Add supertest coverage for graceful shutdown draining in-flight requests

[Jagadeeshftw]

📌 Description

Per the README, SIGTERM/SIGINT triggers createShutdownHandler (src/utils/shutdown.ts) to stop accepting new connections, mark /health/ready unready, and force-exit after 10s if not closed. src/utils/shutdown.test.ts exists but it's worth explicitly verifying the drain behavior end-to-end: an in-flight request started just before shutdown should still complete successfully.

🧩 Requirements and context

• Add a test that starts a slow request (mock a delayed handler or use an existing route with an artificial delay hook), triggers shutdown mid-request, and asserts the response still completes with its normal status.
• Assert /health/ready flips to 503 immediately on shutdown start, before the in-flight request finishes.
• Assert no new request initiated after shutdown begins is accepted (connection refused or immediate rejection).

🛠️ Suggested execution

• Extend src/utils/shutdown.test.ts (or add src/index.test.ts coverage) using a real HTTP server instance and CloseableServer.
• If a gap is found (e.g. readiness doesn't flip immediately), fix it in shutdown.ts/utils/readiness.ts.
• Keep the 10s force-exit path covered separately with a fast-forwarded/mocked timer.

✅ Acceptance criteria

• In-flight request completes successfully during a graceful shutdown.
• /health/ready flips to 503 at shutdown start, not at completion.
• New connections are rejected once shutdown has begun.

🔒 Security notes

No new attack surface; hardens an operational correctness guarantee already documented in the README.

📋 Guidelines

• Minimum 95% test coverage
• Clear documentation
• Timeframe: 96 hours

[GBOYEE]

Hey, I'd like to help with this (Add supertest coverage for graceful shutdown draining in-flight req...). I'll write the missing test coverage and wire it in. Happy to submit a PR for this once the bot assigns it.

[GBOYEE]

Hi team \u2014 I'd like to take this on (Add supertest coverage for graceful shutdown draining in-flight req...). I'll implement it to spec and add tests. Happy to coordinate if anyone's already looking at it.

[Jagadeeshftw]

@GBOYEE thanks for the interest — you're currently at the 6 open-issue assignment cap for this repo, so I can't assign this one right now (backfill automation). Please finish or release one of your existing assigned issues, then request this one again and it'll be picked up.

[grantfox-oss]

🦊 GrantFox — @GBOYEE has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

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

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