From 75e64b534d932cb1d96a7faba97a455bd5ef7212 Mon Sep 17 00:00:00 2001
From: William Valentin <william.valentin.info@gmail.com>
Date: Mon, 2 Feb 2026 20:54:17 -0800
Subject: [PATCH] feat: add Anthropic client wrapper

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
---
 src/models/anthropic.test.ts | 33 ++++++++++++++++++++++++++
 src/models/anthropic.ts      | 46 ++++++++++++++++++++++++++++++++++++
 src/models/index.ts          |  2 ++
 src/models/types.ts          | 23 ++++++++++++++++++
 4 files changed, 104 insertions(+)
 create mode 100644 src/models/anthropic.test.ts
 create mode 100644 src/models/anthropic.ts
 create mode 100644 src/models/index.ts
 create mode 100644 src/models/types.ts

diff --git a/src/models/anthropic.test.ts b/src/models/anthropic.test.ts
new file mode 100644
index 0000000..3aed256
--- /dev/null
+++ b/src/models/anthropic.test.ts
@@ -0,0 +1,33 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { AnthropicClient } from './anthropic.js';
+
+// Mock the SDK
+vi.mock('@anthropic-ai/sdk', () => ({
+  default: vi.fn().mockImplementation(() => ({
+    messages: {
+      create: vi.fn().mockResolvedValue({
+        content: [{ type: 'text', text: 'Hello from Claude!' }],
+        stop_reason: 'end_turn',
+        usage: { input_tokens: 10, output_tokens: 5 },
+      }),
+    },
+  })),
+}));
+
+describe('AnthropicClient', () => {
+  it('sends messages and returns response', async () => {
+    const client = new AnthropicClient({
+      apiKey: 'test-key',
+      model: 'claude-sonnet-4-20250514',
+    });
+
+    const response = await client.chat({
+      messages: [{ role: 'user', content: 'Hello' }],
+    });
+
+    expect(response.content).toBe('Hello from Claude!');
+    expect(response.stopReason).toBe('end_turn');
+    expect(response.usage.inputTokens).toBe(10);
+    expect(response.usage.outputTokens).toBe(5);
+  });
+});
diff --git a/src/models/anthropic.ts b/src/models/anthropic.ts
new file mode 100644
index 0000000..70c44b0
--- /dev/null
+++ b/src/models/anthropic.ts
@@ -0,0 +1,46 @@
+import Anthropic from '@anthropic-ai/sdk';
+import type { ChatRequest, ChatResponse, ModelClient } from './types.js';
+
+export interface AnthropicClientConfig {
+  apiKey?: string;  // Falls back to ANTHROPIC_API_KEY env var
+  model: string;
+  maxTokens?: number;
+}
+
+export class AnthropicClient implements ModelClient {
+  private client: Anthropic;
+  private model: string;
+  private defaultMaxTokens: number;
+
+  constructor(config: AnthropicClientConfig) {
+    this.client = new Anthropic({
+      apiKey: config.apiKey,
+    });
+    this.model = config.model;
+    this.defaultMaxTokens = config.maxTokens ?? 4096;
+  }
+
+  async chat(request: ChatRequest): Promise<ChatResponse> {
+    const response = await this.client.messages.create({
+      model: this.model,
+      max_tokens: request.maxTokens ?? this.defaultMaxTokens,
+      system: request.system,
+      messages: request.messages.map((m) => ({
+        role: m.role,
+        content: m.content,
+      })),
+    });
+
+    const textContent = response.content.find((c) => c.type === 'text');
+    const content = textContent?.type === 'text' ? textContent.text : '';
+
+    return {
+      content,
+      stopReason: response.stop_reason ?? 'end_turn',
+      usage: {
+        inputTokens: response.usage.input_tokens,
+        outputTokens: response.usage.output_tokens,
+      },
+    };
+  }
+}
diff --git a/src/models/index.ts b/src/models/index.ts
new file mode 100644
index 0000000..6e2626a
--- /dev/null
+++ b/src/models/index.ts
@@ -0,0 +1,2 @@
+export { AnthropicClient, type AnthropicClientConfig } from './anthropic.js';
+export type { Message, ChatRequest, ChatResponse, ModelClient } from './types.js';
diff --git a/src/models/types.ts b/src/models/types.ts
new file mode 100644
index 0000000..731e803
--- /dev/null
+++ b/src/models/types.ts
@@ -0,0 +1,23 @@
+export interface Message {
+  role: 'user' | 'assistant';
+  content: string;
+}
+
+export interface ChatRequest {
+  messages: Message[];
+  system?: string;
+  maxTokens?: number;
+}
+
+export interface ChatResponse {
+  content: string;
+  stopReason: 'end_turn' | 'max_tokens' | 'stop_sequence' | string;
+  usage: {
+    inputTokens: number;
+    outputTokens: number;
+  };
+}
+
+export interface ModelClient {
+  chat(request: ChatRequest): Promise<ChatResponse>;
+}