fix(node): register the service-mode task with Register-ScheduledTask -LogonType S4U

schtasks.exe has no flag naming the logon type directly -- it only infers
S4U vs Interactive from whether /rp is present, and both readings broke
live on a blank-password account: /rp "" fails schtasks' own credential
validation, and omitting /rp registers "Interactive only", which never
launches the process at boot or on demand despite installing cleanly.

Register-ScheduledTask -LogonType S4U names the logon type explicitly, no
inference. Confirmed live: install, manual start, and unattended boot-time
start all now work.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

2 files changed, 68 insertions, 25 deletions

diff --git a/packages/meshbay-node/tests/test_packaging_win.py b/packages/meshbay-node/tests/test_packaging_win.py
index 0cf6367..df5a24f 100644
--- a/packages/meshbay-node/tests/test_packaging_win.py
+++ b/packages/meshbay-node/tests/test_packaging_win.py
@@ -284,29 +284,39 @@ def test_service_ps1_and_service_mode_ps1_are_extraresources():
 
 def test_service_install_uses_s4u_not_a_stored_password():
     """
-    schtasks /create ... /ru <user> /rp "" with no /it registers an S4U logon:
-    no password stored anywhere, and — unlike LocalSystem/NetworkService — it
-    loads this account's own profile, so %LOCALAPPDATA%\\meshbay\\ needs no
-    relocation. Losing the empty /rp "" (e.g. "fixing" it into a real prompt
-    for a password) would either store a secret or silently stop working.
+    Register-ScheduledTask -LogonType S4U: no password stored anywhere, and
+    — unlike LocalSystem/NetworkService — it loads this account's own
+    profile, so %LOCALAPPDATA%\\meshbay\\ needs no relocation.
+
+    Not `schtasks /create`: schtasks only *infers* the logon type from
+    whether /rp is present, and both readings broke live on a blank-password
+    account (common on a personal PC, 2026-09-05) -- `/rp ""` fails
+    credential validation ("the user name or password is incorrect", even
+    though nothing is wrong), and omitting /rp registers "Interactive only"
+    instead of S4U, which never runs at boot and does not launch anything
+    even run on demand while signed in. -LogonType S4U is explicit, so losing
+    it (e.g. "simplifying" back to schtasks, or dropping -ErrorAction Stop so
+    a permission failure silently falls through to "installed") would
+    reintroduce one of those two live-reproduced failures.
     """
     src = (WIN / "service.ps1").read_text(encoding="utf-8")
-    # The prose above the actual command is allowed to say "/it" while
-    # explaining why it is absent (the same "read the comment, not the
-    # directive" trap CLAUDE.md already tracks) -- so check the real
-    # invocation line, not the whole file.
-    create_line = next(
-        (line for line in src.splitlines() if line.strip().startswith("& schtasks")
-         and "/create" in line), None)
-    assert create_line, "no schtasks /create invocation found"
-    tokens = create_line.split()
-    assert "/sc" in tokens and tokens[tokens.index("/sc") + 1] == "onstart", (
-        "must trigger at boot, not at sign-in (/sc onlogon)")
-    assert "/ru" in tokens
-    assert "/rp" in tokens and tokens[tokens.index("/rp") + 1] == '""', (
-        "must pass an empty run-as password (S4U)")
-    assert "/it" not in tokens, "an interactive-token task would need the user signed in"
+    # Isolate the actual "install" case from the docstring above it (which
+    # names these same cmdlets in prose) -- checks below must see only code.
+    lines = src.splitlines()
+    install_start = next(i for i, line in enumerate(lines) if '"install" {' in line)
+    remove_start = next(i for i, line in enumerate(lines) if '"remove" {' in line)
+    install_block = "\n".join(lines[install_start:remove_start])
+
+    assert "New-ScheduledTaskTrigger -AtStartup" in install_block, (
+        "must trigger at boot, not at sign-in")
+    assert "-LogonType S4U" in install_block, (
+        "must request S4U explicitly, not infer it from /rp")
+    assert "Register-ScheduledTask" in install_block
+    assert "-ErrorAction Stop" in install_block, (
+        "a permission failure must throw, not fall through as if it installed")
     assert "Get-Credential" not in src, "no password should ever be prompted for"
+    assert "schtasks" not in install_block, (
+        "the install branch must not fall back to schtasks /create")
 
 
 def test_service_task_name_is_the_same_everywhere():
diff --git a/packages/meshbay-node/tests/test_platform.py b/packages/meshbay-node/tests/test_platform.py
index 91713be..92e74df 100644
--- a/packages/meshbay-node/tests/test_platform.py
+++ b/packages/meshbay-node/tests/test_platform.py
@@ -346,24 +346,57 @@ def test_service_install_removes_the_startup_launcher_first(win_startup, monkeyp
     monkeypatch.setattr(plat, "_current_user", lambda: "DOMAIN\\user")
     calls = []
     monkeypatch.setattr(
-        plat, "_schtasks",
-        lambda *args: calls.append(args) or Mock(returncode=0, stdout="", stderr=""))
+        plat.subprocess, "run",
+        lambda argv, **kw: calls.append((argv, kw)) or Mock(returncode=0, stdout="", stderr=""))
 
     plat.service_install(exe=r"C:\x\meshbay-node.exe")
 
     assert not win_startup.exists()       # removed as part of service_install
-    assert calls and calls[0][0] == "/create"
+    assert calls and calls[0][0][0] == "powershell"
+    env = calls[0][1]["env"]
+    assert env["MESHBAY_SVC_USER"] == "DOMAIN\\user"
+    assert env["MESHBAY_SVC_EXE"] == r"C:\x\meshbay-node.exe"
+
+
+def test_service_install_uses_s4u_not_a_stored_password(monkeypatch):
+    """Register-ScheduledTask -LogonType S4U, not schtasks: schtasks only
+    infers the logon type from whether /rp is present, and both readings
+    broke live on a blank-password account (2026-09-05) -- /rp "" fails
+    credential validation, and omitting /rp registers "Interactive only",
+    which never runs at boot or on demand. See platform.py's service mode
+    comment for the full story."""
+    monkeypatch.setattr(plat, "_current_user", lambda: "DOMAIN\\user")
+    calls = []
+    monkeypatch.setattr(
+        plat.subprocess, "run",
+        lambda argv, **kw: calls.append((argv, kw)) or Mock(returncode=0, stdout="", stderr=""))
+
+    plat.service_install(exe=r"C:\x\meshbay-node.exe")
+
+    script = calls[0][0][-1]
+    assert "-LogonType S4U" in script
+    assert "New-ScheduledTaskTrigger -AtStartup" in script
 
 
 def test_service_install_tolerates_no_startup_launcher_present(win_startup, monkeypatch):
     assert not win_startup.exists()
     monkeypatch.setattr(plat, "_current_user", lambda: "DOMAIN\\user")
-    monkeypatch.setattr(plat, "_schtasks",
-                        lambda *args: Mock(returncode=0, stdout="", stderr=""))
+    monkeypatch.setattr(plat.subprocess, "run",
+                        lambda argv, **kw: Mock(returncode=0, stdout="", stderr=""))
     plat.service_install(exe=r"C:\x\meshbay-node.exe")   # no error
     assert not win_startup.exists()
 
 
+def test_service_install_raises_with_powershells_error_message(monkeypatch):
+    monkeypatch.setattr(plat, "_current_user", lambda: "DOMAIN\\user")
+    monkeypatch.setattr(
+        plat.subprocess, "run",
+        lambda argv, **kw: Mock(returncode=1, stdout="", stderr="Access is denied."))
+
+    with pytest.raises(RuntimeError, match="Access is denied"):
+        plat.service_install(exe=r"C:\x\meshbay-node.exe")
+
+
 # ── Packaged defaults ────────────────────────────────────────────────────────
 
 def test_frozen_build_finds_default_env_beside_the_executable(monkeypatch, tmp_path):