Desktop-to-mobile session sync is stale/missing for some conversations

Using the same account on both desktop and mobile versions of the app (not the terminal CLI — pure app-to-app, no session bridging involved):

• A long-running conversation started on desktop does appear in the mobile app's session list, but its content is stale — it doesn't reflect recent messages/updates from the desktop side.
• A separate, more recently-started conversation (also created natively in the desktop app via "+ New," not via CLI) does not appear in the mobile app's list at all.

Both conversations exist purely within the app (no CLI/remote-control bridging involved), so this looks like a gap or delay in whatever mechanism syncs session state to the mobile client, distinct from the CLI-session-bridging issue already filed (#83477).