AI Stream Snapshot Design Grill

Goal

Stress-test the next-step design for AI insert-mode preview state, especially whether snapshot state should live in plugin state, what the public surface should be, and how to avoid a performance regression on long documents.

Checklist

• [in_progress] Inspect current AI/plugin state patterns in the repo
• [pending] Decide whether preview state should live in plugin state, transform state, or private module state
• [pending] Decide whether the public surface should be api, tf, or package-private helpers
• [pending] Walk the remaining design forks with explicit recommendations

Findings

• The current implementation stores preview state in a module-level WeakMap keyed by editor.
• The current helper surface is low-level snapshot terminology, not workflow terminology.