backend: gate existing endpoints behind auth and app permissions

Move /api/pair, /api/apps, and /api/stream/start under the session
auth middleware so they require a valid session token. Add app-level
permission filtering: non-admin users only see and can stream apps
they have been explicitly granted access to. Admins bypass all
permission checks.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

gamestream-webtransport-proxy/src/apps.rs

@@ -47,7 +47,16 @@ struct GetAppsResponse {
 impl crate::backend::Backend {
     #[craft(endpoint(status_codes(StatusCode::OK, StatusCode::INTERNAL_SERVER_ERROR)))]
     pub async fn get_apps(self: ::std::sync::Arc<Self>, depot: &mut Depot) -> AppResult<Json<GetAppsResponse>> {
-        let user = auth::get_user_from_depot(depot).cloned();
+        let user = match auth::get_user_from_depot(depot) {
+            Some(u) => u.clone(),
+            None => {
+                error!("get_apps reached without authenticated user in depot");
+                return Err(AppError {
+                    status_code: StatusCode::UNAUTHORIZED,
+                    description: "Not authenticated".to_string(),
+                });
+            }
+        };
         let standard_error = Err(AppError {
             status_code: StatusCode::INTERNAL_SERVER_ERROR,
             description: "failed to get available apps".to_string(),
@@ -146,7 +155,6 @@ impl crate::backend::Backend {
         }
 
         // Filter apps by user permissions (admins see everything)
-        if let Some(ref user) = user {
         if !user.is_admin {
             let permissions = self.db.get_permissions(&user.id).unwrap_or_default();
             for (server_name, apps) in get_apps_resp.apps.iter_mut() {
@@ -158,7 +166,6 @@ impl crate::backend::Backend {
             }
             get_apps_resp.apps.retain(|_, apps| !apps.is_empty());
         }
-        }
 
         Ok(Json(get_apps_resp))
     }

gamestream-webtransport-proxy/src/stream.rs

@@ -90,7 +90,16 @@ impl crate::backend::Backend {
         });
 
         // Check app permission
-        if let Some(user) = auth::get_user_from_depot(depot) {
+        let user = match auth::get_user_from_depot(depot) {
+            Some(u) => u.clone(),
+            None => {
+                error!("post_stream_start reached without authenticated user in depot");
+                return Err(AppError {
+                    status_code: StatusCode::UNAUTHORIZED,
+                    description: "Not authenticated".to_string(),
+                });
+            }
+        };
         if !user.is_admin {
             match self.db.check_app_permission(&user.id, &body.server, body.id as i64) {
                 Ok(true) => {}
@@ -106,7 +115,6 @@ impl crate::backend::Backend {
                 }
             }
         }
-        }
 
         let reader = self.state.read().await;