Found on the docker-dev rig during the #761 Wave-4 gate run (2026-11-12): the documented
bodyless headless deploy (docker-dev/deploy.sh, README "Headless deploy") returned 404 on
both centrals, while the same POST with a JSON body was accepted.
Cause: the optional body was an inferred `DeployRequest?` parameter, which stamps
Accepts(application/json) metadata on the endpoint. For a request with no Content-Type the
routing AcceptsMatcherPolicy prefers endpoints that declare no consumes metadata, and on a
fused admin+driver host MapOtOpcUaMeshGrpcServices has mapped grpc-dotnet's
`{unimplementedService}/{unimplementedMethod}` catch-all, so the request was routed away
from the deploy handler and 404'd. The deploy API on its own does not reproduce it.
The handler now reads the optional body itself: no body (absent or zero-length) is the
headless form, a non-JSON body answers 415 and malformed JSON 400, as the framework's
binding did. New DeployApiBodylessPostTests compose the deploy API with the mesh gRPC
services and drive real HTTP; with the fix reverted the two bodyless cases fail with 404.
Claude-Session: https://claude.ai/code/session_01GT67ACmpMR7b9LGRPLijMi
Joseph Doherty