fix: make uint32 saturation portable

client.go

@@ -25,7 +25,13 @@
 
 // saturateUint32 converts v to uint32, clamping to math.MaxUint32 on overflow.
 func saturateUint32(v int) uint32 {
-	return uint32(min(max(v, 0), math.MaxUint32)) //nolint:gosec // clamped to [0, MaxUint32]
+	if v <= 0 {
+		return 0
+	}
+	if uint64(v) > uint64(math.MaxUint32) {
+		return math.MaxUint32
+	}
+	return uint32(v) //nolint:gosec // checked to be in [0, MaxUint32]
 }
 
 // Client is the module-side endpoint that connects to a compositor and

saturate_test.go

@@ -0,0 +1,51 @@
+package compose
+
+import (
+	"math"
+	"testing"
+)
+
+func TestSaturateUint32(t *testing.T) {
+	maxUint32 := uint64(math.MaxUint32)
+	maxInt := int(^uint(0) >> 1)
+	wantMaxInt := uint32(maxInt)
+	if uint64(maxInt) > maxUint32 {
+		wantMaxInt = math.MaxUint32
+	}
+
+	tests := []struct {
+		name  string
+		input int
+		want  uint32
+	}{
+		{name: "negative", input: -1, want: 0},
+		{name: "zero", input: 0, want: 0},
+		{name: "one", input: 1, want: 1},
+		{name: "max int", input: maxInt, want: wantMaxInt},
+	}
+
+	// math.MaxUint32 is wider than int on 32-bit systems, so these cases
+	// are added only where the boundary is representable as an int.
+	if uint64(maxInt) >= maxUint32 {
+		tests = append(tests, struct {
+			name  string
+			input int
+			want  uint32
+		}{name: "max uint32", input: int(maxUint32), want: math.MaxUint32})
+	}
+	if uint64(maxInt) > maxUint32 {
+		tests = append(tests, struct {
+			name  string
+			input int
+			want  uint32
+		}{name: "above max uint32", input: int(maxUint32 + 1), want: math.MaxUint32})
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := saturateUint32(tt.input); got != tt.want {
+				t.Fatalf("saturateUint32(%d) = %d, want %d", tt.input, got, tt.want)
+			}
+		})
+	}
+}