Add value mapping to modifier config

Extend ModifierConfig with valueMap and mapTarget fields so that modifier values can be declaratively mapped to different data attribute values. This is the smallest SPEC-033 feature and eliminates 2 existing postTransform uses.

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Criteria completion

No incremental history — criteria tracking started on Apr 21.

Relationships

ID:SPEC-033Status:accepted

Structure Slots and Declarative Flexibility

ID:WORK-112Status:done

Implement named slots with ordering for structure entries

Priority:highComplexity:moderateMilestone:v1.0.0

ID:WORK-115Status:ready

Migrate community package postTransform uses to declarative config

Priority:mediumComplexity:moderateMilestone:v1.0.0

main current done

claude/file-naming-convention-LJdwR done changeset-release/main done

Apr 21, 01:46 PMe900a90
Created (done)by bjornolofandersson
Apr 10, 06:58 PMf262d7b
Content editedby Claude
Apr 8, 08:18 PMda12420
statusready→done
by Claude
Apr 3, 01:38 PM41d5c52
Created (ready)by Claude
Accept SPEC-033 and break down into work items WORK-110–116

Acceptance Criteria

ModifierConfig in packages/transform/src/types.ts has valueMap?: Record<string, string> and mapTarget?: string fields
The engine's modifier resolution in packages/transform/src/engine.ts applies valueMap before emitting data attributes — mapped values go to mapTarget (or the same attribute if mapTarget is not set)
Unmapped values pass through unchanged
mergeThemeConfig correctly merges valueMap overrides (theme replaces base valueMap per modifier)
Unit tests cover: basic mapping, unmapped passthrough, mapTarget redirection, merge behavior
TypeScript compiles cleanly across all packages
All existing tests pass

Approach

Add valueMap and mapTarget to ModifierConfig in packages/transform/src/types.ts
In the engine's modifier application logic, after resolving the raw value from meta tags, check for valueMap — if present, look up the value and replace it (or pass through if not found)
If mapTarget is set, emit the mapped value as a separate data attribute (e.g., data-checked) in addition to or instead of the original modifier attribute
Update mergeThemeConfig in packages/transform/src/merge.ts to handle valueMap (theme valueMap replaces base, not deep-merged)
Write tests validating the mapping behavior

References

SPEC-033 (Feature 2 — Value Mapping)