fix(followups): F5 - no test switch in the stall watcher

stall_watch read MAM_TEST_UNRELIABLE_AGENT to pretend an adapter's
agent_status was unreliable (PR #41 M7). The branch is gone. S13 now runs
the real stall_watch.main() in a process where the adapter itself reports
agent_status_reliable = False (_UNRELIABLE_MAIN), and checks the same
things as before: no idle notice or nudge, the blocked notice, and the
"idle judgement off" log line. A static check keeps MAM_TEST_ out of the
watcher (fails at 0051fd6). Without the seam S13 fails on this tree.

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

tests/test_issue30_stall_watch.py

@@ -193,11 +193,20 @@ def _kill(p: subprocess.Popen) -> None:
     p.wait()
 
 
-def _watch(env: dict, reg: Path, jid: str, target: str, agent: str) -> subprocess.Popen:
+# The real watcher's main() in a process whose `agent` adapter reports an
+# agent_status that cannot drive the idle judgement (S13) - the production
+# code has no switch for it.
+_UNRELIABLE_MAIN = ("import sys; from lib_py.agents.registry import get_adapter; "
+                    "type(get_adapter(sys.argv[1])).agent_status_reliable = property(lambda self: False); "
+                    "import lib_py.stall_watch as sw; sys.exit(sw.main(sys.argv[2:]))")
+
+
+def _watch(env: dict, reg: Path, jid: str, target: str, agent: str, unreliable: bool = False) -> subprocess.Popen:
     tok = _record(reg, jid)["dispatch_token"]
-    return subprocess.Popen([sys.executable, "-m", "lib_py.stall_watch", "--job", jid,
-                             "--registry-dir", str(reg), "--target", target, "--agent", agent,
-                             "--expect-dispatch-token", tok],
+    argv = ["--job", jid, "--registry-dir", str(reg), "--target", target, "--agent", agent,
+            "--expect-dispatch-token", tok]
+    entry = ["-c", _UNRELIABLE_MAIN, agent] if unreliable else ["-m", "lib_py.stall_watch"]
+    return subprocess.Popen([sys.executable, *entry, *argv],
                             env=env, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, text=True)
 
 
@@ -444,13 +453,12 @@ def test_s12_the_watcher_can_only_publish_progress():
 
 def test_s13_unreliable_agent_status_turns_idle_off_but_keeps_blocked(box):
     _, state, reg, env = box
-    env["MAM_TEST_UNRELIABLE_AGENT"] = "claude"
     jid = _job(env, reg)
     agent = _proc("exec sleep 300")
     try:
         _agent(state, "creator-claude-t", "claude", agent.pid, "idle", _pane("claude"),
                detection="Do you want to proceed?")
-        w = _watch(env, reg, jid, "creator-claude-t", "claude")
+        w = _watch(env, reg, jid, "creator-claude-t", "claude", unreliable=True)
         time.sleep(5)
         assert _details(reg, jid) == [] and not _prompts(state)
         st = json.loads(state.read_text())
@@ -464,6 +472,12 @@ def test_s13_unreliable_agent_status_turns_idle_off_but_keeps_blocked(box):
         _kill(agent)
 
 
+def test_s13_the_unreliable_case_needs_no_switch_in_the_product():
+    """PR #41 M7: the test sets the adapter up (_UNRELIABLE_MAIN); the watcher
+    reads no environment variable to pretend an adapter is unreliable."""
+    assert "MAM_TEST_" not in STALL_WATCH.read_text()
+
+
 # ---------------------------------------------------------------------------
 # scope - the #34 rule reaches the python herdr calls
 # ---------------------------------------------------------------------------