fix(simulation): stabilize PX4 readiness supervision

tests/test_simulation_s1_orchestrator.py

@@ -212,6 +212,10 @@ def test_start_failure_and_profile_drift_fail_terminal(tmp_path: Path) -> None:
     )
     assert failed.state is RunState.FAILED
     assert failed.terminal_reason == "orchestrator-start-failed"
+    assert any(
+        event.payload.get("detail") == "RuntimeError: synthetic start failure"
+        for event in service.store.list_events("run-s1b-001")
+    )
 
     store = QualificationRunStore(tmp_path / "drift")
     store.create(_run())
@@ -343,11 +347,13 @@ def test_process_supervisor_rolls_back_partial_start(tmp_path: Path) -> None:
 @pytest.mark.skipif(os.name != "posix", reason="target supervisor is POSIX-only")
 def test_process_supervisor_waits_for_all_declared_ready_markers(tmp_path: Path) -> None:
     child = (
-        "import signal,time;"
+        "import signal,sys,time;"
         "signal.signal(signal.SIGINT,lambda *_:exit(0));"
         "print('provider booting',flush=True);"
         "time.sleep(0.05);"
-        "print('transport connected',flush=True);"
+        "sys.stdout.write('transport ');sys.stdout.flush();"
+        "time.sleep(0.05);"
+        "print('connected',flush=True);"
         "time.sleep(60)"
     )
     supervisor = PosixProcessSupervisor(tmp_path / "runtime")
@@ -432,7 +438,10 @@ def test_stock_rover_profile_builds_exact_reviewed_provider_graph() -> None:
     )
     assert specs[0].ready_log_patterns == ("running...",)
     assert specs[1].argv[-2:] == ("px4_sitl", "gz_rover_ackermann")
-    assert specs[1].ready_log_patterns[-1] == "Running, connected"
+    assert specs[1].ready_log_patterns[-1] == (
+        "successfully created rt/fmu/out/vehicle_status_v1 data writer"
+    )
+    assert specs[1].keep_stdin_open
     assert dict(specs[1].environment) == {
         "HEADLESS": "1",
         "PX4_SIM_SPEED_FACTOR": "1",