diff --git a/src/commands/doctor.ts b/src/commands/doctor.ts
index f27772ac8..29840f180 100644
--- a/src/commands/doctor.ts
+++ b/src/commands/doctor.ts
@@ -3394,6 +3394,32 @@ export async function checkSyncFreshness(
     let hasWarnings = false;
     let hasFailures = false;
 
+    // BUG 4 (v0.42.x): a source with a LIVE, non-expired per-source sync lock is
+    // actively syncing RIGHT NOW — it must not read as stale or never-synced.
+    // The live lock is the only honest "in progress" signal. Checkpoint banking
+    // is NOT usable: a blocked sync banks the good files then writes no anchor
+    // (test/sync-resumable-import.serial.test.ts), so banking can't tell
+    // in-progress from wedged. A blocked/failed sync's process has exited (no
+    // lock row) and a wedged holder stops refreshing (TTL lapses), so either
+    // correctly falls through to the stale path and is NEVER masked. Same
+    // dynamic import as the stale_locks check; any throw (stub engine in unit
+    // tests, pre-lock-table brain) is swallowed to false, so this can only ADD
+    // an in-progress verdict, never suppress a real stale one.
+    let isActivelySyncing: (sourceId: string) => Promise<boolean> = async () => false;
+    try {
+      const { inspectLock, syncLockId } = await import('../core/db-lock.ts');
+      isActivelySyncing = async (sourceId: string): Promise<boolean> => {
+        try {
+          const snap = await inspectLock(engine, syncLockId(sourceId));
+          return !!snap && !snap.ttl_expired;
+        } catch {
+          return false;
+        }
+      };
+    } catch {
+      /* db-lock unavailable — skip in-progress detection, staleness stands. */
+    }
+
     for (const source of sources) {
       // Embed source.id in user-visible messages so `gbrain sync --source <id>`
       // matches what the user copy-pastes. Show display name in parens when set.
@@ -3401,6 +3427,13 @@ export async function checkSyncFreshness(
         ? `'${source.id}' (${source.name})`
         : `'${source.id}'`;
 
+      // BUG 4: actively syncing (live lock) → healthy, count as synced_recently
+      // and skip the staleness checks. Keeps the 3-bucket invariant intact.
+      if (await isActivelySyncing(source.id)) {
+        synced_recently_count++;
+        continue;
+      }
+
       if (!source.last_sync_at) {
         issues.push(`Source ${display} has never been synced`);
         hasFailures = true;
diff --git a/test/doctor.test.ts b/test/doctor.test.ts
index fab1201d0..30d39a525 100644
--- a/test/doctor.test.ts
+++ b/test/doctor.test.ts
@@ -1330,3 +1330,110 @@ describe('v0.42 (#1699) — quarantined_pages + flagged_pages checks', () => {
     expect(source).toMatch(/name: 'flagged_pages'/);
   });
 });
+
+// ============================================================================
+// BUG 4 (v0.42.x) — doctor reports an actively-running sync via the live lock,
+// not stale freshness. Uses a REAL PGLiteEngine so inspectLock/syncLockId run
+// against actual gbrain_cycle_locks rows (the stub engine can't model a lock).
+// ============================================================================
+describe('BUG 4 — in-progress sync via live lock, not stale freshness', () => {
+  let engine: any;
+  let syncLockId: (s: string) => string;
+
+  beforeAll(async () => {
+    const { PGLiteEngine } = await import('../src/core/pglite-engine.ts');
+    ({ syncLockId } = await import('../src/core/db-lock.ts'));
+    engine = new PGLiteEngine();
+    await engine.connect({});
+    await engine.initSchema();
+  });
+
+  afterAll(async () => {
+    await engine.disconnect();
+  });
+
+  beforeEach(async () => {
+    const { resetPgliteState } = await import('./helpers/reset-pglite.ts');
+    await resetPgliteState(engine);
+    await engine.executeRaw(`DELETE FROM gbrain_cycle_locks`);
+  });
+
+  const staleDate = () => new Date(Date.now() - 5 * 24 * 60 * 60 * 1000); // 5d ago
+
+  async function addSource(id: string, lastSyncAt: Date | null) {
+    await engine.executeRaw(
+      `INSERT INTO sources (id, name, local_path, last_sync_at, config)
+       VALUES ($1, $1, $2, $3, '{"federated":true}'::jsonb)
+       ON CONFLICT (id) DO UPDATE SET last_sync_at = EXCLUDED.last_sync_at`,
+      [id, `/tmp/${id}`, lastSyncAt],
+    );
+  }
+
+  // ttlMinutes > 0 → live lock; <= 0 → already-expired (wedged) holder.
+  async function holdLock(sourceId: string, ttlMinutes: number) {
+    await engine.executeRaw(
+      `INSERT INTO gbrain_cycle_locks (id, holder_pid, holder_host, acquired_at, ttl_expires_at, last_refreshed_at)
+       VALUES ($1, 4242, 'testhost', now(), now() + ($2 || ' minutes')::interval, now())`,
+      [syncLockId(sourceId), String(ttlMinutes)],
+    );
+  }
+
+  test('stale source with NO live lock → fail (blocked/wedged is not masked)', async () => {
+    const { checkSyncFreshness } = await import('../src/commands/doctor.ts');
+    await addSource('wiki', staleDate());
+    const result = await checkSyncFreshness(engine);
+    expect(result.status).toBe('fail');
+    expect(result.message).toContain(`'wiki'`);
+  });
+
+  test('stale source WITH a live (non-expired) lock → ok (sync in progress)', async () => {
+    const { checkSyncFreshness } = await import('../src/commands/doctor.ts');
+    await addSource('wiki', staleDate());
+    await holdLock('wiki', 30);
+    const result = await checkSyncFreshness(engine);
+    expect(result.status).toBe('ok');
+    expect(result.details?.synced_recently_count).toBe(1);
+    expect(result.details?.stale_count).toBe(0);
+  });
+
+  test('never-synced source WITH a live lock → ok (initial sync in progress)', async () => {
+    const { checkSyncFreshness } = await import('../src/commands/doctor.ts');
+    await addSource('wiki', null);
+    await holdLock('wiki', 30);
+    const result = await checkSyncFreshness(engine);
+    expect(result.status).toBe('ok');
+    expect(result.details?.synced_recently_count).toBe(1);
+  });
+
+  test('never-synced source with NO lock → fail (unchanged behavior)', async () => {
+    const { checkSyncFreshness } = await import('../src/commands/doctor.ts');
+    await addSource('wiki', null);
+    const result = await checkSyncFreshness(engine);
+    expect(result.status).toBe('fail');
+    expect(result.message).toContain('never been synced');
+  });
+
+  test('expired-TTL lock does NOT mask staleness (wedged-but-not-refreshing holder)', async () => {
+    const { checkSyncFreshness } = await import('../src/commands/doctor.ts');
+    await addSource('wiki', staleDate());
+    await holdLock('wiki', -5); // ttl_expires_at 5 min in the past
+    const result = await checkSyncFreshness(engine);
+    expect(result.status).toBe('fail');
+  });
+
+  test('blocked source with banked checkpoint rows but NO live lock → still fail', async () => {
+    const { checkSyncFreshness } = await import('../src/commands/doctor.ts');
+    await addSource('wiki', staleDate());
+    // A blocked sync banks the good files then exits without an anchor and
+    // without a held lock. Banking must NOT be read as "in progress".
+    await engine.executeRaw(
+      `INSERT INTO op_checkpoints (op, fingerprint, completed_keys, updated_at)
+       VALUES ('sync', 'fp-blocked', '[]'::jsonb, now())`,
+    );
+    await engine.executeRaw(
+      `INSERT INTO op_checkpoint_paths (op, fingerprint, path) VALUES ('sync', 'fp-blocked', 'banked.md')`,
+    );
+    const result = await checkSyncFreshness(engine);
+    expect(result.status).toBe('fail');
+  });
+});