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/);
+  });
+});