fix(chat): always emit narrative summary, even when tool-round cap is hit

Surfaced by the live Path B test: AI fired 7 tool calls (fs.read,
fs.edit, kill, dev_server.start, curl, dev_server.logs, ...) in a single
turn, the loop exited at MAX_TOOL_ROUNDS, and the user saw only a tray
of ✓ icons — no text reply.

Two changes:

1. Bump MAX_TOOL_ROUNDS 6 → 12. Path B iteration chains routinely run
   long; 6 was tuned for Path A's much-shorter Coolify-orchestration
   sequences.

2. When the loop exits because of the cap (the last assistant turn was
   a tool call, not a finish), force one more no-tools Gemini call
   with an explicit "summarize the result, do NOT call tools" prompt.
   That gives the user a sentence or two of context instead of a wall
   of green checkmarks. Wrapped in try/catch so the stream still
   terminates cleanly if Gemini errors.

Made-with: Cursor

app/api/chat/route.ts

@@ -19,7 +19,12 @@ import { callGeminiChat, streamGeminiChat } from '@/lib/ai/gemini-chat';
 import { VIBN_TOOL_DEFINITIONS, executeMcpTool } from '@/lib/ai/vibn-tools';
 import type { ChatMessage, ToolCall } from '@/lib/ai/gemini-chat';
 
-const MAX_TOOL_ROUNDS = 6;
+// Bumped from 6 to 12 because Path B chains (devcontainer.ensure →
+// fs.read → fs.edit → kill → start → curl → logs) routinely fire 7-10
+// tool calls in one user turn. When the cap IS hit, we still emit a
+// narrative summary instead of leaving the user staring at a tool tray
+// (see the no-tools follow-up call below).
+const MAX_TOOL_ROUNDS = 12;
 
 let chatTablesReady = false;
 async function ensureChatTables() {
@@ -286,6 +291,32 @@ export async function POST(request: Request) {
           }
         }
 
+        // If the loop exited because we hit MAX_TOOL_ROUNDS while the
+        // model still wanted to call tools, the user has only seen a
+        // tray of ✓ icons with no narrative. Force one final no-tools
+        // call so we always end on a human-readable summary.
+        const lastTurnHadTools =
+          messages.length > 0 &&
+          messages[messages.length - 1].role === 'tool';
+        if (round >= MAX_TOOL_ROUNDS && lastTurnHadTools) {
+          try {
+            const summary = await callGeminiChat({
+              systemPrompt:
+                systemPrompt +
+                '\n\nYou have just executed a chain of tool calls. Summarize the result for the user in 1-3 sentences. Do NOT call any more tools.',
+              messages,
+              tools: [],
+              temperature: 0.3,
+            });
+            if (summary.text) {
+              assistantText += summary.text;
+              emit({ type: 'text', text: summary.text });
+            }
+          } catch {
+            // Don't let a failed summary kill the stream.
+          }
+        }
+
         // Persist final assistant message
         const finalMsg: ChatMessage = {
           role: 'assistant',