fix(ui): defer event-handler global-signal writes; retain traces for flakes

.github/workflows/build.yml

@@ -311,12 +311,20 @@ jobs:
       run: npx playwright test
       working-directory: ./ui/tests
 
+    # `always()`, not `failure()`: with `retries: 2` an intermittent test is
+    # reported as "flaky" and the job still succeeds, so a `failure()` guard
+    # threw away the one artifact that could explain it (see freenet/river#538,
+    # where the trace was gone and the attached hypothesis turned out to be
+    # wrong). The playwright config keeps a trace `on-first-retry`, so this
+    # uploads the flake evidence too. On a clean run the directory is empty and
+    # this is a no-op.
     - name: Upload test results
-      if: failure()
+      if: always()
       uses: actions/upload-artifact@v4
       with:
         name: playwright-report
         path: ui/tests/test-results/
+        if-no-files-found: ignore
 
   claude-ci-analysis:
     name: Claude CI Analysis

ui/src/components/room_list.rs

@@ -389,8 +389,13 @@ pub fn RoomList() -> Element {
                         "data-testid": "create-room-button",
                         class: "p-1.5 rounded-md text-text-muted hover:text-accent hover:bg-surface transition-colors",
                         title: "Create Room",
+                        // Signal mutation from an event handler must be deferred
+                        // (dioxus-signal-safety: direct writes here are the
+                        // Firefox mobile RefCell re-entrancy crash path).
                         onclick: move |_| {
-                            CREATE_ROOM_MODAL.write().show = true;
+                            crate::util::defer(move || {
+                                CREATE_ROOM_MODAL.write().show = true;
+                            });
                         },
                         Icon { width: 14, height: 14, icon: FaPlus }
                     }

ui/src/components/room_list/create_room_modal.rs

@@ -136,9 +136,14 @@ pub fn CreateRoomModal() -> Element {
         // Backdrop
         div {
             class: "fixed inset-0 bg-black/50 z-40",
+            // Signal mutation from an event handler must be deferred
+            // (dioxus-signal-safety: direct writes here are the Firefox
+            // mobile RefCell re-entrancy crash path).
             onclick: move |_| {
-                CREATE_ROOM_MODAL.with_mut(|modal| {
-                    modal.show = false;
+                crate::util::defer(move || {
+                    CREATE_ROOM_MODAL.with_mut(|modal| {
+                        modal.show = false;
+                    });
                 });
             }
         }
@@ -211,9 +216,13 @@ pub fn CreateRoomModal() -> Element {
                     button {
                         "data-testid": "create-room-cancel-button",
                         class: "px-4 py-2 text-sm text-text-muted hover:text-text hover:bg-surface rounded-lg transition-colors",
+                        // Deferred close — same signal-safety rule as the
+                        // backdrop handler above.
                         onclick: move |_| {
-                            CREATE_ROOM_MODAL.with_mut(|modal| {
-                                modal.show = false;
+                            crate::util::defer(move || {
+                                CREATE_ROOM_MODAL.with_mut(|modal| {
+                                    modal.show = false;
+                                });
                             });
                         },
                         "Cancel"

ui/src/components/room_list/edit_room_modal.rs

@@ -62,8 +62,13 @@ pub fn EditRoomModal() -> Element {
                 // Overlay
                 div {
                     class: "absolute inset-0 bg-black/50",
+                    // Signal mutation from an event handler must be deferred
+                    // (dioxus-signal-safety: direct writes here are the Firefox
+                    // mobile RefCell re-entrancy crash path).
                     onclick: move |_| {
-                        EDIT_ROOM_MODAL.write().room = None;
+                        crate::util::defer(move || {
+                            EDIT_ROOM_MODAL.write().room = None;
+                        });
                     }
                 }
                 // Modal content
@@ -371,8 +376,12 @@ pub fn EditRoomModal() -> Element {
                     button {
                         "data-testid": "edit-room-close-button",
                         class: "absolute top-3 right-3 p-1 text-text-muted hover:text-text transition-colors",
+                        // Deferred close — same signal-safety rule as the
+                        // backdrop handler above.
                         onclick: move |_| {
-                            EDIT_ROOM_MODAL.write().room = None;
+                            crate::util::defer(move || {
+                                EDIT_ROOM_MODAL.write().room = None;
+                            });
                         },
                         "✕"
                     }

ui/src/components/room_list/receive_invitation_modal.rs

@@ -592,21 +592,37 @@ fn render_error_state(
                             let _ = element.set_focus(true).await;
                         });
                     },
+                    // Signal mutation from an event handler must be deferred
+                    // (dioxus-signal-safety: direct writes here are the Firefox
+                    // mobile RefCell re-entrancy crash path).
                     onclick: move |_| {
-                        // Reset to PendingSubscription so the synchronizer retries
-                        PENDING_INVITES.with_mut(|pending| {
-                            if let Some(join) = pending.map.get_mut(&room_key) {
-                                join.status = PendingRoomStatus::PendingSubscription;
-                            }
+                        crate::util::defer(move || {
+                            // Reset to PendingSubscription so the synchronizer retries
+                            PENDING_INVITES.with_mut(|pending| {
+                                if let Some(join) = pending.map.get_mut(&room_key) {
+                                    join.status = PendingRoomStatus::PendingSubscription;
+                                }
+                            });
                         });
                     },
                     "Retry"
                 }
                 button {
                     class: "px-4 py-2 bg-surface hover:bg-surface-hover text-text rounded-lg transition-colors",
+                    // Deferred — same signal-safety rule as the Retry handler
+                    // above. BOTH statements go inside the defer so their
+                    // relative order is preserved (code after a `defer()` runs
+                    // BEFORE the deferred closure), and because
+                    // `dismiss_invitation_persistently` itself writes a signal
+                    // via `invitation.set(None)`. The clone is needed because
+                    // an `onclick` is `FnMut`, so the non-`Copy` invitation
+                    // cannot be moved out of the captured environment.
                     onclick: move |_| {
-                        PENDING_INVITES.write().map.remove(&room_key);
-                        dismiss_invitation_persistently(&inv_for_dismiss, invitation);
+                        let inv = inv_for_dismiss.clone();
+                        crate::util::defer(move || {
+                            PENDING_INVITES.write().map.remove(&room_key);
+                            dismiss_invitation_persistently(&inv, invitation);
+                        });
                     },
                     "Dismiss"
                 }