Prompt-cache warmth is computed but invisible

Claude Code Desktop #95783 is a clean harness catch: the bundled CLI already computes a prompt_cache object per session (warm, ttl, expires_at, recache_tokens_if_cold, hit_ratio, misses, last_miss_cause). The terminal CLI /usage line and statusLine can render it; the VS Code extension can warn on cold resume. The Desktop Code tab surfaces none of it — usage ring shows context and plan only, statusLine is inert there, and get_usage MCP exposes no cache fields. The data exists; the decision surface does not.

Ask HN 49783040 (provider KV caching for agent swarms / long-run agents) is the same operator itch from the other side: when cache lifetime and forkability stay black-box, you cannot pace a swarm or a long desktop session against a TTL you cannot see. On expensive context, one silent cold rewrite costs many warm turns — and nothing in the window warns before or after.