diff --git a/bin/gstack-gbrain-detect b/bin/gstack-gbrain-detect
index ad2380df2..2100f913b 100755
--- a/bin/gstack-gbrain-detect
+++ b/bin/gstack-gbrain-detect
@@ -18,7 +18,7 @@
  *     "gstack_brain_sync_mode": "off"|"artifacts-only"|"full",
  *     "gstack_brain_git": true|false,
  *     "gstack_artifacts_remote": "https://..." | "",
- *     "gbrain_local_status": "ok"|"no-cli"|"missing-config"|"broken-config"|"broken-db"|"timeout",
+ *     "gbrain_local_status": "ok"|"no-cli"|"missing-config"|"broken-config"|"broken-db"|"engine-locked"|"timeout",
  *     "gbrain_pooler_mode": "transaction"|"session"|null
  *   }
  *
diff --git a/bin/gstack-gbrain-sync.ts b/bin/gstack-gbrain-sync.ts
index e55cec0ad..07a94af3f 100644
--- a/bin/gstack-gbrain-sync.ts
+++ b/bin/gstack-gbrain-sync.ts
@@ -717,6 +717,7 @@ function dreamMarkerPid(): number | null {
  *   missing-config → "no local engine; run /setup-gbrain to add local PGLite"
  *   broken-config  → "config file at ~/.gbrain/config.json is malformed; see /setup-gbrain Step 1.5"
  *   broken-db      → "config points at unreachable DB; see /setup-gbrain Step 1.5"
+ *   engine-locked  → PGLite is busy; stop its holder or sync outside the live session
  *   timeout        → kept for Record totality; stages PROCEED on timeout (#1964)
  *                    via the gate's warnProbeTimeout path, never this skip.
  */
@@ -733,6 +734,8 @@ function skipStageForLocalStatus(
       "config at ~/.gbrain/config.json is malformed; see /setup-gbrain Step 1.5",
     "broken-db":
       "config points at unreachable DB; see /setup-gbrain Step 1.5",
+    "engine-locked":
+      "PGLite is busy (often held by gbrain serve); stop the holding process or run /sync-gbrain outside the live Claude session, then retry",
     "timeout":
       "engine probe timed out; raise GSTACK_GBRAIN_PROBE_TIMEOUT_MS if your pooler is slow",
   };
diff --git a/lib/gbrain-local-status.ts b/lib/gbrain-local-status.ts
index 9e26d5ba4..2b6caa780 100644
--- a/lib/gbrain-local-status.ts
+++ b/lib/gbrain-local-status.ts
@@ -19,6 +19,8 @@
  * Broken-config → config exists but `gbrain sources list` fails with config parse error
  *                 (or any non-recognized error — defensive default per codex #8).
  * Broken-db → config exists, DB unreachable per stderr classification.
+ * Engine-locked → PGLite probe hit gbrain's own connect timeout, usually
+ *                 because another `gbrain serve` process owns the embedded DB.
  * Timeout → probe exceeded GSTACK_GBRAIN_PROBE_TIMEOUT_MS (default 15s) with no
  *           recognized error — engine is likely healthy but slow (e.g. a cold
  *           pooler connection, #1964). Consumers treat this as usable.
@@ -47,6 +49,7 @@ export type LocalEngineStatus =
   | "missing-config"
   | "broken-config"
   | "broken-db"
+  | "engine-locked"
   | "timeout";
 
 export interface ClassifyOptions {
@@ -118,6 +121,15 @@ function gbrainConfigPath(env?: NodeJS.ProcessEnv): string {
   return join(gbrainHome, "config.json");
 }
 
+function configuredEngine(env?: NodeJS.ProcessEnv): "pglite" | "postgres" | null {
+  try {
+    const parsed = JSON.parse(readFileSync(gbrainConfigPath(env), "utf-8")) as { engine?: string };
+    return parsed.engine === "pglite" || parsed.engine === "postgres" ? parsed.engine : null;
+  } catch {
+    return null;
+  }
+}
+
 function hashPath(p: string): string {
   return createHash("sha256").update(p).digest("hex").slice(0, 16);
 }
@@ -281,6 +293,7 @@ function freshClassify(env?: NodeJS.ProcessEnv): LocalEngineStatus {
       stderr?: Buffer | string;
       killed?: boolean;
       signal?: NodeJS.Signals | null;
+      status?: number | null;
     };
     const stderr = (e.stderr ? e.stderr.toString() : "") || "";
 
@@ -292,6 +305,14 @@ function freshClassify(env?: NodeJS.ProcessEnv): LocalEngineStatus {
     if (stderr.includes("Cannot connect to database")) return "broken-db";
     if (stderr.includes("config.json")) return "broken-config";
 
+    // PGLite is single-process. A long-lived `gbrain serve` can own the
+    // embedded database, causing the CLI to finish with its own exit 124 and
+    // "connect timed out" message. This is neither our watchdog timeout nor
+    // evidence that the valid config is malformed (#2194).
+    if (stderr.includes("connect timed out") || e.status === 124) {
+      return configuredEngine(env) === "pglite" ? "engine-locked" : "broken-db";
+    }
+
     // Probe killed by the timeout with no recognized error: the engine is
     // most likely healthy but slow (cold pooler connections measured at
     // 6.9-10.7s in #1964). Don't tell the user their config is malformed.
diff --git a/setup-gbrain/SKILL.md b/setup-gbrain/SKILL.md
index 89c2ffbc3..a3892f1c9 100644
--- a/setup-gbrain/SKILL.md
+++ b/setup-gbrain/SKILL.md
@@ -820,7 +820,7 @@ Capture the JSON output. It contains: `gbrain_on_path`, `gbrain_version`,
 `gbrain_config_exists`, `gbrain_engine`, `gbrain_doctor_ok`, `gbrain_mcp_mode`,
 `gstack_brain_sync_mode`, `gstack_brain_git`, `gstack_artifacts_remote`, and
 the v1.34.0.0+ `gbrain_local_status` field (one of: `ok`, `no-cli`,
-`missing-config`, `broken-config`, `broken-db`, `timeout`). Treat `timeout`
+`missing-config`, `broken-config`, `broken-db`, `engine-locked`, `timeout`). Treat `timeout`
 like `ok` (slow-but-healthy engine, #1964) — it never triggers Step 1.5
 remediation.
 
diff --git a/setup-gbrain/SKILL.md.tmpl b/setup-gbrain/SKILL.md.tmpl
index f48581543..f475987c1 100644
--- a/setup-gbrain/SKILL.md.tmpl
+++ b/setup-gbrain/SKILL.md.tmpl
@@ -66,7 +66,7 @@ Capture the JSON output. It contains: `gbrain_on_path`, `gbrain_version`,
 `gbrain_config_exists`, `gbrain_engine`, `gbrain_doctor_ok`, `gbrain_mcp_mode`,
 `gstack_brain_sync_mode`, `gstack_brain_git`, `gstack_artifacts_remote`, and
 the v1.34.0.0+ `gbrain_local_status` field (one of: `ok`, `no-cli`,
-`missing-config`, `broken-config`, `broken-db`, `timeout`). Treat `timeout`
+`missing-config`, `broken-config`, `broken-db`, `engine-locked`, `timeout`). Treat `timeout`
 like `ok` (slow-but-healthy engine, #1964) — it never triggers Step 1.5
 remediation.
 
diff --git a/sync-gbrain/SKILL.md b/sync-gbrain/SKILL.md
index bfaf291d2..02055bb6f 100644
--- a/sync-gbrain/SKILL.md
+++ b/sync-gbrain/SKILL.md
@@ -893,6 +893,10 @@ BEFORE invoking the orchestrator:
   slow (cold pooler connection, #1964). Tell the user in one line: "Engine
   probe timed out (>15s) — proceeding; raise `GSTACK_GBRAIN_PROBE_TIMEOUT_MS`
   if your pooler is slow." Do NOT treat this as a broken config.
+- **`engine-locked`**: STOP. "The local PGLite database is busy, usually
+  because `gbrain serve` from a live Claude session owns it. Stop that process
+  or run `/sync-gbrain` outside the live session, then retry. This identifies
+  the conflict but does not remove PGLite's single-process limit."
 - **`no-cli`**: STOP. "Local gbrain CLI not installed. Run `/setup-gbrain`
   first."
 - **`missing-config`** AND `gbrain_mcp_mode == "remote-http"`: tell the user
diff --git a/sync-gbrain/SKILL.md.tmpl b/sync-gbrain/SKILL.md.tmpl
index 2ec065472..aa97f7eb7 100644
--- a/sync-gbrain/SKILL.md.tmpl
+++ b/sync-gbrain/SKILL.md.tmpl
@@ -139,6 +139,10 @@ BEFORE invoking the orchestrator:
   slow (cold pooler connection, #1964). Tell the user in one line: "Engine
   probe timed out (>15s) — proceeding; raise `GSTACK_GBRAIN_PROBE_TIMEOUT_MS`
   if your pooler is slow." Do NOT treat this as a broken config.
+- **`engine-locked`**: STOP. "The local PGLite database is busy, usually
+  because `gbrain serve` from a live Claude session owns it. Stop that process
+  or run `/sync-gbrain` outside the live session, then retry. This identifies
+  the conflict but does not remove PGLite's single-process limit."
 - **`no-cli`**: STOP. "Local gbrain CLI not installed. Run `/setup-gbrain`
   first."
 - **`missing-config`** AND `gbrain_mcp_mode == "remote-http"`: tell the user
diff --git a/test/gbrain-local-status.test.ts b/test/gbrain-local-status.test.ts
index 703adfcad..0d5a44539 100644
--- a/test/gbrain-local-status.test.ts
+++ b/test/gbrain-local-status.test.ts
@@ -6,13 +6,14 @@
  * on PATH that emits canned exit codes + stderr matching the patterns the
  * classifier looks for.
  *
- * Six status cases:
+ * Seven status cases:
  *   1. no-cli         — gbrain absent from PATH
  *   2. missing-config — gbrain present, config.json absent (honors GBRAIN_HOME)
  *   3. broken-config  — gbrain present, config exists, stderr contains "config.json"
  *   4. broken-db      — gbrain present, config exists, stderr contains "Cannot connect to database"
  *   5. timeout        — probe exceeds GSTACK_GBRAIN_PROBE_TIMEOUT_MS with no recognized error (#1964)
- *   6. ok             — gbrain present, config exists, sources list returns valid JSON
+ *   6. engine-locked  — PGLite CLI exits 124 because another process owns the DB (#2194)
+ *   7. ok             — gbrain present, config exists, sources list returns valid JSON
  *
  * Plus cache behavior: hit, TTL expiry, invariant invalidation (HOME change,
  * probe-timeout change), --no-cache bypass. Timeout tests keep runtime sane by
@@ -61,7 +62,7 @@ interface FakeEnv {
  */
 function makeEnv(opts: {
   withGbrain?: boolean;
-  gbrainBehavior?: "ok" | "broken-db" | "broken-config" | "throws" | "slow";
+  gbrainBehavior?: "ok" | "broken-db" | "broken-config" | "engine-locked" | "throws" | "slow";
   withConfig?: boolean;
 }): FakeEnv {
   const tmp = mkdtempSync(join(tmpdir(), "gbrain-local-status-test-"));
@@ -102,7 +103,7 @@ function makeEnv(opts: {
 }
 
 function makeFakeGbrainScript(
-  behavior: "ok" | "broken-db" | "broken-config" | "throws" | "slow",
+  behavior: "ok" | "broken-db" | "broken-config" | "engine-locked" | "throws" | "slow",
 ): string {
   // "slow": healthy engine on a cold pooler connection (#1964) — sleeps past
   // the (test-lowered) probe timeout, then would answer fine.
@@ -125,10 +126,12 @@ exit 0
       ? 'echo "Cannot connect to database: . Fix: Check your connection URL in ~/.gbrain/config.json" >&2'
       : behavior === "broken-config"
         ? 'echo "Error: malformed config.json at ~/.gbrain/config.json" >&2'
+        : behavior === "engine-locked"
+          ? 'echo "gbrain sources: connect timed out (default 10000ms; pass --timeout=Ns to override)." >&2'
         : behavior === "throws"
           ? 'echo "unexpected gbrain failure" >&2'
           : "";
-  const exitCode = behavior === "ok" ? 0 : 1;
+  const exitCode = behavior === "ok" ? 0 : behavior === "engine-locked" ? 124 : 1;
   return `#!/bin/sh
 if [ "$1" = "--version" ]; then
   echo "gbrain 0.33.1.0"
@@ -225,6 +228,19 @@ describe("lib/gbrain-local-status — status classification", () => {
     expect(localEngineStatus({ noCache: true })).toBe("broken-config");
   });
 
+  it("returns 'engine-locked' when PGLite exits 124 with its own connect timeout (#2194)", () => {
+    env = makeEnv({ withGbrain: true, gbrainBehavior: "engine-locked", withConfig: true });
+    restoreEnv = applyEnv(env);
+    expect(localEngineStatus({ noCache: true })).toBe("engine-locked");
+  });
+
+  it("classifies a non-PGLite connect timeout as unreachable DB, not malformed config", () => {
+    env = makeEnv({ withGbrain: true, gbrainBehavior: "engine-locked", withConfig: true });
+    restoreEnv = applyEnv(env);
+    writeFileSync(env.configPath, JSON.stringify({ engine: "postgres", database_url: "postgres://fake" }));
+    expect(localEngineStatus({ noCache: true })).toBe("broken-db");
+  });
+
   it("returns 'ok' when sources list succeeds", () => {
     env = makeEnv({ withGbrain: true, gbrainBehavior: "ok", withConfig: true });
     restoreEnv = applyEnv(env);
diff --git a/test/gbrain-sync-skip.test.ts b/test/gbrain-sync-skip.test.ts
index 1d7423c98..902256b3b 100644
--- a/test/gbrain-sync-skip.test.ts
+++ b/test/gbrain-sync-skip.test.ts
@@ -42,7 +42,7 @@ interface FakeEnv {
  */
 function makeEnv(opts: {
   withGbrain: boolean;
-  gbrainBehavior?: "ok" | "broken-db" | "broken-config" | "slow";
+  gbrainBehavior?: "ok" | "broken-db" | "broken-config" | "engine-locked" | "slow";
   withConfig: boolean;
 }): FakeEnv {
   const tmp = mkdtempSync(join(tmpdir(), "gbrain-sync-skip-"));
@@ -75,6 +75,9 @@ function makeEnv(opts: {
         : behavior === "ok"
           ? `  echo '{"sources":[]}'
   exit 0`
+          : behavior === "engine-locked"
+            ? `  echo "gbrain sources: connect timed out (default 10000ms; pass --timeout=Ns to override)." >&2
+  exit 124`
           : `  ${
               behavior === "broken-db"
                 ? 'echo "Cannot connect to database: . Fix: Check your connection URL in ~/.gbrain/config.json" >&2'
@@ -207,6 +210,20 @@ describe("gstack-gbrain-sync — split-engine SKIP (plan D12)", () => {
     }
   });
 
+  it("SKIPs with actionable guidance when PGLite is held by gbrain serve (#2194)", () => {
+    const env = makeEnv({ withGbrain: true, gbrainBehavior: "engine-locked", withConfig: true });
+    try {
+      const r = runOrchestrator(env, ["--code-only"]);
+      const out = r.stdout + r.stderr;
+      expect(out).toContain("local engine engine-locked");
+      expect(out).toContain("gbrain serve");
+      expect(out).toContain("outside the live Claude session");
+      expect(out).not.toContain("config.json is malformed");
+    } finally {
+      env.cleanup();
+    }
+  });
+
   it("SKIPs code stage when gbrain CLI is missing (no-cli)", () => {
     const env = makeEnv({ withGbrain: false, withConfig: false });
     try {