Every decision paging needs, as pure functions: which page a URL is asking for, which page is actually showable given how much there is, which slice of the items that is, and what page size to use. Pure because that is the only thing this project can unit-test — vitest runs in a node environment with no jsdom and no testing-library, so a hook or a component is only reachable through Playwright. Keeping the rules here means the rules have tests and the React wrapper stays thin enough not to need any, which is the same split filters.ts already uses for the URL.
An unrecognised page size is refused rather than clamped. A stored or hand-edited 5000 would render the entire catalogue in one page, which is the exact failure this issue exists to prevent, and clamping would quietly honour a value nobody offered. Storage access is guarded on both sides because localStorage is absent when there is no window and throws outright in some privacy modes, and neither is a reason for a customer to lose the catalogue — the worst acceptable outcome of a broken preference is the default.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Nine sites across five specs do `collection.find(...)` and dereference the result immediately. When the row is missing the test dies with "Cannot read properties of undefined" naming a line of test plumbing, which says nothing about what was expected — and that is exactly how favorites-filter:169 failed without producing a usable signal.
The message names what was wanted and how many rows were searched. That distinction carries real diagnostic weight: "0 rows" means the fixture never landed, "37 rows" means it landed and the predicate is wrong, and those are different bugs to chase.
It lives in its own module importing nothing, rather than in support/api.ts. That file imports @playwright/test, and vitest.config.ts runs tests/unit with environment: 'node' — putting six lines of pure logic there would drag a browser harness into the unit suite to test them. api.ts re-exports it so specs still reach it through fixtures.
Throws rather than returning null, because every caller wants the row: an error at the point of the miss beats a null threaded through three more lines before something unrelated fails.
Frontend: 30 unit tests pass, lint unchanged at 2 pre-existing warnings, build clean.
Ref #241
Restores the escape hatch for a status list matching no preset. filtersFromSearchParams accepts any non-empty subset of {available, reserved, sold}, and only three of those seven lists are presets; the other four reported as the not-sold fallback and produced no chip, so ?status=reserved was an empty grid reading "No items yet - check back soon" with no Clear filters button and no way out but editing the URL. hasActiveFilters covered all seven before this branch, so that was a regression against main. availabilityDimension now emits a chip for any status that is not the not-sold preset, labelled from SALE_STATE_LABELS when the list matches one and from statusLabel when it does not. The Segmented still reads "Not sold" beside such a chip, which is a cosmetic wart and the cheaper half of the trade.
Runs the frontend unit suite in CI. The 22 tests added over the dimensions were invoked by nothing: the workflow's only frontend steps were the build and the end-to-end run, and its test:unit:cov step is the backend's. The new step is guarded and named in the gate like every other suite, per the invariant workflowGate.test.ts asserts.
Restores the comment explaining why availabilityDimension's render and chips pass different fallbacks to saleStateFromStatuses. The control must read "All" while sold favorites are on screen; chips must stay silent because the customer never chose it. Unifying them would give every signed-in favorites view a phantom All chip and a tally of 2, and nothing said so after the old markup was deleted.
Derives the storefront's "is anything filtered" and FilterBar's tally through one exported chipsFor rather than two expressions over two identically-built contexts. They agreed only by convention, which is the exact defect this branch exists to remove.
Documents that statusDimension and availabilityDimension are alternatives over one field, since composing both type-checks and would render two controls that double-count it, and asserts the price chip's label text, which was the only chip label nothing checked.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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