Slate v2 Phase 9 Browser-Boundary Family

Supporting plan. For current queue and roadmap truth, see master-roadmap.md.

Goal

Turn the browser-boundary family from comparison-only into an honest current family claim if the current v2 seam is already real.

Scope

• add current shadow-dom and iframe rows to the replacement matrix
• implement minimal current example surfaces only if those rows fail for missing current examples
• sync the family ledger and scoreboard if the current rows land

Constraints

• no broad rich-text iframe rewrite
• no fake “all browser-boundary parity” claim
• keep the current surfaces minimal and editor-shaped
• verify through the cross-repo local runner on current port 3010

Progress

• added current shadow-dom and iframe rows to the replacement matrix
• added minimal current shadow-dom and iframe example surfaces in /Users/zbeyens/git/slate-v2/site/examples/ts/
• added JS mirrors and example registry entries for those current surfaces
• proved the expanded family through the cross-repo local runner
• synced the scoreboard, family ledger, and current-surface docs so the browser-boundary family is now preserved instead of comparison-only
• verification:
  • bash ./scripts/run-cross-repo-local.sh 3010 /examples/shadow-dom ../slate 3210 /examples/shadow-dom "yarn build:slate-browser:playwright && yarn exec playwright test playwright/integration/examples/replacement-compatibility.test.ts --project=chromium --workers=1"