New server.engine_request_min_interval_ms (engine name → ms, 0/unset =
off). _rate_gate spaces inference dispatch STARTS to an engine by at
least the interval, capping request rate and inserting idle time between
GPU submissions — a stability lever for a marginal card (e.g. RX 580)
that wedges under sustained back-to-back Vulkan compute. Wired into all
three inference dispatch paths after the swap-gate; the request itself
runs unthrottled, only the start cadence is gated.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014S8VtAvG499SsCbeESRK7V