test(issue-17): every test that sources lib.sh does it under its own WORKSPACE_ROOT (review grok, codex)

d198dd5 fixed one helper; the same defect was in eleven more modules
(reviews grok and codex R1/R2): their shells inherited the process
environment, so each `source lib.sh` rewrote <WORKSPACE_ROOT>/.mam/shim/herdr
- the checkout's own when the variable is unset or names this checkout (which
pytest_configure keeps), another workspace's under --noconftest.

- conftest: own_workspace_root, an opt-in fixture setting WORKSPACE_ROOT to
  <tmp_path>/.mam-test-state/workspace. Not autouse: runner.py and
  mqtt_common read WORKSPACE_ROOT in-process, and some tests unset it on
  purpose. mam_sandbox and explicit envs run later and still win.
- pytestmark usefixtures("own_workspace_root") in test_version_consistency,
  test_b19_headless_reconcile_fixes, test_b8_send_keys_verification,
  test_issue6_fail_closed, test_loop_cli, test_issue5_phase3_loop,
  test_issue5_phase4_runtime, test_o3_scoped_guard, test_issue25_plan_reuse,
  test_orc_onboard (their shells inherit os.environ, many with no env at all).
- test_orc_onboard (R2): SCRUBBED_ENV is taken at import and no longer
  carries WORKSPACE_ROOT; every call builds _scrubbed_env(root) with the root
  of the call (ws / cwd / mam_sandbox, else this test's).
- test_workspace_scope (unittest) and test_issue21_worktree_prereqs._mutate
  pin the root they already create.

Tests (test_issue17_workspace_root_isolation.py): W1 copies the checkout and
runs one test of each of those modules there with WORKSPACE_ROOT naming the
copy - the copy gets no .mam; W2 imports test_orc_onboard under a sentinel
root, then calls it under another - the sentinel stays empty. At d198dd5 both
fail (the copy gets .mam/shim/herdr; the sentinel gets it).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HCGpJXhSZasJLU38ksDghe

tests/test_workspace_scope.py

@@ -27,7 +27,9 @@ class TestWorkspaceScope(unittest.TestCase):
         cmd = f"source {lib_sh} && env -u HERDR_SESSION_NAME -u HERDR_SERVER_NAME bash -c 'source {lib_sh} && resolve_herdr_session \"test-session\" \"{self.ws_dir}\"'"
         # `source` is a bash builtin; on hosts where /bin/sh is dash `shell=True`
         # fails with "source: not found" (Issue #28), so run the string under bash.
-        res = subprocess.run(["bash", "-c", cmd], capture_output=True, text=True)
+        # Issue #17: lib.sh rewrites $WORKSPACE_ROOT/.mam/shim/herdr - this test's own, not an inherited one
+        res = subprocess.run(["bash", "-c", cmd], capture_output=True, text=True,
+                             env=dict(os.environ, WORKSPACE_ROOT=self.ws_dir))
         self.assertEqual(res.returncode, 0, f"Command failed: {res.stderr}")
         parent = os.path.basename(os.path.dirname(os.path.abspath(self.ws_dir))).lower().replace('_', '-')
         work = os.path.basename(os.path.abspath(self.ws_dir)).lower().replace('_', '-')