feat(structural): locate parser failures in warnings

[nia-sg-bot]

Summary

• report the first Tree-sitter syntax-error location in deterministic PARSE_FAILURE warnings
• retain the existing scoped-warning/no-topology behavior when parsing fails
• update the parser-failure golden fixture with the stable line and column diagnostic

Validation

• python3 -m pytest (160 passed)
• git diff --check

Compatibility

This only makes the existing string-valued warning detail more actionable. The schema, warning code, artifact topology, and v2 extension contract are unchanged.

Part of #22

Summary by CodeRabbit

• Bug Fixes
  • Python syntax error messages now include the specific line and column where the issue was detected.
  • Error reporting is deterministic and more actionable when parsing fails.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 91cf23ed-e142-488f-9e99-5fd248f356fa

📥 Commits

Reviewing files that changed from the base of the PR and between 6389927 and 9fa70d0.

📒 Files selected for processing (2)

• diffgraph/structural.py
• tests/fixtures/python_parser_failure.json

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

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Walkthrough

The Python parser now reports the first syntax error or missing node location. The parser failure fixture reflects the updated message with line and column details.

Changes

Python parser error reporting

Layer / File(s)	Summary
Syntax error location reporting diffgraph/structural.py, tests/fixtures/python_parser_failure.json	_syntax_error_detail finds the first parser error in source order. _parse_python uses the helper when raising ValueError. The fixture includes the reported line and column.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to 9fa70

Python parse-failure warnings now include a deterministic line and column for the first syntax error, with the expected diagnostic captured in the parser-failure fixture. No current merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 66.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 1 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 describes the main change: adding source locations to parser failure warnings.
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 66.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 1 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-22-parser-diagnostic-location

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