Reviewer reports treated 'git fetch prgs master' as read-only
diagnostics while claiming 'Git/worktree mutations: None'. Fetch edits
no files but updates remote-tracking refs, so hiding it under
diagnostics understates what the run mutated.
Add git_ref_mutating_commands() classifying fetch, pull, push, merge,
update-ref, remote update, branch -d/-D, and reset --hard as git ref
mutations, and assess_git_ref_mutation_report() which fails a report
when ref-updating commands ran but the report lacks a non-none 'Git ref
mutations' entry, omits 'fetched <remote>/<branch>' for a targeted
fetch, still claims 'Git/worktree mutations: None', or lists the
command under read-only diagnostics.
Tests cover fetch-only review, missing ledger entry, missing fetch
target, contradictory none-claim, read-only misclassification, worktree
creation (not a ref mutation), merge, cleanup branch deletion,
no-mutation blocked handoff, and dict command-log entries.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
