Task list UI not rendered after session resume — requires a write operation to trigger re-render

Summary

After resuming a session with claude --resume (or claude --continue), the task list UI panel does not render, even though task data persists on disk at ~/.claude/tasks/. Calling TaskList (read-only) does not restore the UI. Only a write operation (TaskCreate or TaskUpdate) triggers the UI to re-render.

Reproduction

1. Start a session and create several tasks via TaskCreate
2. Confirm the task list UI panel is visible
3. Exit the session normally
4. Resume the session (claude --resume or claude --continue)
5. Observed: Task list UI panel is gone
6. Call TaskList — agent receives correct data, but UI panel still not visible
7. Call TaskCreate (or TaskUpdate) — UI panel re-appears immediately

Expected behavior

Task list UI should render on session resume if tasks exist in ~/.claude/tasks/ for the current session.

Environment

• CLI version: latest (as of 2026-04-19)
• Platform: macOS (Darwin 25.3.0, arm64)
• Terminal: cmux (Ghostty-based)
• Agent Teams: NOT enabled — this occurs in a normal single-agent session
• Task data: persists correctly in ~/.claude/tasks/<session-id>/, only the UI rendering is affected

Workaround

Perform any task write operation (e.g., create a dummy task and delete it) to force the UI to re-render.

Potentially related

• #39968 — Agent Teams bottom bar UI regression (similar symptom but requires Agent Teams enabled; this issue occurs without Agent Teams)