[Silu Panda (SiluPanda)]

Description

Forward the initializer-data callback into OrtGraphToProto subgraph recursion, keeping the same mutable callback state throughout a traversal. Preserve the empty-callback path and both public function signatures.

The recursive call currently omits the callback, so nested initializers silently stay inline and nested callback errors are never reported. Passing the std::function by value instead would copy mutable captures into each branch, potentially reusing external-data offsets. A conditional std::ref wrapper shares the active callback during synchronous recursion without wrapping an empty function.

Adds generated, CPU-only regressions in the existing EP graph suite:

• root, sibling and depth-two initializers, including same-named initializers with different values;
• a mutable value-captured offset, checking every external-data location/offset/length and the corresponding bytes;
• external-file reload and actual inference for every If branch;
• both GraphProto/ModelProto overloads, omitted/empty callbacks, and exact nested error propagation with no subsequent callbacks.

Validation

Built and tested on macOS arm64, Apple Clang 17, CPU-only Release shared-library build, based on a8246c0d094f1ab0d6bf236228e5e67683321cd7. No minimal build or operator exclusions were used.

source .venv/bin/activate
python tools/ci_build/build.py \
  --build_dir build/MacOS --config Release --update --build --parallel 4 \
  --target onnxruntime_ep_graph_test --build_shared_lib \
  --cmake_generator Ninja --skip_submodule_sync --skip_tests \
  --cmake_extra_defines FETCHCONTENT_TRY_FIND_PACKAGE_MODE=NEVER
# Target-only builds do not run the general test target's fixture-copy step.
cmake -E copy_directory onnxruntime/test/testdata build/MacOS/Release/testdata
cd build/MacOS/Release
./onnxruntime_ep_graph_test --gtest_filter='EpGraphTest.*'

• Before: both added regressions fail against the unmodified header. The nested fixture serializes eight initializers but invokes the callback once; nested rejection incorrectly returns success.
• After: all 20 EP graph tests pass, including the two added regressions; no skips.
• Mutation checks: forwarding the callback by value fails the offset/data/output assertions; unconditionally wrapping the empty callback fails the inline serialization control. The intended fix was restored, rebuilt and the full suite rerun afterward.
• lintrunner and git diff --check pass.

Selected output from the actual local runs

Baseline:

Expected equality of these values:
  callback_calls
    Which is: 1
  inline_initializers.size()
    Which is: 8

Value of: status.IsOK()
  Actual: true
Expected: false

[  PASSED  ] 0 tests.
[  FAILED  ] 2 tests

Restored final patch:

[==========] 20 tests from 1 test suite ran. (48 ms total)
[  PASSED  ] 20 tests.

Windows execution has not been tested locally. Existing macOS telemetry duplicate-class and model-fixture warnings were not suppressed.

Motivation and Context

Fixes #34137. Thanks to Zarana Kiran Desai (@zadesai) for the reproducer and the reference-forwarding approach.

This fixes the existing header-only EP utility. #33921 concerns FLOAT16 tensor attributes, while #34014 adds a separate serialization C API; neither fixes this callback omission.

AI assistance: OpenAI Codex assisted with implementation, independent source review, and execution of the reported local tests. The results above are from those actual automated runs.

[azure-pipelines]

Azure Pipelines:
There may be pipelines that require an authorized user to comment /azp run to run.

[Copilot]

🟢 Approval recommended

No active review issues were identified for the changes that propagate initializer callbacks into nested subgraphs while sharing callback state.

No open issues 🎉

What changed in this PR

Fixes #34137 in the header-only OrtGraphToProto utility by propagating initializer callbacks into nested subgraphs while sharing mutable callback state. Public signatures and serialization without a callback remain unchanged.

Changes:

• Forward nonempty callbacks by reference during recursive serialization and document traversal-wide state sharing.
• Add CPU regressions covering nested initializer storage, external-data reload and inference, both overloads, empty callbacks, and nested error propagation.

File	Description
onnxruntime/​test/​ep_graph/​test_ep_graph.cc	Adds generated nested-graph tests for callback state, external data, inference, and errors.
include/​onnxruntime/​core/​providers/​utils/​ort_graph_to_proto.h	Forwards callbacks into subgraphs and documents shared callback state.

_{Review effort: Balanced}

[Silu Panda (SiluPanda)]

Hi Adrian Lizarraga (@adrianlizarraga) Chi Lo (@chilo-ms), could you please review this fix and approve the CI runs if you have access? They currently show action_required before any jobs start. CLA has passed, and all 20 EP graph tests pass locally, with both new regressions failing before the fix. Thanks for your time!