Incident Dossier

Cache invalidation skipped on write

A user updates their display name through the service. The database has the new value, but every subsequent read through the cache returns the old name until restart.

Initial failing signalCache returns stale data after a writeExpected behavior: cached entry reflects the new name · actual behavior: cached entry still has the old name

Progress

1Reproduce the bugRun checks

2Edit the fixOpen

3Pass checksOpen

4Submit fixOpen

Reproduction Steps

Run npm test.
Trace the write from `updateName` down to `saveUser` and check whether it touches the cache.
Compare the read path to the write path and decide where the cache should learn about the new value.
Make the writer refresh (or invalidate) the cache after a successful save.

Focus Mode

Start

src/service.js

Likely area

src/repo.js
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

DifficultyHard

Est. time28 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