Add configurable INBOX-only search optimisation to mail_move

[bartonfriedland]

Problem

The mail_move operation searches through ALL mailboxes in ALL accounts to find emails by Message-ID. This creates a cross-account performance penalty:

• When one or more accounts have many mailboxes (e.g., 200+ folders with extensive organisation)
• Operations on emails in other accounts still search through all mailboxes across all accounts
• Operations can take 10-30+ seconds and Mail.app becomes unresponsive during search
• Performance penalty applies regardless of which account contains the email

Solution

Added optional searchInboxOnly parameter (default: false) to mail_move:

• When true: Only searches INBOX mailboxes (typically 2-5 folders across all accounts)
• When false: Default behaviour, searches all mailboxes (backward compatible)
• Performance gain: ~10-20x faster for INBOX operations (1-2 sec vs 10-30 sec)

Changes

Modified files:

1. lib/mail-operations.ts - Added searchInboxOnly parameter to moveEmails()
2. lib/schemas.ts - Added parameter to Zod schema
3. index.ts - Added parameter to tool input schema and handler
4. README.md - Documented parameter and added "Performance Considerations" section

Testing

Tested with multiple accounts including one with 200+ mailboxes:

• searchInboxOnly: true - ✅ Success, ~1-2 seconds
• searchInboxOnly: false - ✅ Success, ~10-30 seconds (Mail.app unresponsive during search)
• Message-ID remains invariant across moves

Backward Compatibility

✅ Default is false - existing behaviour preserved
✅ No breaking changes to API
✅ Optional parameter - existing code continues to work

Future Enhancements

For discussion in a separate PR:

• sourceAccount parameter to limit search scope to specific accounts
• Early exit when all Message-IDs are found
• Other performance optimisations