Add a persistence adapter so usage, services, and API keys survive process restarts

[mikewheeleer]

Implement a persistence adapter so usage, services, and API keys survive process restarts

Description

Every data store in src/index.ts is an in-memory Map/Set (usageStore, servicesStore, servicesMetadata, servicesDisabled, apiKeyStore, webhookStore, eventLog) and the comments openly state that "a process restart resets the counters." For a metering and billing backend this is a correctness hazard: a restart silently drops unsettled usage that real money is owed against. This issue introduces a storage abstraction with a pluggable backend so durability becomes possible without rewriting every handler.

Requirements and context

• Repository scope: Agentpay-Org/Agentpay-backend only.
• Define a Store interface (get/set/delete/entries/scan-by-prefix) in a new src/store/index.ts that the existing handlers consume instead of touching Map directly.
• Ship an InMemoryStore implementation (preserving current behaviour) and a file-backed or SQLite-backed implementation selected via an env var (e.g. STORAGE_DRIVER=memory|sqlite).
• Migrate usageStore, servicesStore, servicesDisabled, servicesMetadata, and apiKeyStore to the new interface without changing any HTTP response shape.
• Keep the composite key convention ${agent}::${serviceId} (usageKey in src/index.ts) intact so existing exports and rollups still work.
• Add graceful-shutdown flush so the SIGTERM/SIGINT handler persists state before exit.

Suggested execution

• Fork the repo and create a branch
• git checkout -b feature/db-01-persistence-adapter
• Implement changes
  • Write code in: new src/store/index.ts and refactor the store accesses in src/index.ts.
  • Write comprehensive tests in: new src/store/store.test.ts — round-trip persistence, restart simulation, prefix scans.
  • Add documentation: update README.md with a "Persistence" section documenting STORAGE_DRIVER and the on-disk format.
  • Add TSDoc comments on every method of the Store interface.
  • Validate security assumptions: no path traversal on the file path, safe serialization, no secret keys written in plaintext logs.
• Test and commit

Test and commit

• Run npm run build, npm test, and npm run lint.
• Cover edge cases: empty store, restart with existing data, concurrent writes, corrupt/missing data file.
• Include the full npm test output and a short note on the durability guarantees in the PR description.

Example commit message

feat: add pluggable persistence adapter with in-memory and sqlite drivers

Guidelines

• Minimum 95 percent test coverage for impacted modules.
• Clear, reviewer-focused documentation.
• Timeframe: 96 hours.

Community & contribution rewards

• 💬 Join the AgentPay community on Discord for questions, reviews, and faster merges: https://discord.gg/eXvRKkgcv
• ⭐ This is a GrantFox OSS / Official Campaign task and may be rewarded. When your PR is merged you'll be prompted to rate the project — if this issue and the maintainers helped you ship, we'd be grateful for a 5-star rating. Clear questions in Discord and tidy, well-tested PRs are the fastest path to a merge and a reward.

[felixvippp-ai]

/claim

[felixvippp-ai]

/attempt #121

[felixvippp-ai]

GrantFox status update: I have registered for the Official Campaign and applied for this issue as @felixvippp-ai. The implementation is ready in #121 (previously closed only because assignment was missing). If this application is accepted, please assign the issue to me and I can reopen or submit a replacement PR immediately.

[eischideraa-unn]

Hello Maintainer,

I'd like to work on this issue. I have experience contributing to similar codebases and can quickly get up to speed with the existing architecture. My plan is to identify the root cause, implement a clean fix that follows project conventions, and thoroughly test the solution before submitting a PR.

Looking forward to contributing.