fix scanPrototypesFor cache when class init is in flight#37
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The memoization in 7d67a95 caches the merged prototype-chain values per (constructor, key) pair. When `customElements.define` upgrades a pre-existing element mid-class-body, the constructor runs before the subclass's `static <key> = ...` fields have initialized, so the first scan caches a result missing the subclass's own value. All subsequent instances then inherit the wrong merged metadata (e.g. empty assignableAttributes). Track the constructor's own-property status alongside each cached entry and recompute when it flips. Plugin-style in-place mutations to the cached arrays still propagate. Add a regression test in test/supportTest.js. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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The memoization in 7d67a95 caches the merged prototype-chain values per (constructor, key) pair. When `customElements.define` upgrades a pre-existing element mid-class-body, the constructor runs before the subclass's `static <key> = ...` fields have initialized, so the first scan caches a result missing the subclass's own value. All subsequent instances then inherit the wrong merged metadata (e.g. empty assignableAttributes). Track the constructor's own-property status alongside each cached entry and recompute when it flips. Plugin-style in-place mutations to the cached arrays still propagate. Add a regression test in test/supportTest.js. Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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* main: fix scanPrototypesFor cache when class init is in flight (#37)
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Summary
Fixes a regression introduced by 7d67a95 (
memoize scanPrototypesFor to avoid per-instance prototype walks). The memoization caches the merged prototype-chain values per(constructor, key)pair, but whencustomElements.define(called bystatic { this.define() }) upgrades a pre-existing element mid-class-body, the constructor fires before the subclass'sstatic <key> = ...field initializers run. The first scan caches a result missing the subclass's own value, and every subsequent instance then inherits the wrong merged metadata — e.g. an emptyassignableAttributes.Discovered when adding the new
Masonrycomponent (#36): if a<komp-masonry>element exists in the DOM at script load, the upgrade triggers the constructor beforestatic assignableAttributes = {...}runs, and the cache locks in[{}](justKompElement's default).The fix tracks
obj.hasOwnProperty(key)alongside each cached entry and invalidates when it flips. Plugin-style in-place mutations to the cached arrays still propagate, so the existingthis.events.push(...)pattern continues to work.Test plan
npm test— 37 passing, including newsupportTest.jsregression coverage<komp-masonry>rendered before the script imports), confirmassignableAttributesare now resolved on first instance🤖 Generated with Claude Code