Feature request: --session-name flag for naming sessions at startup

Problem

When launching Claude Code programmatically (e.g., via terminal multiplexer layouts like Zellij/tmux), there's no way to set a human-readable session name at startup. The only way to name a session is via the /session rename slash command from within an active interactive session, which requires manual user input.

Use Case

I use a shell orchestrator (work) that creates git worktrees and launches Claude instances in Zellij tabs with pre-configured prompts. Each session maps to a specific task (e.g., garments-breadboard, invoicing-schema). Being able to name sessions at launch would make --resume and session management much more useful — currently all sessions show up as unnamed UUIDs unless the user manually renames each one.

Example of how this would be used:

# In a Zellij KDL layout:
pane command="claude" {
    args "--session-name" "garments-breadboard" "--dangerously-skip-permissions" "Read .session-prompt.md for your task instructions."
}

Or from the command line:

claude --session-name "invoicing-schema" --resume

Proposed Solution

Add a --session-name <name> CLI flag that sets the session's display name at creation time. This would be the equivalent of running /session rename <name> immediately after startup, but without requiring interactive input.

Alternatives Considered

• --append-system-prompt with rename instruction: Claude can't execute slash commands, so this doesn't work.
• Wrapper script piping stdin: /session rename only works from interactive user input, not piped stdin.
• Prompt file instruction: Unreliable — depends on the model choosing to tell the user to rename.

Environment

• Claude Code v1.0.33 (current at time of writing)
• macOS, Zellij 0.43.1