fix: native fetch with OAuth Bearer auth

package.json

@@ -5,7 +5,6 @@
     "start": "node server.js"
   },
   "dependencies": {
-    "@anthropic-ai/sdk": "^0.39.0",
     "express": "^4.19.2"
   }
 }

server.js

@@ -2,7 +2,6 @@ const express = require('express');
 const path = require('path');
 const fs = require('fs');
 const os = require('os');
-const { createRequire } = require('module');
 
 const app = express();
 app.use(express.json({ limit: '10mb' }));
@@ -24,17 +23,6 @@ function getAccessToken() {
     }
 }
 
-function createClient(accessToken) {
-    const Anthropic = require('@anthropic-ai/sdk');
-    // OAuth token: use as apiKey — SDK sends x-api-key header
-    // Some versions also support authToken for Bearer auth
-    try {
-        return new Anthropic({ authToken: accessToken });
-    } catch (e) {
-        return new Anthropic({ apiKey: accessToken });
-    }
-}
-
 app.post('/api/chat', async (req, res) => {
     const { text, model = 'sonnet' } = req.body;
     if (!text?.trim()) return res.status(400).json({ error: 'text required' });
@@ -43,7 +31,7 @@ app.post('/api/chat', async (req, res) => {
     const accessToken = getAccessToken();
 
     if (!accessToken) {
-        return res.status(500).json({ error: 'No credentials found in ' + (process.env.CLAUDE_CONFIG_DIR || '~/.claude') });
+        return res.status(500).json({ error: 'No credentials in ' + (process.env.CLAUDE_CONFIG_DIR || '~/.claude') });
     }
 
     res.setHeader('Content-Type', 'text/event-stream');
@@ -54,16 +42,50 @@ app.post('/api/chat', async (req, res) => {
     const heartbeat = setInterval(() => res.write(': ping\n\n'), 15000);
 
     try {
-        const client = createClient(accessToken);
-        const stream = await client.messages.stream({
+        const apiResp = await fetch('https://api.anthropic.com/v1/messages', {
+            method: 'POST',
+            headers: {
+                'Content-Type': 'application/json',
+                'Authorization': `Bearer ${accessToken}`,
+                'anthropic-version': '2023-06-01',
+                'anthropic-beta': 'oauth-2025-04-20',
+            },
+            body: JSON.stringify({
                 model: modelId,
                 max_tokens: 8192,
+                stream: true,
+                system: 'You are Claude, a helpful assistant. Respond directly and concisely.',
                 messages: [{ role: 'user', content: text }],
+            }),
         });
 
-        for await (const event of stream) {
-            if (event.type === 'content_block_delta' && event.delta?.type === 'text_delta') {
-                res.write(`data: ${JSON.stringify({ text: event.delta.text })}\n\n`);
+        if (!apiResp.ok) {
+            const errText = await apiResp.text();
+            res.write(`data: ${JSON.stringify({ error: `${apiResp.status}: ${errText.substring(0, 500)}` })}\n\n`);
+            return;
+        }
+
+        const reader = apiResp.body.getReader();
+        const decoder = new TextDecoder();
+        let buf = '';
+
+        while (true) {
+            const { done, value } = await reader.read();
+            if (done) break;
+            buf += decoder.decode(value, { stream: true });
+            const events = buf.split('\n\n');
+            buf = events.pop();
+            for (const ev of events) {
+                const dataLine = ev.split('\n').find(l => l.startsWith('data: '));
+                if (!dataLine) continue;
+                const payload = dataLine.slice(6);
+                if (payload === '[DONE]') continue;
+                try {
+                    const obj = JSON.parse(payload);
+                    if (obj.type === 'content_block_delta' && obj.delta?.type === 'text_delta') {
+                        res.write(`data: ${JSON.stringify({ text: obj.delta.text })}\n\n`);
+                    }
+                } catch (e) {}
             }
         }
     } catch (err) {