Allow configurable session/auth token TTL to prevent daily re-login

Problem

When using Claude Code CLI on a machine that isn't used every day (e.g., a secondary laptop), the OAuth session expires after roughly 24 hours of inactivity. This forces a /login re-authentication via browser on the next use.

For users who alternate between machines (e.g., iMac for daily work, MBP for evenings/weekends), this means re-authenticating every time they return to the less-frequently-used machine.

Current Behavior

• OAuth token stored in macOS Keychain
• Token refresh cycle runs while Claude Code is active (~5 min interval)
• Once the session is closed, the refresh token expires server-side after ~24 hours
• No client-side setting to extend this duration

Desired Behavior

A configurable session persistence option, such as:

• "sessionTTL": "7d" in settings.json or ~/.claude.json
• A "remember me" flag during /login (e.g., /login --persist 7d)
• Or simply a longer default refresh token lifetime (7-30 days, consistent with tools like gh auth, aws sso, Tailscale)

Workarounds Considered (and rejected)

• Heartbeat script / LaunchAgent: Works but shouldn't be necessary for auth persistence
• API key instead of OAuth: Loses the convenience of the OAuth flow
• Leaving a tmux session open: Fragile, not a real solution

Environment

• macOS (Sequoia 15.4)
• Claude Code CLI (latest)
• Multi-machine workflow over Tailscale

Notes

This is a quality-of-life issue for power users who rely on Claude Code across multiple machines but don't use every machine every day. A 7-day refresh token would eliminate the friction entirely.