Incident Dossier

The N+1 That Wasn't

The dashboard performs a normal number of queries, yet production CPU and payload sizes balloon after a release.

Initial failing signalDashboard returns correct data but repeats expensive aggregationExpected behavior: aggregate computed once · actual behavior: aggregate computed once per row

Progress

1Reproduce the bugRun checks

2Edit the fixOpen

3Pass checksOpen

4Submit fixOpen

Reproduction Steps

Run npm test.
Compare query count, response size, and aggregate work as row count grows.
Trace where the dashboard summary is produced during serialization.
Remove the scaling defect without changing the response contract.

Focus Mode

Start

src/dashboard.js

Likely area

src/dashboard.js

Challenge Coach

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

TopicDatabase

DifficultyMedium

Est. time26 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