`cmd_dashboard` started the background MCP discovery thread before importing
`hermes_cli.web_server`. The thread's first act is the ~350ms `mcp` SDK
import, which holds the GIL against the main thread's own web_server import,
so the HERMES_BACKEND_READY sentinel — and every renderer paint behind it —
moved ~300ms later on every Desktop cold start with any MCP server configured.
Desktop `serve` (headless + HERMES_DESKTOP=1) now arms discovery one second
after the sentinel instead. Starting it AT the bind was measured to give back
most of the gain (the renderer's WebSocket connect + first hydration reads
contend on the same loop). An agent build inside that window pulls the
deferred start forward itself via `wait_for_mcp_discovery`, so the bounded
join and the late-binding tool refresh behave exactly as before. Dashboard
and non-Desktop `serve` keep the eager pre-import ordering.
Minimal reimplementation of the MCP-deferral slice of #96751 by @helix4u;
the plugin-route deferral / 503 middleware / cron-after-bind slices were
measured at ~0-10ms each and are not taken.
Co-authored-by: Gille <4317663+helix4u@users.noreply.github.com>
Teknium
4155ea97e8