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Cache Reaping

Our cache keeps everything forever. Let's clean up old entries so it doesn't keep growing as we explore.

We'll record when each entry was added, then use setInterval to check for old entries. This cleanup is called reaping. Use the same interval for the timer and the maximum entry age. For example, with a 5-second interval, each cleanup removes entries older than 5 seconds. An entry can stay in the cache until the next cleanup after it expires.

A Node.js interval keeps the process running, so we'll also need a way to stop it with clearInterval.

Assignment

Create a CacheEntry<T> type with createdAt (a number from Date.now()) and val (a T). Update the map to store CacheEntry<unknown> values, and update add and get to use them.
Add a constructor that accepts an interval in milliseconds. Store it in a private #interval field.
Add a private #reap() method that removes entries older than the interval.
Start a repeating timer in the constructor to call #reap(). Store the timer ID in a private #reapIntervalId: NodeJS.Timeout | undefined field.
Add a public stopReapLoop() method that clears the timer and resets its ID to undefined.
Update your existing tests for the new constructor. Test that fresh entries stay available and old entries are eventually removed. Stop each test's timer when the test finishes, even if an assertion fails.

Run and submit the CLI tests from the root of the repo.

Tip

Wrap assertions in try/finally and stop the timer in finally. You can use Vitest's expect.poll to wait for an entry to disappear without relying on one perfectly timed check.