Semantic topic clusters: local embeddings replace Louvain

Louvain only ever found the reasoning chains (the graph is disconnected
by nature — every connected component became its own cluster) and
edge-orphans could never join anything. Clusters are now RELATED TOPICS:
propositions grouped by meaning.

- Embedder (src/server/embeddings.ts): in-process transformers.js v4
  running EmbeddingGemma-300M q8 (MTEB 68.4, ~300MB one-time download),
  MRL-truncated to 512d, "title: none | text:" prefix on 100% of inputs,
  L2-normalized so cosine = dot. Model/dim mismatch voids the ledger
  (full re-embed). Injected at the composition root — the agent layer
  never imports the server layer (architecture law).
- Ledger (data/graph/embeddings.json): model + dim + vectors + the
  persisted cluster partition. Reclustering runs at the END of every
  embedding batch (post-merge hook, both front doors) — never per read
  (the agglomerative pass is ~1.5s at 338 nodes).
- Clustering (src/core/semantic-clusters.ts): hand-rolled average-linkage
  agglomerative over cosine (npm HDBSCAN is an abandoned alpha). Stragglers
  stay singletons by default; attachStragglers is the all-in toggle.
  Threshold 0.60 swept on the real graph: 26 topics, 74/90 edge-orphans
  land in real topics, 10 stragglers.
- Consumers (snapshot, settle, namer, replay) read the persisted
  partition — one cluster concept everywhere; core-survival label
  matching unchanged (20/26 topics kept labels).
- Louvain retired: detectCommunities + graphology* deps deleted
  (graphology-louvain had leaked into the client bundle since the
  clusters wave); scripts/bench-graph.ts (dead FA2 bench) removed.
- scripts/embed-graph.ts: backfill/cold-start (338 nodes in 150s
  including the one-time model download).
This commit is contained in:
amosblomqvist
2026-09-13 14:29:16 +03:00
parent 3a1c18b9de
commit f5edc7f0a5
28 changed files with 1443 additions and 431 deletions
+52
View File
@@ -40,6 +40,7 @@ import type {
import type { GraphStore } from "../src/core/ports.ts";
import { abortExtraction, createExtractionPipeline, extractionStatuses, transcriptView } from "../src/agent/subagents/extraction.ts";
import { clusterNamingSettled, refreshClusterLabels } from "../src/agent/subagents/cluster-namer.ts";
import { semanticClusters } from "../src/core/semantic-clusters.ts";
import { chatStore } from "../src/store/chats.ts";
import { PATHS } from "../config.ts";
@@ -67,6 +68,13 @@ function memoryLedgers() {
const sources = new Map<string, NotesSource>();
const clusterLabels: ClusterLabeling[] = [];
const positions = new Map<string, { x: number; y: number }>();
const embeddings = {
model: "",
dim: 0,
updatedAt: "",
vectors: new Map<string, number[]>(),
clusters: new Array<Array<string>>(),
};
return {
appendNode: (n: GraphNode) => void nodes.push(n),
readNodes: () => nodes.map((n) => ({ ...n })),
@@ -102,6 +110,16 @@ function memoryLedgers() {
positions.clear();
for (const [id, p] of Object.entries(next)) positions.set(id, { x: p.x, y: p.y });
},
// The embedding ledger — the embedder writes it after a merge.
readEmbeddings: () => ({ model: embeddings.model, dim: embeddings.dim, vectors: Object.fromEntries([...embeddings.vectors].map(([id, v]) => [id, [...v]])), clusters: [...embeddings.clusters.map((c) => ({ members: [...c] }))], updatedAt: embeddings.updatedAt }),
writeEmbeddings: (next) => {
embeddings.model = next.model;
embeddings.dim = next.dim;
embeddings.updatedAt = next.updatedAt;
embeddings.vectors.clear();
for (const [id, v] of Object.entries(next.vectors)) embeddings.vectors.set(id, [...v]);
embeddings.clusters = next.clusters.map((c) => [...c.members]);
},
} satisfies GraphStore;
}
@@ -319,6 +337,7 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
const pipeline = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
extractor: submitModel("submit_findings", FINDINGS),
auditor: submitModel("submit_review", verdict),
labeler: submitModel("submit_labels", { labels: [] }),
@@ -360,6 +379,7 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
const pipeline = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
extractor: submitModel("submit_findings", FINDINGS),
auditor: silentModel(), // never submits the review
labeler: submitModel("submit_labels", { labels: [] }),
@@ -371,6 +391,7 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
const failingExtractor = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
extractor: silentModel(),
auditor: submitModel("submit_review", { ...FINDINGS, dropped: [] }),
labeler: submitModel("submit_labels", { labels: [] }),
@@ -402,6 +423,7 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
const pipeline = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
// Each stage's first generate is the observation point: the
// registry must already carry this chat at the right phase.
extractor: submitModel("submit_findings", FINDINGS, () => seen.push(phaseOf())),
@@ -435,6 +457,7 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
const pipeline = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
// During the auditor's generate, the registry must already carry
// the extractor's fully accumulated live usage (2 steps × 10/5).
extractor: submitModel("submit_findings", FINDINGS),
@@ -476,6 +499,7 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
const pipeline = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
extractor: hangingModel(), // hangs until aborted — no step finishes
auditor: submitModel("submit_review", { propositions: [], edges: [], attribution: { quiz: {} }, dropped: [] }),
labeler: submitModel("submit_labels", { labels: [] }),
@@ -527,6 +551,7 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
const pipeline = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
extractor: gatedExtractor,
auditor: silentModel(),
labeler: submitModel("submit_labels", { labels: [] }),
@@ -545,6 +570,7 @@ describe("the extraction pipeline (extractor → auditor → merger)", () => {
const pipeline = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
extractor: silentModel(),
auditor: silentModel(),
labeler: submitModel("submit_labels", { labels: [] }),
@@ -603,6 +629,27 @@ const CLUSTER_VERDICT = {
dropped: [],
} as const;
/** Test seam for the embedder: fakes the post-merge embedding batch —
* one identical unit vector per node → semanticClusters merges them all
* into ONE topic — then persists the partition like the real embedder. */
const fakeEmbedder = async (store: GraphStore) => {
const seen = new Set<string>();
const ids: string[] = [];
for (const n of store.readNodes()) {
if (seen.has(n.id)) continue;
seen.add(n.id);
ids.push(n.id);
}
const vectors = Object.fromEntries(ids.map((id) => [id, [1, 0, 0]]));
store.writeEmbeddings({
model: "test/embedder",
dim: 3,
vectors,
clusters: semanticClusters(vectors),
updatedAt: "2026-09-13T00:00:00.000Z",
});
};
describe("cluster naming (the post-extraction garnish)", () => {
it("names a new community after a notes merge — one record, claimed on the next refresh", async () => {
const ledgers = memoryLedgers();
@@ -611,6 +658,7 @@ describe("cluster naming (the post-extraction garnish)", () => {
const pipeline = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
extractor: submitModel("submit_findings", CLUSTER_FINDINGS),
auditor: submitModel("submit_review", CLUSTER_VERDICT),
labeler,
@@ -638,6 +686,7 @@ describe("cluster naming (the post-extraction garnish)", () => {
const pipeline = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
extractor: submitModel("submit_findings", CLUSTER_FINDINGS),
auditor: submitModel("submit_review", CLUSTER_VERDICT),
labeler: silentModel(), // never submits — the namer throws
@@ -656,6 +705,7 @@ describe("the notes front door (importNotes — format-agnostic)", () => {
const pipeline = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
extractor: submitModel("submit_findings", NOTES_FINDINGS),
// During the auditor's call the registry must show the notes run.
auditor: submitModel("submit_review", NOTES_VERDICT, () => {
@@ -704,6 +754,7 @@ describe("the notes front door (importNotes — format-agnostic)", () => {
createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
extractor: submitModel("submit_findings", NOTES_FINDINGS),
auditor: submitModel("submit_review", NOTES_VERDICT),
labeler: submitModel("submit_labels", { labels: [] }),
@@ -724,6 +775,7 @@ describe("the notes front door (importNotes — format-agnostic)", () => {
const pipeline = createExtractionPipeline({
chatStore,
graphStore: ledgers,
embedder: fakeEmbedder,
extractor: hangingModel(),
auditor: submitModel("submit_review", NOTES_VERDICT),
labeler: submitModel("submit_labels", { labels: [] }),