diff --git a/.changeset/fierce-finches-munch.md b/.changeset/fierce-finches-munch.md
new file mode 100644
index 000000000..d6e9a8b16
--- /dev/null
+++ b/.changeset/fierce-finches-munch.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 613
+---
+**Fresh installs now ship `managed-hooks-registry.cjs` next to `gsd-check-update-worker.js`, so the background update checker no longer crashes silently (#606)** — the worker `require()`s that sibling, but it had been missing from the hooks copy allowlist, so on a clean install the worker threw `Cannot find module` in the background and the update cache was never written. The file is now in the allowlist, and a regression guard asserts that every same-directory `require()` target of a shipped hook is itself shipped. Thanks @baksohyeon for the clean-room reproduction.
diff --git a/scripts/build-hooks.js b/scripts/build-hooks.js
index 550b4a053..3072a5e50 100644
--- a/scripts/build-hooks.js
+++ b/scripts/build-hooks.js
@@ -237,4 +237,4 @@ if (require.main === module) {
   build();
 }
 
-module.exports = { HOOKS_TO_COPY };
+module.exports = { HOOKS_TO_COPY, HOOKS_SUBDIRS_TO_COPY };
diff --git a/tests/orphaned-hooks.test.cjs b/tests/orphaned-hooks.test.cjs
index 4bd41d4a3..277e678af 100644
--- a/tests/orphaned-hooks.test.cjs
+++ b/tests/orphaned-hooks.test.cjs
@@ -26,7 +26,7 @@ const HOOKS_DIR = path.join(__dirname, '..', 'hooks');
 
 // Typed imports — no source-grep needed (#455)
 const { MANAGED_HOOKS } = require(path.join(HOOKS_DIR, 'managed-hooks-registry.cjs'));
-const { HOOKS_TO_COPY } = require(path.join(__dirname, '..', 'scripts', 'build-hooks.js'));
+const { HOOKS_TO_COPY, HOOKS_SUBDIRS_TO_COPY } = require(path.join(__dirname, '..', 'scripts', 'build-hooks.js'));
 
 describe('orphaned hooks stale detection (#1750)', () => {
   test('MANAGED_HOOKS is an array and does not use a broad gsd-* wildcard', () => {
@@ -111,4 +111,46 @@ describe('orphaned hooks stale detection (#1750)', () => {
       );
     }
   });
+
+  test('every same-dir require() target of a shipped hook is itself shipped (#606)', () => {
+    // Regression guard for #606: gsd-check-update-worker.js does
+    // require('./managed-hooks-registry.cjs'), but that sibling was missing from
+    // HOOKS_TO_COPY, so the installer never placed it next to the worker and the
+    // background worker crashed at runtime with "Cannot find module". The fix added
+    // the file to HOOKS_TO_COPY; this guard fails if any shipped hook ever again
+    // requires a same-directory file that the installer would not ship.
+    //
+    // Scope: only *same-directory* relative requires — require('./x') and
+    // require('./subdir/x'). A require('../...') target reaches out of the hooks/
+    // dir into sibling package dirs (e.g. get-shit-done/) whose shipping is governed
+    // by package.json "files", not by this allowlist, so it is out of scope here.
+    assert.ok(Array.isArray(HOOKS_SUBDIRS_TO_COPY), 'HOOKS_SUBDIRS_TO_COPY must be exported as an array');
+
+    const SAME_DIR_REQUIRE = /require\(\s*['"](\.\/[^'"]+)['"]\s*\)/g;
+    const jsHooks = HOOKS_TO_COPY.filter(h => /\.c?js$/.test(h));
+    assert.ok(jsHooks.length >= 5, `expected at least 5 JS/CJS hooks in HOOKS_TO_COPY, got ${jsHooks.length}`);
+
+    for (const hook of jsHooks) {
+      const source = fs.readFileSync(path.join(HOOKS_DIR, hook), 'utf8');
+      for (const match of source.matchAll(SAME_DIR_REQUIRE)) {
+        const rel = match[1].slice(2); // strip leading './'
+        const slash = rel.indexOf('/');
+        if (slash === -1) {
+          assert.ok(
+            HOOKS_TO_COPY.includes(rel),
+            `${hook} requires './${rel}', but '${rel}' is not in HOOKS_TO_COPY — the installer ` +
+            `would not place it next to ${hook}, so the require would throw at runtime (the #606 class of bug). ` +
+            `Add '${rel}' to HOOKS_TO_COPY in scripts/build-hooks.js.`
+          );
+        } else {
+          const subdir = rel.slice(0, slash);
+          assert.ok(
+            HOOKS_SUBDIRS_TO_COPY.includes(subdir),
+            `${hook} requires './${rel}', but subdirectory '${subdir}' is not in HOOKS_SUBDIRS_TO_COPY — ` +
+            `the installer would not ship it. Add '${subdir}' to HOOKS_SUBDIRS_TO_COPY in scripts/build-hooks.js.`
+          );
+        }
+      }
+    }
+  });
 });