diff --git a/apps/worker/src/whatsapp/tag-detector.test.ts b/apps/worker/src/whatsapp/tag-detector.test.ts
new file mode 100644
index 0000000..f0d0996
--- /dev/null
+++ b/apps/worker/src/whatsapp/tag-detector.test.ts
@@ -0,0 +1,55 @@
+import { detectTags, isFlagged } from './tag-detector';
+
+const ADMINS = ['1234567890@s.whatsapp.net', '0987654321@s.whatsapp.net'];
+
+describe('detectTags', () => {
+  it('detects #important hashtag (case-insensitive)', () => {
+    expect(detectTags('Check this #IMPORTANT update', 'user@s.whatsapp.net', ADMINS))
+      .toContain('#important');
+  });
+
+  it('detects #upparivar hashtag (case-insensitive)', () => {
+    expect(detectTags('Welcome to #UPParivar community', 'user@s.whatsapp.net', ADMINS))
+      .toContain('#upparivar');
+  });
+
+  it('detects #event hashtag', () => {
+    expect(detectTags('Join our #event on Saturday', 'user@s.whatsapp.net', ADMINS))
+      .toContain('#event');
+  });
+
+  it('detects /tower command prefix', () => {
+    expect(detectTags('/tower save this message', 'user@s.whatsapp.net', ADMINS))
+      .toContain('#tower-command');
+  });
+
+  it('detects multiple tags in one message', () => {
+    const tags = detectTags('#important #event happening', 'user@s.whatsapp.net', ADMINS);
+    expect(tags).toContain('#important');
+    expect(tags).toContain('#event');
+  });
+
+  it('detects admin sender', () => {
+    expect(detectTags('Regular message', '1234567890@s.whatsapp.net', ADMINS))
+      .toContain('#admin');
+  });
+
+  it('returns empty array for untagged message from non-admin', () => {
+    expect(detectTags('Just a regular chat message', 'nobody@s.whatsapp.net', ADMINS))
+      .toEqual([]);
+  });
+
+  it('returns empty array for empty text', () => {
+    expect(detectTags('', 'nobody@s.whatsapp.net', ADMINS)).toEqual([]);
+  });
+});
+
+describe('isFlagged', () => {
+  it('returns true when tags array is non-empty', () => {
+    expect(isFlagged(['#important'])).toBe(true);
+  });
+
+  it('returns false when tags array is empty', () => {
+    expect(isFlagged([])).toBe(false);
+  });
+});
diff --git a/apps/worker/src/whatsapp/tag-detector.ts b/apps/worker/src/whatsapp/tag-detector.ts
new file mode 100644
index 0000000..0855ab3
--- /dev/null
+++ b/apps/worker/src/whatsapp/tag-detector.ts
@@ -0,0 +1,23 @@
+const HASHTAGS: Array<{ pattern: RegExp; tag: string }> = [
+  { pattern: /#important/i, tag: '#important' },
+  { pattern: /#upparivar/i, tag: '#upparivar' },
+  { pattern: /#event/i, tag: '#event' },
+];
+
+export function detectTags(text: string, senderJid: string, adminJids: string[]): string[] {
+  const tags: string[] = [];
+
+  for (const { pattern, tag } of HASHTAGS) {
+    if (pattern.test(text)) tags.push(tag);
+  }
+
+  if (text.trimStart().startsWith('/tower')) tags.push('#tower-command');
+
+  if (adminJids.includes(senderJid)) tags.push('#admin');
+
+  return tags;
+}
+
+export function isFlagged(tags: string[]): boolean {
+  return tags.length > 0;
+}