Land the fallback InferenceRuntime strategy that satisfies C7-IT-05:
when the TRT-direct path (AZ-298) cannot deserialise a cached engine
or when the operator explicitly selects ORT, the system stays in the
air at degraded latency rather than dropping the request. Conforms to
the AZ-297 Protocol; current_runtime_label() == "onnx_trt_ep".
Production
- onnx_trt_ep_runtime.py: compile_engine is a no-op returning an
EngineCacheEntry pointing at the source .onnx; deserialize_engine
is gate-first for .engine entries and gate-skip for .onnx, builds
an ORT InferenceSession with the provider list
[TensorrtExecutionProvider, CUDAExecutionProvider,
CPUExecutionProvider], stages cached engines into the ORT TRT EP
cache directory via symlink-or-copy, warms up with one session.run
after construction, and honours config.inference.ort_disallow_cpu_
fallback by raising EngineDeserializeError when the active provider
resolves to CPU; infer emits a one-shot c7.fallback_to_onnx_trt_ep
WARN log plus gcs_alert callback on first call when is_fallback=
True; release_engine is idempotent. _build_provider_args is the
single point that pins TRT EP option-key names (Risk-3) and caps
trt_max_workspace_size at gpu_memory_budget_bytes // 4 (AC-8).
- config.py: adds ort_trt_cache_dir (validated non-empty) and
ort_disallow_cpu_fallback to C7InferenceConfig.
- fdr_client/records.py: adds c7.fallback_to_onnx_trt_ep and
c7.cpu_fallback FDR record kinds.
Tests
- test_onnx_trt_ep_runtime.py: covers AC-1..AC-8 + Risk-2 CPU-fallback
alert + Risk-3 option-key pin + NFR-reliability error rewrap; Tier-1
via fake ORT session; Tier-2 placeholders skip on macOS dev for
numerical FP16 comparison and session-creation perf NFR.
- test_protocol_conformance.py: drops onnx_trt_ep from the missing-
module parametrize now that the module ships.
- test_az272_fdr_record_schema.py: extends per-kind fixture builder
to cover the two new C7 FDR kinds in the roundtrip / schema-version
AC tests.
Docs
- module-layout.md: replaces the pending onnx_trt_runtime row with
the shipped onnx_trt_ep_runtime row + capabilities list.
- batch_32_cycle1_report.md + reviews/batch_32_review.md: full batch
+ self-review (PASS_WITH_WARNINGS, 4 Low findings accepted).
Tests run: c7_inference 139 passing + 17 Tier-2 skips; combined unit
suite (excluding pending components) 529 passing, 19 env-skipped.
Co-authored-by: Cursor <cursoragent@cursor.com>
Oleksandr Bezdieniezhnykh