Stored filter artifacts are restored unvalidated; FilterHandler has no way to parse an artifact

[matej21]

Summary

Filter artifacts are restored from storage without any check of their shape, and FilterHandler has no way to parse one. A stored record written by an older release, a hand-edited URL parameter, or a saved filter preset from a database all reach handler.toWhere() and isActive() as whatever JSON.parse returned.

Environment

• @contember/bindx@0.1.52 / @contember/bindx-dataview@0.1.52
• contember/bindx@main as of 78c1712

Reproduction

// stateStorage: 'url', storageKey: 'grid'; the URL carries ?grid:filters={"title":{}}
const filtering = useFilteringState({
	filters: new Map([['title', { handler: createTextFilterHandler('title') }]]),
	stateStorage: 'url',
	storageKey: 'grid',
})
filtering.resolvedWhere // the text handler reads `artifact.query.length` on `{}` and throws

createWebStorage / createUrlStorage (packages/bindx-dataview/src/stateStorage.ts) return JSON.parse(raw) as T, and useFilteringState (packages/bindx-dataview/src/useDataViewState.ts) uses the record as is.

An application that stores filter presets itself (restored through setAllArtifacts) has the same problem one level up: FilterArtifact is a closed union, so turning a parsed JSON object into a Record<string, FilterArtifact> needs either a cast (raw as unknown as Record<string, FilterArtifact>) or a re-implementation of every built-in artifact's shape outside bindx.

Expected behavior

• A stored artifact that the handler does not recognize is treated as absent (the filter starts at its default), not passed to the handler.
• An application can validate an artifact against the handler that will read it, without re-implementing bindx's artifact shapes.

Proposal

Add a parser to the handler contract:

interface FilterHandler<TArtifact = FilterArtifact> {
	toWhere(artifact: TArtifact): Record<string, unknown> | undefined
	isActive(artifact: TArtifact): boolean
	defaultArtifact(): TArtifact
	/** The artifact `raw` represents, or `undefined` when it is not one this handler reads. */
	parseArtifact?(raw: unknown): TArtifact | undefined
}

• Implement it for every built-in handler (create*FilterHandler).
• In useFilteringState, run each stored entry through its handler's parseArtifact when present and drop entries it rejects (they then resolve like a missing name — see Grid filter cannot start at a non-default artifact; a stored record missing a filter disagrees with the query #125).
• setAllArtifacts could accept Record<string, unknown> and parse the same way, which removes the cast on the application side entirely.

Open design questions for the maintainers: optional (non-breaking for custom handlers, which then keep today's trust) or required; and whether setAllArtifacts should take unparsed input or keep its typed signature with a separate parseArtifacts(record) helper on the filtering state.