# Implementation Plan - Fix RRULE Object Mapping

## Phase 1: Reproduction
- [ ] Task: Reproduce `Unknown RRULE property` error
    - [ ] Modify the test case in `icalendar_test.ts` to use `frequency` instead of `freq` in the mock object.
    - [ ] Run the test and confirm it fails with the expected error.
- [ ] Task: Conductor - User Manual Verification 'Reproduction' (Protocol in workflow.md)

## Phase 2: Fix Implementation
- [ ] Task: Implement mapping logic in `icalendar.ts`
    - [ ] Create a mapping object for verbose keys to iCal keys.
    - [ ] Update `expandRecurrences` to use this mapping.
    - [ ] Run the test to confirm it passes.
- [ ] Task: Conductor - User Manual Verification 'Fix Implementation' (Protocol in workflow.md)

## Phase 3: Verification & Cleanup
- [ ] Task: Full Regression Check
    - [ ] Run all tests in `icalendar_test.ts`.
- [ ] Task: Conductor - User Manual Verification 'Verification & Cleanup' (Protocol in workflow.md)