test(issue-20): state isolation regression tests

S1/S2 per-test defaults and the mam_sandbox override, S3 submit with WORKSPACE_ROOT on a checkout leaves its .mam alone, S6 a nested pytest started with a pane's binding sees none of it (import-time copy included) and leaves the target untouched, S7 lib.sh takes the session registry from a test's WORKSPACE_ROOT.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Sdga4A8i1iSc8DaaW9iKU2

tests/test_issue20_state_isolation.py

@@ -101,3 +101,102 @@ def test_s5_watch_roots_follow_the_recorded_binding(tmp_path):
     rec = {"MAM_JOBS_DIR": str(odd)}
     jobs, logs = guard.state_dirs(guard.watch_roots(repo, rec), rec)
     assert str(odd.resolve()) in jobs and str(odd.resolve()) not in logs
+
+
+# ---------------------------------------------------------------------------
+# per-test defaults and the dropped binding (S1-S3, S6, S7)
+# ---------------------------------------------------------------------------
+# Copied at import, like test_orc_onboard.SCRUBBED_ENV: the binding has to be
+# gone before collection, not merely before the first test (S6).
+_IMPORT_ENV = dict(os.environ)
+PROBE_ENV = "MAM_ISSUE20_PROBE"
+BINDING = ("WORKSPACE_ROOT", "AGENT_SESSIONS_YAML", "MAM_JOBS_DIR", "DELEGATE_JOB_LOGS_DIR")
+
+
+def _tree(root: Path) -> dict:
+    return {str(p.relative_to(root)): hashlib.sha256(p.read_bytes()).hexdigest() if p.is_file() else None
+            for p in sorted(root.rglob("*"))}
+
+
+def _binding(root: Path) -> dict:
+    """The four variables a worktree creator's pane carries, aimed at `root`."""
+    mam = root / ".mam"
+    return {"WORKSPACE_ROOT": str(root), "AGENT_SESSIONS_YAML": str(mam / "agent-sessions.yaml"),
+            "MAM_JOBS_DIR": str(mam / "jobs"), "DELEGATE_JOB_LOGS_DIR": str(mam / "delegate_job_logs")}
+
+
+def test_s1_every_test_defaults_to_state_dirs_under_tmp_path(tmp_path, monkeypatch):
+    from lib_py.delegation import mqtt_common
+
+    state = tmp_path / ".mam-test-state"
+    assert os.environ["MAM_JOBS_DIR"] == str(state / "jobs")
+    assert os.environ["DELEGATE_JOB_LOGS_DIR"] == str(state / "delegate_job_logs")
+    # a WORKSPACE_ROOT on a checkout with a .mam no longer decides where state goes
+    monkeypatch.setenv("WORKSPACE_ROOT", str(_fake_control_plane(tmp_path / "repo")))
+    assert mqtt_common.default_registry_dir() == str(state / "jobs")
+    assert mqtt_common.get_logs_dir() == str(state / "delegate_job_logs")
+
+
+def test_s2_mam_sandbox_overrides_the_default(mam_sandbox):
+    assert os.environ["MAM_JOBS_DIR"] == str(mam_sandbox / ".mam" / "jobs")
+    assert os.environ["DELEGATE_JOB_LOGS_DIR"] == str(mam_sandbox / ".mam" / "delegate_job_logs")
+
+
+def test_s3_submit_with_workspace_root_on_a_checkout_leaves_its_mam_alone(tmp_path):
+    """The issue's acceptance check in small: WORKSPACE_ROOT names a checkout
+    with a real-looking .mam and the test sets nothing else."""
+    repo = _fake_control_plane(tmp_path / "repo", sessions=("creator-real",))
+    before = _tree(repo)
+    env = dict(os.environ, WORKSPACE_ROOT=str(repo), MAM_ENV_FILE=str(tmp_path / ".mam.env.absent"),
+               PYTHONPATH=f"{SKILLS}:{os.environ.get('PYTHONPATH', '')}")
+    res = subprocess.run(
+        [sys.executable, "-m", "lib_py.delegation.cli", "submit", "--prompt", "issue 20 probe",
+         "--agent", "claude-code", "--agent-session", "herdr:issue20-probe"],
+        capture_output=True, text=True, env=env, cwd=str(REPO_ROOT), timeout=60,
+    )
+    assert res.returncode == 0, res.stderr
+    state = tmp_path / ".mam-test-state"
+    records = list((state / "jobs").glob("*.json"))
+    assert len(records) == 1, records
+    assert (state / "delegate_job_logs" / records[0].stem).is_dir()
+    assert _tree(repo) == before
+
+
+def test_s6_a_pane_binding_is_dropped_before_collection(tmp_path):
+    """A pytest started with a worktree creator pane's binding - all four at
+    another checkout F - sees none of it, not even in a module-level copy of
+    os.environ, and leaves F untouched."""
+    fake_main = _fake_control_plane(tmp_path / "main", sessions=("creator-real",))
+    before = _tree(fake_main)
+    env = dict(os.environ, **_binding(fake_main), **{PROBE_ENV: "1"})
+    # An explicit basetemp: the inner run must not clean up the outer one's.
+    res = subprocess.run(
+        [sys.executable, "-m", "pytest", f"{__file__}::test_s6_probe", "-q", "-p", "no:cacheprovider",
+         f"--basetemp={tmp_path / 'inner'}"],
+        capture_output=True, text=True, env=env, cwd=str(REPO_ROOT), timeout=300,
+    )
+    assert res.returncode == 0, res.stdout[-4000:] + res.stderr[-2000:]
+    assert "1 passed" in res.stdout, res.stdout[-2000:]
+    assert _tree(fake_main) == before
+
+
+@pytest.mark.skipif(not os.environ.get(PROBE_ENV), reason="the inner half of S6 (nested pytest) only")
+def test_s6_probe(tmp_path):
+    assert not [k for k in BINDING if k in _IMPORT_ENV], {k: _IMPORT_ENV[k] for k in BINDING if k in _IMPORT_ENV}
+    assert "AGENT_SESSIONS_YAML" not in os.environ
+    assert "WORKSPACE_ROOT" not in os.environ  # it named another checkout
+    state = tmp_path / ".mam-test-state"
+    assert os.environ["MAM_JOBS_DIR"] == str(state / "jobs")
+    assert os.environ["DELEGATE_JOB_LOGS_DIR"] == str(state / "delegate_job_logs")
+
+
+def test_s7_lib_sh_takes_the_session_registry_from_a_tests_workspace_root(tmp_path):
+    """An ambient AGENT_SESSIONS_YAML (a worktree pane's) would win over the
+    test's WORKSPACE_ROOT in lib.sh; conftest dropped it before collection."""
+    assert "AGENT_SESSIONS_YAML" not in os.environ
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    script = f'source "{SKILLS / "lib.sh"}" >/dev/null 2>&1; printf %s "$AGENT_SESSIONS_YAML"'
+    res = subprocess.run(["bash", "-c", script], capture_output=True, text=True,
+                         env=dict(os.environ, WORKSPACE_ROOT=str(repo)), timeout=60)
+    assert res.stdout == str(repo / ".mam" / "agent-sessions.yaml"), (res.stdout, res.stderr)