fix: add API key/auth token support across all model clients

src/backends/native/agent.ts

@@ -1,17 +1,19 @@
 import type { ModelClient, Message } from '../../models/types.js';
+import type { ModelRouter, ModelTier } from '../../models/router.js';
 import type { Session } from '../../session/index.js';
 
 export interface NativeAgentConfig {
-  modelClient: ModelClient;
+  modelClient: ModelClient | ModelRouter;
   systemPrompt: string;
   session?: Session;
 }
 
 export class NativeAgent {
-  private modelClient: ModelClient;
+  private modelClient: ModelClient | ModelRouter;
   private systemPrompt: string;
   private session?: Session;
   private inMemoryHistory: Message[] = [];
+  private currentTier: ModelTier = 'default';
 
   constructor(config: NativeAgentConfig) {
     this.modelClient = config.modelClient;
@@ -32,10 +34,15 @@ export class NativeAgent {
       this.inMemoryHistory.push(userMsg);
     }
 
-    const response = await this.modelClient.chat({
+    const request = {
       messages: this.history,
       system: this.systemPrompt,
-    });
+    };
+
+    // Use tier if modelClient is a ModelRouter
+    const response = 'getClient' in this.modelClient
+      ? await (this.modelClient as ModelRouter).chat(request, this.currentTier)
+      : await this.modelClient.chat(request);
 
     const assistantMsg: Message = { role: 'assistant', content: response.content };
 
@@ -59,4 +66,12 @@ export class NativeAgent {
   getHistory(): Message[] {
     return [...this.history];
   }
+
+  setModelTier(tier: ModelTier): void {
+    this.currentTier = tier;
+  }
+
+  getModelTier(): ModelTier {
+    return this.currentTier;
+  }
 }