[emerardd]

Description

Coordinate patching rejects valid gradient_pursuit decompositions when they are supplied explicitly or reused through the per-position/cache path. Its compatibility validator currently applies NNLS KKT stationarity to both supported algorithms, although gradient pursuit deliberately performs approximate projected-gradient updates.

For example, with dictionary rows [[1, 0, 0], [0.7, 0.7, 0], [0, 0, 1]], activation [1, 0.3, 0], and k=2, a fresh gradient-pursuit patch from atom 0 to atom 2 returns [0, 0.3, 1]. Passing its own decomposition back into the solver instead raises NNLS result violates stationarity on positive coordinates. solve_coordinate_patch_positions() encounters the same error even on its first call because it passes the freshly computed decomposition through the reuse validator.

This change validates gradient-pursuit coordinates by replaying the coefficient updates over the recorded selected atoms, including the solver's final active-support pruning. It avoids a vocabulary-wide selection scan on reuse. The existing NNLS KKT validation and shared activation/dictionary/reconstruction checks remain in place, so self-consistently rescaled coordinates and stale activations are still rejected.

The existing algorithm argument now selects the validation rule for supplied/cached decompositions as well as the fresh solver; its docstrings state that it must match the decomposition's producer. No decomposition fields or public signatures change.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Validation

The regression coverage includes correlated atoms, explicit reuse, per-position calls, cache misses/hits, both coefficient-update algorithms, activation scales, invalid coordinates, empty supports, unknown algorithms, and hook/offline parity through JacobianLens.

• Coordinate-patch, sparse-decomposition and coordinate-patch-hook tests: 231 passed.
• Full mypy .: 389 source files passed.
• Pinned pycln/isort/Black checks on all four changed files and git diff --check: passed.

The complete unit suite and GPU/MPS tests were not run.

Checklist

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (API docstrings)
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes (affected files run; full suite not run)
• I have not rewritten tests relating to key interfaces which would affect backward compatibility