From f5ef107eaa43a9f9abc4c0f9e7f1a32cb3051374 Mon Sep 17 00:00:00 2001
From: David Montero Crespo <davidmonterocrespo24@gmail.com>
Date: Thu, 16 Apr 2026 00:57:30 -0300
Subject: [PATCH] feat: implement asyncio exception handler and update
 entrypoint script for process management

---
 backend/app/main.py                      | 21 +++++++++++++++++++++
 backend/requirements.txt                 |  1 +
 deploy/entrypoint.sh                     | 18 +++++++++++++++---
 frontend/public/components-metadata.json |  2 +-
 scripts/generate-component-metadata.ts   | 11 ++++++++++-
 wokwi-libs/ngspice-wasm                  |  1 +
 6 files changed, 49 insertions(+), 5 deletions(-)
 create mode 160000 wokwi-libs/ngspice-wasm

diff --git a/backend/app/main.py b/backend/app/main.py
index 04d1724f..7cc255a2 100644
--- a/backend/app/main.py
+++ b/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
diff --git a/backend/requirements.txt b/backend/requirements.txt
index e22e6c8d..b3322098 100644
--- a/backend/requirements.txt
+++ b/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
diff --git a/deploy/entrypoint.sh b/deploy/entrypoint.sh
index db82836e..433108c0 100644
--- a/deploy/entrypoint.sh
+++ b/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
diff --git a/frontend/public/components-metadata.json b/frontend/public/components-metadata.json
index 1e82397e..2ae8a80f 100644
--- a/frontend/public/components-metadata.json
+++ b/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>",
diff --git a/scripts/generate-component-metadata.ts b/scripts/generate-component-metadata.ts
index 4783b40d..e4cfb77c 100644
--- a/scripts/generate-component-metadata.ts
+++ b/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,
               });
             }
           }
diff --git a/wokwi-libs/ngspice-wasm b/wokwi-libs/ngspice-wasm
new file mode 160000
index 00000000..a0c3b1ab
--- /dev/null
+++ b/wokwi-libs/ngspice-wasm
@@ -0,0 +1 @@
+Subproject commit a0c3b1ab9a4e83ebeff4081b74ecef89bc9ff83c