[BUG] claude agents: cursor not visible in typing window on first session attach (Windows Terminal, Windows 11, 2.1.169)

Description

When attaching to any session via claude agents, the typing/input window renders with no visible cursor. Typing is fully functional — input is accepted and messages send normally — but the missing cursor makes editing difficult.

Steps to Reproduce

1. Run claude agents
2. Select any session and attach
3. Observe typing window — no cursor visible

100% reproducible on first attach.

Expected Behavior

Cursor visible and positioned in the typing window input area.

Environment

• Claude Code: 2.1.169
• OS: Windows 11 Pro (build 26200)
• Terminal: Windows Terminal — reproducible under both Command Prompt and PowerShell profiles

Notes

Typing works — cursor is missing visually only.

Related: #66275 (same symptom, different trigger: post-subagent vs first attach), #65989 (2.1.163 cursor regression), #65558 (agents keyboard regression, separate).