fix(outbox): two tabs no longer overwrite each other's queue (#268)

OutboxFeature loaded lotus_outbox_v1 once and then saved its own
in-memory list over the key on every change, so a second tab's save
dropped the first tab's unsent messages. persist() now re-reads the
stored list and applies the change (add/remove by txnId) to it.

Fixes #268

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/features/outbox/OutboxFeature.tsx

@@ -94,10 +94,15 @@ export function OutboxFeature() {
       OFFLINE.has(mx.getSyncState()) ||
       (typeof navigator !== 'undefined' && navigator.onLine === false);
 
-    const persist = (next: OutboxEntry[]) => {
-      if (next === entries) return;
+    // [Gitea #268] Read-modify-write: another tab may have queued or cleared
+    // entries since we last looked, and saving our own copy over the key
+    // would drop theirs. Entries are added/removed by txnId, so applying our
+    // change to the stored list merges cleanly.
+    const persist = (update: (list: OutboxEntry[]) => OutboxEntry[]) => {
+      const stored = loadOutbox(userId);
+      const next = update(stored);
       entries = next;
-      saveOutbox(userId, entries);
+      if (next !== stored) saveOutbox(userId, next);
     };
 
     /**
@@ -123,8 +128,8 @@ export function OutboxFeature() {
         if (!shouldKeepInOutbox(event.getType(), event.getContent())) return;
         live.set(txnId, { event, room });
         if (event.status === EventStatus.NOT_SENT) scheduleBlipRetry(event);
-        persist(
-          withEntry(entries, {
+        persist((list) =>
+          withEntry(list, {
             txnId,
             roomId: room.roomId,
             threadId: event.threadRootId ?? null,
@@ -138,7 +143,7 @@ export function OutboxFeature() {
       // SENT, CANCELLED, or the remote echo replaced it (status null).
       live.delete(txnId);
       autoRetries.delete(txnId);
-      persist(withoutEntry(entries, txnId));
+      persist((list) => withoutEntry(list, txnId));
     };
 
     /** Re-send network failures, oldest first; a room stops at its first failure. */
@@ -191,7 +196,7 @@ export function OutboxFeature() {
           return !!room && isDelivered(room, entry.txnId);
         },
       );
-      plan.drop.forEach((entry) => persist(withoutEntry(entries, entry.txnId)));
+      plan.drop.forEach((entry) => persist((list) => withoutEntry(list, entry.txnId)));
       plan.restore.forEach((entry) => {
         const room = mx.getRoom(entry.roomId);
         if (!room || live.has(entry.txnId)) return;