[BUG] Agent View: opening a session from the list hangs indefinitely at "opening"

Summary

When using Agent View (claude agents), selecting a session from the list to enter it gets stuck at the "opening" state and never finishes loading. The session itself does not open; the UI just stays on the "opening" indicator with no error and no timeout.

Environment

• Claude Code version: 2.1.142
• Platform: Windows 11 Home Single Language (10.0.26200)
• Shell: PowerShell 7 (also reproduces in default Windows Terminal)
• Plan: Max
• Date observed: 2026-05-16 (Asia/Bangkok)

Steps to reproduce

1. Run claude agents to open Agent View.
2. The list of sessions renders correctly (running / done / blocked).
3. Select a session (any state) and press Enter to open it.
4. Expected: the session opens and the TUI swaps to that session's view.
5. Actual: the UI stays on "opening" indefinitely. No error message, no progress, no fallback. Has to be killed via Ctrl+C / closing the terminal.

Frequency

Consistently reproducible on this machine across multiple claude agents launches today.

Notes

• This is not the same as #54434 (SSE stream stalls inside a running session) — the hang here is during the transition from Agent View list into a session, before any conversation activity.
• Not the same as the existing "ESC key non-functional in agents view" issue either — here the entry-point itself never completes.

Happy to provide additional info (debug logs, exact session metadata, network capture, repro video) if a maintainer can point me at what would help most.