The Smargon at the SLS 2.0 MX beamlines reports its own axis positions with
readout noise, so a chi parked at zero comes back as about -1e-7 degrees. The
schema bounded chi_deg to [0, 90], so an ordinary "chi is at zero" setup was
refused - and the same holds at the other end of the arc, where a chi parked at
90 reads just above it. Both end-stops are exactly where a static positioner is
left, so widening the range would only move the problem.
The bound bought nothing. Chi never enters any computation: OpenAPIConvert puts
it in SmargonPosition, DiffractionExperiment::BuildTransformationChain hands it
to a rotation transformation verbatim, HDF5NXmx writes it and HDF5MetadataSource
reads it back. No downstream reads its sign, and a rotation is defined for any
angle. phi, the sibling angle in the same object with the same semantics, has
never been bounded. What was left was a restatement of a hardware travel limit
that the goniometer enforces itself, and its only observable effect was to
refuse a value the instrument genuinely reported.
It was also not enforced where a server-side check would matter: the
cpp-pistache-server generator does not recurse into a nested object model, so
Dataset_settings::validate never calls the Smargon model's. The rejection was
raised by the generated python and TypeScript clients, which do check.
Regenerated the C++ server model, the TypeScript client and redoc-static.html;
python-client is gitignored and comes from gen_python_client.sh.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EFEJG6WBQv8th4UJFNe53N
leonarski_fandClaude Opus 5
aa6073d41f