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

frontend/src/views/KnowledgeView.vue

@@ -3,7 +3,10 @@ import { ref, computed, watch, onMounted, onUnmounted, nextTick } from "vue";
 import { useRouter } from "vue-router";
 import { apiGet } from "@/api/client";
 import type { TaskKind, TaskStatus, TaskPriority } from "@/types/note";
+import type { RecordUsage } from "@/types/usage";
+import { deadWeightAdvice } from "@/utils/deadWeight";
 import KindBadge from "@/components/KindBadge.vue";
+import UsageBadge from "@/components/UsageBadge.vue";
 import NoteSweepPane from "@/components/NoteSweepPane.vue";
 import StatusBadge from "@/components/StatusBadge.vue";
 import PriorityBadge from "@/components/PriorityBadge.vue";
@@ -44,6 +47,10 @@ interface KnowledgeItem {
   project_id: number | null;
   created_at: string;
   updated_at: string;
+  /** Surfaced-vs-opened counts, zero-filled by the route for EVERY row, so
+   *  "never surfaced" is a value here rather than a missing field (#4230).
+   *  `UsageBadge` renders nothing at all below one surfacing. */
+  usage?: RecordUsage | null;
   // Set only when another user owns this record — their suggestion, not one of
   // yours. Absent means it's yours.
   shared?: boolean;
@@ -659,6 +666,16 @@ onUnmounted(() => {
                 class="shared-tag"
                 :title="`Shared by ${item.owner ?? 'another user'} — their record, not yours`"
               >by {{ item.owner ?? "another user" }}</span>
+              <!-- Surfaced-vs-opened (#4230). This is the only list in the UI
+                   that browses notes and lessons, so it is the only place
+                   those two kinds can show the counter at all. The advice is
+                   looked up per row because this feed is mixed — the remedy
+                   for a snippet nobody opens is not the remedy for a lesson. -->
+              <UsageBadge
+                :usage="item.usage"
+                :noun="item.note_type"
+                :dead-weight-advice="deadWeightAdvice(item.note_type)"
+              />
               <span class="k-card-date">{{ formatDate(item.updated_at) }}</span>
             </div>
           </div>