The Month That Was Always One Ahead Debugging Lab

The Month That Was Always One AheadDate/TimeEasyPreparing workspaceAutosaved

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Incident Dossier

The Month That Was Always One Ahead

An ops dashboard renders daily counts grouped by month. Every row is mislabelled by exactly one — January rows say February, June says July, and November silently falls back to an Unknown placeholder. The byte-counts and timestamps in the data are correct; only the human label is wrong. The team notices on the December report when the label flips to a blank 'Unknown' and the totals stop matching.

Initial failing signalmonthName(0) returns the wrong labelExpected monthName(0) === 'January' · received monthName(0) === 'February'

Progress

1Reproduce the bugRun checks

2Edit the fixOpen

3Pass checksOpen

4Submit fixOpen

Reproduction Steps

Run npm test.
Inspect the failing assertion in tests/month-name.test.mjs.
Trace how monthName() looks up the name in src/month-name.js.
Fix the index so that 0..11 maps to the correct month name.

Focus Mode

Start

src/month-name.js

Likely area

src/month-name.js

Progressive hints

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

TopicDate/Time

DifficultyEasy

Est. time10 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...