Learnings

// Bad — lock expires if tick is slow
await lock.acquire(ttl: 30_000);
await runTick(); // might take 45s
await lock.release();

// Good — heartbeat keeps the lock alive
await lock.acquire(ttl: 30_000);
await runTick({ onProgress: () => lock.extend(30_000) });
await lock.release();

// Bad — silent overwrite
await ddb.put({ TableName, Item });

// Good — fails if item already exists
await ddb.put({
  TableName,
  Item,
  ConditionExpression: 'attribute_not_exists(pk)',
});

// Bad — one failure kills the batch
await Promise.all(tokens.map((t) => sendPush(t, payload)));

// Good — collect individual results
const results = await Promise.allSettled(tokens.map((t) => sendPush(t, payload)));
const failures = results.filter((r) => r.status === 'rejected');

// Bad — error vanishes
void this.processUpdate(update);

// Good — error is captured
void this.processUpdate(update).catch((err) =>
  this.logger.error('processUpdate failed', { err }),
);

// Bad — client re-processes
Text(team.code.prefix(3))

// Good — backend sends the right value
Text(team.abbreviation) // "PBKS" from API

// Bad
const dryRun = !!process.env.DRY_RUN;

// Good
const dryRun = process.env.DRY_RUN === 'true';

struct Match: Codable, Sendable {
  let id: String

  // Required for Swift 6 + Sendable
  nonisolated init(from decoder: Decoder) throws { ... }
  nonisolated func encode(to encoder: Encoder) throws { ... }
}

// Good — fallback chain
func parseISO8601(_ string: String) -> Date? {
  fractionalFormatter.date(from: string)
    ?? standardFormatter.date(from: string)
}