[Bug]: Terminal closed from mobile app reappears as a brand-new terminal #7345

Operating system

Other

Orca version

Mobile app: v0.0.18 (3). Desktop: recent build (code references below are against current main, a074ed6)

Details

Short summary:
Closing a terminal from the Orca mobile app never sticks — the terminal disappears for a moment, then reappears as a brand-new terminal (fresh shell). Closing the same terminal from the desktop app works fine. Markdown/file/browser tabs close fine from mobile; only terminal tabs resurrect.

How can we reproduce it?

1. Pair the mobile app with a running desktop session.
2. Create a terminal from mobile (or use one only ever driven from mobile).
3. Long-press the terminal tab on mobile → Close.
4. The terminal briefly disappears, then comes back as a brand-new terminal.

Root cause (traced in code):
Terminal tabs are the only tab type on mobile whose Close goes through the handle-only terminal.close RPC instead of the session-tab close path, and the two halves of that path re-create the terminal:

1. Mobile Close calls handleCloseTerminal → terminal.close (mobile/app/h/[hostId]/session/[worktreeId].tsx:4110). Host-side closeTerminal (src/main/runtime/orca-runtime.ts:16363) only kills the PTY — it does not remove the session tab or drop its persisted binding.
2. On PTY exit the runtime keeps the tab in the mobile session snapshot and republishes it as status: 'pending-handle', terminal: null (orca-runtime.ts:18548-18550, republished via touchMobileSessionSnapshotsForPty at :6959). The closed tab is still present — and still marked active.
3. handleCloseTerminal removes the terminal only from the legacy terminals list; it never removes the tab from sessionTabs, never clears activeSessionTabId, and sets no tombstone. When the pending snapshot arrives, the auto-activation effect ([worktreeId].tsx:4187) sees an active pending terminal tab and calls session.tabs.activate with notifyClients: false → host hits shouldMaterializePendingTerminal (orca-runtime.ts:3841-3862) → createHeadlessMobileSessionTerminal spawns a new PTY into the same tab. That is the resurrection.

This exact resurrection class was already fixed for the other tab types: handleCloseSessionTab tombstones closed tabs ([worktreeId].tsx:4154), and host closeMobileSessionTab documents the authoritative-teardown requirement (orca-runtime.ts:4082-4087). The terminal Close button just doesn't use either fix.

Suggested fix:

• Mobile: route the terminal action sheet's Close through the session-tab close path (session.tabs.close + tombstone + clear activeSessionTabId) instead of handle-only terminal.close.
• Host (defense in depth): in runtime.closeTerminal, when the handle maps to a runtime-owned mobile session tab, perform the same authoritative teardown as closeMobileSessionTab (kill PTY + drop persisted binding + prune and emit snapshot) so stale clients cannot resurrect the tab.

Likely shares a root cause with #6927 (headless-server pairing: tab never closes from mobile) — same close path, different manifestation.