/resume session names inconsistent — reverts from custom title to auto-generated summary

Version: 2.1.62 (macOS)

Description

When a session has been renamed via /rename, the custom title shows correctly in /resume sometimes, but other times reverts to an auto-generated summary string instead of the saved custom title.

Root cause (suspected)

sessions-index.json does not appear to be updated when new sessions are created. When /resume falls back to scanning .jsonl files directly, it may generate summaries independently of the stored custom-title records already present in those files.

Steps to reproduce

1. Rename a session with /rename
2. Exit Claude Code
3. Reopen and run /resume
4. The session may show the custom name or an auto-generated summary inconsistently across sessions

Expected behavior

/resume should always display the custom title set via /rename.

Actual behavior

The title shown in /resume is inconsistent — sometimes the custom title, sometimes an auto-generated summary.