chore(telemetry): add path-confusion loop breaker and strict blank-preview diagnostic protocol

vibn-frontend/app/api/chat/route.ts

@@ -310,6 +310,15 @@ Each project has a persistent \`vibn-dev\` container. Edit files via \`fs_*\` an
 - After \`dev_server_start\` returns a \`previewUrl\` AND \`healthCheck.status === 200\`, call \`browser_console { url: previewUrl }\` to capture frontend console errors.
 - **CRITICAL:** Next.js HMR overlay syntax errors do NOT crash the \`dev_server_start\` command. Even if \`dev_server_start\` returns \`Status: success\`, you MUST call \`browser_console\` to verify that there are no red syntax error overlays on the screen. If \`browser_console\` returns errors, fix them with \`fs_edit\` before declaring done. A green \`healthCheck\` plus a clean console is the real "done" signal for UI work.
 
+**BLANK PREVIEW / NOT LOADING PROTOCOL:**
+If the user tells you the preview is blank, not loading, or shows nothing:
+1. **DO NOT GUESS OR EDIT CODE YET.**
+2. Run \`dev_server_list\` to check if the server is actually running.
+3. If it is not running, run \`dev_server_start\`.
+4. If it is running, run \`dev_server_logs\` on its port to check for compilation hangs (e.g. Turbopack slow filesystem hangs) or fatal errors.
+5. Run \`browser_console\` on the previewUrl.
+6. ONLY edit code or configuration once the logs/console explicitly identify the source file or error.
+
 **HMR through the proxy (apply when scaffolding):**
 - **Vite (verified working):** in \`vite.config\` set \`server: { host: '0.0.0.0', port: <3000-3009>, strictPort: true, hmr: { clientPort: 443, protocol: 'wss', host: '<the previewUrl host, no protocol>' } }\`. The \`hmr.host\` is REQUIRED — without it Vite's HMR client can guess the wrong host and the WS handshake fails through Traefik. Default localhost binding looks fine locally but breaks HMR through the proxy.
 - **Next dev:** \`next dev -p 3000 -H 0.0.0.0\` (WSS HMR works automatically through the proxy without extra config).
@@ -822,6 +831,7 @@ export async function POST(request: Request) {
 
       let lastVerifySig: string | null = null;
       let lastRoundToolSig: string | null = null;
+      let lastRoundResults: any[] = [];
       let fileHashes = new Map<string, string>();
       let stallRounds = 0;
 
@@ -1064,7 +1074,16 @@ export async function POST(request: Request) {
               "Stalled (Repeated the exact same tool calls twice without advancing)";
           }
 
+          const pathConfusion = detectPathConfusion(
+            currentRoundResults,
+            lastRoundResults,
+          );
+          if (pathConfusion) {
+            loopBreakReason = `PATH_CONFUSION: ${pathConfusion}`;
+          }
+
           lastRoundToolSig = currentRoundToolSig;
+          lastRoundResults = currentRoundResults;
 
           if (loopBreakReason) break;
         }
@@ -1546,3 +1565,44 @@ function checkRoundProgress(
 
   return { progressed, nextHashes };
 }
+
+function detectPathConfusion(current: any[], last: any[]): string | null {
+  const missingFiles = new Set<string>();
+
+  const extractMissingFiles = (results: any[]) => {
+    for (const tr of results) {
+      if (!tr.content) continue;
+      try {
+        const parsed = JSON.parse(tr.content);
+        const resultStr =
+          typeof parsed === "string" ? parsed : JSON.stringify(parsed);
+        const argsStr = typeof tr.toolName === "string" ? tr.toolName : "";
+        const allStr = resultStr + argsStr;
+
+        if (
+          allStr.includes("not a file or missing") ||
+          allStr.includes("No such file or directory")
+        ) {
+          const match = allStr.match(/([a-zA-Z0-9_\-\.]+\.[a-zA-Z0-9]+)/);
+          if (match && match[1]) {
+            missingFiles.add(match[1]);
+          }
+        }
+      } catch (e) {}
+    }
+  };
+
+  extractMissingFiles(current);
+  extractMissingFiles(last);
+
+  // If the agent hit a "Not a file" error on the same basename across two different rounds
+  if (missingFiles.size > 0 && current.length > 0 && last.length > 0) {
+    for (const file of missingFiles) {
+      // Very basic heuristic: if it complains about the same file twice, break the loop
+      // and instruct it to use \`find\`
+      return `You are trying to read ${file} but the path is wrong. Stop guessing paths. Run 'shell_exec { command: "find . -name ${file}" }' to discover the exact path to this file, then use it exactly once.`;
+    }
+  }
+
+  return null;
+}