feat: add demo video, env var config, default to claude-opus-4-6

- Support ANTHROPIC_BASE_URL, OPENAI_BASE_URL, MINI_CLAUDE_MODEL env vars
- Default model changed to claude-opus-4-6
- Add demo video to README
- Update quick start with clear API configuration docs

Author: Windy4096

README.md

@@ -6,6 +6,8 @@
 
 **用 ~1300 行 TypeScript 复现 Claude Code 的核心能力。** 这不是 demo，而是一份分步教程——每一步都对照 Claude Code 真实源码讲解"它怎么做的 → 我们怎么简化的"，帮你彻底理解 coding agent 的工作原理。
 
+<https://github.com/Windy3f3f3f3f/claude-code-from-scratch/raw/main/demo.mp4>
+
 ## 分步教程
 
 **[在线阅读 →](https://windy3f3f3f3f.github.io/claude-code-from-scratch/)**
@@ -29,18 +31,48 @@
 git clone https://github.com/Windy3f3f3f3f/claude-code-from-scratch.git
 cd claude-code-from-scratch
 npm install && npm run build
-export ANTHROPIC_API_KEY="your-key-here"
+```
+
+### 配置 API
+
+支持两种后端，通过环境变量自动识别：
+
+**方式一：Anthropic 格式（推荐）**
+
+```bash
+export ANTHROPIC_API_KEY="sk-ant-xxx"
+# 可选：使用代理
+export ANTHROPIC_BASE_URL="https://aihubmix.com"
+```
+
+**方式二：OpenAI 兼容格式**
 
-npm start                              # 交互式 REPL 模式
-npm start -- "修复 src/app.ts 的 bug"    # 单次执行模式
-npm start -- --yolo "跑所有测试并修复"    # 跳过安全确认
-npm start -- --resume                    # 恢复上次会话
+```bash
+export OPENAI_API_KEY="sk-xxx"
+export OPENAI_BASE_URL="https://api.openai.com/v1"
+```
+
+默认模型为 `claude-opus-4-6`，可通过环境变量或命令行参数自定义：
+
+```bash
+export MINI_CLAUDE_MODEL="claude-sonnet-4-6"    # 环境变量方式
+npm start -- --model gpt-4o                      # 命令行方式（优先级更高）
+```
+
+### 运行
+
+```bash
+npm start                    # 交互式 REPL 模式（推荐）
+npm start -- --resume        # 恢复上次会话继续对话
+npm start -- --yolo          # 跳过安全确认（危险命令自动执行）
 ```
 
-### 使用 OpenAI 兼容 API
+全局安装后可在任意目录使用：
 
 ```bash
-npm start -- --api-base https://aihubmix.com/v1 --api-key sk-xxx --model gpt-4o "hello"
+npm link                     # 全局安装
+cd ~/your-project
+mini-claude                  # 直接启动
 ```
 
 ### REPL 命令

README_EN.md

@@ -6,6 +6,8 @@
 
 **Recreate Claude Code's core capabilities in ~1300 lines of TypeScript.** This isn't a demo — it's a step-by-step tutorial where each chapter compares Claude Code's real source with our simplified implementation, helping you truly understand how coding agents work.
 
+<https://github.com/Windy3f3f3f3f/claude-code-from-scratch/raw/main/demo.mp4>
+
 ## Step-by-Step Tutorial
 
 **[Read Online →](https://windy3f3f3f3f.github.io/claude-code-from-scratch/)**
@@ -29,18 +31,48 @@
 git clone https://github.com/Windy3f3f3f3f/claude-code-from-scratch.git
 cd claude-code-from-scratch
 npm install && npm run build
-export ANTHROPIC_API_KEY="your-key-here"
+```
+
+### API Configuration
+
+Two backends supported, auto-detected via environment variables:
+
+**Option 1: Anthropic Format (Recommended)**
+
+```bash
+export ANTHROPIC_API_KEY="sk-ant-xxx"
+# Optional: use a proxy
+export ANTHROPIC_BASE_URL="https://aihubmix.com"
+```
+
+**Option 2: OpenAI-Compatible Format**
 
-npm start                                    # Interactive REPL
-npm start -- "fix the bug in src/app.ts"     # One-shot mode
-npm start -- --yolo "run tests and fix"      # Skip confirmations
-npm start -- --resume                        # Restore last session
+```bash
+export OPENAI_API_KEY="sk-xxx"
+export OPENAI_BASE_URL="https://api.openai.com/v1"
+```
+
+Default model is `claude-opus-4-6`. Customize via env var or CLI flag:
+
+```bash
+export MINI_CLAUDE_MODEL="claude-sonnet-4-6"    # env var
+npm start -- --model gpt-4o                      # CLI flag (higher priority)
+```
+
+### Run
+
+```bash
+npm start                    # Interactive REPL mode (recommended)
+npm start -- --resume        # Resume last session
+npm start -- --yolo          # Skip safety confirmations
 ```
 
-### OpenAI-Compatible API
+Install globally to use from any directory:
 
 ```bash
-npm start -- --api-base https://aihubmix.com/v1 --api-key sk-xxx --model gpt-4o "hello"
+npm link                     # Global install
+cd ~/your-project
+mini-claude                  # Launch directly
 ```
 
 ### REPL Commands

demo.mp4

@@ -49,8 +49,10 @@ async function withRetry<T>(
 // ─── Model context windows ──────────────────────────────────
 
 const MODEL_CONTEXT: Record<string, number> = {
+  "claude-opus-4-6": 200000,
+  "claude-sonnet-4-6": 200000,
   "claude-sonnet-4-20250514": 200000,
-  "claude-haiku-4-20250414": 200000,
+  "claude-haiku-4-5-20251001": 200000,
   "claude-opus-4-20250514": 200000,
   "gpt-4o": 128000,
   "gpt-4o-mini": 128000,
@@ -78,7 +80,8 @@ function toOpenAITools(): OpenAI.ChatCompletionTool[] {
 interface AgentOptions {
   yolo?: boolean;
   model?: string;
-  apiBase?: string;
+  apiBase?: string;          // OpenAI-compatible base URL
+  anthropicBaseURL?: string; // Anthropic base URL (e.g. proxy)
   apiKey?: string;
   thinking?: boolean;
 }
@@ -111,7 +114,7 @@ export class Agent {
   constructor(options: AgentOptions = {}) {
     this.yolo = options.yolo || false;
     this.thinking = options.thinking || false;
-    this.model = options.model || "claude-sonnet-4-20250514";
+    this.model = options.model || "claude-opus-4-6";
     this.useOpenAI = !!options.apiBase;
     this.systemPrompt = buildSystemPrompt();
     this.effectiveWindow = getContextWindow(this.model) - 20000;
@@ -125,7 +128,10 @@ export class Agent {
       });
       this.openaiMessages.push({ role: "system", content: this.systemPrompt });
     } else {
-      this.anthropicClient = new Anthropic({ apiKey: options.apiKey });
+      this.anthropicClient = new Anthropic({
+        apiKey: options.apiKey,
+        ...(options.anthropicBaseURL ? { baseURL: options.anthropicBaseURL } : {}),
+      });
     }
   }
 

src/agent.ts

@@ -19,7 +19,7 @@ function parseArgs(): ParsedArgs {
   const args = process.argv.slice(2);
   let yolo = false;
   let thinking = false;
-  let model = "claude-sonnet-4-20250514";
+  let model = process.env.MINI_CLAUDE_MODEL || "claude-opus-4-6";
   let apiBase: string | undefined;
   let apiKey: string | undefined;
   let resume = false;
@@ -45,7 +45,7 @@ Usage: mini-claude [options] [prompt]
 Options:
   --yolo, -y       Skip all confirmation prompts
   --thinking        Enable extended thinking (Anthropic only)
-  --model, -m      Model to use (default: claude-sonnet-4-20250514)
+  --model, -m      Model to use (default: claude-opus-4-6, or MINI_CLAUDE_MODEL env)
   --api-base URL   Use OpenAI-compatible API endpoint
   --api-key KEY    API key for the specified endpoint
   --resume         Resume the last session
@@ -164,21 +164,45 @@ async function runRepl(agent: Agent) {
 async function main() {
   const { yolo, model, apiBase, apiKey, prompt, resume, thinking } = parseArgs();
 
-  // Determine API key: --api-key flag > env vars
-  const resolvedApiKey =
-    apiKey ||
-    (apiBase ? process.env.OPENAI_API_KEY : process.env.ANTHROPIC_API_KEY);
+  // Resolve API config: CLI flags > env vars
+  // Priority: --api-base/--api-key flags first, then env vars
+  let resolvedApiBase = apiBase;
+  let resolvedApiKey = apiKey;
+  let resolvedUseOpenAI = !!apiBase;
+
+  if (!resolvedApiKey) {
+    // Check OPENAI env vars first (if OPENAI_BASE_URL is set, use OpenAI format)
+    if (process.env.OPENAI_API_KEY && process.env.OPENAI_BASE_URL) {
+      resolvedApiKey = process.env.OPENAI_API_KEY;
+      resolvedApiBase = resolvedApiBase || process.env.OPENAI_BASE_URL;
+      resolvedUseOpenAI = true;
+    } else if (process.env.ANTHROPIC_API_KEY) {
+      resolvedApiKey = process.env.ANTHROPIC_API_KEY;
+      resolvedApiBase = resolvedApiBase || process.env.ANTHROPIC_BASE_URL;
+      resolvedUseOpenAI = false;
+    } else if (process.env.OPENAI_API_KEY) {
+      resolvedApiKey = process.env.OPENAI_API_KEY;
+      resolvedApiBase = resolvedApiBase || process.env.OPENAI_BASE_URL;
+      resolvedUseOpenAI = true;
+    }
+  }
 
   if (!resolvedApiKey) {
-    const envVar = apiBase ? "OPENAI_API_KEY" : "ANTHROPIC_API_KEY";
     printError(
       `API key is required.\n` +
-        `  Use --api-key flag or set ${envVar} environment variable.`
+        `  Set ANTHROPIC_API_KEY (+ optional ANTHROPIC_BASE_URL) for Anthropic format,\n` +
+        `  or OPENAI_API_KEY + OPENAI_BASE_URL for OpenAI-compatible format,\n` +
+        `  or use --api-key / --api-base flags.`
     );
     process.exit(1);
   }
 
-  const agent = new Agent({ yolo, model, apiBase, apiKey: resolvedApiKey, thinking });
+  const agent = new Agent({
+    yolo, model, thinking,
+    apiBase: resolvedUseOpenAI ? resolvedApiBase : undefined,
+    anthropicBaseURL: !resolvedUseOpenAI ? resolvedApiBase : undefined,
+    apiKey: resolvedApiKey,
+  });
 
   // Resume session if requested
   if (resume) {