The decisions-append gate's ledger diff (internal/core/lint/decisionsappend.go, analyse) pins --unified=0 and the diff algorithm but not the other hunk-shaping options a repository's own config supplies. A repo-config diff.interHunkContext above zero folds neighbouring -U0 hunks into one with context lines between them, and the old-line arithmetic (removed line k is old line a+k-1; an addition sits after a+b-1) then counts across the context: two separate DA002 findings collapse into one at the wrong span. diff.indentHeuristic=false likewise slides an ambiguous hunk, which moves the line a finding names. Config is not in the tree and CI's is trusted, and the shell gate had the same exposure, so the effect is on a local run over a hostile or merely unusual config. Fix: pin --inter-hunk-context=0 and --indent-heuristic (git's default, which the rules and their cases were written against) on the diff.

The decisions-append gate's ledger diff (internal/core/lint/decisionsappend.go, analyse) pins --unified=0 and the diff algorithm but not the other hunk-shaping options a repository's own config supplies. A repo-config diff.interHunkContext above zero folds neighbouring -U0 hunks into one with context lines between them, and the old-line arithmetic (removed line k is old line a+k-1; an addition sits after a+b-1) then counts across the context: two separate DA002 findings collapse into one at the wrong span. diff.indentHeuristic=false likewise slides an ambiguous hunk, which moves the line a finding names. Config is not in the tree and CI's is trusted, and the shell gate had the same exposure, so the effect is on a local run over a hostile or merely unusual config. Fix: pin --inter-hunk-context=0 and --indent-heuristic (git's default, which the rules and their cases were written against) on the diff.

Grounds

• pursued: TestDecisionsAppendIgnoresRepoDiffConfig sets diff.interHunkContext=5 and diff.indentHeuristic=false in fixture repos and requires the same findings as without; it failed before the fix (DA001 lost and two DA002 merged; a DA001 moved from line 6 to 7). A finding that changes under any other repo diff.* key would show it wrong.