Dedupe window too short Debugging Lab

Dedupe window too shortEvents & ConcurrencyEasyPreparing workspaceAutosaved

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Incident Dossier

Dedupe window too short

A retry storm from a payment provider arrives ten minutes after the original event. The dedupe cache has already forgotten the event id and the second delivery is treated as a fresh event, charging the customer twice.

Initial failing signalRetried webhook is no longer recognised after 30 minutesExpected dedupe.hasSeen('evt_42') returns true after a 30-minute retry delay · received dedupe.hasSeen('evt_42') returns false after a 30-minute retry delay

Progress

1Reproduce the bugRun checks

2Edit the fixOpen

3Pass checksOpen

4Submit fixOpen

Reproduction Steps

Run npm test.
Mark an event id in the dedupe store and advance the clock by 30 minutes.
Confirm that the retry is no longer recognised.
Increase the TTL so the default window covers provider retry behaviour.

Focus Mode

Start

src/dedupe.js

Likely area

src/dedupe.js

Progressive hints

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

TopicEvents & Concurrency

DifficultyEasy

Est. time14 min

Workspacecreating

Explorer

Preparing workspace files…

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$ workspace boot

Workspace booting...