Based on #42658 by @mnajafian-nv.
Preserves the real downstream provider/tool exception when NeMo Relay's
managed adaptive execution wraps a failing callback as an internal runtime
error. Without this, the original exception (and its retry-classification
signal, e.g. status_code) is lost behind Relay's wrapper.
Salvage changes on top of the original PR:
- Tolerant Relay-wrapper match: _is_relay_wrapped_callback_error now uses
str.startswith on the "internal error: <cls>: <msg>" prefix instead of
exact equality, so a future Relay version appending a traceback/suffix
doesn't silently defeat the unwrap. On a total format change it returns
False and falls back to the pre-fix behavior (surfacing Relay's error)
rather than masking it.
- Deduplicated the LLM and tool execute paths into a shared
_run_managed_with_downstream_preservation helper, removing ~20 lines of
copy-pasted nonlocal/try-except scaffolding that could drift out of sync.
- Added a real-middleware regression guard
(test_nemo_relay_downstream_unwrap_matches_real_middleware_wrapper_shape)
that drives hermes_cli.middleware._run_execution_chain and asserts the
plugin's _original_downstream_error unwraps the actual private
_DownstreamExecutionError wrapper. The original synthetic tests modeled the
wrapper with a local class, so a rename or shape change in core middleware
would not have been caught; this test fails loudly if that contract drifts.
Co-authored-by: mnajafian-nv <mnajafian@nvidia.com>
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