[eric] apps: a preview whose dev server never binds shows an honest failure card with retry instead of spinning Starting preview forever (Alex's report)

backend/apps/outputs/outputs.py

@@ -497,6 +497,7 @@ def runtime_status_payload(workspace_id: str, instance: int = 1) -> dict:
         "running": rt.running,
         # 'spawned' vs 'serving': ready flips only once the primary port answered the bind poll (and un-flips when the process dies or is frozen).
         "ready": rt.ready,
+        "boot_failed": bool(getattr(rt, "boot_failed", False)),
         # True when the app is served as a built bundle with no dev-server process (ENG-209).
         "serve_static": rt.serve_static,
         "port": rt.port,

backend/apps/outputs/runtime.py

@@ -113,6 +113,8 @@ class AppRuntime:
         self.serve_static: bool = False
         # New-mode only: flips True once something is actually listening on frontend_port (we kick off a background poll task in p_start_new_mode). frontend_url returns null until this flips, so the preview pane doesn't try to navigate to an unbound port and show a "Site can't be reached" error mid-npm-install.
         self.p_frontend_ready: bool = False
+        # Set when the bind poll gave up; the status payload carries it so the card can stop spinning honestly.
+        self.boot_failed = False
         # True only while a live bind-poll task owns the global vite boot lock; start() releases it otherwise.
         self.p_boot_lock_handed_off: bool = False
         # True while the process tree is SIGSTOP'd in the idle pool. A frozen vite still holds its port but can't answer it, so frontend_url must stay null while suspended (else the webview loads a dead port = the ERR_FAILED on fast app-switching).
@@ -427,6 +429,8 @@ class AppRuntime:
                     pass
                 await asyncio.sleep(FRONTEND_BIND_POLL_INTERVAL)
             # Timed out; keep the runtime up (Terminal might show useful errors) but surface why the preview never appeared.
+            # boot_failed reaches the CARD: the log line lands in a Terminal most users never open, so the spinner span "Starting preview" forever (Alex's report).
+            self.boot_failed = True
             self.p_broadcast(LogLine(
                 "runtime",
                 f"[runtime] frontend did NOT bind on port {port} after "

backend/main.py

@@ -315,6 +315,7 @@ async def websocket_runtime_logs(websocket: WebSocket, workspace_id: str, instan
                 # The property is the one honest gate (crashed/suspended vite -> None, static -> serve URL); a duplicate running check here nulled every serve-static app's URL, whose card then waited forever on a process that never exists (the "Starting preview" wedge).
                 "frontend_url": rt.frontend_url,
                 "is_new_mode": rt.is_new_mode,
+                "boot_failed": bool(getattr(rt, "boot_failed", False)),
             },
         }