Problem

Claude Code silently deletes conversation transcripts after 30 days by default (cleanupPeriodDays: 30). Most users are unaware of this setting until they lose data. Multiple issues have been filed on the Claude Code repo:

• anthropics/claude-code#4172 — "Disable auto-deletion of past conversations"
• anthropics/claude-code#22547 — "data loss through bad default settings"
• anthropics/claude-code#23710 — cleanupPeriodDays: 0 silently disables ALL transcript persistence
• anthropics/claude-code#18881 — Same-day sessions deleted unexpectedly
• anthropics/claude-code#15935 — Files deleted despite setting 1825 days

Proposal

Add a toggle in Settings → General → Window Behavior, positioned below the existing "Skip Claude Code first-run confirmation" toggle:

Title: "Keep conversation history"
Description: "Prevent Claude Code from auto-deleting conversation transcripts (default: 30 days)"

When enabled: set cleanupPeriodDays: 99999 in ~/.claude/settings.json
When disabled: remove the cleanupPeriodDays field (revert to Claude Code's default behavior)

Why CC Switch

CC Switch already manages Claude Code settings (e.g., skipClaudeOnboarding writes to ~/.claude.json). This is a natural extension — protecting users from a known data loss footgun during initial setup.

Implementation Notes

• Target file: ~/.claude/settings.json (different from ~/.claude.json used by onboarding skip)
• Follows the existing ToggleRow pattern in WindowSettings.tsx
• Requires new Tauri commands for reading/writing cleanupPeriodDays
• i18n: EN/ZH/JA translations needed

I'll submit a PR for this.