diff --git a/src/resources/extensions/gsd/session-lock.ts b/src/resources/extensions/gsd/session-lock.ts
index 1d5a4e7a3..e3bbe7c49 100644
--- a/src/resources/extensions/gsd/session-lock.ts
+++ b/src/resources/extensions/gsd/session-lock.ts
@@ -288,6 +288,20 @@ export function acquireSessionLock(basePath: string): SessionLockResult {
   const gsdDir = gsdRoot(basePath);
   const lockTarget = effectiveLockTarget(gsdDir);
 
+  // #3218: Pre-flight stale lock cleanup — if the .lock/ directory exists but
+  // no auto.lock metadata is present (or the PID is dead), remove the lock
+  // directory before attempting acquisition. This prevents the 30-min stale
+  // window from blocking /gsd after crashes, SIGKILL, or laptop sleep.
+  const lockDir = lockTarget + ".lock";
+  if (existsSync(lockDir)) {
+    const existingData = readExistingLockData(lp);
+    const isOrphan = !existingData || (existingData.pid && !isPidAlive(existingData.pid));
+    if (isOrphan) {
+      try { rmSync(lockDir, { recursive: true, force: true }); } catch { /* best-effort */ }
+      try { if (existsSync(lp)) unlinkSync(lp); } catch { /* best-effort */ }
+    }
+  }
+
   try {
     // Try to acquire an exclusive OS-level lock on the lock target.
     // We lock a directory since proper-lockfile works best on directories,
@@ -344,9 +358,11 @@ export function acquireSessionLock(basePath: string): SessionLockResult {
       }
     }
 
+    // #3218: Provide actionable workaround when lock recovery fails
+    const lockDirPath = lockTarget + ".lock";
     const reason = existingPid
       ? `Another auto-mode session (PID ${existingPid}) appears to be running.\nStop it with \`kill ${existingPid}\` before starting a new session.`
-      : `Another auto-mode session is already running on this project.`;
+      : `Another auto-mode session lock is stuck on this project.\nRun: rm -rf "${lockDirPath}" && rm -f "${lp}"`;
 
     return { acquired: false, reason, existingPid };
   }
diff --git a/src/resources/extensions/gsd/tests/stale-lockfile-recovery.test.ts b/src/resources/extensions/gsd/tests/stale-lockfile-recovery.test.ts
new file mode 100644
index 000000000..c7a4ab2ab
--- /dev/null
+++ b/src/resources/extensions/gsd/tests/stale-lockfile-recovery.test.ts
@@ -0,0 +1,36 @@
+/**
+ * stale-lockfile-recovery.test.ts — #3668
+ *
+ * Verify that session-lock.ts contains pre-flight stale lock cleanup logic
+ * that removes orphaned lock directories when the owning PID is dead,
+ * preventing the 30-min stale window from blocking /gsd after crashes.
+ */
+
+import { describe, test } from "node:test";
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import { join, dirname } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const sourceFile = join(__dirname, "..", "session-lock.ts");
+
+describe("stale lockfile auto-recovery (#3668)", () => {
+  const source = readFileSync(sourceFile, "utf-8");
+
+  test("checks for orphan lock with isPidAlive", () => {
+    assert.match(source, /isPidAlive\(existingData\.pid\)/);
+  });
+
+  test("removes stale lock directory with rmSync", () => {
+    assert.match(source, /rmSync\(lockDir,\s*\{\s*recursive:\s*true/);
+  });
+
+  test("references issue #3218 in pre-flight cleanup comment", () => {
+    assert.match(source, /#3218.*Pre-flight stale lock cleanup/);
+  });
+
+  test("provides actionable rm -rf workaround in error message", () => {
+    assert.match(source, /rm\s+-rf/);
+  });
+});