Add integration test for the buy endpoint recording a price snapshot after each confirmed transaction

[Chucks1093]

Summary

A price snapshot should be recorded in the database after every confirmed buy, capturing the new supply and price so the price history endpoint has accurate data. An integration test should confirm a snapshot is created for each buy and that the snapshot values match the post-buy contract state.

Scope

• Execute a buy of 5 keys and assert one price snapshot is created
• Assert the snapshot supply matches the post-buy supply
• Assert the snapshot price matches get_price at the new supply
• Execute a second buy and assert two total snapshots exist for that creator
• Assert no snapshot is created when a buy fails

Acceptance Criteria

• One snapshot created per confirmed buy
• Snapshot supply matches post-buy supply
• Snapshot price matches on-chain price at new supply
• No snapshot created on failed buy

ETA: 12 hours

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Coordinate on Telegram

[LumDev86]

Hi — I'd like to take this one.

Express + Prisma + PostgreSQL is my daily stack. The case I'd be most
careful with is the last one in the scope: no snapshot on a failed buy. If
the snapshot write isn't tied to the same confirmation path as the buy, a
rejected transaction still leaves a row behind, and every price history
response after that is quietly wrong. That's the assertion that actually
protects the data.

Plan:

• Buy 5 keys, assert exactly one snapshot row exists for that creator
• Assert the snapshot supply equals the post-buy supply
• Assert the snapshot price equals get_price at the new supply, read from
  the contract rather than a hardcoded number — otherwise the test just
  restates the implementation instead of verifying it
• Execute a second buy, assert two snapshots total for that creator and
  that the first one is unchanged
• Force a failing buy and assert the snapshot count does not move

Jest against a seeded Postgres using the docker compose setup already in
the repo, run with pnpm test, following the existing integration test
layout.

I saw the 12-hour ETA. Could you assign it to me? Happy to coordinate on
Telegram.

[guptakumarranjeet150]

Hi maintainers,

I would love to take this on. My planned approach:

• Structure backend handlers for Add integration test for the buy endpoint recording a price snapshot after each confirmed transaction with strict input validation, proper HTTP error codes, and idempotent execution.
• Cover implementation with end-to-end integration tests for standard and edge-case inputs.

Excited to work on this—please assign to me and I'll submit a clean PR shortly!