diff --git a/AGENTS.md b/AGENTS.md
index e59468c54..1346facc9 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -155,9 +155,9 @@ npx gitnexus analyze --embeddings    # also generate embeddings for new/changed
 npx gitnexus analyze --drop-embeddings  # explicit opt-in to wipe existing embeddings
 ```
 
-`analyze` runs **incrementally by default**: only files whose content has changed since the last index are re-parsed (chunk-level parse cache at `.gitnexus/parse-cache.json`) and only their rows are rewritten in LadybugDB. Output is byte-equivalent to a full rebuild. Pass `--force` to wipe and re-index from scratch (e.g., to recover from a corrupt index, or after upgrading GitNexus).
+`analyze` runs **incrementally by default**. The pipeline still parses every file every run (cross-file resolution requires it), but tree-sitter parsing is **served from a content-addressed cache** at `.gitnexus/parse-cache.json` for chunks whose file contents haven't changed since the last run. Only changed-file rows (and their importers) are rewritten in LadybugDB; unchanged-file rows are preserved. Output is byte-equivalent to a full rebuild. Pass `--force` to wipe and re-index from scratch (e.g., to recover from a corrupt index, or after upgrading GitNexus).
 
-The parse cache is **content-addressed**, so it survives `--force` runs. Safe to delete `.gitnexus/parse-cache.json` at any time — it'll be rebuilt on the next analyze.
+The parse cache key is **content-addressed and version-tagged**: it survives `--force` runs, and is automatically invalidated by a `gitnexus` package upgrade (so a new tree-sitter grammar doesn't silently replay stale parse output). Safe to delete `.gitnexus/parse-cache.json` at any time — it'll be rebuilt on the next analyze.
 
 Check `.gitnexus/meta.json` `stats.embeddings` (0 = none). A plain `analyze` no longer drops existing vectors — pass `--drop-embeddings` to wipe.
 
diff --git a/docs/superpowers/specs/2026-05-10-incremental-indexing-design.md b/docs/superpowers/specs/2026-05-10-incremental-indexing-design.md
deleted file mode 100644
index 88ed0f3c3..000000000
--- a/docs/superpowers/specs/2026-05-10-incremental-indexing-design.md
+++ /dev/null
@@ -1,165 +0,0 @@
-# Incremental Indexing Design
-
-**Date:** 2026-05-10
-**Status:** Implemented and equivalence-verified
-**Owner:** abhigyanpatwari + Claude Code
-**Prior art:** PR #592 (zenprocess), PR #533 (davidbeesley), PR #1146 (azeemshaik025)
-
-## Why
-
-`gitnexus analyze` previously had only a coarse early-exit: if `meta.json.lastCommit == HEAD` and the working tree was clean it no-op'd, otherwise it did a full re-index. On a 1000-file TypeScript repo a full re-index runs ~140s. After a one-line edit, that's wasted work.
-
-Three open community PRs (#592, #533, #1146) attempted incremental re-indexing with different mechanisms; we drew on each but ended up taking a different architectural path after a v1 attempt failed.
-
-## Correctness contract
-
-**Incremental output ≡ full-rebuild output.** A run of `analyze` (default, incremental) on a repo that previously had `analyze --force` against state S₁ and is now at state S₂ produces a LadybugDB whose contents (nodes, edges, graph-wide phase outputs) are identical to running `analyze --force` against S₂ from a fresh state. Verified empirically on this repo: same 24,547 nodes / 32,716 edges / 844 clusters / 300 flows from both paths.
-
-This is the gating invariant — every architectural decision below is in service of preserving it.
-
-## What's in the box (3 layers)
-
-The shipped feature has three independent layers that compose. Each is a self-contained optimization with its own correctness story; together they deliver the headline speedup.
-
-### Layer 1 — Incremental DB writeback
-
-**The big saving on the storage side: don't wipe-and-reload the whole graph when only a few file rows changed.**
-
-After every analyze run we hash all source files and store the map at `meta.json.fileHashes`. The next run computes current hashes and diffs:
-- `changed` — file content differs from stored hash (rows must be replaced)
-- `added` — file is new on disk (insert rows)
-- `deleted` — file was in stored map, gone from disk (drop rows)
-
-Eligibility check: not `--force`, not first run, `schemaVersion=1`, `lastCommit` resolvable, no `incrementalInProgress` dirty flag. When eligible:
-1. Open the existing LadybugDB (no wipe).
-2. `deleteNodesForFile(f)` for each f in changed ∪ added ∪ deleted.
-3. `deleteAllCommunitiesAndProcesses()` — Community/Process are graph-wide, regenerated by their phases on the merged graph (preserves the "Leiden runs on the FULL graph" invariant).
-4. From the in-memory `ctx.graph` (which the pipeline produced from the FULL file set), extract the subgraph of `nodes whose filePath ∈ writable_set ∪ {Community, Process}` plus edges with at least one endpoint in that set.
-5. `loadGraphToLbug(subgraph)` — only the changed-file rows + graph-wide rows hit the DB. Unchanged-file rows in the DB are never touched.
-
-Crash recovery: `incrementalInProgress` is set to a `{ startedAt, toWriteCount }` record BEFORE any DB mutation, cleared by the success-path meta save. A crash anywhere in between leaves the flag set; the next run sees it and forces a full rebuild — cheapest path back to a known-good index.
-
-Modules:
-- `gitnexus/src/storage/file-hash.ts` — `computeFileHashes`, `diffFileHashes`
-- `gitnexus/src/core/incremental/subgraph-extract.ts` — `extractChangedSubgraph`
-- `gitnexus/src/core/lbug/lbug-adapter.ts` — `deleteAllCommunitiesAndProcesses` (new)
-- `gitnexus/src/core/run-analyze.ts` — orchestration with branched DB writeback
-
-### Layer 2 — Chunk-level parse cache
-
-**The big saving on the parse side: don't re-tree-sitter-parse files whose content hasn't changed.**
-
-The parse phase chunks files into byte-budget groups (default 2MB) and dispatches each chunk to the worker pool. Each worker returns a `ParseWorkerResult` for its sub-batch. We cache those raw results.
-
-Cache file: `<repo>/.gitnexus/parse-cache.json`. Versioned. Atomic write (tmp + rename).
-Cache key: `sha256(sorted("filePath:fileContentHash" for each file in chunk))`.
-Cache value: `ParseWorkerResult[]` — the raw worker output before merge.
-
-On each chunk:
-- Compute the chunk hash from current file contents.
-- Cache hit → call `mergeChunkResults(graph, symbolTable, cachedRaw)` and skip the worker dispatch entirely.
-- Cache miss → dispatch to workers, capture the raw results via `outRawResults`, store them under the chunk hash for next run.
-
-Two stability fixes the cache depends on:
-- **Map-preserving JSON serialization.** `ParsedFile.scopes[*].typeBindings` is a `ReadonlyMap<string, TypeRef>` which `JSON.stringify` collapses to `{}`. Added a replacer/reviver pair (`{__$mapEntries$__: [...]}` tagged form) so Maps round-trip cleanly. Without this, the first cache hit crashes with "typeBindings is not iterable".
-- **Stable chunk ordering.** The byte-budget chunker walked files in filesystem-scan order, which on Windows isn't guaranteed stable across runs. Sorted `parseableScanned` alphabetically before chunking so a single-file edit invalidates exactly one chunk, not all of them.
-
-Modules:
-- `gitnexus/src/storage/parse-cache.ts` — load, save, hash, replacer/reviver
-- `gitnexus/src/core/ingestion/parsing-processor.ts` — extracted `mergeChunkResults` from `processParsingWithWorkers`; `processParsing` accepts an `outRawResults` out-parameter
-- `gitnexus/src/core/ingestion/pipeline-phases/parse-impl.ts` — chunk hash + cache lookup + replay, alphabetical sort
-
-Cache survives `--force` because it's content-addressed: the same bytes always produce the same key. `--force` only matters for the LadybugDB writeback step.
-
-### Layer 3 — Scope-resolution short-circuit
-
-**The big saving on cross-file resolution: stop redoing parse work the workers already did.**
-
-The `scopeResolution` pipeline phase iterates files, calls `extractParsedFile` per file (which re-parses with tree-sitter), then runs the resolution work. The re-parse cost dominates: ~58s on a 1000-file repo. Workers can't pass tree-sitter `Tree` objects across `MessageChannel` (native objects), so `parse-phase.scopeTreeCache` is empty in worker mode and `extractParsedFile` always falls back to a fresh parse.
-
-But — and this was hiding in plain sight — the workers ALREADY call `extractParsedFile` and produce `ParsedFile` artifacts in `ParseWorkerResult.parsedFiles`. The previous code threw them away. The fix:
-
-1. Aggregate `parsedFiles` across chunks in `parse-impl` (`allParsedFiles[]` that pushes from every chunk's worker output).
-2. Surface them on `ParseOutput.parsedFiles`.
-3. In `scopeResolutionPhase`, build a `Map<filePath, ParsedFile>` from `ParseOutput.parsedFiles`.
-4. Pass it to `runScopeResolution` as a new `preExtractedParsedFiles` parameter.
-5. `runScopeResolution`'s extract loop checks the map first; on hit, uses the cached `ParsedFile` directly (skipping `extractParsedFile`); on miss, falls back to the original path.
-
-Worker-produced `ParsedFile` is byte-equivalent to one re-derived in scope-resolution: both call `extractParsedFile(provider, content, path, ...)`, both go through the same deterministic `emitScopeCaptures` + `extractScope` path. The only original difference was that one had a tree-sitter tree on hand (worker) and the other had to re-parse (main thread); the resulting `ParsedFile` is identical.
-
-`provider.populateOwners(parsed)` still runs on the cached `ParsedFile` — this is the same call the original path made post-extract, in-place mutation of the artifact.
-
-Module:
-- `gitnexus/src/core/ingestion/pipeline-phases/parse.ts` — `ParseOutput.parsedFiles` (new)
-- `gitnexus/src/core/ingestion/scope-resolution/pipeline/run.ts` — `RunScopeResolutionInput.preExtractedParsedFiles`, fast-path branch in extract loop
-- `gitnexus/src/core/ingestion/scope-resolution/pipeline/phase.ts` — builds the map, passes it through
-
-Effect: scopeResolution phase 58s → 5s. This is the bulk of the cold-rebuild speedup (the parse cache only helps on warm runs).
-
-## Decisions (locked in)
-
-1. **Re-parse scope (corrected from the original spec).** v1 tried to parse only changed files into a fresh graph and hydrate the rest from DB. That broke cross-file resolution because the resolution context (`exportedTypeMap`, `bindingAccumulator`) only saw closure files. Equivalence test failed. **Final design parses every file every run** — the "speedup" comes from skipping tree-sitter on cached chunks (Layer 2) and skipping scope-resolution's re-parse (Layer 3), not from skipping files outright.
-2. **Change detection: file content hash, not git diff.** The implementation uses SHA-256 of file content, not `git diff`. This works on non-git folders and on dirty working trees uniformly. (Earlier discussion considered git-only — the simpler content-hash path won.)
-3. **Rollout: incremental is the default.** `--force` is the explicit opt-out. The existing `lastCommit==HEAD` early-return now also checks for a clean working tree (uncommitted edits no longer slip through as "already up to date").
-4. **Embeddings preserved as before.** The incremental DB writeback path skips the embedding cache+restore cycle (would PK-conflict against rows that weren't deleted). Existing semantics preserved: plain `analyze` keeps existing embeddings on unchanged-file rows; `--embeddings` regenerates for new/changed; `--drop-embeddings` wipes.
-5. **Leiden RNG seeded for reproducibility.** `mulberry32` with constant seed `0xC0DE` in `community-processor.ts`. Required for the equivalence test.
-
-## v1 attempt (reverted)
-
-The original spec described a "hydrate phase" that loads node/edge state from DB for unchanged files into a fresh `ctx.graph`, then runs the parse phase only on a closure of changed-files-plus-importers. That design failed the equivalence test:
-
-| Same edited state | Nodes | Edges | Clusters | Flows |
-|---|---|---|---|---|
-| `--force` (full rebuild) | 24,624 | 32,822 | 850 | 300 |
-| v1 incremental | 24,574 | **32,397** | 845 | **252** |
-
-Δ −425 edges and −48 process flows. Root cause: `crossFile` and `scopeResolution` operated on partial parse data (only the closure files were parsed), so CALLS edges that resolved through unchanged files silently fell off. The reverted commits and the post-mortem are preserved on the branch (commits `aa8d7ae3` … `d4b9de47`, with the revert at `37ef3dda`) so reviewers can see what we ruled out.
-
-The Option B design (parse-cache + incremental-DB-writeback + scope-resolution-short-circuit) sidesteps this entirely: the pipeline parses every file every run, so cross-file always sees full data.
-
-## Measured results
-
-Benchmarked on this repo (993 files / 24,547 nodes / 32,716 edges, Windows):
-
-| Run | Time |
-|---|---|
-| Cold full reindex | 86s |
-| Warm cache, no source changes | 3s (early-return) |
-| Warm cache + 1-file edit, **incremental** | 38s |
-| Warm cache + 1-file edit, `--force` from same state | similar to cold |
-
-40% faster cold rebuild, 72% faster on the practical "edit one file, reindex" workflow. All paths produce byte-identical graph state.
-
-## Crash recovery
-
-`meta.json.incrementalInProgress = { startedAt, toWriteCount }` is written BEFORE any destructive DB mutation in the incremental writeback path and cleared on success by overwriting meta.json. If a run crashes between, the next run detects the flag at startup and forces a full rebuild — cheapest path back to a known-good index. Works regardless of LadybugDB transactional semantics.
-
-## Out of scope (future follow-ups)
-
-- **GitNexus auto-writes mutate cache-relevant files.** During analyze, GitNexus updates `AGENTS.md`, `CLAUDE.md`, `.claude/skills/...` etc. with current stats. Those files get re-indexed on the next run with new content → chunk hash differs → cache miss for chunks containing them. Mitigations: (a) add the auto-gen output paths to a workspace-level ignore, (b) make the auto-gen output stable across runs, (c) extract the chunk hash from non-mutating fields only. None of these are blocking for the current PR.
-- **Sequential-mode parses don't populate `parsedFiles`.** The worker emits `ParsedFile` via `extractParsedFile` but the sequential fallback writes directly to graph without producing the artifact. Small repos that don't trigger workers don't benefit from the scope-resolution short-circuit. Acceptable: small repos are fast either way.
-- **Per-file (instead of per-chunk) cache granularity.** Per-file would invalidate even less on a large edit. Requires changing the worker contract to emit per-file results; non-trivial, not justified by current measurements.
-- **Cache file size.** 100-300MB on large repos. Compact JSON, no compression. Could be optimized later (gzip, MessagePack, binary).
-
-## Pre-PR checklist
-
-- [x] `npx tsc --noEmit` clean across `gitnexus` + `gitnexus-shared`
-- [x] Equivalence test verified on this repo (incremental ≡ `--force`)
-- [x] Crash-recovery dirty flag implemented + manually tested
-- [x] Dirty-tree gate on `lastCommit==HEAD` early-return
-- [ ] AGENTS.md / GUARDRAILS.md note on new default behavior
-- [ ] PR description with credits to zenprocess / davidbeesley / azeemshaik025
-
-## Code map
-
-| Concern | Files |
-|---|---|
-| File-hash diff | `gitnexus/src/storage/file-hash.ts` |
-| Subgraph extract | `gitnexus/src/core/incremental/subgraph-extract.ts` |
-| Parse cache | `gitnexus/src/storage/parse-cache.ts` |
-| DB primitives | `gitnexus/src/core/lbug/lbug-adapter.ts` (`deleteAllCommunitiesAndProcesses`) |
-| Pipeline plumbing | `gitnexus/src/core/ingestion/pipeline.ts` (`PipelineOptions.parseCache`); `parse.ts` (`ParseOutput.parsedFiles`); `parse-impl.ts` (chunk loop with cache); `parsing-processor.ts` (`mergeChunkResults`, `outRawResults`) |
-| Scope-resolution | `gitnexus/src/core/ingestion/scope-resolution/pipeline/run.ts` (`preExtractedParsedFiles`); `phase.ts` (map construction) |
-| Orchestration | `gitnexus/src/core/run-analyze.ts` (incremental detection + DB-writeback branch + cache lifecycle) |
-| Schema | `gitnexus/src/storage/repo-manager.ts` (`RepoMeta.schemaVersion`, `fileHashes`, `incrementalInProgress`) |
-| Determinism | `gitnexus/src/core/ingestion/community-processor.ts` (seeded Leiden RNG) |
diff --git a/gitnexus/src/core/lbug/lbug-adapter.ts b/gitnexus/src/core/lbug/lbug-adapter.ts
index ec879ebef..caa7a58a1 100644
--- a/gitnexus/src/core/lbug/lbug-adapter.ts
+++ b/gitnexus/src/core/lbug/lbug-adapter.ts
@@ -1204,6 +1204,46 @@ export const deleteNodesForFile = async (
 
 export const getEmbeddingTableName = (): string => EMBEDDING_TABLE_NAME;
 
+/**
+ * Return the distinct repo-relative paths of files that import
+ * `targetFilePath` according to the IMPORTS edges currently in the
+ * DB. Used by the incremental writeback path to expand the
+ * "files-to-rewrite" set so that files importing a changed file get
+ * their edges (which may have been refined by cross-file resolution)
+ * re-emitted, rather than left stale in the DB.
+ *
+ * The DB query reads the *previous* run's state — pre-pipeline, before
+ * any nodes are deleted — so the returned importers are "files that
+ * USED TO import the target". That's the right set to invalidate:
+ * those are the files whose edges in the DB might no longer match
+ * what cross-file resolution produces given the changed file's new
+ * exports.
+ */
+export const queryImporters = async (targetFilePath: string): Promise<string[]> => {
+  if (!conn) {
+    throw new Error('LadybugDB not initialized. Call initLbug first.');
+  }
+  const escaped = targetFilePath.replace(/'/g, "''");
+  const cypher = `
+    MATCH (a)-[r:${REL_TABLE_NAME}]->(b)
+    WHERE r.type = 'IMPORTS' AND b.filePath = '${escaped}'
+    RETURN DISTINCT a.filePath AS importer
+  `;
+  try {
+    const queryResult = await conn.query(cypher);
+    const result = Array.isArray(queryResult) ? queryResult[0] : queryResult;
+    const rows = await result.getAll();
+    const out: string[] = [];
+    for (const row of rows) {
+      const v = (row as { importer?: unknown }).importer;
+      if (typeof v === 'string' && v.length > 0) out.push(v);
+    }
+    return out;
+  } catch {
+    return [];
+  }
+};
+
 /**
  * Drop every Community and Process node (and their MEMBER_OF /
  * STEP_IN_PROCESS edges via DETACH DELETE). Used at the start of an
diff --git a/gitnexus/src/core/run-analyze.ts b/gitnexus/src/core/run-analyze.ts
index e42577507..91150b2e8 100644
--- a/gitnexus/src/core/run-analyze.ts
+++ b/gitnexus/src/core/run-analyze.ts
@@ -23,6 +23,7 @@ import {
   loadCachedEmbeddings,
   deleteNodesForFile,
   deleteAllCommunitiesAndProcesses,
+  queryImporters,
 } from './lbug/lbug-adapter.js';
 import { createSearchFTSIndexes } from './search/fts-indexes.js';
 import {
@@ -436,8 +437,37 @@ export async function runFullAnalysis(
     let lbugMsgCount = 0;
     if (isIncremental && hashDiff) {
       // ── Incremental DB writeback ───────────────────────────────────
+      // 0. Expand the writable set with importers of changed/deleted
+      //    files. Reason (Bugbot/Claude review on PR #1479): when a
+      //    barrel/re-export file changes, cross-file resolution may
+      //    update CALLS edges between two unchanged files. Those edges
+      //    live in `ctx.graph` (the pipeline's authoritative output)
+      //    but would be excluded from the subgraph if neither endpoint
+      //    is in the changed set, leaving the DB stale. Pulling the
+      //    importers in (1-hop transitive) puts those edges' source
+      //    files into the writable set so deleteNodesForFile clears
+      //    their old rows and the subgraph re-emits the refined ones.
+      //    Reads `IMPORTS` from the pre-pipeline DB state; importers
+      //    that no longer import the changed file get rewritten too,
+      //    which is harmless (idempotent re-emission) and necessary
+      //    for the "incremental ≡ full-rebuild" invariant.
+      const writableFiles = new Set<string>(hashDiff.toWrite);
+      const directlyChangedCount = writableFiles.size;
+      for (const f of [...hashDiff.toWrite, ...hashDiff.deleted]) {
+        try {
+          const importers = await queryImporters(f);
+          for (const i of importers) writableFiles.add(i);
+        } catch {
+          /* importer query failure → don't expand; correctness degrades but DB stays writable */
+        }
+      }
+      const importerExpansion = writableFiles.size - directlyChangedCount;
+      if (importerExpansion > 0) {
+        log(`Incremental: +${importerExpansion} importer(s) added to writable set`);
+      }
+
       // 1. Delete rows for files we're about to rewrite + deleted files.
-      const filesToDelete = [...hashDiff.toWrite, ...hashDiff.deleted];
+      const filesToDelete = [...writableFiles, ...hashDiff.deleted];
       for (let i = 0; i < filesToDelete.length; i++) {
         const f = filesToDelete[i];
         try {
@@ -456,7 +486,7 @@ export async function runFullAnalysis(
 
       // 3. Extract the changed subgraph from the FULL ctx.graph and write
       //    only that. Unchanged-file rows in the DB stay untouched.
-      const subgraph = extractChangedSubgraph(pipelineResult.graph, new Set(hashDiff.toWrite));
+      const subgraph = extractChangedSubgraph(pipelineResult.graph, writableFiles);
       await loadGraphToLbug(subgraph, pipelineResult.repoPath, storagePath, (msg) => {
         lbugMsgCount++;
         const pct = Math.min(84, 65 + Math.round((lbugMsgCount / (lbugMsgCount + 10)) * 19));
diff --git a/gitnexus/src/storage/parse-cache.ts b/gitnexus/src/storage/parse-cache.ts
index b04799de4..a1abf76fa 100644
--- a/gitnexus/src/storage/parse-cache.ts
+++ b/gitnexus/src/storage/parse-cache.ts
@@ -23,25 +23,65 @@
  */
 
 import { createHash } from 'crypto';
+import { createRequire } from 'module';
 import fs from 'fs/promises';
 import path from 'path';
+import { fileURLToPath } from 'url';
 import type { ParseWorkerResult } from '../core/ingestion/workers/parse-worker.js';
 
-/** Bump on incompatible changes to ParseWorkerResult or upstream parse semantics. */
-export const PARSE_CACHE_VERSION = 1;
+/**
+ * Cache version composed of:
+ *   - A schema bump knob (`SCHEMA_BUMP`) for hand-controlled invalidation
+ *     when ParseWorkerResult shape or upstream parse semantics change.
+ *   - The current `gitnexus` npm package version, read at module load.
+ *     Any release that ships an updated tree-sitter grammar or revised
+ *     extractor logic implies a version bump in package.json, which
+ *     automatically invalidates the on-disk cache. Without this, a user
+ *     running `npm i -g gitnexus@latest` after a parser-affecting
+ *     release would silently replay pre-upgrade ParseWorkerResults
+ *     against the new graph schema (Bugbot/Claude review on #1479).
+ *
+ * On version mismatch, `loadParseCache` returns an empty cache and the
+ * next save overwrites the on-disk file with the new version baked in.
+ */
+const SCHEMA_BUMP = 1;
+const GITNEXUS_PKG_VERSION = (() => {
+  try {
+    // package.json sits at gitnexus/package.json — two levels up from
+    // gitnexus/src/storage/parse-cache.ts (or its dist/ equivalent).
+    const here = path.dirname(fileURLToPath(import.meta.url));
+    const candidates = [
+      path.join(here, '..', '..', 'package.json'), // src/storage → gitnexus/
+      path.join(here, '..', '..', '..', 'package.json'), // dist/storage → gitnexus/
+    ];
+    const requireCJS = createRequire(import.meta.url);
+    for (const c of candidates) {
+      try {
+        const pkg = requireCJS(c);
+        if (typeof pkg?.version === 'string') return pkg.version;
+      } catch {
+        /* try next candidate */
+      }
+    }
+  } catch {
+    /* fall through to fallback */
+  }
+  return '0.0.0-unknown';
+})();
+export const PARSE_CACHE_VERSION = `${SCHEMA_BUMP}+${GITNEXUS_PKG_VERSION}`;
 
 const CACHE_FILENAME = 'parse-cache.json';
 
 /** On-disk shape. */
 interface ParseCacheFile {
-  version: number;
+  version: string;
   /** key = chunk hash (hex) → cached chunk result list. */
   entries: Record<string, ParseWorkerResult[]>;
 }
 
 /** Runtime view: keyed Map for fast lookup; mutated in place during a run. */
 export interface ParseCache {
-  version: number;
+  version: string;
   entries: Map<string, ParseWorkerResult[]>;
   /**
    * Hashes referenced (hit OR miss-and-stored) by the current run.
diff --git a/gitnexus/test/unit/incremental-file-hash.test.ts b/gitnexus/test/unit/incremental-file-hash.test.ts
new file mode 100644
index 000000000..0f59dfb09
--- /dev/null
+++ b/gitnexus/test/unit/incremental-file-hash.test.ts
@@ -0,0 +1,124 @@
+import { describe, it, expect } from 'vitest';
+import { mkdtemp, writeFile, rm } from 'fs/promises';
+import { tmpdir } from 'os';
+import path from 'path';
+import { computeFileHash, computeFileHashes, diffFileHashes } from '../../src/storage/file-hash.js';
+
+describe('diffFileHashes', () => {
+  it('classifies files into changed / added / deleted / toWrite', () => {
+    const stored = { a: 'h-a', b: 'h-b', c: 'h-c' };
+    const current = new Map<string, string>([
+      ['a', 'h-a'], // unchanged
+      ['b', 'h-b-NEW'], // changed
+      ['d', 'h-d'], // added
+      // 'c' is gone → deleted
+    ]);
+    const diff = diffFileHashes(current, stored);
+    expect(diff.changed).toEqual(['b']);
+    expect(diff.added).toEqual(['d']);
+    expect(diff.deleted).toEqual(['c']);
+    // toWrite is the union of changed ∪ added (rows to be (re)written)
+    expect(diff.toWrite.sort()).toEqual(['b', 'd']);
+  });
+
+  it('treats no stored map as "everything is added"', () => {
+    const current = new Map<string, string>([
+      ['x', 'h1'],
+      ['y', 'h2'],
+    ]);
+    const diff = diffFileHashes(current, undefined);
+    expect(diff.added.sort()).toEqual(['x', 'y']);
+    expect(diff.changed).toEqual([]);
+    expect(diff.deleted).toEqual([]);
+    expect(diff.toWrite.sort()).toEqual(['x', 'y']);
+  });
+
+  it('returns sorted arrays for stable cross-platform comparison', () => {
+    const stored = { z: 'h', a: 'h', m: 'h' };
+    const current = new Map<string, string>([
+      ['z', 'h2'],
+      ['a', 'h2'],
+      ['m', 'h2'],
+    ]);
+    const diff = diffFileHashes(current, stored);
+    expect(diff.changed).toEqual(['a', 'm', 'z']);
+    expect(diff.toWrite).toEqual(['a', 'm', 'z']);
+  });
+
+  it('handles empty current map (all stored files become deleted)', () => {
+    const stored = { a: 'h1', b: 'h2' };
+    const diff = diffFileHashes(new Map(), stored);
+    expect(diff.deleted).toEqual(['a', 'b']);
+    expect(diff.changed).toEqual([]);
+    expect(diff.added).toEqual([]);
+  });
+});
+
+describe('computeFileHash', () => {
+  it('produces a stable SHA-256 hex digest', async () => {
+    const dir = await mkdtemp(path.join(tmpdir(), 'gnx-fh-'));
+    try {
+      const f = path.join(dir, 'a.txt');
+      await writeFile(f, 'hello world\n', 'utf-8');
+      const h1 = await computeFileHash(f);
+      const h2 = await computeFileHash(f);
+      expect(h1).toBe(h2);
+      expect(h1).toMatch(/^[a-f0-9]{64}$/);
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+
+  it('returns null on missing file (caller treats as "no signature")', async () => {
+    const h = await computeFileHash('/definitely/does/not/exist/here.xyz');
+    expect(h).toBeNull();
+  });
+
+  it('different content → different hash', async () => {
+    const dir = await mkdtemp(path.join(tmpdir(), 'gnx-fh-'));
+    try {
+      const a = path.join(dir, 'a.txt');
+      const b = path.join(dir, 'b.txt');
+      await writeFile(a, 'hello', 'utf-8');
+      await writeFile(b, 'goodbye', 'utf-8');
+      const ha = await computeFileHash(a);
+      const hb = await computeFileHash(b);
+      expect(ha).not.toBeNull();
+      expect(hb).not.toBeNull();
+      expect(ha).not.toBe(hb);
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+});
+
+describe('computeFileHashes', () => {
+  it('hashes a small batch of files in parallel', async () => {
+    const dir = await mkdtemp(path.join(tmpdir(), 'gnx-fh-'));
+    try {
+      await writeFile(path.join(dir, 'one.txt'), 'A', 'utf-8');
+      await writeFile(path.join(dir, 'two.txt'), 'B', 'utf-8');
+      await writeFile(path.join(dir, 'three.txt'), 'C', 'utf-8');
+      const map = await computeFileHashes(dir, ['one.txt', 'two.txt', 'three.txt']);
+      expect(map.size).toBe(3);
+      expect(map.get('one.txt')).toMatch(/^[a-f0-9]{64}$/);
+      // All distinct since contents differ
+      const hashes = [...map.values()];
+      expect(new Set(hashes).size).toBe(3);
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+
+  it('omits files that fail to read (no entry in result)', async () => {
+    const dir = await mkdtemp(path.join(tmpdir(), 'gnx-fh-'));
+    try {
+      await writeFile(path.join(dir, 'real.txt'), 'X', 'utf-8');
+      const map = await computeFileHashes(dir, ['real.txt', 'phantom.txt']);
+      expect(map.has('real.txt')).toBe(true);
+      expect(map.has('phantom.txt')).toBe(false);
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+});
diff --git a/gitnexus/test/unit/incremental-parse-cache.test.ts b/gitnexus/test/unit/incremental-parse-cache.test.ts
new file mode 100644
index 000000000..757b9cf3a
--- /dev/null
+++ b/gitnexus/test/unit/incremental-parse-cache.test.ts
@@ -0,0 +1,243 @@
+import { describe, it, expect } from 'vitest';
+import { mkdtemp, rm } from 'fs/promises';
+import { tmpdir } from 'os';
+import path from 'path';
+import {
+  PARSE_CACHE_VERSION,
+  computeChunkHash,
+  fileContentHash,
+  loadParseCache,
+  saveParseCache,
+  pruneCache,
+  type ParseCache,
+} from '../../src/storage/parse-cache.js';
+import type { ParseWorkerResult } from '../../src/core/ingestion/workers/parse-worker.js';
+
+const minimalResult = (overrides: Partial<ParseWorkerResult> = {}): ParseWorkerResult => ({
+  nodes: [],
+  relationships: [],
+  symbols: [],
+  imports: [],
+  calls: [],
+  assignments: [],
+  heritage: [],
+  routes: [],
+  fetchCalls: [],
+  decoratorRoutes: [],
+  toolDefs: [],
+  ormQueries: [],
+  constructorBindings: [],
+  fileScopeBindings: [],
+  parsedFiles: [],
+  skippedLanguages: {},
+  fileCount: 0,
+  ...overrides,
+});
+
+describe('computeChunkHash', () => {
+  it('produces a stable hex hash for a fixed set of (filePath, contentHash) entries', () => {
+    const entries = [
+      { filePath: 'a.ts', contentHash: 'h-a' },
+      { filePath: 'b.ts', contentHash: 'h-b' },
+      { filePath: 'c.ts', contentHash: 'h-c' },
+    ];
+    const h1 = computeChunkHash(entries);
+    const h2 = computeChunkHash(entries);
+    expect(h1).toBe(h2);
+    expect(h1).toMatch(/^[a-f0-9]{64}$/);
+  });
+
+  it('is order-independent (same files in different order → same hash)', () => {
+    const order1 = [
+      { filePath: 'a.ts', contentHash: 'h-a' },
+      { filePath: 'b.ts', contentHash: 'h-b' },
+    ];
+    const order2 = [
+      { filePath: 'b.ts', contentHash: 'h-b' },
+      { filePath: 'a.ts', contentHash: 'h-a' },
+    ];
+    expect(computeChunkHash(order1)).toBe(computeChunkHash(order2));
+  });
+
+  it('changes when any file content changes', () => {
+    const before = [
+      { filePath: 'a.ts', contentHash: 'h-a' },
+      { filePath: 'b.ts', contentHash: 'h-b' },
+    ];
+    const after = [
+      { filePath: 'a.ts', contentHash: 'h-a' },
+      { filePath: 'b.ts', contentHash: 'h-b-NEW' }, // b.ts content changed
+    ];
+    expect(computeChunkHash(before)).not.toBe(computeChunkHash(after));
+  });
+
+  it('changes when chunk membership changes (file added or removed)', () => {
+    const small = [
+      { filePath: 'a.ts', contentHash: 'h-a' },
+      { filePath: 'b.ts', contentHash: 'h-b' },
+    ];
+    const bigger = [...small, { filePath: 'c.ts', contentHash: 'h-c' }];
+    expect(computeChunkHash(small)).not.toBe(computeChunkHash(bigger));
+  });
+});
+
+describe('fileContentHash', () => {
+  it('hashes a string deterministically', () => {
+    expect(fileContentHash('hello')).toBe(fileContentHash('hello'));
+    expect(fileContentHash('hello')).not.toBe(fileContentHash('hello!'));
+    expect(fileContentHash('hello')).toMatch(/^[a-f0-9]{64}$/);
+  });
+
+  it('handles Buffer input identical to its string form', () => {
+    const s = 'sentinel';
+    expect(fileContentHash(Buffer.from(s))).toBe(fileContentHash(s));
+  });
+});
+
+describe('PARSE_CACHE_VERSION', () => {
+  it('embeds the gitnexus package version (so upgrades invalidate the cache)', () => {
+    // Looks like "1+1.6.4" — schema bump prefix + actual gitnexus version
+    expect(PARSE_CACHE_VERSION).toMatch(/^\d+\+\d+\.\d+\.\d+/);
+  });
+});
+
+describe('pruneCache', () => {
+  it('drops entries whose hashes are not in the used-set', () => {
+    const cache: ParseCache = {
+      version: PARSE_CACHE_VERSION,
+      entries: new Map<string, ParseWorkerResult[]>([
+        ['hash-A', [minimalResult()]],
+        ['hash-B', [minimalResult()]],
+        ['hash-C', [minimalResult()]],
+      ]),
+      usedKeys: new Set<string>(['hash-A']),
+    };
+    const removed = pruneCache(cache, cache.usedKeys);
+    expect(removed).toBe(2);
+    expect([...cache.entries.keys()].sort()).toEqual(['hash-A']);
+  });
+
+  it('returns 0 when every entry is in use', () => {
+    const cache: ParseCache = {
+      version: PARSE_CACHE_VERSION,
+      entries: new Map<string, ParseWorkerResult[]>([
+        ['hash-A', [minimalResult()]],
+        ['hash-B', [minimalResult()]],
+      ]),
+      usedKeys: new Set<string>(['hash-A', 'hash-B']),
+    };
+    expect(pruneCache(cache, cache.usedKeys)).toBe(0);
+    expect(cache.entries.size).toBe(2);
+  });
+});
+
+describe('loadParseCache / saveParseCache (round-trip)', () => {
+  it('round-trips an empty cache', async () => {
+    const dir = await mkdtemp(path.join(tmpdir(), 'gnx-pc-'));
+    try {
+      const cache: ParseCache = {
+        version: PARSE_CACHE_VERSION,
+        entries: new Map(),
+        usedKeys: new Set(),
+      };
+      await saveParseCache(dir, cache);
+      const loaded = await loadParseCache(dir);
+      expect(loaded.version).toBe(PARSE_CACHE_VERSION);
+      expect(loaded.entries.size).toBe(0);
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+
+  it('returns an empty cache when the file is missing', async () => {
+    const dir = await mkdtemp(path.join(tmpdir(), 'gnx-pc-'));
+    try {
+      const loaded = await loadParseCache(dir);
+      expect(loaded.entries.size).toBe(0);
+      expect(loaded.usedKeys.size).toBe(0);
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+
+  it('returns an empty cache on version mismatch (next-run regen)', async () => {
+    const dir = await mkdtemp(path.join(tmpdir(), 'gnx-pc-'));
+    try {
+      // Write a cache file with a different version directly
+      const fs = await import('fs/promises');
+      await fs.writeFile(
+        path.join(dir, 'parse-cache.json'),
+        JSON.stringify({ version: 'foreign-99', entries: { h: [] } }),
+        'utf-8',
+      );
+      const loaded = await loadParseCache(dir);
+      expect(loaded.entries.size).toBe(0); // mismatch → empty
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+
+  it('returns an empty cache on corrupt JSON', async () => {
+    const dir = await mkdtemp(path.join(tmpdir(), 'gnx-pc-'));
+    try {
+      const fs = await import('fs/promises');
+      await fs.writeFile(path.join(dir, 'parse-cache.json'), '{not-json', 'utf-8');
+      const loaded = await loadParseCache(dir);
+      expect(loaded.entries.size).toBe(0);
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+
+  it('round-trips Map and Set values through the JSON replacer/reviver', async () => {
+    // ParsedFile.scopes[*].typeBindings is a ReadonlyMap<string, TypeRef>.
+    // Without the replacer/reviver pair, JSON.stringify collapses Maps to
+    // {} and downstream code that does .get() / iterates entries crashes
+    // with "is not iterable". This test pins the round-trip behaviour.
+    const dir = await mkdtemp(path.join(tmpdir(), 'gnx-pc-'));
+    try {
+      const innerMap = new Map<string, string>([
+        ['k1', 'v1'],
+        ['k2', 'v2'],
+      ]);
+      const innerSet = new Set<string>(['s1', 's2']);
+      // Stash the live Map/Set inside a synthetic ParseWorkerResult — we
+      // only need the serializer to traverse them. Casting to bypass the
+      // strict shape isn't a problem here: this test is about JSON
+      // round-tripping of arbitrary nested Map/Set values, not full
+      // ParseWorkerResult contents.
+      const fake = minimalResult({
+        parsedFiles: [
+          {
+            filePath: 't.ts',
+            // Cast through unknown to satisfy the readonly Scope shape
+            // while still smuggling a live Map into the serializer's
+            // traversal path — see comment block above.
+            scopes: [{ id: 's1', typeBindings: innerMap, extras: innerSet }],
+          } as unknown as ParseWorkerResult['parsedFiles'][number],
+        ],
+      });
+
+      const cache: ParseCache = {
+        version: PARSE_CACHE_VERSION,
+        entries: new Map<string, ParseWorkerResult[]>([['chunk-h', [fake]]]),
+        usedKeys: new Set(['chunk-h']),
+      };
+      await saveParseCache(dir, cache);
+      const loaded = await loadParseCache(dir);
+      const reloaded = loaded.entries.get('chunk-h')?.[0];
+      expect(reloaded).toBeDefined();
+      const scope = (reloaded as ParseWorkerResult).parsedFiles[0]?.scopes[0] as unknown as {
+        typeBindings?: unknown;
+        extras?: unknown;
+      };
+      expect(scope.typeBindings).toBeInstanceOf(Map);
+      expect((scope.typeBindings as Map<string, string>).get('k1')).toBe('v1');
+      expect((scope.typeBindings as Map<string, string>).size).toBe(2);
+      expect(scope.extras).toBeInstanceOf(Set);
+      expect((scope.extras as Set<string>).has('s2')).toBe(true);
+    } finally {
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+});
diff --git a/gitnexus/test/unit/incremental-subgraph-extract.test.ts b/gitnexus/test/unit/incremental-subgraph-extract.test.ts
new file mode 100644
index 000000000..f2a8c3e3e
--- /dev/null
+++ b/gitnexus/test/unit/incremental-subgraph-extract.test.ts
@@ -0,0 +1,105 @@
+import { describe, it, expect } from 'vitest';
+import { createKnowledgeGraph } from '../../src/core/graph/graph.js';
+import { extractChangedSubgraph } from '../../src/core/incremental/subgraph-extract.js';
+import type { GraphNode, GraphRelationship } from 'gitnexus-shared';
+
+const fileNode = (
+  id: string,
+  filePath: string,
+  label: GraphNode['label'] = 'Function',
+): GraphNode => ({
+  id,
+  label,
+  properties: { name: id, filePath },
+});
+
+const wideNode = (id: string, label: GraphNode['label']): GraphNode => ({
+  id,
+  label,
+  properties: { name: id },
+});
+
+const rel = (
+  id: string,
+  type: GraphRelationship['type'],
+  src: string,
+  dst: string,
+): GraphRelationship => ({
+  id,
+  type,
+  sourceId: src,
+  targetId: dst,
+  confidence: 1,
+  reason: 't',
+});
+
+describe('extractChangedSubgraph', () => {
+  it('keeps file nodes whose filePath is in the writable set', () => {
+    const g = createKnowledgeGraph();
+    g.addNode(fileNode('Function:a.ts:foo', 'a.ts'));
+    g.addNode(fileNode('Function:b.ts:bar', 'b.ts'));
+    g.addNode(fileNode('Function:c.ts:baz', 'c.ts'));
+
+    const sub = extractChangedSubgraph(g, new Set(['a.ts', 'c.ts']));
+    expect(sub.nodeCount).toBe(2);
+    expect(sub.getNode('Function:a.ts:foo')).toBeDefined();
+    expect(sub.getNode('Function:c.ts:baz')).toBeDefined();
+    expect(sub.getNode('Function:b.ts:bar')).toBeUndefined();
+  });
+
+  it('always keeps Community and Process nodes (regenerated graph-wide)', () => {
+    const g = createKnowledgeGraph();
+    g.addNode(fileNode('Function:a.ts:foo', 'a.ts'));
+    g.addNode(wideNode('comm_1', 'Community'));
+    g.addNode(wideNode('proc_1', 'Process'));
+
+    // Empty writable set: only graph-wide nodes survive
+    const sub = extractChangedSubgraph(g, new Set());
+    expect(sub.getNode('Function:a.ts:foo')).toBeUndefined();
+    expect(sub.getNode('comm_1')).toBeDefined();
+    expect(sub.getNode('proc_1')).toBeDefined();
+  });
+
+  it('keeps edges where at least one endpoint is in the writable subgraph', () => {
+    const g = createKnowledgeGraph();
+    g.addNode(fileNode('Function:a.ts:foo', 'a.ts'));
+    g.addNode(fileNode('Function:b.ts:bar', 'b.ts'));
+    g.addNode(fileNode('Function:c.ts:baz', 'c.ts'));
+    g.addRelationship(rel('r-ab', 'CALLS', 'Function:a.ts:foo', 'Function:b.ts:bar'));
+    g.addRelationship(rel('r-bc', 'CALLS', 'Function:b.ts:bar', 'Function:c.ts:baz'));
+    g.addRelationship(rel('r-ac', 'CALLS', 'Function:a.ts:foo', 'Function:c.ts:baz'));
+
+    const sub = extractChangedSubgraph(g, new Set(['a.ts']));
+    // r-ab: src in a.ts (writable) → kept
+    // r-ac: src in a.ts (writable) → kept
+    // r-bc: src in b.ts, dst in c.ts (both unchanged) → dropped
+    const rels = [...sub.iterRelationships()].map((r) => r.id).sort();
+    expect(rels).toEqual(['r-ab', 'r-ac']);
+  });
+
+  it('keeps MEMBER_OF edges (Community endpoints are graph-wide)', () => {
+    const g = createKnowledgeGraph();
+    g.addNode(fileNode('Function:a.ts:foo', 'a.ts'));
+    g.addNode(fileNode('Function:b.ts:bar', 'b.ts'));
+    g.addNode(wideNode('comm_1', 'Community'));
+    // Both functions are members of the same community
+    g.addRelationship(rel('r-a-comm', 'MEMBER_OF', 'Function:a.ts:foo', 'comm_1'));
+    g.addRelationship(rel('r-b-comm', 'MEMBER_OF', 'Function:b.ts:bar', 'comm_1'));
+
+    const sub = extractChangedSubgraph(g, new Set(['a.ts']));
+    // r-a-comm: src in a.ts (writable) — kept
+    // r-b-comm: src in b.ts (NOT writable) but dst is graph-wide (Community is in writable subgraph) — kept
+    const rels = [...sub.iterRelationships()].map((r) => r.id).sort();
+    expect(rels).toEqual(['r-a-comm', 'r-b-comm']);
+  });
+
+  it('produces an empty subgraph when no nodes match', () => {
+    const g = createKnowledgeGraph();
+    g.addNode(fileNode('Function:a.ts:foo', 'a.ts'));
+    g.addRelationship(rel('r1', 'CALLS', 'Function:a.ts:foo', 'Function:a.ts:foo'));
+
+    const sub = extractChangedSubgraph(g, new Set(['nonexistent.ts']));
+    expect(sub.nodeCount).toBe(0);
+    expect(sub.relationshipCount).toBe(0);
+  });
+});