feat: add Ollama client for local LLM support

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/models/local/index.ts

@@ -0,0 +1 @@
+export { OllamaClient, type OllamaClientConfig } from './ollama.js';

src/models/local/ollama.test.ts

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+import { describe, it, expect, vi } from 'vitest';
+import { OllamaClient } from './ollama.js';
+
+vi.mock('ollama', () => ({
+  Ollama: vi.fn().mockImplementation(() => ({
+    chat: vi.fn().mockResolvedValue({
+      message: { content: 'Hello from Ollama!' },
+      done_reason: 'stop',
+      prompt_eval_count: 10,
+      eval_count: 5,
+    }),
+  })),
+}));
+
+describe('OllamaClient', () => {
+  it('sends messages and returns response', async () => {
+    const client = new OllamaClient({
+      model: 'llama3.2',
+    });
+
+    const response = await client.chat({
+      messages: [{ role: 'user', content: 'Hello' }],
+    });
+
+    expect(response.content).toBe('Hello from Ollama!');
+    expect(response.stopReason).toBe('stop');
+    expect(response.usage.inputTokens).toBe(10);
+    expect(response.usage.outputTokens).toBe(5);
+  });
+});

src/models/local/ollama.ts

@@ -0,0 +1,45 @@
+import { Ollama } from 'ollama';
+import type { ChatRequest, ChatResponse, ModelClient } from '../types.js';
+
+export interface OllamaClientConfig {
+  host?: string;
+  model: string;
+}
+
+export class OllamaClient implements ModelClient {
+  private client: Ollama;
+  private model: string;
+
+  constructor(config: OllamaClientConfig) {
+    this.client = new Ollama({
+      host: config.host ?? 'http://localhost:11434',
+    });
+    this.model = config.model;
+  }
+
+  async chat(request: ChatRequest): Promise<ChatResponse> {
+    const messages: Array<{ role: 'system' | 'user' | 'assistant'; content: string }> = [];
+
+    if (request.system) {
+      messages.push({ role: 'system', content: request.system });
+    }
+
+    for (const msg of request.messages) {
+      messages.push({ role: msg.role, content: msg.content });
+    }
+
+    const response = await this.client.chat({
+      model: this.model,
+      messages,
+    });
+
+    return {
+      content: response.message.content,
+      stopReason: response.done_reason ?? 'stop',
+      usage: {
+        inputTokens: response.prompt_eval_count ?? 0,
+        outputTokens: response.eval_count ?? 0,
+      },
+    };
+  }
+}