Treat streaming as semantic asynchronous state

Queued, generating, tool activity, partial, completed, stopped and failed states are distinguishable and accessible.

Guidance

Reserve layout, preserve focus and user input, expose stop, batch live announcements and label partial output as partial. Completion is a state transition, not the last received token.

Do

Stabilize geometry before output arrives
Announce meaningful chunks rather than every token
Keep stop and retry keyboard reachable

Do not

Move the active target as content streams
Present partial output as confirmed
Use typing theater without status meaning

Verification contract

Keyboard stop, focus retention, screen-reader announcement, reduced-motion and layout-shift tests

Supporting references

Implementations and verification artifacts

artifact.doc.ai-interaction-contracts — AI interaction contracts doc · design-system/case-studies/elite-systems/ai-interaction-contracts.md
artifact.script.ai-interaction-contract — Executable AI interaction contract script · packages/core/src/design-contracts.ts