Cross-machine reattach: session enumeration and workroom UI state on the host (OQ8) #255

Parent

Part of #154 (remote agent sessions). Phase 4. Design doc docs/designs/remote-workrooms.md: open question 8, Phase 4 "Cross-machine session enumeration" (from Phase 1's S4 note), and the Success Criteria item "Do the same from a different Mac".

What to build

Open a remote workroom from a second Mac and land in the same sessions, in the same tabs. Today session identity and the pane-to-tab layout live in the app on the Mac that created them, so a second Mac sees the host's sessions with no idea where they belong.

• Answer OQ8 first: how much workroom UI state moves to the agent. At minimum, agent-side session naming and a pane-to-tab mapping carried on the wire.
• Store the workroom's UI state with the workroom (on the host, through the agent), so any Mac that opens it can rebuild its tabs and panes.
• Enumerate a host's sessions from a Mac that did not create them, and reattach to them.

Acceptance criteria

• OQ8 is answered in the design doc, with what moves to the agent and what stays per Mac.
• Start a long-running program in a remote workroom on one Mac, open the same workroom on a second Mac, and land in the same session, in the same tab layout, with a full-screen program correctly repainted.
• Closing the app on one Mac does not disturb the other Mac's attachment.

Blocked by

#253 (remote workrooms in the app).

Filed by Claude Code at the owner's request, 2026-09-27.