#850 Extension publish score is non-monotonic: yanking versions lowers a user's score

Summary

computeExtensionScore's publish term is non-monotonic: yanking extension versions lowers a user's score. This conflicts with the monotonic-ledger goal (scores should only ever accumulate).

Root cause

The publish input, countVersionsByUser (lib/infrastructure/mongo-extension-repository.ts), excludes yanked versions:

async countVersionsByUser(userId: string): Promise<number> {
  const notYanked = { yankedAt: { $in: [null, undefined] } };
  return await this.versions.countDocuments({ pushedByUserId: userId, ...notYanked }, AGG_OPTS);
}

Publish points = versionCount * POINTS_PER_PUBLISH (500/version). Yank a version and the count — and the score — drops. Example: 20 versions = 10,000 pts -> yank 5 -> 15 versions = 7,500 pts (loses 2,500).

Why it surfaced now

The pull/publish caps in lib/domain/scoring/extension-score.ts were removed (MAX_PUBLISH_SCORE = 5000). The cap was incidentally masking this: any author with >10 versions sat at the 5,000 ceiling, so yanking from 20->15 versions (10,000->7,500 raw) was invisible — both clamped to 5,000.

The cap removal did NOT create this bug; it unmasked a latent non-monotonicity that already existed in the formula.

Scope

• Pulls are unaffected — countAuthorPulls reads append-only pull events; monotonic up.
• Only the publish term regresses, only for authors who both had >10 versions AND yank. Bounded at 500/version.

Suggested fix

Make the publish input monotonic for scoring, independent of yank state. Options:

1. Count versions ever-published (ignore yankedAt) for the scoring query specifically, or
2. Track a per-user high-water mark of version count.

Note yank still needs to hide versions everywhere else (listings, registry) — only the scoring count should be yank-agnostic.

Verification

scripts/verify-uncapped-extension-score.ts (deno task verify:ext-score) proves pulls/publishes are uncapped, but does not yet assert publish-term monotonicity under yank. A regression check belongs there once the input is fixed.