feat: flag suspicious XP gain patterns

[saurabhhhcodes]

Summary

• add a daily Inngest detector for suspicious XP/review patterns from issue Flag accounts with suspicious XP gain patterns #90
• create a flagged_accounts table with Drizzle schema support for open/reviewed/dismissed flags
• surface open suspicious-account signals on the maintainer dashboard with reason, severity, XP, and evidence summary
• add pure detection helpers and unit coverage for daily XP spikes, rapid merge bursts, and reviewer approval concentration

Detection rules

• more than 5 XP events for a user in the previous UTC day
• more than 3 merged PRs by one contributor inside a 1-hour window
• more than 4 approvals from the same reviewer to the same contributor in a 7-day window

Validation

• node_modules/.bin/tsc --noEmit
• node_modules/.bin/eslint src/lib/xp/suspicious-patterns.ts src/lib/xp/suspicious-patterns.test.ts src/inngest/functions/maintenance.ts src/app/actions/maintainer.ts 'src/app/(app)/maintainer/page.tsx' src/app/api/inngest/route.ts
• git diff --check

Note: node_modules/.bin/vitest run src/lib/xp/suspicious-patterns.test.ts is blocked locally by Rollup's optional native @rollup/rollup-darwin-arm64 package failing macOS code-signature loading in this environment. The test file is included and TypeScript/ESLint pass.

Closes #90

[vercel]

@saurabhhhcodes is attempting to deploy a commit to the codersogs-3057's projects Team on Vercel.

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[github-actions]

Hey @saurabhhhcodes

You have 4 open PRs right now. The limit is 3 at a time.

Please get your existing PRs merged or closed before opening new ones:

• fix: enable RLS for failed webhook events #177 - fix: enable RLS for failed webhook events
• Add manual mentor PR verification #140 - Add manual mentor PR verification
• feat(xp): add suspicious XP flag audit #136 - feat(xp): add suspicious XP flag audit

This PR will remain open but won't be reviewed until you're under the limit. See our Contributing Guidelines for details.

[saurabhhhcodes]

Quick housekeeping update: I closed older PR #140, so I am now back within the repo's 3-open-PR limit.\n\nThis PR is the current scoped implementation for suspicious XP gain patterns, and the claim-limit check is passing. The only visible external status is Vercel team authorization, which I cannot approve from my fork. Ready for maintainer review whenever convenient.

[saurabhhhcodes]

Quick validation update for #90:

• targeted suspicious XP detector tests pass: node node_modules/vitest/vitest.mjs run src/lib/xp/suspicious-patterns.test.ts
• full TypeScript check passes: node node_modules/typescript/bin/tsc --noEmit
• git diff --check passes

The PR is mergeable from GitHub's side. The only red status I can see is Vercel team authorization, which needs maintainer/project access and is not an app failure from this branch.

For scoring on merge, this should fit GSSOC26, backend/infrastructure, and advanced/security-style review labels because it adds fraud/suspicious-XP detection plus tests and maintainer surfacing.

[Siddhartha-singh01]

Much cleaner re-implementation than #136 @saurabhhhcodes sequential migration
number, pure detection helpers, sensible dedupe-on-open via the unique constraint,
RLS-enabled service-role-only audit table. Good shape overall.

Two things before this can merge:

1. Unbounded queries (regression from #136). The detection cron's three reads
   xp_events, pull_requests (merged), pull_request_reviews have no .limit()
   / .range() / pagination. Supabase caps results at 1000 rows by default, so once
   the platform has >1000 events in a day (or >1000 reviews in a week), the audit
   silently misses everything past the cap. We caught this same issue in #136 and
   you fixed it with a fetchAllAuditRows paginator that fix didn't carry over to
   this fresh PR. Please paginate again (or use an explicit ordered window). For an
   anti-abuse audit, silently missing data defeats the purpose. Same applies to the
   existingRows and fetchPullRequestsById queries.

2. CI hasn't run, and the PR notes vitest couldn't run locally (Rollup macOS dlopen
   thing). So typecheck and prettier are verified, but tests aren't let's not
   merge until CI / check is green. A maintainer will need to approve workflows on
   this fork PR each time.

Small housekeeping: #136 is still open and closes the same #90 with the same
feature. Could you close #136 explicitly (since #185 is the canonical version) so we
aren't tracking two PRs for the same thing?

Once the queries are paginated and CI is green, this is in good shape. The detection
logic itself looks right.

[saurabhhhcodes]

Thanks for the careful review. I pushed commit 199ecda to address the pagination regression.\n\nWhat changed:\n- added a reusable audit paginator with 1000-row pages\n- paginated the daily xp_events, merged pull_requests, and weekly approved pull_request_reviews reads with deterministic ordering\n- chunked + paginated the flagged_accounts open-dedupe lookup\n- chunked + paginated fetchPullRequestsById so reviewer PR enrichment also cannot silently stop at Supabase defaults\n- formatted the two files that CI had already flagged, plus the touched maintenance file\n\nValidation from my side:\n- tsc --noEmit passes\n- prettier --check . passes\n- next lint passes with the repo's existing warnings only\n- full Vitest suite passes: 42 files / 324 tests via bundled Node\n- git diff --check passes\n\nI will close #136 as the duplicate/canonical cleanup item next so this PR remains the single tracked implementation for #90.

[saurabhhhcodes]

Housekeeping follow-up: #136 is now closed unmerged, so #185 is the only active PR for #90 from my side.

Current status from my side:

• pagination fix is in 199ecda
• GitHub check is green
• PR is mergeable
• remaining non-code status is the external Vercel authorization item

[saurabhhhcodes]

Rebased this PR onto the latest main again and pushed the refreshed branch. There were no conflicts.

Validation after rebase:

• node node_modules/typescript/bin/tsc --noEmit
• node node_modules/prettier/bin/prettier.cjs --check src/lib/xp/suspicious-patterns.ts src/lib/xp/suspicious-patterns.test.ts src/lib/xp/audit.ts supabase/migrations/0012_flagged_accounts.sql
• git diff --check origin/main...HEAD

Those passed locally. I also retried the focused Vitest command, but it is still blocked locally by the repo/macOS Rollup optional native package loading issue (@rollup/rollup-darwin-arm64 code-signature/dlopen failure), so I am not counting that as a local pass. The previous GitHub CI check was green after the pagination fix, so the fresh push should let CI re-confirm it.

[saurabhhhcodes]

Synced this branch with the latest main and resolved the Inngest maintenance conflicts by keeping both scheduled jobs registered: flagSuspiciousXpAccounts from this PR and upstream's autoUnclaimStale cleanup. The paginated audit reads and duplicate open-flag protection from the previous review fix are preserved.\n\nValidation run locally:\n- node node_modules/typescript/bin/tsc --noEmit\n- node node_modules/prettier/bin/prettier.cjs --check src/app/api/inngest/route.ts src/inngest/functions/maintenance.ts\n- git diff --check\n\nI also tried the targeted Vitest files, but the local run is blocked before tests start by the existing Rollup optional native package/code-signing issue on macOS. The PR is mergeable again; the remaining Vercel failure appears to be the external GitHub/Vercel team authorization gate.

[saurabhhhcodes]

Quick re-review note on the earlier requested-changes review:

The three merge blockers called out there are addressed on the current branch state:

• the detection/audit queries were repaginated in 199ecda, including the open-flag dedupe lookup and PR enrichment path
• duplicate PR feat(xp): add suspicious XP flag audit #136 is now closed, so feat: flag suspicious XP gain patterns #185 is the only active PR for issue Flag accounts with suspicious XP gain patterns #90
• the branch was refreshed again afterward, and the current visible non-code blocker is the external Vercel authorization item rather than an application failure

Issue #90 is still assigned to me and carries GSSOC26, infrastructure, and backend labels. If the current implementation looks good now, could you please re-review this refreshed branch and mirror the applicable tracking labels on the PR when merging?