Incident Dossier

Cache key delimiter collision

Two tenants with overlapping identifiers see each other's cached values because the cache key concatenates without a separator.

Initial failing signalTwo distinct keys reduce to the same stringExpected behavior: cache.get(makeKey('a','bc')).secret remains 'tenant-a-bc' after caching makeKey('ab','c'). · actual behavior: cache.get(makeKey('a','bc')).secret returns 'tenant-ab-c' after the second cache write.

Progress

1Reproduce the bugRun checks

2Edit the fixOpen

3Pass checksOpen

4Submit fixOpen

Reproduction Steps

Run npm test.
Inspect how the cache key is built from its parts.
Find a pair of inputs that reduce to the same string when concatenated.
Add a separator that cannot be produced by either part alone.

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