V3 deterministic no-index diff capability pack. By-value connector composition (service_kind=cli, no separate ingredient): the local git CLI compares two source files with git diff --no-index and writes a patch file via the file.diff_no_index catalog operation. Fixed-function and reproducible: the executor materializes an ordered file_ref array into discrete argv elements, owns the throwaway output directory, git writes a fixed diff.patch result, and exit codes 0 (no differences) and 1 (differences found) are both successful. Requires git on PATH (Debian/Ubuntu: apt install git; macOS: git is commonly installed with developer tools). Local and no-egress.