Wave 7 close-out: the embedding ledger seam dies; notes birth via mapping lines

Part 1 — the ledger + remnants interlude (master-dispatched, owner ruling
2026-09-23: nothing configures the graph beyond chat models):

- The embedding ledger surface is gone: readEmbeddings/writeEmbeddings
  ports, the EmbeddingsLedger contract, EMBEDDINGS_FILE (config, store
  impls, graphRevision source list), and graph-deletion's vector-pruning
  step. On-disk data files stay untouched (inert history).
- The extraction embedder seam dies wholesale: ExtractionPipelineDeps
  drops the embedder dep (chat-handler + backfill/import-notes stubs go
  with it), the 'embedding' phase leaves ExtractionPhase, the usage
  capture/persist helpers die, and stages.embedding leaves
  ExtractionRunUsage (historical records keep their shape — reads are
  lenient). Extraction is two stages again, like the local-embedder era.
- Consumer-less remnants: latestQuizOutcomes + QUIZ_EVENT_KINDS,
  clusterContentId, matchClusterLabelings + Community + ClusterLabeling,
  the readClusterLabels/appendClusterLabel port seams + store impls +
  LEDGER_FILES.clusterLabels. NamingRunUsage/readNamingRuns STAY
  (standing ruling — the cost pill renders historical naming spend);
  clusterHue + MIN_CLUSTER_SIZE stay (live).
- The 'labeler' role dies: BACKGROUND_MODEL_ROLES, ROLE_SLOT, ModelRole,
  the catalog pin projections, and the UI roster strings. RolePins keys
  shrink with the union.

The notes birth fallback (owner-approved 2026-09-23, surfaced by the
interlude's live smoke: production notes imports create provenance-EMPTY
nodes (importNotes passes messages: null — the file's anchor is the
mapping line), so the provenance-only birth rule left every imported
file unclustered and invisible to the prober's session list, against the
locked file-birth ruling. A provenance-empty node now births under its
FIRST mapping line's chatId (ledger order); only notes-born nodes ever
hit the fallback (chat nodes always carry provenance; a re-encountered
node's link-append re-opens the provenance rule). Deletion-safe: mapping
lines of deleted chats are stripped alongside their provenance.

Live-verified on port 3004: a fresh notes import clusters under its
src_ id with the file path as the label, end to end with no embedder.

845/845 tests, typecheck/lint/build green.
EOF
)

src/core/clusters.ts

@@ -1,71 +1,14 @@
 /**
- * CLUSTER LABEL MATCHING (vision §1). DETECTION is birth-session
+ * CLUSTER PRESENTATION RULES (vision §1). DETECTION is birth-session
  * clustering since wave 7 (core/session-clusters.ts; the semantic
- * embedder and its Louvain predecessor are both dead). What REMAINS here
- * is the
- * cluster contract + core-survival label matching, which is
- * detection-agnostic: it consumes the same { members } shape semantic
- * clustering emits.
+ * embedder, its Louvain predecessor, and the LLM label matcher are all
+ * dead — labels are session names now). What remains here is the
+ * one presentation rule the snapshot and the renderer share.
  *
- * Labelings key to sorted MEMBER SETS, never to detection indices —
- * a labeling record outlives any reshuffle of the partition.
- *
- * Browser-safe pure logic (no node builtins, no fs): the server runs
- * matching for the snapshot payload, tests run it directly.
+ * Browser-safe pure logic (no node builtins, no fs).
  */
-import type { ClusterLabeling } from "./contracts.ts";
-
-/** A detected community. Members are SORTED node ids — the member set IS
- * the identity a labeling record can outlive a reshuffle with. */
-export interface Community {
-	members: string[];
-}
 
 /** Communities below this size are not rendered, not named — presentation
  *  rule (user-decided 2026-09-13): a region of the world model needs at
  *  least three propositions to be worth a hull and a label. */
-export const MIN_CLUSTER_SIZE = 3;
-
-/**
- * Claim labeling records for detected communities — CORE-SURVIVAL (DECIDED
- * 2026-09-13): a community keeps a record's label while AT LEAST HALF of
- * the record's core survives in it (overlap * 2 >= core.length; exactly
- * half survives). Both sides are single-successor: one community holds at
- * most one label, one record is claimed by at most one community — on a
- * split, only the branch carrying the majority of the core keeps the name;
- * on a merge, the best-overlapping record wins.
- *
- * Greedy assignment by overlap size (largest first; ties broken by newer
- * record). Returns a claim (or null) per community, in input order —
- * unclaimed communities are the namer's input. Pure: same inputs, same
- * claims.
- */
-export function matchClusterLabelings(
-	communities: readonly Community[],
-	labelings: readonly ClusterLabeling[],
-): (ClusterLabeling | null)[] {
-	interface Pair {
-		community: number;
-		labeling: ClusterLabeling;
-		overlap: number;
-	}
-	const pairs: Pair[] = [];
-	communities.forEach((community, ci) => {
-		const members = new Set(community.members);
-		for (const labeling of labelings) {
-			const overlap = labeling.core.reduce((n, id) => n + (members.has(id) ? 1 : 0), 0);
-			if (overlap * 2 >= labeling.core.length && overlap > 0) {
-				pairs.push({ community: ci, labeling, overlap });
-			}
-		}
-	});
-	pairs.sort((a, b) => b.overlap - a.overlap || (a.labeling.createdAt < b.labeling.createdAt ? 1 : -1));
-	const claims: (ClusterLabeling | null)[] = communities.map(() => null);
-	const takenRecords = new Set<string>();
-	for (const pair of pairs) {
-		if (claims[pair.community] || takenRecords.has(pair.labeling.id)) continue;
-		claims[pair.community] = pair.labeling;
-		takenRecords.add(pair.labeling.id);
-	}
-	return claims;
-}
+export const MIN_CLUSTER_SIZE = 3;