fix: address model spec crash

[gabwow]

Summary

The PR #1491 broke model spec.
This fix is a small type fix and then some unit tests. 1491 is not in release/0.5 so targeting main

Related Issue

closes https://linear.app/nvidia/issue/AIRCORE-1111/model-spec-task-crashes-converting-core-modelspec-to-plugin-modelspec

Changes

Small type fix

Type of Change

• [x ] Code change (feature, bug fix, or refactor)
• Code change with documentation updates
• Documentation only
• Contributor tooling or automation
• CI, build, or test infrastructure

Quality Gates

• Tests added or updated for changed behavior
• Existing tests cover changed behavior — justification:
• Tests not applicable — justification:
• Documentation updated for user-visible behavior
• Documentation not applicable — justification:

Verification

• Pull request title follows the repository's Conventional Commit format
• Every commit includes an appropriate Signed-off-by: trailer
• [ x] uv run pre-commit run -a passes, or any blocked checks are identified below
• [ x] Targeted tests pass, or tests are marked not applicable above
• [ x] No secrets, API keys, or credentials are included

Targeted validation:

Summary by CodeRabbit

Bug Fixes

• Improved checkpoint analysis by accurately validating inferred model configurations.
• Added clear error handling when no job-step configuration path is available.
• Improved reliability when handling model configuration and storage paths.

Tests

• Added coverage for checkpoint analysis, including configuration details, parallelism values, checkpoint downloads, and model updates.

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Reviewing files that changed from the base of the PR and between fd0af23 and 3fe77ce.

📒 Files selected for processing (1)

• services/core/models/tests/unit/tasks/model_spec/test_run.py

🚧 Files skipped from review as they are similar to previous changes (1)

• services/core/models/tests/unit/tasks/model_spec/test_run.py

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📝 Walkthrough

Walkthrough

Changes

Model specification analysis

Layer / File(s)	Summary
Model specification runtime and context services/core/models/src/nmp/core/models/tasks/model_spec/run.py, services/core/models/src/nmp/core/models/tasks/model_spec/schemas.py	Checkpoint inference passes string paths and serialized model data to plugin validation. Missing configuration paths raise ModelSpecCreationError. Context filesystem fields use Path.
Model specification analysis test coverage services/core/models/tests/unit/tasks/model_spec/test_run.py	Unit coverage verifies nested configuration conversion, GPU requirements, model persistence, returned data, inference arguments, and checkpoint download arguments.

Merge Risk: ⚪ Minimal · up to 3fe77

The change adds unit coverage for model-spec checkpoint path typing to prevent the reported conversion crash. No concrete current-head merge-blocking risk is identified.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 30.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the main change: fixing a model spec crash caused by the model spec conversion issue.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 1

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Inline comments:
In `@services/core/models/tests/unit/tasks/model_spec/test_run.py`:
- Line 157: Update the test around infer_model_cfg_from_hf to assert its exact
invocation, including that the checkpoint path argument is str(dest_dir) rather
than dest_dir. Use the mock’s call assertion so the test rejects a Path value
while preserving the existing inferred_spec behavior.

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Configuration used: Path: .coderabbit.yaml

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📥 Commits

Reviewing files that changed from the base of the PR and between e3e3549 and fd0af23.

📒 Files selected for processing (3)

• services/core/models/src/nmp/core/models/tasks/model_spec/run.py
• services/core/models/src/nmp/core/models/tasks/model_spec/schemas.py
• services/core/models/tests/unit/tasks/model_spec/test_run.py

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[github-actions]

Suite	Lines Covered	Line Rate	Branch Rate
Unit Tests	38443/49020	78.4%	62.5%
Integration Tests	23128/46258	50.0%	22.7%