crosscue

ADR-0012 — Challenge Boards v1: live-compute lifetime + bounded retention

Status: Accepted (locked) · Date: 2026-06-09 (#159) Plan of record: ../../challenge-boards-159-breakdown.md

Context

The original #159 design called for a weekly rollover pipeline (daily_results / player_board_stats / processed_lifetime_weeks + a Monday cron) to materialize lifetime standings.

Decision

v1 computes weekly and lifetime leaderboards live from retained challenge_results rows, and does not build the rollover pipeline. Because results are the lifetime source under this model, challenge_results rows are intentionally never purged; retention applies only to the audit-only board_events table (14-day daily cron). The rollover acceptance criteria on #159 are superseded.

Consequences

• Far less moving machinery for v1-scale boards (≤20 players, one result per player per daily puzzle — compact rows).
• Revisit (new ADR) if per-puzzle result volume grows unexpectedly or a player_board_stats rollover is introduced — only then may results retention change.
• Leaderboard read cost grows with history; #241 already batched the aggregation across boards.