The served-token fallback adopts whatever token the dashboard HTML
injects. That is correct when our own child regenerated the token (env
pin lost across a shell-wrapped spawn), but wrong when the readiness
probe answered from a process we did not spawn: /api/status is public,
so an orphaned dashboard squatting the port passes waitForHermes while
our child dies on the bind conflict. Silently adopting that process's
token would authenticate the renderer against a foreign backend,
possibly on the wrong profile.
Discriminate on child liveness: the desktop pins
HERMES_DASHBOARD_SESSION_TOKEN on every spawn, so a live child always
serves our token. Served-token mismatch + dead child = foreign backend;
fail the boot loudly instead of connecting. Mismatch + live child keeps
the adopt-served-token salvage from #43720.
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