Streaming UX Latency Plan

Design the perceived-latency strategy for this AI feature. Users judge responsiveness by time to first token far more than by total generation time.

Produce:

1. LATENCY BUDGET: target time to first token, target total, and where the current implementation spends its time.
2. TTFT REDUCERS ranked by impact: shorter input context, prompt caching, a smaller routing model for the opening, speculative prefetch, and moving retrieval off the critical path.
3. WHAT TO SHOW DURING THE WAIT, per phase. Skeletons, streaming partials, tool-call status, and what NOT to show because it makes the wait feel longer.
4. STREAMING FAILURE HANDLING: what the user sees when a stream dies at 80 percent, and how to make retry non-destructive.
5. THE ONE CHANGE with the best perceived-latency return.

Feature:
[DESCRIBE]
Current measured latency:
[TTFT AND TOTAL]