test(issue-20): session guard for new entries in the recorded control planes' .mam/jobs and .mam/delegate_job_logs

Watches this checkout's .mam and the ones the recorded binding named. A new entry is a leak when it is an audit log without a registry record, or when its agent_session is missing or not a registered session; live delegations write the record first and target a registered session. Reports, never deletes. The #19 guard's docstring pointed at a #15 session guard that never existed.

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

tests/_mam_state_guard.py

@@ -0,0 +1,157 @@
+"""Issue #20 - helpers for the session guard over real control planes.
+
+A pytest process can reach two kinds of `.mam`: this checkout's own, and the
+one the agent pane's control-plane binding named before conftest's
+pytest_configure dropped it (a worktree creator's pane carries
+WORKSPACE_ROOT, AGENT_SESSIONS_YAML, MAM_JOBS_DIR and DELEGATE_JOB_LOGS_DIR,
+all at the live main checkout). The session guard snapshots their job
+registries and audit-log roots and, at the end, reports the new entries no
+live delegation explains. Pure functions, unit-tested in
+test_issue20_state_isolation.py (S4, S5); the name does not start with
+`test_`, so pytest never collects it.
+"""
+from __future__ import annotations
+
+import json
+import os
+import re
+
+SESSION_PREFIXES = ("herdr:", "remote:")
+# Top-level items of `herdr_sessions:` as atomic_dump_yaml writes them
+# (`- name: <session>` at column 0); indented `- name:` lines belong to nested
+# lists such as mcp_attachments. A regex keeps the guard free of PyYAML.
+_SESSION_LINE = re.compile(r"""^- name:\s*['"]?([^'"\s]+)""")
+
+
+def _listdir(path):
+    try:
+        return os.listdir(path)
+    except OSError:
+        return []
+
+
+def _load(path):
+    try:
+        with open(path, encoding="utf-8") as fh:
+            data = json.load(fh)
+    except (OSError, ValueError):
+        return {}
+    return data if isinstance(data, dict) else {}
+
+
+def watch_roots(repo_root, recorded):
+    """`.mam` directories to watch, realpath-deduplicated, in order: this
+    checkout's own (always, so a leak that creates it is still seen), then
+    those the recorded binding names - `$WORKSPACE_ROOT/.mam` and the parents
+    of MAM_JOBS_DIR / DELEGATE_JOB_LOGS_DIR - when they exist."""
+    roots = [os.path.realpath(os.path.join(str(repo_root), ".mam"))]
+    candidates = []
+    if recorded.get("WORKSPACE_ROOT"):
+        candidates.append(os.path.join(recorded["WORKSPACE_ROOT"], ".mam"))
+    for var in ("MAM_JOBS_DIR", "DELEGATE_JOB_LOGS_DIR"):
+        if recorded.get(var):
+            candidates.append(os.path.dirname(os.path.abspath(recorded[var])))
+    for path in candidates:
+        real = os.path.realpath(path)
+        if os.path.isdir(real) and real not in roots:
+            roots.append(real)
+    return roots
+
+
+def state_dirs(roots, recorded):
+    """(registry dirs, audit-log dirs): `<root>/jobs` and
+    `<root>/delegate_job_logs` of every root, plus a recorded MAM_JOBS_DIR /
+    DELEGATE_JOB_LOGS_DIR that is not one of those."""
+    jobs = [os.path.join(r, "jobs") for r in roots]
+    logs = [os.path.join(r, "delegate_job_logs") for r in roots]
+    for var, dirs in (("MAM_JOBS_DIR", jobs), ("DELEGATE_JOB_LOGS_DIR", logs)):
+        if recorded.get(var):
+            real = os.path.realpath(recorded[var])
+            if os.path.isdir(real) and real not in dirs:
+                dirs.append(real)
+    return jobs, logs
+
+
+def snapshot(roots, recorded):
+    """Registry records (`*.json`) and audit-log entries per watched dir; a
+    missing dir counts as empty."""
+    jobs, logs = state_dirs(roots, recorded)
+    return {
+        "jobs": {d: {n for n in _listdir(d) if n.endswith(".json")} for d in jobs},
+        "logs": {d: set(_listdir(d)) for d in logs},
+    }
+
+
+def session_names(yaml_path):
+    """Session names registered in an agent-sessions.yaml; empty if unreadable."""
+    try:
+        with open(yaml_path, encoding="utf-8", errors="replace") as fh:
+            return {m.group(1) for m in map(_SESSION_LINE.match, fh) if m}
+    except OSError:
+        return set()
+
+
+def _bare(session):
+    for prefix in SESSION_PREFIXES:
+        if session.startswith(prefix):
+            return session[len(prefix):]
+    return session
+
+
+def leaks(roots, before, recorded):
+    """New entries since `before` that no live delegation explains.
+
+    A real delegation writes its registry record before its audit log and
+    targets a registered session (registry.register_job), so a new entry is a
+    leak when
+      (a) it is an audit log whose job has no record in any watched registry, or
+      (b) its record's agent_session is missing or names no session in the
+          watched agent-sessions.yaml files.
+    Returns [{"path", "reason", "agent_session", "prompt"}] sorted by path."""
+    now = snapshot(roots, recorded)
+    yamls = [os.path.join(r, "agent-sessions.yaml") for r in roots]
+    if recorded.get("AGENT_SESSIONS_YAML"):
+        yamls.append(recorded["AGENT_SESSIONS_YAML"])
+    known = set()
+    for path in yamls:
+        known |= session_names(path)
+    records = {}
+    for d, names in now["jobs"].items():
+        for name in names:
+            records.setdefault(name[:-len(".json")], os.path.join(d, name))
+
+    found = []
+
+    def judge(path, meta, reason=None):
+        session = meta.get("agent_session")
+        if reason is None:
+            if not session:
+                reason = "no agent_session"
+            elif _bare(session) not in known:
+                reason = "agent_session names no registered session"
+            else:
+                return
+        found.append({"path": path, "reason": reason, "agent_session": session,
+                      "prompt": str(meta.get("prompt", ""))[:60]})
+
+    for d, names in now["jobs"].items():
+        for name in names - before["jobs"].get(d, set()):
+            path = os.path.join(d, name)
+            judge(path, _load(path))
+    for d, names in now["logs"].items():
+        for name in names - before["logs"].get(d, set()):
+            path = os.path.join(d, name)
+            if name in records:
+                judge(path, _load(records[name]))
+            else:
+                judge(path, _load(os.path.join(path, "meta.json")), "audit log without a registry record")
+    return sorted(found, key=lambda f: f["path"])
+
+
+def describe(found):
+    """Failure message for the session guard."""
+    lines = ["Issue #20: {} entr{} made during this session in a real control plane "
+             "(left in place; check and remove by hand):".format(len(found), "y" if len(found) == 1 else "ies")]
+    lines += ["  {path}  [{reason}]  agent_session={agent_session!r}  prompt={prompt!r}".format(**f)
+              for f in found]
+    return "\n".join(lines)