--resume "name" fails: sessions-index.json does not index custom-title/agent-name fields from .jsonl

Bug Description

--resume "name" cannot find sessions that were named via Plan mode, because sessions-index.json does not index the custom-title / agent-name records stored in .jsonl files.

Root Cause

When a session is named (e.g. via Plan mode completion), the name is written directly into the session's .jsonl file as event records:

{"type": "custom-title", "customTitle": "discount-rate-limit-preset", "sessionId": "bfc3d699-..."}
{"type": "agent-name",   "agentName":  "discount-rate-limit-preset", "sessionId": "bfc3d699-..."}

These records appear repeatedly throughout the session file. However, sessions-index.json stores "firstPrompt": "No prompt" for all such sessions — the customTitle/agentName fields are never indexed.

As a result, --resume "discount-rate-limit-preset" returns no results even though the session file clearly contains the name.

Steps to Reproduce

1. Start a session, enter Plan mode, let it complete and generate a session name (e.g. discount-rate-limit-preset)
2. End the session
3. After ~7+ days, try: claude --resume "discount-rate-limit-preset"
4. Result: session not found

Expected Behavior

--resume "name" should search customTitle / agentName fields in .jsonl files (or have sessions-index.json index them), so named sessions remain findable by name regardless of age.

Actual Behavior

• sessions-index.json has "firstPrompt": "No prompt" — name lookup fails
• Sessions also disappear from the interactive picker after ~7–11 days
• Workaround: claude --resume <uuid> (requires knowing the UUID via grep on history.jsonl)

Environment

• Claude Code version: 2.1.104
• OS: WSL2 (Ubuntu on Windows)

Workaround

# Find UUID from history
grep -i "keyword" ~/.claude/history.jsonl

# Or search session files for the custom-title
find ~/.claude/projects/ -name "*.jsonl" \
  | xargs grep -l '"customTitle":"discount-rate-limit-preset"' 2>/dev/null

# Resume by UUID
claude --resume bfc3d699-499a-4085-947f-5166105e42b3