Task 218: Animation Transfer Overlap Validation & Fix

Status: DONE

Human directive: Phase 21, item 25

Problem

EP01 diagram-04 (ペリジュピター捕獲 IF分析) has two transfers in the same scenario ("perijove") with overlapping time windows:

• Transfer 1 (approach→periapsis): [0, 72000]
• Transfer 2 (periapsis→Ganymede): [36000, 72000]

This causes two ship markers to animate simultaneously during t=36000–72000s. Transfer 1's endTime should be 36000, not 72000.

The human wants a systematic fix — not just a data patch, but TDD-based validation to prevent this across all analyses.

Plan

Phase 1: Build-time validation (TDD)

1. Add validation in templates.ts or a dedicated validator: same-scenario transfers must not have overlapping [startTime, endTime] windows
2. Write unit tests first, then implement
3. Validation should run during build (fail fast)

Phase 2: Fix EP01 diagram-04 data

1. Fix Transfer 1 endTime from 72000 → 36000 in ep01.md
2. Verify other diagrams don't have this issue (scan all episode MDX files)

Phase 3: E2E test

1. Add Playwright test that verifies no diagram has overlapping same-scenario transfers
2. Or verify via build-time validation + existing test coverage

Files

• ts/src/templates.ts — rendering + validation
• ts/src/templates.test.ts — unit tests
• reports/data/episodes/ep01.md — buggy data
• ts/src/orbital-animation.js — browser hydration