fix(auto): register SIGHUP/SIGINT handlers to clean lock files on crash (#1821)

When VSCode crashes or the parent process dies, only SIGTERM was handled,
leaving stranded .gsd.lock/ and auto.lock files. Now registers handlers
on SIGTERM, SIGHUP, and SIGINT, and calls both clearLock() and
releaseSessionLock() for complete cleanup.

Fixes #1797

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/resources/extensions/gsd/auto-supervisor.ts

@@ -1,16 +1,24 @@
 /**
- * Auto-mode Supervisor — SIGTERM handling and working-tree activity detection.
+ * Auto-mode Supervisor — signal handling and working-tree activity detection.
  *
  * Pure functions — no module-level globals or AutoContext dependency.
  */
 
 import { clearLock } from "./crash-recovery.js";
+import { releaseSessionLock } from "./session-lock.js";
 import { nativeHasChanges } from "./native-git-bridge.js";
 
-// ─── SIGTERM Handling ─────────────────────────────────────────────────────────
+// ─── Signal Handling ─────────────────────────────────────────────────────────
+
+/** Signals that should trigger lock cleanup on process termination. */
+const CLEANUP_SIGNALS: NodeJS.Signals[] = ["SIGTERM", "SIGHUP", "SIGINT"];
 
 /**
- * Register a SIGTERM handler that clears the lock file and exits cleanly.
+ * Register signal handlers that clear lock files and exit cleanly.
+ * Installs handlers on SIGTERM, SIGHUP, and SIGINT so that lock files
+ * are cleaned up regardless of how the process is terminated (normal kill,
+ * parent process death, or Ctrl+C).
+ *
  * Captures the active base path at registration time so the handler
  * always references the correct path even if the module variable changes.
  * Removes any previously registered handler before installing the new one.
@@ -21,19 +29,22 @@ export function registerSigtermHandler(
   currentBasePath: string,
   previousHandler: (() => void) | null,
 ): () => void {
-  if (previousHandler) process.off("SIGTERM", previousHandler);
+  if (previousHandler) {
+    for (const sig of CLEANUP_SIGNALS) process.off(sig, previousHandler);
+  }
   const handler = () => {
     clearLock(currentBasePath);
+    releaseSessionLock(currentBasePath);
     process.exit(0);
   };
-  process.on("SIGTERM", handler);
+  for (const sig of CLEANUP_SIGNALS) process.on(sig, handler);
   return handler;
 }
 
-/** Deregister the SIGTERM handler (called on stop/pause). */
+/** Deregister signal handlers from all cleanup signals (called on stop/pause). */
 export function deregisterSigtermHandler(handler: (() => void) | null): void {
   if (handler) {
-    process.off("SIGTERM", handler);
+    for (const sig of CLEANUP_SIGNALS) process.off(sig, handler);
   }
 }
 

src/resources/extensions/gsd/tests/signal-handlers.test.ts

@@ -0,0 +1,103 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import {
+  registerSigtermHandler,
+  deregisterSigtermHandler,
+} from "../auto-supervisor.ts";
+
+/**
+ * Tests for signal handler registration (SIGTERM, SIGHUP, SIGINT).
+ *
+ * Validates that registerSigtermHandler installs handlers on all three
+ * signals and deregisterSigtermHandler removes them from all three.
+ * Fixes #1797 — stranded lock files on VSCode crash due to missing
+ * SIGHUP and SIGINT handlers.
+ */
+
+test("registerSigtermHandler installs handlers on SIGTERM, SIGHUP, and SIGINT", () => {
+  const before = {
+    SIGTERM: process.listenerCount("SIGTERM"),
+    SIGHUP: process.listenerCount("SIGHUP"),
+    SIGINT: process.listenerCount("SIGINT"),
+  };
+
+  const handler = registerSigtermHandler("/tmp/test-signal-handlers", null);
+
+  assert.equal(
+    process.listenerCount("SIGTERM"),
+    before.SIGTERM + 1,
+    "SIGTERM listener should be added",
+  );
+  assert.equal(
+    process.listenerCount("SIGHUP"),
+    before.SIGHUP + 1,
+    "SIGHUP listener should be added",
+  );
+  assert.equal(
+    process.listenerCount("SIGINT"),
+    before.SIGINT + 1,
+    "SIGINT listener should be added",
+  );
+
+  // Clean up
+  deregisterSigtermHandler(handler);
+});
+
+test("deregisterSigtermHandler removes handlers from all three signals", () => {
+  const handler = registerSigtermHandler("/tmp/test-signal-handlers", null);
+
+  const during = {
+    SIGTERM: process.listenerCount("SIGTERM"),
+    SIGHUP: process.listenerCount("SIGHUP"),
+    SIGINT: process.listenerCount("SIGINT"),
+  };
+
+  deregisterSigtermHandler(handler);
+
+  assert.equal(
+    process.listenerCount("SIGTERM"),
+    during.SIGTERM - 1,
+    "SIGTERM listener should be removed",
+  );
+  assert.equal(
+    process.listenerCount("SIGHUP"),
+    during.SIGHUP - 1,
+    "SIGHUP listener should be removed",
+  );
+  assert.equal(
+    process.listenerCount("SIGINT"),
+    during.SIGINT - 1,
+    "SIGINT listener should be removed",
+  );
+});
+
+test("registerSigtermHandler deregisters previous handler from all signals", () => {
+  const before = {
+    SIGTERM: process.listenerCount("SIGTERM"),
+    SIGHUP: process.listenerCount("SIGHUP"),
+    SIGINT: process.listenerCount("SIGINT"),
+  };
+
+  const handler1 = registerSigtermHandler("/tmp/test-signal-handlers", null);
+  const handler2 = registerSigtermHandler("/tmp/test-signal-handlers-2", handler1);
+
+  // Should still only have one extra listener per signal (old one removed, new one added)
+  assert.equal(
+    process.listenerCount("SIGTERM"),
+    before.SIGTERM + 1,
+    "SIGTERM should have exactly one handler after re-registration",
+  );
+  assert.equal(
+    process.listenerCount("SIGHUP"),
+    before.SIGHUP + 1,
+    "SIGHUP should have exactly one handler after re-registration",
+  );
+  assert.equal(
+    process.listenerCount("SIGINT"),
+    before.SIGINT + 1,
+    "SIGINT should have exactly one handler after re-registration",
+  );
+
+  // Clean up
+  deregisterSigtermHandler(handler2);
+});