fix: prevent stale SDK session and tool-marker parroting after idle timeout

src/app/api/chat/sessions/[id]/route.ts

@@ -1,5 +1,5 @@
 import { NextRequest } from 'next/server';
-import { deleteSession, getSession, updateSessionWorkingDirectory, updateSessionTitle, updateSessionMode, updateSessionModel, updateSessionProviderId, clearSessionMessages } from '@/lib/db';
+import { deleteSession, getSession, updateSessionWorkingDirectory, updateSessionTitle, updateSessionMode, updateSessionModel, updateSessionProviderId, clearSessionMessages, updateSdkSessionId } from '@/lib/db';
 
 export async function GET(
   _request: NextRequest,
@@ -46,6 +46,9 @@ export async function PATCH(
     if (body.provider_id !== undefined) {
       updateSessionProviderId(id, body.provider_id);
     }
+    if (body.sdk_session_id !== undefined) {
+      updateSdkSessionId(id, body.sdk_session_id);
+    }
     if (body.clear_messages) {
       clearSessionMessages(id);
     }

src/lib/claude-client.ts

@@ -235,24 +235,23 @@ function buildPromptWithHistory(
 ): string {
   if (!history || history.length === 0) return prompt;
 
-  const lines: string[] = ['<conversation_history>'];
+  const lines: string[] = [
+    '<conversation_history>',
+    '(This is a summary of earlier conversation turns for context. Tool calls shown here were already executed — do not repeat them or output their markers as text.)',
+  ];
   for (const msg of history) {
-    // For assistant messages with tool blocks (JSON arrays), summarize
+    // For assistant messages with tool blocks (JSON arrays), extract only the text portions.
+    // Tool-use and tool-result blocks are omitted to avoid Claude parroting them as plain text.
     let content = msg.content;
     if (msg.role === 'assistant' && content.startsWith('[')) {
       try {
         const blocks = JSON.parse(content);
         const parts: string[] = [];
         for (const b of blocks) {
           if (b.type === 'text' && b.text) parts.push(b.text);
-          else if (b.type === 'tool_use') parts.push(`[Used tool: ${b.name}]`);
-          else if (b.type === 'tool_result') {
-            const resultStr = typeof b.content === 'string' ? b.content : JSON.stringify(b.content);
-            // Truncate long tool results
-            parts.push(`[Tool result: ${resultStr.slice(0, 500)}${resultStr.length > 500 ? '...' : ''}]`);
-          }
+          // Skip tool_use and tool_result — they were already executed
         }
-        content = parts.join('\n');
+        content = parts.length > 0 ? parts.join('\n') : '(assistant used tools)';
       } catch {
         // Not JSON, use as-is
       }

src/lib/stream-session-manager.ts

@@ -392,6 +392,12 @@ async function runStream(stream: ActiveStream, params: StartStreamParams): Promi
         stream.toolResultsArray = [];
         stream.toolOutputAccumulated = '';
         emit(stream, 'completed');
+        // Clear stale SDK session so next message starts fresh
+        fetch(`/api/chat/sessions/${encodeURIComponent(stream.sessionId)}`, {
+          method: 'PATCH',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({ sdk_session_id: '' }),
+        }).catch(() => {});
         scheduleGC(stream);
       } else if (stream.toolTimeoutInfo) {
         // Tool timeout — auto-retry