fix(contract): preserve actionable Git resolver warning codes

[nia-sg-bot]

Summary

• preserve every supported Git snapshot resolver warning as its own machine-readable DiffGraph v2 warning code
• extend the public schema enum for commit-range, pathspec, untracked, and gitlink resolver failures
• cover invalid refs and out-of-repository pathspecs through the structural CLI artifact

Part of #21

Remaining #21 work is the broader end-to-end coverage of any unimplemented Git snapshot edge cases; this PR specifically makes already-detected resolver failures actionable to artifact consumers without detail-string parsing.

Validation

• python3 -m pytest tests/test_structural.py -k 'invalid_ref_warning_code or scoped_pathspec_warning_code' -q\n- python3 -m pytest tests/test_git_snapshot.py -q\n- python3 -m pytest -q

Summary by CodeRabbit

• New Features

  • Added machine-readable warning codes for Git snapshot resolution issues, including invalid references, merge-base failures, malformed metadata, untracked-file detection failures, and gitlink problems.
  • Added a distinct warning for path specifications located outside the repository.
  • Preserved the existing unmerged-index warning code.

• Bug Fixes

  • Structural JSON output now reports specific resolution warning codes instead of the generic UNKNOWN code when applicable.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Team

Run ID: 1dba810f-e50a-421e-b164-6fb1f4b38d56

📥 Commits

Reviewing files that changed from the base of the PR and between e88a9b8 and 6d2aa17.

📒 Files selected for processing (3)

• diffgraph/schema/diffgraph-v2.schema.json
• diffgraph/structural.py
• tests/test_structural.py

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.

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Walkthrough

The change adds recognized Git snapshot-resolution warning codes to the DiffGraph schema and structural warning handling. Structural JSON now preserves codes such as invalid_base_ref and pathspec_outside_repository instead of converting them to UNKNOWN. Tests cover both cases.

Changes

Resolution warning codes

Layer / File(s)	Summary
Warning code contract diffgraph/schema/diffgraph-v2.schema.json, diffgraph/structural.py	The schema and public RESOLUTION_WARNING_CODES set include the expanded resolution warning code list.
Warning propagation and coverage diffgraph/structural.py, tests/test_structural.py	_resolution_warning preserves recognized codes. Tests validate invalid_base_ref and pathspec_outside_repository output.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 6d2aa

Structural JSON now retains supported Git resolution warning codes for consumers, with coverage for invalid base references and pathspecs outside the repository. No concrete current-head merge risk remains.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 2 files. (1 skipped: 1…	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 and concisely describes the main change: preserving actionable Git resolver warning codes in the contract.
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.

Full details: Docstring Coverage

Explanation

Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 2 files. (1 skipped: 1 unsupported.)

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch nia/issue-21-resolver-warning-contract

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[nia-sg-bot]

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