Introduce root_checkout_guard helper and enforce it in verify_preflight_purity
so author, reviewer, and merger mutations fail closed when the stable control
checkout is on the wrong branch, detached, dirty, or diverged from prgs/master.
Isolated branches/... worktrees and reconciler paths remain allowed.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Share canonical workspace/repo-root resolution between gitea_get_runtime_context
and verify_preflight_purity so valid branches/ worktrees are not rejected when
the MCP process root differs from the stable control checkout. Fix relative
git-common-dir resolution and add regression tests.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Hardens #274 branches-only guard for gitea_create_issue:
- verify_preflight_purity: validate resolved worktree exists, is a directory,
and belongs to the target repository before author mutations.
- gitea_create_issue: add worktree_path threaded into preflight guard.
- tests/test_create_issue_workspace_guard.py: stable-control-checkout rejection
and invalid-path fail-closed cases (PROJECT_ROOT simulated as control checkout).
Preserves WIP commit 8530109 implementation; test fix completes stable-checkout path.
Closes#450
sysadmin
