Fix flaky skill watch test: add non-recursive watchers on skill subdirectories

src/vs/platform/agentHost/node/copilot/sessionCustomizationDiscovery.ts

@@ -1010,6 +1010,13 @@ export class SessionCustomizationDiscovery extends Disposable {
 						if (skillStat.isFile && !seen.has(skillFile)) {
 							seen.add(skillFile);
 							files.push({ uri: skillFile, etag: skillStat.etag });
+							// Watch the skill subdirectory directly for SKILL.md content changes.
+							// The recursive watcher on rootUri is sufficient for structural changes
+							// (skill directories added/deleted), but on some platforms (e.g. macOS VMs)
+							// a recursive watcher may not reliably fire for content-only changes deep
+							// in the tree. Adding an explicit non-recursive watcher on each skill's
+							// subdirectory ensures SKILL.md modifications are always detected.
+							addWatch(watchRootUris, child.resource, false, skillFile);
 						}
 					} catch {
 						// SKILL.md missing — skip this skill directory.

src/vs/platform/agentHost/test/node/sessionCustomizationDiscovery.test.ts

@@ -435,12 +435,18 @@ suite('SessionCustomizationDiscovery', () => {
 		assert.strictEqual(watched.get(URI.joinPath(workspace, '.claude').toString()), false);
 		assert.strictEqual(watched.get(URI.joinPath(workspace, '.github', 'agents').toString()), false);
 		assert.strictEqual(watched.get(URI.joinPath(workspace, '.github', 'skills').toString()), true);
+		// Each discovered skill subdirectory is also watched non-recursively so that
+		// content changes to SKILL.md are detected even when the recursive watcher
+		// on the skills root does not fire reliably (e.g. on macOS VMs).
+		assert.strictEqual(watched.get(URI.joinPath(workspace, '.github', 'skills', 'bar').toString()), false);
 		assert.strictEqual(watched.get(URI.joinPath(workspace, '.github', 'instructions').toString()), true);
 		assert.strictEqual(watched.get(URI.joinPath(workspace, '.github', 'hooks').toString()), true);
 		assert.strictEqual(watched.get(URI.joinPath(userHome, '.copilot').toString()), false);
 		assert.strictEqual(watched.get(URI.joinPath(userHome, '.copilot', 'agents').toString()), false);
 		assert.strictEqual(watched.get(URI.joinPath(userHome, '.copilot', 'skills').toString()), true);
+		assert.strictEqual(watched.get(URI.joinPath(userHome, '.copilot', 'skills', 'copilot-user-skill').toString()), false);
 		assert.strictEqual(watched.get(URI.joinPath(userHome, '.agents', 'skills').toString()), true);
+		assert.strictEqual(watched.get(URI.joinPath(userHome, '.agents', 'skills', 'user-skill').toString()), false);
 		assert.strictEqual(watched.get(URI.joinPath(userHome, '.copilot', 'instructions').toString()), true);
 		assert.strictEqual(watched.get(URI.joinPath(userHome, '.copilot', 'hooks').toString()), true);
 	});
@@ -518,6 +524,32 @@ suite('SessionCustomizationDiscovery', () => {
 		assert.strictEqual(changeCount, 1, 'expected onDidChange to fire when an existing agent file is modified');
 	});
 
+	test('fires onDidChange when an existing SKILL.md file is modified', async () => {
+		// Skill files live two levels deep (skillsDir/skill-name/SKILL.md), so a
+		// recursive watcher on the skills root is the primary detection mechanism.
+		// An explicit non-recursive watcher on each skill subdirectory is also added
+		// as a more reliable secondary trigger for content-only changes.
+		await seed('/workspace/.github/skills/my-skill/SKILL.md', 'skill body');
+
+		const discovery = disposables.add(instantiationService.createInstance(SessionCustomizationDiscovery, workspace, userHome, URI.file));
+		await discovery.scan(CancellationToken.None);
+		await timeout(50);
+
+		let changeCount = 0;
+		const fired = new DeferredPromise<void>();
+		disposables.add(discovery.onDidChange(() => {
+			changeCount++;
+			fired.complete();
+		}));
+
+		// Overwrite the skill file to produce an UPDATED event via the non-recursive
+		// watcher on the skill subdirectory (`my-skill/`).
+		await seed('/workspace/.github/skills/my-skill/SKILL.md', 'skill body (updated)');
+		await raceTimeout(fired.p, 500);
+
+		assert.strictEqual(changeCount, 1, 'expected onDidChange to fire when an existing SKILL.md is modified');
+	});
+
 	test('fires onDidChange when an existing agent file is deleted under a non-recursively watched root', async () => {
 		const agentUri = await seed('/workspace/.github/agents/foo.agent.md', 'workspace agent');
 		// Seed a second agent so the parent directory still exists after the deletion.