fix(content): prune stale glob() entries when a collection becomes empty (#17937)

Author: matthewp

.changeset/two-experts-flash.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes a bug where the `glob()` content loader kept stale entries in the data store after the last file in a collection was deleted. Empty collections are now pruned correctly, and the file watcher is registered in dev so the first file added to an empty collection is picked up without a restart.

packages/astro/src/content/loaders/glob.ts

@@ -292,7 +292,6 @@ export function glob(globOptions: GlobOptions & { [secretLegacyFlag]?: boolean }
 				logger.warn(
 					`No files found matching "${globOptions.pattern}" in directory "${relativePath}"`,
 				);
-				return;
 			}
 
 			function configForFile(file: string) {

packages/astro/test/units/content-layer/glob-loader.test.ts

@@ -1,5 +1,5 @@
 import { strict as assert } from 'node:assert';
-import { mkdirSync, writeFileSync } from 'node:fs';
+import { mkdirSync, rmSync, writeFileSync } from 'node:fs';
 import { join } from 'node:path';
 import { describe, it } from 'node:test';
 import { fileURLToPath } from 'node:url';
@@ -513,6 +513,44 @@ describe('Glob Loader', () => {
 		assert.ok(warnings.some((w) => w.includes('No files found matching')));
 	});
 
+	it('prunes stale entries when the last file in a collection is deleted', async () => {
+		const tempDir = createTempDir();
+		const contentDir = join(fileURLToPath(tempDir), 'src', 'content', 'posts');
+		mkdirSync(contentDir, { recursive: true });
+		writeFileSync(join(contentDir, 'post.md'), '---\ntitle: Post MD\n---\nContent MD');
+
+		const store = new MutableDataStore();
+		const settings = createMinimalSettings(tempDir, {
+			contentEntryTypes: [createMarkdownEntryType()],
+		});
+		const logger = new AstroLogger({
+			destination: { write: () => true },
+			level: 'silent',
+		});
+
+		const collections = {
+			posts: defineCollection({
+				loader: glob({ pattern: '*.md', base: 'src/content/posts' }),
+			}),
+		};
+
+		const contentLayer = new ContentLayer({
+			settings,
+			logger,
+			store,
+			contentConfigObserver: createTestConfigObserver(collections),
+		});
+
+		await contentLayer.sync();
+		assert.equal(store.values('posts').length, 1);
+
+		// Delete the only file, leaving the (still existing) directory in place
+		rmSync(join(contentDir, 'post.md'));
+
+		await contentLayer.sync();
+		assert.equal(store.values('posts').length, 0);
+	});
+
 	it('throws on duplicate IDs when prerenderConflictBehavior is error', async () => {
 		const tempDir = createTempDir();
 		const contentDir = join(fileURLToPath(tempDir), 'src', 'content', 'posts');