[Bug] Draft PRs are ingested as regular OPEN PRs, allowing WIP drafts to affect scoring/collateral

[admiral223]

Summary

Draft pull requests are currently treated the same as normal OPEN pull requests in the mirror/scoring pipeline. This means work-in-progress drafts can be counted in open-PR paths even though they are not ready for review.

Why this is a problem

• It creates a mismatch between contributor workflow (Draft = WIP) and scoring behavior.
• Draft PRs can influence open-PR collateral/threshold logic before they are review-ready.
• It allows low-signal draft activity to affect miner evaluation.

Evidence

• Draft PR exists in tracked repos (example: entrius/gittensor PR Fix: register issue no build artifact #271 is draft).
• Mirror PR model stores state but no draft flag:
  • packages/das/src/entities/PullRequest.entity.ts
  • packages/db/02_pull_requests.sql
• Backfill query reads state but not isDraft:
  • packages/das/src/webhook/github-fetcher.service.ts
• Loader classifies by state only; OPEN goes directly to open PR bucket:
  • gittensor/validator/oss_contributions/mirror/load.py

Reproduction

1. Create/open a draft PR in a mirrored repository.
2. Let mirror ingestion/backfill run.
3. Run validator scoring/load flow.
4. Observe PR is handled as ordinary OPEN PR (no draft distinction).

Expected behavior

Draft PRs should be represented explicitly and either:

• excluded from open-PR scoring/collateral paths, or
• handled by a clearly defined draft-specific policy.

Suggested fix

1. Add is_draft field in mirror DB/entity.
2. Populate it from:
   • GraphQL isDraft (backfill/metadata paths)
   • webhook pull_request.draft (event path)
3. Update gittensor mirror load/scoring to apply intended policy for draft PRs.
4. Add tests covering OPEN + isDraft=true vs OPEN + isDraft=false.