fix: handle undefined SpacingBetweenSlices tag in _fix_direction

[strixy16]

Summary by CodeRabbit

• Bug Fixes
  • Scan handling improved so scans with undefined or non-numeric slice-spacing metadata are safely skipped from spacing corrections, preventing incorrect direction adjustments and related image-processing errors.

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[coderabbitai]

📝 Walkthrough

Walkthrough

Guard added to Scan._fix_direction to skip numeric parsing and subsequent negative-spacing correction when metadata SpacingBetweenSlices is missing or non-numeric; the method now retrieves the raw value, attempts float conversion, and returns early on absence or failed conversion.

Changes

Cohort / File(s)

Summary

Metadata spacing guard src/imgtools/coretypes/imagetypes/scan.py

_fix_direction now retrieves SpacingBetweenSlices as raw_spacing, attempts float() conversion only if present, and returns early on missing or non-numeric values, avoiding previous unconditional parsing and negative-spacing handling. Area to review: consistent normalization of undefined (None) vs string values (e.g., "None") and whether a centralized metadata-normalization helper is warranted for maintainability.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: handling an undefined SpacingBetweenSlices tag in the _fix_direction method.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing touches

• 📝 Generate docstrings

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

src/imgtools/coretypes/imagetypes/scan.py (1)

71-75: Consider a more robust check for non-numeric values.

The guard for string 'None' addresses the immediate issue, but other non-numeric string values could still cause a ValueError on line 76. A try-except approach would be more defensive:

Also, minor nit: there's trailing whitespace on line 74.

♻️ Suggested improvement for robustness

         # Check if "SpacingBetweenSlices" is undefined - it's an optional tag so this is possible
         # https://dicom.innolitics.com/ciods/ct-image/image-plane/00180088
-        if self.metadata.get('SpacingBetweenSlices') == 'None':
-            return 
-        
-        slice_spacing = float(self.metadata.get("SpacingBetweenSlices") or 0)
+        raw_spacing = self.metadata.get("SpacingBetweenSlices")
+        try:
+            slice_spacing = float(raw_spacing) if raw_spacing else 0.0
+        except (ValueError, TypeError):
+            # SpacingBetweenSlices is undefined or not a valid numeric value
+            return
+
         if (not slice_spacing) or (slice_spacing >= 0):
             return

This handles any non-numeric value (not just 'None') and removes the trailing whitespace.

📜 Review details

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 6def068 and 47cc736.

📒 Files selected for processing (1)

• src/imgtools/coretypes/imagetypes/scan.py

🧰 Additional context used

📓 Path-based instructions (1)

src/**/*.py

⚙️ CodeRabbit configuration file

Review the Python code for compliance with PEP 8 and PEP 257 (docstring conventions). Ensure the following: - Variables and functions follow meaningful naming conventions. - Docstrings are present, accurate, and align with the implementation. - Code is efficient and avoids redundancy while adhering to DRY principles. - Consider suggestions to enhance readability and maintainability. - Highlight any potential performance issues, edge cases, or logical errors. - Ensure all imported libraries are used and necessary.

Files:

• src/imgtools/coretypes/imagetypes/scan.py

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)

• GitHub Check: Build-Docs (ubuntu-latest, docs)

[codecov]

Codecov Report

❌ Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.60%. Comparing base (ee4d7c7) to head (d60dac0).
⚠️ Report is 10 commits behind head on main.

Files with missing lines	Patch %	Lines
src/imgtools/coretypes/imagetypes/scan.py	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #435      +/-   ##
==========================================
- Coverage   54.65%   54.60%   -0.06%     
==========================================
  Files          66       66              
  Lines        4314     4318       +4     
==========================================
  Hits         2358     2358              
- Misses       1956     1960       +4     

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