Auto: focas-f1e — operator messages + block text

Closes #261

src/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/FwlibNative.cs

@@ -141,6 +141,32 @@ internal static class FwlibNative
         short length,
         ref IODBZOFS buffer);
 
+    // ---- Operator messages ----
+
+    /// <summary>
+    ///     <c>cnc_rdopmsg3</c> — read FANUC operator messages by class. <paramref name="type"/>:
+    ///     0 = OPMSG (op-msg ladder/macro), 1 = MACRO, 2 = EXTERN (external operator message),
+    ///     3 = REJ-EXT (rejected EXTERN). <paramref name="length"/>: per <c>fwlib32.h</c> the
+    ///     buffer is <c>4 + 256 = 260</c> bytes per message slot — single-slot reads (length 260)
+    ///     return the most-recent message in that class. Issue #261, plan PR F1-e.
+    /// </summary>
+    [DllImport(Library, EntryPoint = "cnc_rdopmsg3", CharSet = CharSet.Ansi, ExactSpelling = true)]
+    public static extern short RdOpMsg3(
+        ushort handle,
+        short type,
+        short length,
+        ref OPMSG3 buffer);
+
+    // ---- Currently-executing block ----
+
+    /// <summary>
+    ///     <c>cnc_rdactpt</c> — read the currently-executing program block text. The
+    ///     reply struct holds the program / sequence numbers + the active block as a
+    ///     null-padded ASCII string. Issue #261, plan PR F1-e.
+    /// </summary>
+    [DllImport(Library, EntryPoint = "cnc_rdactpt", CharSet = CharSet.Ansi, ExactSpelling = true)]
+    public static extern short RdActPt(ushort handle, ref ODBACTPT buffer);
+
     // ---- Structs ----
 
     /// <summary>
@@ -241,6 +267,37 @@ internal static class FwlibNative
         public byte[] Data;
     }
 
+    /// <summary>
+    ///     OPMSG3 — single-slot operator-message read buffer per <c>fwlib32.h</c>. Per Fanuc
+    ///     reference: <c>short datano</c> + <c>short type</c> + <c>char data[256]</c>. The
+    ///     text is null-terminated + space-padded; the managed side trims trailing nulls /
+    ///     spaces before publishing. Length = 4 + 256 = 260 bytes; total 256 wide enough
+    ///     for the longest documented operator message body (issue #261).
+    /// </summary>
+    [StructLayout(LayoutKind.Sequential, Pack = 1)]
+    public struct OPMSG3
+    {
+        public short Datano;
+        public short Type;
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 256)]
+        public byte[] Data;
+    }
+
+    /// <summary>
+    ///     ODBACTPT — current-block read buffer per <c>fwlib32.h</c>. Per Fanuc reference:
+    ///     <c>long o_no</c> (currently active O-number) + <c>long n_no</c> (sequence) +
+    ///     <c>char data[256]</c> (active block text). The text is null-terminated +
+    ///     space-padded; trimmed before publishing for stable round-trip (issue #261).
+    /// </summary>
+    [StructLayout(LayoutKind.Sequential, Pack = 1)]
+    public struct ODBACTPT
+    {
+        public int ONo;
+        public int NNo;
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 256)]
+        public byte[] Data;
+    }
+
     /// <summary>ODBST — CNC status info. Machine state, alarm flags, automatic / edit mode.</summary>
     [StructLayout(LayoutKind.Sequential, Pack = 1)]
     public struct ODBST