fix: add CatchPanicLayer to capture handler panics

Without this, panics in async handlers silently drop the connection
and the edge proxy returns a generic 503. Now panics are caught,
logged, and returned as 500 with the panic message.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

Cargo.toml

@@ -94,7 +94,7 @@ termimad = "0.34"
 # Channel integrations
 axum = { version = "0.8", features = ["ws"] }
 tower = "0.5"
-tower-http = { version = "0.6", features = ["trace", "cors", "set-header"] }
+tower-http = { version = "0.6", features = ["trace", "cors", "set-header", "catch-panic"] }
 
 # Cron scheduling for routines
 cron = "0.13"

src/channels/web/server.rs

@@ -629,6 +629,25 @@ pub async fn start_server(
         .merge(projects)
         .merge(protected)
         .layer(DefaultBodyLimit::max(10 * 1024 * 1024)) // 10 MB max request body (image uploads)
+        .layer(tower_http::catch_panic::CatchPanicLayer::custom(
+            |panic_info: Box<dyn std::any::Any + Send + 'static>| {
+                let detail = if let Some(s) = panic_info.downcast_ref::<String>() {
+                    s.clone()
+                } else if let Some(s) = panic_info.downcast_ref::<&str>() {
+                    (*s).to_string()
+                } else {
+                    "unknown panic".to_string()
+                };
+                tracing::error!("Handler panicked: {}", detail);
+                axum::http::Response::builder()
+                    .status(axum::http::StatusCode::INTERNAL_SERVER_ERROR)
+                    .header("content-type", "text/plain")
+                    .body(axum::body::Body::from(format!("Internal Server Error: {detail}")))
+                    .unwrap_or_else(|_| {
+                        axum::http::Response::new(axum::body::Body::from("Internal Server Error"))
+                    })
+            },
+        ))
         .layer(cors)
         .layer(SetResponseHeaderLayer::if_not_present(
             header::X_CONTENT_TYPE_OPTIONS,