Files
hyperframes/packages/core/src
Vance Ingalls 1bc32bd47f fix(core): applyPositionEdits fails silently across iframe realms (#2096)
## What

`applyPositionEdits(doc)` in `@hyperframes/core/runtime/position-edits` guarded each candidate element with `instanceof HTMLElement`. `doc` is frequently an iframe's document (the SDK's edit preview, any host embedding a composition), whose elements are `HTMLElement` instances of *that frame's realm* — never this module's. The check silently no-ops on every single element cross-realm, so bulk position edits never apply inside an iframe.

## Why

Found during an audit of `@hyperframes/sdk`'s surface against pacific's movio integration. Pacific's `canvas-react` code has an explicit workaround comment for this exact bug: *"Upstream fix would be duck-typing in `@hyperframes/core` — until then, all host code must use this wrapper."* Every iframe-hosted consumer has had to reimplement the bulk-apply loop themselves to avoid it.

## How

Use the document's own realm's `HTMLElement` constructor (`doc.defaultView?.HTMLElement`) instead of the module-scope global. Duck-type on `.style` when `defaultView` is unavailable (a detached/synthetic document). The single-element `applyPositionEditToElement` was already realm-safe — only the bulk wrapper had the bug.

## Test plan

- [x] New regression test using a real jsdom iframe — confirmed it fails on the old `instanceof HTMLElement` check (0 applied, expected 1) and passes with the fix
- [x] Full existing `positionEdits.test.ts` suite passes (14/14)
- [x] Full `@hyperframes/core` suite passes (81 files / 1131 tests)
- [x] `bun run build` clean (core + full workspace, incl. studio)
2026-07-09 11:16:45 -07:00
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