Session persistence failure: Session ses_3d1c654a7ffew6gK7sAuRuJTFt lost #12310

Bug Description

Session data was lost despite the session ID being displayed. When attempting to resume the session using -s flag, opencode returns "undefined" instead of loading the session.

Steps to Reproduce

1. Create a new opencode session (displays session ID: ses_3d1c654a7ffew6gK7sAuRuJTFt)
2. Work in the session for 1+ hours
3. Try to resume session: opencode -s ses_3d1c654a7ffew6gK7sAuRuJTFt
4. Session loads as "undefined" and all work is lost

Expected Behavior

Session should be resumed with all conversation history and context intact.

Actual Behavior

Session shows "undefined" and appears to be a fresh session.

Environment

• Platform: Linux
• Date: 2026-02-05
• Session created: 2026-02-05T14:34:17.304Z

Additional Context

The session directory was checked at ~/.opencode/messages/ but the session ID ses_3d1c654a7ffew6gK7sAuRuJTFt was not found. Only these sessions existed:

• ses_41ecfcb82ffejhPSBOABNhK9QD
• ses_45c8e3564ffeoihhT8Z8D29sYO
• ses_46c782dcaffekGTzMPEr2LON0A
• ses_4710b1c28ffeLw4Xykahv0XYg7

This suggests the session was never persisted to disk despite being created.