fix(windows): load WTSGetActiveConsoleSessionId from kernel32

getActiveConsoleUser looked up WTSGetActiveConsoleSessionId in
wtsapi32.dll. Windows exports it from kernel32.dll, so Find failed on
every host and console-session discovery always returned no user.

Before #602 the registry fallbacks hid this. Daemon start now uses
session-only discovery, so on Windows every managed start omitted
username even with a user signed in at the console.

Use windows.WTSGetActiveConsoleSessionId from golang.org/x/sys, which
binds the kernel32 export. Add a Windows test that compares
discoverSessionUser with the active console row of quser.

discover_user_windows.go

@@ -14,10 +14,9 @@ import (
 )
 
 var (
-	wtsapi32                         = windows.NewLazySystemDLL("wtsapi32.dll")
-	procWTSGetActiveConsoleSessionId = wtsapi32.NewProc("WTSGetActiveConsoleSessionId")
-	procWTSQuerySessionInformation   = wtsapi32.NewProc("WTSQuerySessionInformationW")
-	procWTSFreeMemory                = wtsapi32.NewProc("WTSFreeMemory")
+	wtsapi32                       = windows.NewLazySystemDLL("wtsapi32.dll")
+	procWTSQuerySessionInformation = wtsapi32.NewProc("WTSQuerySessionInformationW")
+	procWTSFreeMemory              = wtsapi32.NewProc("WTSFreeMemory")
 )
 
 const (
@@ -75,12 +74,8 @@ func discoverSessionUser(ctx context.Context) string {
 
 // getActiveConsoleUser gets the username of the active console session
 func getActiveConsoleUser(ctx context.Context) string {
-	// Guard against missing WTS procedures (e.g., Windows Server Core).
-	if err := procWTSGetActiveConsoleSessionId.Find(); err != nil {
-		LoggerFromCtx(ctx).Debug().Err(err).Msg("WTSGetActiveConsoleSessionId not available, skipping console session check")
-		return ""
-	}
-	sessionId, _, _ := procWTSGetActiveConsoleSessionId.Call()
+	// WTSGetActiveConsoleSessionId is exported by kernel32.dll, not wtsapi32.dll.
+	sessionId := windows.WTSGetActiveConsoleSessionId()
 	if sessionId == 0xFFFFFFFF { // Invalid session
 		LoggerFromCtx(ctx).Debug().Msg("no active console session found")
 		return ""
@@ -95,7 +90,7 @@ func getActiveConsoleUser(ctx context.Context) string {
 	}
 	ret, _, _ := procWTSQuerySessionInformation.Call(
 		0, // WTS_CURRENT_SERVER_HANDLE
-		sessionId,
+		uintptr(sessionId),
 		uintptr(WTSUserName),
 		uintptr(unsafe.Pointer(&buffer)),
 		uintptr(unsafe.Pointer(&bytesReturned)),

discover_user_windows_test.go

@@ -0,0 +1,49 @@
+//go:build windows
+
+package ctrld
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"os/exec"
+	"strings"
+	"testing"
+)
+
+// Every procedure that console-session discovery loads at runtime must exist in
+// the DLL it is loaded from. A wrong DLL makes Find fail on every host, so
+// discovery silently reports no user instead of the signed-in one.
+func TestConsoleSessionProceduresResolve(t *testing.T) {
+	for _, p := range []interface {
+		Find() error
+	}{procWTSQuerySessionInformation, procWTSFreeMemory} {
+		if err := p.Find(); err != nil {
+			t.Fatalf("console session procedure does not resolve: %v", err)
+		}
+	}
+}
+
+// discoverSessionUser must agree with Windows' own view of the console session:
+// the user shown on the active "console" row of `query user`, or no user when
+// that row is absent.
+func TestDiscoverSessionUserMatchesConsoleSession(t *testing.T) {
+	quser, err := exec.LookPath("quser.exe")
+	if err != nil {
+		t.Skip("quser.exe not available")
+	}
+	// quser exits 1 when no session exists; its output still answers the question.
+	out, _ := exec.Command(quser).CombinedOutput()
+	want := ""
+	sc := bufio.NewScanner(bytes.NewReader(out))
+	for sc.Scan() {
+		f := strings.Fields(strings.TrimPrefix(sc.Text(), ">"))
+		if len(f) >= 4 && strings.EqualFold(f[1], "console") && strings.EqualFold(f[3], "Active") {
+			want = f[0]
+		}
+	}
+	got := discoverSessionUser(context.Background())
+	if !strings.EqualFold(got, want) {
+		t.Fatalf("discoverSessionUser() = %q, want %q (quser output: %q)", got, want, out)
+	}
+}