fix(usage): one seam attaches the surfaced-vs-opened chip, and the Knowledge browse uses it (#4230)

`usage_for_notes` is named for notes and works on every note row, yet the chip
reached snippets and rules only. Notes had it nowhere. Lessons had it collected
and shown nowhere a person could reach, because #4196 taught `/api/lessons` to
attach it and `KnowledgeView` — the only lesson list in the UI — browses through
`/api/knowledge`, so `listLessons` still has no consumer.

The cause was not a missing line. SEVEN call sites carried their own copy of the
same few lines: two REST lists, two REST details, two MCP lists, one MCP detail.
Each read perfectly well alone, so "which doors attach usage?" had no answer
anywhere in the code — the same asymmetry test_system_tagging_door_parity.py
records for System tagging (#4249), where whichever door nobody exercised for a
kind is the one that never grew the feature.

`attach_usage(rows, key="id")` is now that answer, and all seven go through it.
A detail payload is a one-row list, so the single-record doors share the seam
rather than keeping a second shape beside it. Deliberately NO try/except: the
fail-open already lives in `usage_for_notes`, which reports through
`_report_failure("readout")` and returns the zero-filled map. Wrapping it again
would swallow the REPORT as well as the error, and a silently-swallowed readout
failure is exactly #2663 — every counter reading zero in production for weeks
while the writes landed fine.

`/api/knowledge` now attaches usage, which closes both holes at once: it is how
notes, lessons and processes are all browsed. `KnowledgeView` renders the badge
on the card footer, looking the advice up per row because the feed is mixed.

The advice moves to utils/deadWeight.ts. Canon #3460 says each caller owns its
own const, and that held while each caller showed ONE kind; a mixed feed would
need five of its own and the next surface another five. The canon's actual
invariant — advice is kind-specific and never baked into the badge — is kept:
it is still a prop. The three existing callers now read the same table, so the
sentence has one home rather than four. Recorded against #3460 so the next
reader is not left re-litigating it.

`_row_id` rejects bools explicitly: `int(True)` is 1, so a row carrying a flag
under the key would be credited with note #1's counts, and a wrong chip is worse
than no chip because it reads as a measurement. A row with no usable id is
skipped rather than failing the page.

Tests pin the PROPERTY, not one route: no door calls the aggregate directly
(AST, so a comment naming it is not a false positive), and every door that shows
usage reaches the seam. Plus the N+1 guard — one aggregate per page, asserted on
await_count, because the per-row version reads more naturally and is invisible
in review.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

src/scribe/mcp/tools/lessons.py

@@ -17,7 +17,7 @@ from scribe.services import lessons as lessons_svc
 from scribe.services import systems as systems_svc
 from scribe.services import trash as trash_svc
 from scribe.mcp.tools import systems as systems_tools
-from scribe.services.note_usage import empty_usage, record_pulled, usage_for_notes
+from scribe.services.note_usage import attach_usage, record_pulled
 
 
 # The payload shape lives in the service (`lesson_to_dict`), shared with the
@@ -65,7 +65,7 @@ async def list_lessons(
     # per lesson (#4196). An agent listing lessons can see which of its own
     # triggers are firing and which are not, which is the reading that leads to
     # `update_lesson` rather than to a second lesson about the same failure.
-    usage = await usage_for_notes([int(it["id"]) for it in labelled])
+    await attach_usage(labelled)
     rows = [
         {
             "id": it["id"], "title": it["title"], "tags": it.get("tags", []),
@@ -73,7 +73,7 @@ async def list_lessons(
             # Projected by `_note_to_item` straight off the `data` mirror —
             # absent when the row carries none, rather than an empty string.
             "when_to_apply": it.get("when_to_apply", ""),
-            "usage": usage.get(int(it["id"]), empty_usage()),
+            "usage": it["usage"],
             **({"shared": True, "owner": it.get("owner")} if it.get("shared") else {}),
         }
         for it in labelled
@@ -212,9 +212,7 @@ async def get_lesson(lesson_id: int, project_id: int = 0) -> dict:
     # Read BEFORE the pull is recorded, so the number an agent is shown is the
     # one that was true when it asked — otherwise every first read of a lesson
     # reports a pull that is its own.
-    out["usage"] = (await usage_for_notes([int(note.id)])).get(
-        int(note.id), empty_usage()
-    )
+    await attach_usage([out])
     record_pulled(
         user_id=uid, note_id=int(note.id),
         source="mcp_get_lesson", project_id=project_id,

src/scribe/mcp/tools/snippets.py

@@ -15,7 +15,7 @@ from scribe.mcp.tools import systems as systems_tools
 from scribe.services import access as access_svc
 from scribe.services import dedup as dedup_svc
 from scribe.services import snippets as snippets_svc
-from scribe.services.note_usage import empty_usage, record_pulled, usage_for_notes
+from scribe.services.note_usage import attach_usage, record_pulled
 from scribe.services import systems as systems_svc
 
 
@@ -90,9 +90,7 @@ async def list_snippets(
         repo=repo, path=path, symbol=symbol, verification=verification,
     )
     labeled = await access_svc.label_shared_items(uid, items)
-    usage = await usage_for_notes([int(it["id"]) for it in labeled])
-    for it in labeled:
-        it["usage"] = usage.get(int(it["id"]), empty_usage())
+    await attach_usage(labeled)
     return {"snippets": labeled, "total": total}