diff --git a/server.js b/server.js
index 1b85be1..b4cd8ab 100644
--- a/server.js
+++ b/server.js
@@ -40,13 +40,36 @@ app.post('/api/chat', (req, res) => {
 
     const env = { ...process.env, CLAUDE_CONFIG_DIR: configDir };
 
-    const proc = spawn(CLAUDE_BIN, ['-p', text, '--model', modelId, '--output-format', 'text'], {
+    const proc = spawn(CLAUDE_BIN, ['-p', text, '--model', modelId, '--output-format', 'stream-json', '--verbose'], {
         env,
         stdio: ['ignore', 'pipe', 'pipe'],
     });
 
+    let buf = '';
     proc.stdout.on('data', (chunk) => {
-        res.write(`data: ${JSON.stringify({ text: chunk.toString() })}\n\n`);
+        buf += chunk.toString();
+        const lines = buf.split('\n');
+        buf = lines.pop(); // keep incomplete line
+        for (const line of lines) {
+            if (!line.trim()) continue;
+            try {
+                const obj = JSON.parse(line);
+                // streaming delta
+                if (obj.type === 'content_block_delta' && obj.delta?.type === 'text_delta') {
+                    res.write(`data: ${JSON.stringify({ text: obj.delta.text })}\n\n`);
+                }
+                // fallback: full assistant message
+                else if (obj.type === 'assistant' && obj.message?.content) {
+                    for (const block of obj.message.content) {
+                        if (block.type === 'text') res.write(`data: ${JSON.stringify({ text: block.text })}\n\n`);
+                    }
+                }
+                // error in result
+                else if (obj.type === 'result' && obj.is_error) {
+                    res.write(`data: ${JSON.stringify({ error: obj.result || 'unknown error' })}\n\n`);
+                }
+            } catch (e) {}
+        }
     });
 
     let stderrBuf = '';