`--resume` can't find recent sessions — sessions-index.json not created/updated since January

What happened

I use Claude Code daily across multiple projects (WSL2, CLI). This past week I noticed --resume can't find my most recent sessions. I'd finish a long session (hours of work, hundreds of messages), come back the next day, --resume, and it's not there. Happened multiple times across April 2-6.

The session .jsonl files are on disk — I can see them, they're 10-36MB — but the resume picker doesn't show them. Trying to resume creates empty stub sessions instead of reconnecting.

Root cause

sessions-index.json doesn't exist for my main project:

$ ls ~/.claude/projects/-mnt-g-Workspace-.../sessions-index.json
No such file or directory

Checked other projects on the same machine — some have the file but all are stale from January 2026:

chatbot-3/sessions-index.json    Jan 23
obsidian/sessions-index.json     Jan 22  
projects/sessions-index.json     Jan 24

No project has had its index updated since January. Whatever creates/updates this file stopped working.

The specific incident

• April 2-3: Long session (46e3e7ed, 292 messages, 36MB). Named it "ui-ux-refactor". Experiments, code changes, doc work.
• April 3, 15:34: New terminal, --resume. Session not listed.
• Two stub sessions created from the failed resume attempt (b3603d1f — 1 message, no jsonl; f7b32ba1 — 3KB stub). PID file references yet another session ID (f413c0a4) that has no .jsonl anywhere.
• April 6: Same problem. The 36MB session is right there on disk but invisible to --resume.

Workaround: claude --resume 46e3e7ed-5f9b-4e44-b8b8-d7ea580e1290 works if you know the ID.

Scale of the problem

Across all my projects:

• 9 session .jsonl files exist on disk for the main project
• --resume shows none of them (no index file)
• 8 orphaned session directories exist with subagents/ dirs but no .jsonl — unclear if these were cleaned up or never persisted
• history.jsonl references all sessions correctly — it knows about sessions the picker can't find

No cleanupPeriodDays configured. Never opted into any cleanup.

Environment

• Claude Code 2.1.92
• WSL2 (Linux 6.6.87.2-microsoft-standard-WSL2)
• bash, CLI mode

Related

• #18897 — sessions-index.json not created for all projects
• #25032 — sessions-index.json not updated
• #41458 — cleanupPeriodDays ignored, sessions deleted

The common thread across all of these: sessions-index.json is unreliable. It's not created for all projects, not updated when it does exist, and the resume picker appears to depend on it rather than scanning .jsonl files directly.