GET /api/markets/:id/predictions/aggregate for outcome pool sizes

[greatest0fallt1me]

Description

Markets pages need at-a-glance pool totals per outcome. Add an aggregate endpoint backed by a small materialized view refreshed by the predictions confirmer worker, so reads are O(rows-in-result) and never scan predictions.

Requirements and Context

• MV market_outcome_totals with (market_id, outcome, total_amount, prediction_count)
• Refreshed at the end of every confirmer tick
• GET /api/markets/:id/predictions/aggregate returns the rows
• Caches Cache-Control: max-age=5 for browser clients
• Must be secure, tested, and documented
• Should be efficient and easy to review

Suggested Execution

1. Fork the repo and create a branch

   git checkout -b feature/market-aggregate-endpoint

2. Implement changes
   • SQL migration creating MV
   • Hook refresh into src/workers/predictionsConfirmer.ts
   • src/routes/markets.ts aggregate handler
3. Test and commit
   • Seed predictions, run confirmer, assert totals
   • Cover edge cases
   • Include test output and notes in the PR

Example commit message

feat: market outcome aggregates endpoint

Acceptance Criteria

• Endpoint p95 < 20ms at 1M predictions
• Aggregates always equal sum of confirmed predictions
• Cache header present and respected by supertest repeat call

Guidelines

• Use numeric(78,0) for total_amount
• Clear documentation and inline comments
• Timeframe: 96 hours

[ChukwuemekaP1]

@ChukwuemekaP1 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Good day, my name is Chukwuemeka and I'd love to work on this issue.

The performance target here is specific enough that it shapes the whole approach — a 20ms p95 at 1M predictions only holds if the materialized view refresh is the expensive part and the read path stays a trivial indexed lookup, so I'd make sure the MV has the right index on market_id before anything else.

I'll write the SQL migration creating market_outcome_totals with market_id, outcome, total_amount as numeric(78,0), and prediction_count, indexed on market_id for fast lookups. I'll hook the refresh into predictionsConfirmer.ts so it runs at the end of every confirmer tick rather than on read. The GET /api/markets/:id/predictions/aggregate handler in markets.ts will query the MV directly, return the rows, and set Cache-Control: max-age=5.

Tests will seed predictions, run the confirmer, and assert the MV totals match the sum of confirmed predictions exactly. I'll cover edge cases like markets with zero predictions and outcomes with no entries yet, verify the cache header is present and respected on a repeat supertest call, and benchmark read latency to confirm it holds under the 20ms p95 target at scale.

ETA: 48 hours from assignment given the performance and testing requirements. Looking forward to your reply!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @ChukwuemekaP1 to this issue.

[grantfox-oss]

🦊 GrantFox — @ChukwuemekaP1 has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #94)
2. Your PR will be reviewed by the Predictify-org maintainers

Good luck! Track your progress on GrantFox.

[drips-wave]

Congratulations, @ChukwuemekaP1! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @ChukwuemekaP1: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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