- Return exact match first (e.g., King's Pawn Game for 1.e4 e5)
- Fill remaining slots with common continuations (Ruy Lopez, Italian Game, etc.)
- Look up to 4 moves deeper to find important opening variations
- Prioritize by depth (closer continuations first), then ECO root flag, then ECO code
- Avoid duplicate ECO families (e.g., don't show multiple C6x openings)
- Add isEcoRoot field to OpeningMetadata interface
- Add test script to verify opening lookup logic
Example: After 1.e4 e5, now returns:
1. King's Pawn Game (C20) - exact match
2. King's Gambit (C30) - continuation
3. King's Knight Opening (C40) - continuation
4. Ruy Lopez (C60) - continuation
5. Italian Game (C50) - continuation
This gives users context about what openings are still possible.
Stefan