Incident Dossier

Cache TTL: ms vs seconds

A feature flag service stores values with a 60 second TTL. Right after every deploy, every flag reads as missing until the cache is warmed manually.

Initial failing signalFreshly stored value reads as undefinedExpected behavior: A value stored with a 30-second TTL remains readable before the TTL elapses. · actual behavior: The freshly stored value is undefined before the 30-second TTL elapses.

Progress

1Reproduce the bugRun checks

2Edit the fixOpen

3Pass checksOpen

4Submit fixOpen

Reproduction Steps

Run npm test.
Walk the read path against the TTL stored at write time.
Compare the unit the writer uses to the unit the reader uses.
Make the read use the same unit the writer stored.

Focus Mode

Start

src/cache.js

Likely area

src/cache.js

Challenge Coach

Hints reveal broad direction first, then narrow toward the suspect path without showing hidden tests or exact solution code.

TopicCaching & Performance

DifficultyEasy

Est. time12 min

Workspacepreparing

Explorer

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Evidence Map

Failing signal loaded from challenge API
Workspace files loaded from workspace API
Results rendered only after API run/submit

Autosaved

workspace

Outputread-onlyready$ prepare workspace

Preparing workspace