Prevent chat from exceeding Claude context limit

- Cap conversation history to last 20 messages
- Truncate tool results over 8KB before sending back to Claude
- Trim long assistant messages in client-side history to 2KB

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/api/chat/route.ts

@@ -260,15 +260,22 @@ export async function POST(req: NextRequest) {
       );
     }
 
-    const { messages, context } = await req.json();
+    const { messages: rawMessages, context } = await req.json();
 
-    if (!messages || !Array.isArray(messages) || messages.length === 0) {
+    if (!rawMessages || !Array.isArray(rawMessages) || rawMessages.length === 0) {
       return NextResponse.json(
         { error: "messages array is required" },
         { status: 400 }
       );
     }
 
+    // Limit conversation history to prevent exceeding Claude's context window.
+    // Keep the last 20 messages (10 user + 10 assistant turns).
+    const MAX_HISTORY = 20;
+    const messages = rawMessages.length > MAX_HISTORY
+      ? rawMessages.slice(-MAX_HISTORY)
+      : rawMessages;
+
     const userId = session.user.id;
     const organizationId = session.user.organizationId;
     const userRole = session.user.role;
@@ -389,11 +396,17 @@ export async function POST(req: NextRequest) {
                 error: result.error,
               });
 
+              // Truncate large tool results to avoid exceeding context limits
+              let resultJson = JSON.stringify(
+                result.success ? result.data : { error: result.error }
+              );
+              if (resultJson.length > 8000) {
+                resultJson = resultJson.slice(0, 8000) + '... [truncated]"}';
+              }
+
               toolResults.push({
                 tool_use_id: toolCall.id,
-                content: JSON.stringify(
-                  result.success ? result.data : { error: result.error }
-                ),
+                content: resultJson,
               });
             }
 

src/hooks/use-chat.ts

@@ -145,9 +145,12 @@ export function useChat(context?: ChatContext) {
         // Build message history for the API — send plain text only.
         // Tool interactions are resolved server-side within a single request,
         // so we never send tool_use/tool_result blocks back in history.
+        // Trim long assistant responses to keep token count manageable.
         const apiMessages = [...messages, userMsg].map((m) => ({
           role: m.role,
-          content: m.content,
+          content: typeof m.content === "string" && m.content.length > 2000
+            ? m.content.slice(0, 2000) + "..."
+            : m.content,
         }));
 
         abortRef.current = new AbortController();