/rename title lost on abnormal exit — stat-log index not synced from JSONL

Bug Description

When a session is renamed via /rename, the custom title is written to the JSONL file as a custom-title entry, but is not persisted to the stat-log index unless the session exits normally (double Ctrl+C). If the terminal is closed, the machine shuts down, or the process is killed, the custom title is lost from the index and claude -r <name> can no longer find the session.

The data is still in the JSONL — only the index lookup is broken.

Steps to Reproduce

1. Start a session: claude
2. Rename it: /rename mytest
3. Close the terminal window (or kill the process, or shut down the machine)
4. Try to resume: claude -r mytest → not found
5. The session can only be resumed by UUID

Root Cause (from source analysis)

Title storage: /rename appends a {"type":"custom-title","customTitle":"mytest","sessionId":"..."} entry to the JSONL immediately — this works fine.

Title lookup (IU function): claude -r mytest searches the stat-log index, not the JSONL directly:

async function IU(query, opts) {
  let statFiles = await getStatFiles();
  let { logs } = await readStatLogs(statFiles, 0, statFiles.length);
  let matches = logs.filter(log => {
    let title = log.customTitle?.toLowerCase().trim();
    if (!title) return false;
    return opts.exact ? title === query : title.includes(query);
  });
  // ...
}

Title indexing: The stat-log index gets customTitle populated during session shutdown:

// Only runs during normal exit
let lastTitleLine = lines.findLast(l => l.startsWith('{"type":"custom-title"'));
if (lastTitleLine) {
  let title = extractField(lastTitleLine, "customTitle");
  this.currentSessionTitle = title || undefined;
}

On abnormal exit, this shutdown path never runs → stat-log index has no customTitle → claude -r mytest returns nothing.

Fix

Either:

1. Write to stat-log index immediately on /rename, not just on shutdown
2. Fall back to scanning JSONL when stat-log lookup fails — the custom-title entry is already there
3. Rebuild the index on startup if it's stale (detect by comparing JSONL mtime vs index mtime)

Related

• #24065 — Same bug, reported 2026-02-08, closed as stale without fix
• #37437 — Same architectural pattern: data exists in JSONL but index/chain walker can't reach it

Environment

• Claude Code 2.1.81
• OS: Arch Linux
• Terminal: Ghostty