[Afloat16]

Problem

The distance-transform metric and path connectivity are separate concerns. Restricting every Manhattan query to axial steps changes existing book-example paths. Callers need an explicit way to request four-connected paths while preserving the default behavior.

Change

• Keep the default connectivity=8, including the existing diagonal query steps and book-example paths for both distance metrics.
• Add connectivity=4 to restrict both the distance transform and path extraction to horizontal and vertical moves. These moves have the same cost for either metric.
• Accept integer connectivity values of 4 or 8, reject invalid values, and expose the selected value through the connectivity property.
• Document the default and the opt-in behavior.

Regression coverage

The tests cover axial steps and distance-map cost for connectivity=4, unchanged default diagonal paths, unreachable diagonal gaps, and invalid connectivity values. The existing book-path compatibility expectations are unchanged.

Validation

CI for current head d282e72c passes, including core tests, the Linux/macOS/Windows test matrix, mypy, coverage and the documentation build. The current head has 24 successful checks and 2 workflow-context skips.

The previously reported three path-compatibility failures occurred on 09519319, before the opt-in change. The current description and validation refer to d282e72cd7e7af645030068718ca25a8f3ffb127.

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 6 complexity · 0 duplication

Metric	Results
Complexity	6
Duplication	0

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[Afloat16]

The follow-up in d282e72c preserves the default eight-connected queries and the existing book-path expectations. Four-connected behavior is now explicit through connectivity=4, which applies to both the distance transform and path extraction.

Current-head CI passes, including the compatibility tests, platform matrix, mypy and documentation build. The title and description now reflect this opt-in behavior.