Implementes TODO in payments-service.ts. convert user admission to postgres stored function

[Mohit-Davar]

refactor(db): convert user admission to postgres stored function

Description

This PR refactors the user admission workflow by introducing a PostgreSQL stored function to replace the application-layer upsert during the invoice confirmation flow.

• Added a new Knex migration to provision the admit_user database function, utilizing atomic ON CONFLICT DO UPDATE constraints and preserving ASSERT_SERIALIZED() transaction guarantees.
• Added corresponding admitUser interface and DB implementations logically grouping this SQL call in UserRepository.

Related Issue

Resolves TODO in payments-service.ts

Motivation and Context

This completes an explicit TODO within the codebase. Offloading the user admission mutation to a PostgreSQL stored function strengthens the concurrency model .

How Has This Been Tested?

Verified existing repository tests pass correctly locally.

Screenshots (if appropriate):

Types of changes

• Non-functional change (docs, style, minor refactor)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my code changes.
• All new and existing tests passed.

[phoenix-server]

Created missing issue #435 for this PR. This PR resolves #435.

[Copilot]

Pull request overview

Refactors the invoice-confirmation “user admission” workflow to use a PostgreSQL stored function (admit_user) instead of performing an application-layer upsert, centralizing the mutation in the database under serializable transaction guarantees.

Changes:

• Replaced the inline userRepository.upsert(...) admission logic in PaymentsService.confirmInvoice with userRepository.admitUser(...).
• Added IUserRepository.admitUser and implemented it via a raw call to the new DB function.
• Introduced a Knex migration that creates the admit_user PostgreSQL function using INSERT ... ON CONFLICT DO UPDATE.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/services/payments-service.ts	Switches invoice-confirmation admission step from upsert to stored-function call.
src/repositories/user-repository.ts	Adds admitUser repository method that invokes admit_user via Knex raw.
src/@types/repositories.ts	Extends IUserRepository interface with admitUser.
migrations/20260409201624_admit_user_func.js	Adds migration creating the admit_user PL/pgSQL function for atomic admission upsert.

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[cameri]

You will need to rebase to fix your commit messages otherwise commitlint will fail.

[Mohit-Davar]

You will need to rebase to fix your commit messages otherwise commitlint will fail.

Thanks for pointing this out! I wasn’t aware that Conventional Commits was enforced in this repository.
I’ll rebase my branch and update the commit messages to follow the required convention so CI checks pass. Appreciate the guidance 👍. I will make sure that my future commits will follow this.

[Mohit-Davar]

Thanks for pointing this out! I wasn’t aware that Conventional Commits was enforced in this repository. I’ll rebase my branch and update the commit messages to follow the required convention so CI checks pass. Appreciate the guidance 👍. I will make sure that my future commits will follow this.

@cameri I’ve updated all my commits to follow the repository’s commit message conventions and rebased the branch.