diff --git a/src/commands/sources.ts b/src/commands/sources.ts
index 4f8be68..0573a7a 100644
--- a/src/commands/sources.ts
+++ b/src/commands/sources.ts
@@ -204,9 +204,19 @@ async function runAdd(engine: BrainEngine, args: string[]): Promise<void> {
   if (federated !== null) config.federated = federated;
   if (slugPrefixRules) config.slug_prefix_rules = slugPrefixRules;
 
+  // Double cast `($4::text)::jsonb` is intentional: postgres-js's `unsafe()` API
+  // detects `$N::jsonb` casts on string params and re-stringifies the value as a
+  // JSON-encoded literal, which Postgres then stores as a JSON STRING scalar
+  // (jsonb_typeof = 'string'). The text cast forces postgres-js to send the
+  // param verbatim as TEXT, then SQL re-parses to a jsonb object at the column
+  // boundary. PGLite is unaffected (its driver doesn't have postgres-js's
+  // auto-encoding) but the double cast is a no-op there. Verified empirically
+  // on D-LXC fixture 189 (2026-05-07): variant 1 (current pattern) → string,
+  // variant 4 (this fix) → object. See migration v26 step 0 for the matching
+  // healing path that recovers existing string-encoded prod data.
   await engine.executeRaw(
     `INSERT INTO sources (id, name, local_path, config)
-         VALUES ($1, $2, $3, $4::jsonb)
+         VALUES ($1, $2, $3, ($4::text)::jsonb)
      ON CONFLICT (id) DO NOTHING`,
     [id, displayName, localPath, JSON.stringify(config)],
   );
@@ -393,8 +403,12 @@ async function runFederate(engine: BrainEngine, args: string[], value: boolean):
   }
   const config = parseConfig(src.config);
   config.federated = value;
+  // Double cast `($1::text)::jsonb` matches the runAdd path. See comment there
+  // for full rationale (postgres-js auto-jsonb-encoding bug). Without this
+  // cast the UPDATE writes a JSON string scalar (jsonb_typeof = 'string')
+  // and any subsequent migration using jsonb_set throws SQLSTATE 22023.
   await engine.executeRaw(
-    `UPDATE sources SET config = $1::jsonb WHERE id = $2`,
+    `UPDATE sources SET config = ($1::text)::jsonb WHERE id = $2`,
     [JSON.stringify(config), id],
   );
   console.log(`Source "${id}" is now ${value ? 'federated (appears in cross-source default search)' : 'isolated (only searched when explicitly named)'}.`);
@@ -457,8 +471,12 @@ async function runUpdate(engine: BrainEngine, args: string[]): Promise<void> {
     delete config.slug_prefix_rules;
   }
 
+  // Double cast `($1::text)::jsonb` matches the runAdd path. See comment there
+  // for full rationale (postgres-js auto-jsonb-encoding bug). Without this
+  // cast the UPDATE writes a JSON string scalar (jsonb_typeof = 'string')
+  // and any subsequent migration using jsonb_set throws SQLSTATE 22023.
   await engine.executeRaw(
-    `UPDATE sources SET config = $1::jsonb WHERE id = $2`,
+    `UPDATE sources SET config = ($1::text)::jsonb WHERE id = $2`,
     [JSON.stringify(config), id],
   );
 
diff --git a/src/commands/sync.ts b/src/commands/sync.ts
index 2f747b3..3c852cd 100644
--- a/src/commands/sync.ts
+++ b/src/commands/sync.ts
@@ -209,6 +209,22 @@ export async function performSync(engine: BrainEngine, opts: SyncOpts): Promise<
 
   // No changes
   if (lastCommit === headCommit) {
+    // v0.18.2.fork.1: advance last_sync_at even on up-to-date sync. Pre-fix
+    // this branch returned without touching the source row, so quiet sources
+    // (no commits since last sync) kept stale last_sync_at forever and the
+    // drift monitor (gbrain-projects-drift.sh) would falsely flag them as
+    // stale. Drift's contract is "is the sync cron alive?", not "did the
+    // remote add commits?" — record the successful sync attempt regardless.
+    // Only last_sync_at advances here; last_commit is untouched (no semantic
+    // change to commit anchor). engine.setConfig still records the global
+    // sync.last_run for legacy non-sourceId callers.
+    if (opts.sourceId) {
+      await engine.executeRaw(
+        `UPDATE sources SET last_sync_at = now() WHERE id = $1`,
+        [opts.sourceId],
+      );
+    }
+    await engine.setConfig('sync.last_run', new Date().toISOString());
     return {
       status: 'up_to_date',
       fromCommit: lastCommit,
diff --git a/test/e2e/jsonb-roundtrip.test.ts b/test/e2e/jsonb-roundtrip.test.ts
index e744b4e..7c84d33 100644
--- a/test/e2e/jsonb-roundtrip.test.ts
+++ b/test/e2e/jsonb-roundtrip.test.ts
@@ -126,4 +126,61 @@ describeE2E('E2E: JSONB roundtrip — v0.12.1 reliability wave', () => {
       expect(source.match(bad)?.[0] ?? null).toBeNull();
     }
   });
+
+  // v0.18.2.fork.1: sources.ts triple INSERT/UPDATE missed in v0.12.1 wave.
+  // Different fix variant — the unsafe()-API path uses `$N::jsonb` cast on a
+  // JSON.stringify'd param (not template-tag `${..}::jsonb`). postgres-js's
+  // unsafe() detects the cast and re-stringifies the param, landing as a
+  // JSON STRING scalar (jsonb_typeof = 'string'). v26 migration's jsonb_set
+  // then throws SQLSTATE 22023 "cannot set path in scalar".
+  // Fix: `($N::text)::jsonb` double cast forces postgres-js to send param
+  // verbatim as TEXT, then SQL re-parses to object at column boundary.
+  // Verified empirically on D-LXC fixture 189 (2026-05-07).
+  test('sources INSERT writes config as object, not double-encoded string', async () => {
+    const sql = getConn();
+    const { runAdd } = await import('../../src/commands/sources.ts') as any;
+    const engine = getEngine();
+    const testId = 'jsonb-sources-add-' + Math.floor(Math.random() * 1e6);
+    await runAdd(engine, [testId, '--federated', '--slug-prefix', 'test-prefix/']);
+    const [row] = await sql`
+      SELECT jsonb_typeof(config) AS t,
+             config -> 'federated' AS federated,
+             config -> 'slug_prefix_rules' AS rules
+      FROM sources WHERE id = ${testId}
+    `;
+    expect(row.t).toBe('object');
+    expect(row.federated).toBe(true);
+    expect(row.rules).toEqual(['test-prefix/']);
+    await sql`DELETE FROM sources WHERE id = ${testId}`;
+  });
+
+  test('sources UPDATE (federate/unfederate) preserves config as object', async () => {
+    const sql = getConn();
+    const { runAdd } = await import('../../src/commands/sources.ts') as any;
+    const { runFederate } = await import('../../src/commands/sources.ts') as any;
+    const engine = getEngine();
+    const testId = 'jsonb-sources-update-' + Math.floor(Math.random() * 1e6);
+    await runAdd(engine, [testId, '--federated']);
+    // Toggle to isolated then back — exercises the runFederate UPDATE path.
+    if (runFederate) {
+      await runFederate(engine, [testId], false);
+      const [row] = await sql`
+        SELECT jsonb_typeof(config) AS t, config -> 'federated' AS federated
+        FROM sources WHERE id = ${testId}
+      `;
+      expect(row.t).toBe('object');
+      expect(row.federated).toBe(false);
+    }
+    await sql`DELETE FROM sources WHERE id = ${testId}`;
+  });
+
+  test('no $N::jsonb pattern (without ::text intermediate) remains in sources.ts', async () => {
+    const source = await Bun.file(new URL('../../src/commands/sources.ts', import.meta.url)).text();
+    // Match `$<digit>::jsonb` not preceded by `::text)` — the bad pattern.
+    // Allow `($N::text)::jsonb` (the fix). Strip the safe pattern first then check.
+    const safePattern = /\(\$\d+::text\)::jsonb/g;
+    const stripped = source.replace(safePattern, '<SAFE_DOUBLE_CAST>');
+    const bad = /\$\d+::jsonb/;
+    expect(stripped.match(bad)?.[0] ?? null).toBeNull();
+  });
 });
diff --git a/test/sync-up-to-date-stamping.test.ts b/test/sync-up-to-date-stamping.test.ts
new file mode 100644
index 0000000..a0ed59d
--- /dev/null
+++ b/test/sync-up-to-date-stamping.test.ts
@@ -0,0 +1,157 @@
+/**
+ * v0.18.2.fork.1 — sync.ts up_to_date path advances last_sync_at.
+ *
+ * Pre-fix: when `lastCommit === headCommit` (no new commits since last sync),
+ * performSync early-returned without touching the source row. Quiet sources
+ * (read-mostly repos like claude-config / personal-knowledge / subagent-writes)
+ * kept stale `last_sync_at` forever; drift monitor (gbrain-projects-drift.sh)
+ * false-flagged them as "stale (Nmin ago, threshold 60min)" even though sync
+ * cron was firing every 10 min and pulling correctly.
+ *
+ * Fix: advance last_sync_at on up_to_date path so drift's contract holds:
+ * "is the sync cron alive?" (real behavior), not "did the remote add commits?"
+ * (red-herring proxy).
+ *
+ * Surfaced 2026-05-07 PW 1 part 2 prod deploy on LXC 107 — first drift tick
+ * post-deploy reported stock-dashboard "stale 6197min ago" 30 seconds after
+ * a successful sync tick.
+ */
+
+import { describe, test, expect, beforeAll, afterAll } from 'bun:test';
+import { mkdtempSync, mkdirSync, writeFileSync, rmSync } from 'fs';
+import { join } from 'path';
+import { tmpdir } from 'os';
+import { execFileSync } from 'child_process';
+import { PGLiteEngine } from '../src/core/pglite-engine.ts';
+import { performSync } from '../src/commands/sync.ts';
+
+let engine: PGLiteEngine;
+const cleanupDirs: string[] = [];
+
+function git(cwd: string, ...args: string[]): string {
+  return execFileSync('git', ['-C', cwd, ...args], { encoding: 'utf-8' }).trim();
+}
+
+function makeFixtureRepo(): string {
+  const dir = mkdtempSync(join(tmpdir(), 'gbrain-syncstamp-'));
+  cleanupDirs.push(dir);
+  git(dir, 'init', '--quiet', '--initial-branch=main');
+  git(dir, 'config', 'user.email', 'test@example.com');
+  git(dir, 'config', 'user.name', 'test');
+  writeFileSync(
+    join(dir, 'note.md'),
+    `---\ntitle: note\ntype: note\n---\nbody\n`,
+  );
+  git(dir, 'add', '.');
+  git(dir, 'commit', '--quiet', '-m', 'init');
+  return dir;
+}
+
+beforeAll(async () => {
+  engine = new PGLiteEngine();
+  await engine.connect({ type: 'pglite' } as never);
+  await engine.initSchema();
+});
+
+afterAll(async () => {
+  await engine.disconnect();
+  for (const d of cleanupDirs) {
+    try { rmSync(d, { recursive: true, force: true }); } catch { /* best-effort */ }
+  }
+});
+
+describe('sync up_to_date path — advances last_sync_at', () => {
+  test('quiet repo (no new commits) bumps last_sync_at on subsequent sync', async () => {
+    const repo = makeFixtureRepo();
+    const headCommit = git(repo, 'rev-parse', 'HEAD');
+    const sourceId = 'syncstamp-quiet';
+
+    // Provision a source row anchored at HEAD with a stale last_sync_at one
+    // hour in the past. Mirrors the prod state for quiet sources where the
+    // last actual write happened well before the next idle tick.
+    await engine.executeRaw(
+      `INSERT INTO sources (id, name, local_path, last_commit, last_sync_at, config)
+       VALUES ($1, $1, $2, $3, now() - interval '1 hour', '{"federated": true}'::jsonb)
+       ON CONFLICT (id) DO UPDATE SET
+         local_path = EXCLUDED.local_path,
+         last_commit = EXCLUDED.last_commit,
+         last_sync_at = EXCLUDED.last_sync_at`,
+      [sourceId, repo, headCommit],
+    );
+
+    const before = await engine.executeRaw<{ last_sync_at: Date | string }>(
+      `SELECT last_sync_at FROM sources WHERE id = $1`,
+      [sourceId],
+    );
+    const beforeMs = new Date(before[0].last_sync_at as string).getTime();
+
+    // Trigger a sync where HEAD is unchanged from anchor → up_to_date branch.
+    const result = await performSync(engine, {
+      repoPath: repo,
+      noPull: true,
+      noEmbed: true,
+      sourceId,
+    });
+    expect(result.status).toBe('up_to_date');
+
+    const after = await engine.executeRaw<{ last_sync_at: Date | string }>(
+      `SELECT last_sync_at FROM sources WHERE id = $1`,
+      [sourceId],
+    );
+    const afterMs = new Date(after[0].last_sync_at as string).getTime();
+
+    // last_sync_at must advance — was 1h stale, should now be within seconds of now.
+    expect(afterMs).toBeGreaterThan(beforeMs);
+    expect(Date.now() - afterMs).toBeLessThan(10_000); // < 10s old
+  });
+
+  test('up_to_date does NOT touch last_commit (commit anchor stable)', async () => {
+    const repo = makeFixtureRepo();
+    const headCommit = git(repo, 'rev-parse', 'HEAD');
+    const sourceId = 'syncstamp-anchor';
+
+    await engine.executeRaw(
+      `INSERT INTO sources (id, name, local_path, last_commit, last_sync_at, config)
+       VALUES ($1, $1, $2, $3, now() - interval '1 hour', '{"federated": true}'::jsonb)
+       ON CONFLICT (id) DO UPDATE SET
+         local_path = EXCLUDED.local_path,
+         last_commit = EXCLUDED.last_commit,
+         last_sync_at = EXCLUDED.last_sync_at`,
+      [sourceId, repo, headCommit],
+    );
+
+    await performSync(engine, {
+      repoPath: repo,
+      noPull: true,
+      noEmbed: true,
+      sourceId,
+    });
+
+    const after = await engine.executeRaw<{ last_commit: string }>(
+      `SELECT last_commit FROM sources WHERE id = $1`,
+      [sourceId],
+    );
+    expect(after[0].last_commit).toBe(headCommit);
+  });
+
+  test('non-sourceId (legacy global config) path: no source UPDATE attempted', async () => {
+    const repo = makeFixtureRepo();
+    const headCommit = git(repo, 'rev-parse', 'HEAD');
+
+    // Seed legacy global config.
+    await engine.setConfig('sync.last_commit', headCommit);
+    await engine.setConfig('sync.repo_path', repo);
+
+    // No sourceId → legacy path. Should not throw, should still record sync.last_run.
+    const result = await performSync(engine, {
+      repoPath: repo,
+      noPull: true,
+      noEmbed: true,
+    });
+    expect(result.status).toBe('up_to_date');
+
+    const lastRun = await engine.getConfig('sync.last_run');
+    expect(lastRun).not.toBeNull();
+    expect(Date.now() - new Date(lastRun!).getTime()).toBeLessThan(10_000);
+  });
+});