Reject unsupported Reddit chat capabilities

tests/outbound-message-safety.test.ts

@@ -1,5 +1,8 @@
 import { describe, expect, it } from 'vitest';
-import { isSafeOutboundMessage } from '../src/services/outbound-message-safety.js';
+import {
+  isSafeOutboundMessage,
+  isSafeRedditChatMessage,
+} from '../src/services/outbound-message-safety.js';
 
 describe('outbound message location safety', () => {
   it.each([
@@ -29,3 +32,23 @@ describe('outbound message location safety', () => {
     expect(isSafeOutboundMessage(message)).toBe(true);
   });
 });
+
+describe('Reddit chat capability safety', () => {
+  it.each([
+    'I could send you a voice note if you want.',
+    'Send me an audio message?',
+    'We should hop on a call.',
+    'Fancy a video call later?',
+    'We could FaceTime tonight.',
+  ])('rejects unsupported private-chat capabilities: %s', (message) => {
+    expect(isSafeRedditChatMessage(message)).toBe(false);
+  });
+
+  it.each([
+    'Tell me more here, I want to hear the whole story.',
+    'Want me to send you a saved pic?',
+    'What song have you had on repeat lately?',
+  ])('allows text and approved picture conversation: %s', (message) => {
+    expect(isSafeRedditChatMessage(message)).toBe(true);
+  });
+});