/rename session name not indexed — cannot resume by name

Description

The /rename command in Claude Code allows users to rename their sessions (e.g., /rename transfer). However, the renamed session cannot be found or resumed by its name — only by UUID.

Current Behavior

1. User renames a session: /rename transfer
2. The rename is stored only as a message inside the session JSONL file:

``jsonl
{"type":"user","message":"<command-name>/rename</command-name><command-args>transfer</command-args>"}
``

1. The sessions-index.json has no name or displayName field — only sessionId, summary, firstPrompt, etc.
2. claude --resume transfer does not find the session
3. User must know the UUID to resume: claude --resume 253352ca-a890-4dd8-8083-c378f38e45b5

Expected Behavior

• /rename should update sessions-index.json with a displayName field
• claude --resume <name> should search by display name (exact or fuzzy match)
• claude --continue or session picker should show the renamed display name

Steps to Reproduce

1. Start a new session: claude
2. Do some work
3. Rename the session: /rename my-important-session
4. Exit: /exit
5. Try to resume by name: claude --resume my-important-session → fails
6. The only way to resume is by UUID from sessions-index.json

Impact

• /rename is effectively a cosmetic-only feature with no functional benefit
• Users who rename sessions expect to find them by name later
• Without name-based lookup, /rename creates a false sense of organization

Proposed Solution

1. Add displayName field to sessions-index.json schema
2. Update /rename to write both to JSONL (for history) AND to sessions-index.json
3. Support claude --resume <name> with exact/fuzzy name matching
4. Show display names in session picker / claude sessions list

Environment

• Claude Code: v2.1.42
• OS: macOS Sequoia 15.3.2
• Shell: zsh