feat(channels): add mattermost adapter and wiring

src/config/schema.test.ts

@@ -438,6 +438,38 @@ describe('configSchema — audio talk mode', () => {
   });
 });
 
+describe('configSchema — mattermost', () => {
+  const minimalConfig = {
+    telegram: { bot_token: 'test', allowed_chat_ids: [1] },
+    models: { default: { provider: 'anthropic', model: 'claude-3' } },
+  };
+
+  it('accepts mattermost config and defaults optional fields', () => {
+    const result = configSchema.parse({
+      ...minimalConfig,
+      mattermost: {
+        server_url: 'https://mattermost.example.com',
+        bot_token: 'mm-token',
+      },
+    });
+
+    expect(result.mattermost).toBeDefined();
+    if (!result.mattermost) {
+      throw new Error('Expected mattermost config');
+    }
+    expect(result.mattermost.server_url).toBe('https://mattermost.example.com');
+    expect(result.mattermost.allowed_channel_ids).toEqual([]);
+    expect(result.mattermost.require_mention).toBe(true);
+    expect(result.mattermost.mention_name).toBe('flynn');
+    expect(result.mattermost.poll_interval_ms).toBe(3000);
+  });
+
+  it('mattermost config is optional', () => {
+    const result = configSchema.parse(minimalConfig);
+    expect(result.mattermost).toBeUndefined();
+  });
+});
+
 describe('configSchema — teams', () => {
   const minimalConfig = {
     telegram: { bot_token: 'test', allowed_chat_ids: [1] },