn't, and the record needs the new
   location adding. Both are cheaper now than after the duplicate settles in.
+- **A `[records this file]` hint is a duty, not a menu.** When the hint says a
+  snippet records the very file you're editing, the record's freshness is now
+  YOUR edit's responsibility: if the edit changes the recorded shape,
+  `update_snippet(id, code=…)` with the new form as part of the same task; if
+  it doesn't, `verify_snippet(id, status="ok", commit_sha=…)` costs one call
+  and re-stamps the record as checked. Scribe never reads the repo — this
+  moment, in the session that has the context, is the only place the record
+  gets kept true.
 
 ## The first time a shape is built — record it