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

src/agents/router.ts

@@ -0,0 +1,61 @@
+/**
+ * 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;
+  }
+}