Fix #682, #683, #684, #685: batch size cap, AMM invariant tests, idle connection recycling, one-shot scheduling

[mercycodes2-sudo]

Summary

• requestBatcher.ts: Add configurable maximum batch size #682 — requestBatcher.ts: constructor now throws RangeError when maxBatchSize is 0; legacy RequestBatcher config's maxBatchSize is now optional (defaults to unlimited) and forwarded correctly.
• ammCalculator.ts: Write tests for constant-product invariant preservation #683 — ammCalculator.ts: added src/__tests__/ammCalculator.test.ts verifying the constant-product invariant (x * y = k) holds after simulated swaps across a range of input sizes, that oversized swaps throw InsufficientLiquidityError, and that a zero-amount swap returns 0 and leaves reserves untouched.
• connectionPool.ts: Fix idle connections not being closed after idleTimeoutMs #684 — connectionPool.ts: each returned connection now arms its own idle-recycle timer on release(), so a slot idle past idleTimeoutMs is recycled even if select()/acquire() is never called again to trigger lazy recycling. Timers are cleared on reuse, recycle, and dispose().
• scheduler.ts: Add one-shot job scheduling alongside recurring jobs #685 — scheduler.ts: added a JobScheduler class with schedule(intervalMs, fn) for recurring jobs and once(delayMs, fn) for one-shot jobs. Both return a cancel handle; a one-shot job is removed from the internal job list once it runs (or is cancelled). The two APIs coexist on the same scheduler instance.

Test plan

• test/requestBatcher.test.ts — new case asserts maxBatchSize: 0 throws RangeError
• src/__tests__/ammCalculator.test.ts — new invariant-preservation tests
• test/connectionPool.test.ts — new cases cover timer-based recycling on release and non-recycling on reuse
• test/scheduler.test.ts — new cases cover once(), cancellation, and coexistence with schedule()

Closes #682
Closes #683
Closes #684
Closes #685

[drips-wave]

@mercycodes2-sudo Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits