feat: add AgentRouter for config-based sender/channel routing

src/agents/router.test.ts

@@ -0,0 +1,72 @@
+import { describe, it, expect } from 'vitest';
+import { AgentRouter } from './router.js';
+import type { RoutingConfig } from '../config/schema.js';
+
+describe('AgentRouter', () => {
+  describe('resolve()', () => {
+    it('returns default_agent when no specific match', () => {
+      const router = new AgentRouter({
+        default_agent: 'assistant',
+        channels: {},
+        senders: {},
+      });
+      expect(router.resolve('telegram', '12345')).toBe('assistant');
+    });
+
+    it('returns undefined when no default and no match', () => {
+      const router = new AgentRouter({
+        channels: {},
+        senders: {},
+      });
+      expect(router.resolve('telegram', '12345')).toBeUndefined();
+    });
+
+    it('matches exact sender', () => {
+      const router = new AgentRouter({
+        default_agent: 'assistant',
+        channels: {},
+        senders: { 'telegram:12345': 'coder' },
+      });
+      expect(router.resolve('telegram', '12345')).toBe('coder');
+    });
+
+    it('matches sender with glob pattern', () => {
+      const router = new AgentRouter({
+        default_agent: 'assistant',
+        channels: {},
+        senders: { 'slack:U0*': 'coder' },
+      });
+      expect(router.resolve('slack', 'U0ABC')).toBe('coder');
+    });
+
+    it('matches channel when no sender match', () => {
+      const router = new AgentRouter({
+        default_agent: 'assistant',
+        channels: { discord: 'coder' },
+        senders: {},
+      });
+      expect(router.resolve('discord', 'any-user')).toBe('coder');
+    });
+
+    it('sender match takes priority over channel match', () => {
+      const router = new AgentRouter({
+        default_agent: 'assistant',
+        channels: { discord: 'coder' },
+        senders: { 'discord:special-user': 'vip' },
+      });
+      expect(router.resolve('discord', 'special-user')).toBe('vip');
+      expect(router.resolve('discord', 'normal-user')).toBe('coder');
+    });
+
+    it('falls through: sender -> channel -> default', () => {
+      const router = new AgentRouter({
+        default_agent: 'fallback',
+        channels: { discord: 'guild-agent' },
+        senders: { 'discord:admin': 'admin-agent' },
+      });
+      expect(router.resolve('discord', 'admin')).toBe('admin-agent');
+      expect(router.resolve('discord', 'regular')).toBe('guild-agent');
+      expect(router.resolve('telegram', 'someone')).toBe('fallback');
+    });
+  });
+});

src/agents/router.ts

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+/**
+ * AgentRouter resolves which agent config to use for a given channel+sender.
+ *
+ * Resolution order (first match wins):
+ * 1. Exact sender match (channel:senderId)
+ * 2. Glob pattern sender match
+ * 3. Channel match
+ * 4. default_agent fallback
+ */
+
+import type { RoutingConfig } from '../config/schema.js';
+
+export type { RoutingConfig };
+
+/**
+ * Convert a simple glob pattern to a RegExp.
+ * Supports `*` (match any sequence of characters).
+ * All other regex-special characters are escaped.
+ */
+function patternToRegex(pattern: string): RegExp {
+  const escaped = pattern
+    .replace(/[.+^${}()|[\]\\]/g, '\\$&')
+    .replace(/\*/g, '.*');
+  return new RegExp(`^${escaped}$`);
+}
+
+export class AgentRouter {
+  private config: RoutingConfig;
+
+  constructor(config: RoutingConfig) {
+    this.config = config;
+  }
+
+  /**
+   * Resolve the agent config name for a channel + sender pair.
+   * Returns undefined if no match and no default is configured.
+   */
+  resolve(channel: string, senderId: string): string | undefined {
+    const senderKey = `${channel}:${senderId}`;
+
+    // 1. Exact sender match
+    if (this.config.senders[senderKey]) {
+      return this.config.senders[senderKey];
+    }
+
+    // 2. Glob pattern sender match
+    for (const [pattern, agentName] of Object.entries(this.config.senders)) {
+      if (pattern.includes('*') && patternToRegex(pattern).test(senderKey)) {
+        return agentName;
+      }
+    }
+
+    // 3. Channel match
+    if (this.config.channels[channel]) {
+      return this.config.channels[channel];
+    }
+
+    // 4. Default fallback
+    return this.config.default_agent;
+  }
+}