When implementing set-based selection/reconciliation algorithms, ensure **(1) deterministic outcomes** and **(2) invariant-preserving persisted state** across runs. **A. Deterministic tie-breaking (order-independent “argmax”)** If you pick a “best” owner based on computed scores, explicitly define what happens when scores are equal—do not rely on `Map`/array iteration order. ```js function pickBestOwner(scores) { let best = null; let bestScore = -Infinity; for (const [owner, score] of scores) { if (score > bestScore) { best = owner; bestScore = score; } else if (score === bestScore) { // deterministic tie-break (example: lexical) if (best === null || owner < best) best = owner; } } return best; } ``` **B. Persist the canonical desired set (not a derived delta)** In multi-run reconciliation (markers/comments, requested reviewers, etc.), persisted state must represent the **canonical target**. If you persist a filtered/derived view (e.g., `desired - reviewed`), later runs can lose elements and permanently drift from the intended target. ```js // Canonical marker persistence: store full desired, not effectiveDesired. const newMarkerBody = `${MARKER} {"desired":${JSON.stringify([...desired].sort())}} -->`; ``` **Checklist for PRs in this area** - Equal-score/ equal-priority choices have an explicit, order-independent tie-break. - Any persisted “desired/current” marker/comment reflects the canonical target set, not an intermediate computation that changes after events (like reviews). - Marker parsing and drift logic are consistent with what you persisted (so “restore” semantics work reliably across runs).