[bug] miners API: CLOSED pull requests filtered by created_at instead of closed_at

[kiannidev]

Duplicate check

Item	Relation
#71 (closed)	Backfill GraphQL stops at created_at — ingestion layer, not miner query
#16 / #15 (closed)	Backfill lookback window — not REST miners API
#100 (open)	Pagination — orthogonal
No open/closed issue	Miner /pulls CLOSED branch uses created_at

Description

GET/POST /api/v1/miners/:githubId/pulls applies inconsistent time windows across PR states. MERGED PRs correctly use merged_at >= since. CLOSED (unmerged) PRs use created_at >= since, while the sibling /issues endpoint uses closed_at >= since for closed issues. Old PRs closed inside the scoring window but opened before since are omitted from miner pull results.

Steps to Reproduce

1. Mirror a repo with a miner-authored PR: created_at = 60 days ago, closed_at = 5 days ago, state = CLOSED (not merged).
2. Call GET /api/v1/miners/{authorId}/pulls?since= (ISO timestamp 30 days ago).
3. Call GET /api/v1/miners/{authorId}/issues?since= (same timestamp).
4. The closed issue appears ( closed_at >= since ); the closed PR does not (created_at < since).
5. Repeat with POST .../pulls and since_by_repo — same filter in getPullRequestsByRepo.

Expected Behavior

CLOSED PRs should enter the window when closed_at >= since, matching issues and matching how MERGED uses merged_at.

Actual Behavior

-- miners.service.ts (GET and POST variants)
(p.state = 'OPEN'   AND p.created_at >= $2)
OR (p.state = 'MERGED' AND p.merged_at >= $2)
OR (p.state = 'CLOSED' AND p.created_at >= $2)   -- should use closed_at

Issues endpoint for comparison:

(i.state = 'CLOSED' AND i.closed_at >= $2)

Environment

• OS: Linux
• Runtime/Node version: Node 20
• Browser (if applicable): N/A

Additional Context

Files: packages/das/src/api/miners/miners.service.ts (lines ~186–190 and ~235–238)

Fix: Change CLOSED branch to p.closed_at >= $2 (and w.since in POST path); ensure closed_at is populated on webhook upsert (already stored in pull-request.handler.ts).

PR scope: ~5–15 lines + integration test or SQL fixture.