feat: implement asyncio exception handler and update entrypoint script for process management

backend/app/main.py

@@ -26,8 +26,29 @@ import app.models.user  # noqa: F401
 import app.models.project  # noqa: F401
 
 
+logger = logging.getLogger(__name__)
+
+
+def _asyncio_exception_handler(loop: asyncio.AbstractEventLoop, context: dict) -> None:
+    """Prevent unhandled asyncio task exceptions from killing the uvicorn process.
+
+    Normally uvicorn re-raises unhandled task exceptions at the event-loop level,
+    which can crash the whole process. The main culprit is a race condition in
+    websockets <12.0 (legacy/protocol.py AssertionError during keepalive ping).
+    Upgrading websockets>=12.0 is the primary fix; this handler is a safety net.
+    """
+    exc = context.get("exception")
+    msg = context.get("message", "")
+    if exc is not None:
+        logger.error("Unhandled asyncio task exception (swallowed): %s — %r", msg, exc)
+    else:
+        # No exception object — let default handler deal with it
+        loop.default_exception_handler(context)
+
+
 @asynccontextmanager
 async def lifespan(_app: FastAPI):
+    asyncio.get_event_loop().set_exception_handler(_asyncio_exception_handler)
     async with async_engine.begin() as conn:
         await conn.run_sync(Base.metadata.create_all)
         # Add is_admin column to existing databases that predate this feature

backend/requirements.txt

@@ -1,5 +1,6 @@
 fastapi==0.115.0
 uvicorn[standard]==0.32.0
+websockets>=12.0
 sqlalchemy==2.0.36
 aiosqlite==0.20.0
 pydantic>=2.11.0

deploy/entrypoint.sh

@@ -39,10 +39,22 @@ fi
 # Start FastAPI backend in the background on port 8001
 echo "🚀 Starting Velxio Backend..."
 uvicorn app.main:app --host 127.0.0.1 --port 8001 &
+UVICORN_PID=$!
 
-# Wait for backend to be healthy (optional but good practice)
+# Wait for backend to be healthy before starting nginx
 sleep 2
 
-# Start Nginx in the foreground to keep the container running
+# Start Nginx in the background (not exec — we need to monitor both)
 echo "🌐 Starting Nginx Web Server on port 80..."
-exec nginx -g "daemon off;"
+nginx -g "daemon off;" &
+NGINX_PID=$!
+
+# Exit as soon as either process dies so Docker can restart the container.
+# wait -n requires bash 4.3+ (standard on Debian Bullseye / Ubuntu 20.04+).
+wait -n $UVICORN_PID $NGINX_PID
+EXIT_CODE=$?
+
+echo "⚠️  A process exited (code $EXIT_CODE) — shutting down container"
+kill $UVICORN_PID $NGINX_PID 2>/dev/null || true
+wait $UVICORN_PID $NGINX_PID 2>/dev/null || true
+exit $EXIT_CODE

frontend/public/components-metadata.json

@@ -1,6 +1,6 @@
 {
   "version": "1.0.0",
-  "generatedAt": "2026-04-15T22:57:24.963Z",
+  "generatedAt": "2026-04-16T03:35:24.515Z",
   "components": [
     {
       "thumbnail": "<svg width=\"64\" height=\"64\" xmlns=\"http://www.w3.org/2000/svg\">\n      <rect width=\"64\" height=\"64\" fill=\"#e0e0e0\" rx=\"4\"/>\n      <text x=\"50%\" y=\"50%\" text-anchor=\"middle\" dy=\".3em\" font-size=\"10\" fill=\"#666\">\n        DIODE-1N4007\n      </text>\n    </svg>",

scripts/generate-component-metadata.ts

@@ -332,10 +332,19 @@ class MetadataGenerator {
               const type = member.type?.getText() || 'any';
               const defaultValue = member.initializer?.getText();
 
+              let resolvedDefault: unknown;
+              if (defaultValue) {
+                try {
+                  resolvedDefault = eval(defaultValue);
+                } catch {
+                  // Initializer references an identifier not in scope (e.g. imported constant)
+                  resolvedDefault = undefined;
+                }
+              }
               properties.push({
                 name,
                 type,
-                defaultValue: defaultValue ? eval(defaultValue) : undefined,
+                defaultValue: resolvedDefault,
               });
             }
           }

wokwi-libs/ngspice-wasm

@@ -0,0 +1 @@
+Subproject commit a0c3b1ab9a4e83ebeff4081b74ecef89bc9ff83c