Degradation Contract

Use this when considering virtualization, shell islands, model-backed selection, or staged mounting.

Rule

Optimize the native DOM-present path first. Degrade only for named cohorts, and state which native behaviors change.

Contract

For each degraded mode, record:

• cohort threshold
• browser find behavior
• screen-reader behavior
• native selection behavior
• copy/paste behavior
• IME/composition behavior
• mobile behavior
• undo/history behavior
• collaboration behavior
• escape hatch or explicit opt-in

Reject

• virtualization as a default before repeated-unit budgets are exhausted
• shell mode described as "same editor, just faster"
• model-backed copy/paste without visible contract