0114 — Cockpit closes terminals and detaches windows
Close Pane and Close Tab end the selected work. Close Window and Quit detach Phux-backed views without ending work or removing shared layout.
Full source summary
Close Pane and Close Tab end the selected work. Close Window and Quit detach Phux-backed views without ending work or removing shared layout. Cockpit-created sessions opt into keep-empty. Closing their last terminal leaves an Empty session view; closing that view retains the named session. Scratch terminals remain ephemeral. These rules apply to every command surface.
Status: Accepted Date: 2026-09-11
Context
The approved everyday UX contract behavior 19 distinguishes resource termination from client-view lifetime. The previous Cockpit shared-window removal was layout-only, despite being exposed as Close Tab. OS-window closure and tab closure cannot share that operation.
ADR-0105 makes keep-empty an opt-in session property; ADR-0107 preserves real satellite terminal ownership even when a hub projects its leaf. Cockpit’s emptied-window decision predates keep-empty. None of these permits a client to claim detach after kill.
Decision
| Action | Phux-backed work | Ephemeral scratch work |
|---|---|---|
| Close Pane; Cmd+W with a pane focused | End the exact terminal and its agent children; remove its shared pane. | End the terminal and remove the pane. |
| Close Tab | End the tab’s terminals and remove its shared layout. | End the tab’s terminals and remove the tab. |
| Close Window; macOS close button | Remove only this window’s views; retain terminals and shared layout. Other windows remain attached. | End scratch terminals owned by the window. |
| Disconnect Machine | Remove this app’s views/connections for that machine; retain work and saved registration. | Not applicable. |
| Quit | Detach all Phux views; retain work and layout for reopening. | End this app’s scratch terminals. |
| Process exit | Mark the terminal ended; remaining panes continue. Preserve a keep-empty session after its last exit. | End the terminal; remaining panes continue. |
| End Session | End the named session and its terminals on its owning coordinator, visible to other clients. | Not applicable. |
Keep-empty is explicit. New Session in Cockpit opts in. Existing CLI-created sessions keep their lifetime setting. Closing the last terminal in a keep-empty session shows Empty session with New Tab. Cmd+W there closes the client window, retaining the named session. An emptied window otherwise closes. The last macOS window closing quits the app. This is the keep-empty exception to the earlier emptied-window decision; it does not change default CLI session reaping.
A view is not its execution authority. Several windows showing one session share its layout and terminal identities. Closing one window releases only its view; the session attachment is released when no visible view needs it. One canonical PTY geometry is derived from the existing visibility/layout policy, never by letting independent windows alternately resize the same terminal. Sessions A and B on one machine use independent attachment contexts, fenced by session id and creation time. Selecting B in one window leaves A elsewhere.
Destructive completion is authoritative. Close Tab and End Session use all-or-nothing resource teardown where supported. Live views are not removed on enqueue: retain them until an acknowledged outcome or authoritative ended publication. A refusal keeps the work visible with its reason. An unknown or partial outcome refreshes the owning coordinator and reports per-terminal truth; it is never blindly resubmitted on a replacement connection. Captured actions retain resource, session, connection and invoking-view identity.
Satellite leaves remain real terminals. Close Pane/Tab terminates their satellite resources through the existing relay, preserving ADR-0107. Its term “window” means a server layout window (Cockpit tab), not an OS window. Close Window/Quit detach those views like other Phux-backed terminals; no satellite session id is adopted or interpreted as a hub session id.
Cleanup is distinct from intentional termination. Failed or abandoned spawn cleanup remains conditional on its instance token and unattached state under ADR-0109. Changing closure behavior does not authorize unconditional delayed cleanup. Connection loss freezes the last output, refuses new input and shows Reconnecting, rather than reporting process exit. A cold restart that lost work does not recreate its identity from a reused numeric id.
Why
Pane/tab closure follows ordinary terminal intent; window closure is safe for durable work. Explicit labels and server-owned outcomes make the same action predictable from pointer, menu, keyboard and Commands. Keeping lifetime on the session lets CLI and GUI observers agree after the last terminal exits.
Tradeoffs
- Close Tab now ends work rather than only hiding its layout. Tests and labels must cover the changed authority, including agent-child cascade.
- Detaching a view needs projection ownership independent of resource teardown.
- Each matrix row needs an independent CLI/client observer; a disappearing Cockpit pane is insufficient evidence that the intended resource survived or ended. Headless model checks do not establish native-window acceptance.
Alternatives
Keep layout-only Close Tab. Rejected: it contradicts the approved action and leaves running work hidden by an ordinary terminal-ending control.
Kill on Close Window. Rejected for Phux-backed work: it conflates a client projection with the lifetime of shared, durable execution.
Make every session keep-empty. Rejected: it changes existing CLI policy and server self-exit semantics. Cockpit opts in only when it creates a session.