[Backend] No database connection pooling configured — PrismaClient instantiated per request in some services

[Pvsaint]

Problem

Several services instantiate new PrismaClient() locally rather than importing the shared singleton. Each instantiation creates a new connection pool, rapidly exhausting PostgreSQL's connection limit under load.

Acceptance Criteria

• A single shared prisma singleton exported from src/config/prisma.ts (or equivalent)
• All services import the singleton instead of instantiating their own
• prisma.$disconnect() called only in shutdown.service.ts, not in individual services
• DATABASE_URL connection string includes connection_limit parameter appropriate for environment
• Load test verifies no connection exhaustion under 100 concurrent requests

Branch & Commit

branch: fix/prisma-singleton-pool
commit: fix(database): enforce single PrismaClient singleton across all services

[midenotch]

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

I've reviewed the task and have a clear implementation plan. Looking forward to contributing with a quality PR.

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

[drips-wave]

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

🧑‍💻 @Almikefred: 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.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[laurentketterle-hub]

/claim