Incident Dossier

Pagination skips rows on timestamp ties

Walking the product catalog page-by-page misses a product. Several products share an `updated_at`, and the cursor advances only by timestamp — so any row whose timestamp equals the cursor boundary is excluded by the strict-less filter on the next page.

Initial failing signalWalk-through pagination loses product idsExpected behavior: walkAllProducts(3) returns all 8 product ids · actual behavior: walkAllProducts(3) returns only 7 ids; product with updated_at equal to the page-boundary is missing

Progress

1Reproduce the bugRun checks

2Edit the fixOpen

3Pass checksOpen

4Submit fixOpen

Reproduction Steps

Run npm test.
Notice that walkAllProducts returns fewer product ids than the fixture.
Inspect pageAfter in src/products.js and the cursor logic in walkAllProducts.
Identify why rows that share a timestamp with the previous page's tail are skipped on the next page.
Adopt keyset pagination: include a tiebreaker in the cursor and the filter.

Focus Mode

Start

src/products.js

Likely area

src/products.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. time22 min

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Evidence Map

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workspace

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