fix(focas): decode all four bytes of an axis/spindle name record, up to the first NUL

ReadNameRecord read only the first 2 bytes of each 4-byte 0x0089/0x008A record,
so the real 31i-B's paired axes 'AA6'/'AA7' (live capture ref-axisname-0x0089.bin)
both decoded as 'AA' -- the 'Makino with two AA axes' that #548 then had to
disambiguate as AA_1/AA_2. The name is now the record's ASCII up to its FIRST
NUL (not trailing-NUL trimming), so buffer residue such as Z-34184's spindle
record 53 31 00 4e ('S1' + an 'N' left from an earlier 'CNC') is discarded.

Client-visible: on such a machine Axes/AA_1 and Axes/AA_2 become Axes/AA6 and
Axes/AA7 (the old names were a decode artefact). #548's disambiguation stays as
the guard for genuinely duplicate names.

Ported from the sister ignitionoee FOCAS driver (Focas.Wire-001, Focas.Wire-022
/ v0.18.1).

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/FixedTreeNames.cs

@@ -41,11 +41,18 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.FOCAS;
 ///     config redeploy).
 ///     </para>
 ///     <para>
-///     Suffix collisions with genuine names are structurally impossible for axes (FOCAS axis
-///     displays are at most two characters — name + suffix — so they cannot contain <c>_</c>),
-///     but the generator still checks: a generated segment that would collide with anything
-///     else in the set escalates its ordinal until unique, so the output is always
-///     collision-free whatever the input.
+///     Suffix collisions with genuine names are not expected (a FOCAS name record is at most four
+///     ASCII characters and controls do not use <c>_</c>), but the generator still checks: a
+///     generated segment that would collide with anything else in the set escalates its ordinal
+///     until unique, so the output is always collision-free whatever the input.
+///     </para>
+///     <para>
+///     <b>Note on the Makino that motivated this.</b> Its two "AA" axes were a decode artefact:
+///     the name records actually read <c>"AA6"</c> and <c>"AA7"</c>, and the wire layer read only
+///     the first two bytes of each 4-byte record. With the full record decoded
+///     (<see cref="Wire.FocasWireProtocol.ReadNameRecord"/>) that machine reports unique names and
+///     its axes publish bare (<c>Axes/AA6</c>, <c>Axes/AA7</c>). This disambiguation remains as the
+///     guard for a control that genuinely reports duplicates.
 ///     </para>
 /// </remarks>
 internal static class FixedTreeNames

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/Wire/FocasWireClient.cs

@@ -1114,7 +1114,17 @@ public sealed class FocasWireClient : IAsyncDisposable, IDisposable
         return alarms;
     }
 
-    private static IReadOnlyList<T> ReadNameRecords<T>(byte[] payload, short maxCount, Func<short, string, T> factory)
+    /// <summary>
+    ///     Decode an axis-name (0x0089) or spindle-name (0x008A) payload: an array of 4-byte records,
+    ///     each named by <see cref="FocasWireProtocol.ReadNameRecord"/>. Blank records are skipped but
+    ///     keep their slot's 1-based index.
+    /// </summary>
+    /// <typeparam name="T">The record type the factory builds.</typeparam>
+    /// <param name="payload">The response-block payload.</param>
+    /// <param name="maxCount">Maximum number of records to inspect.</param>
+    /// <param name="factory">Builds one record from its 1-based index and name.</param>
+    /// <returns>The non-blank records, in wire order.</returns>
+    internal static IReadOnlyList<T> ReadNameRecords<T>(byte[] payload, short maxCount, Func<short, string, T> factory)
     {
         var names = new List<T>();
         for (var offset = 0; offset + 4 <= payload.Length && offset / 4 < maxCount; offset += 4)

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/Wire/FocasWireProtocol.cs

@@ -239,19 +239,34 @@ internal static class FocasWireProtocol
     }
 
     /// <summary>
-    ///     Read an axis/spindle name record — the first 2 bytes of a 2-byte (axis) or 4-byte
-    ///     (spindle) slot. Trailing spaces and NULs are stripped so <c>"X "</c> becomes
-    ///     <c>"X"</c>.
+    ///     Read one 4-byte axis/spindle name record: the ASCII up to (not including) the record's
+    ///     FIRST NUL, at most 4 bytes, with trailing spaces trimmed — <c>"X \0\0"</c> → <c>"X"</c>,
+    ///     <c>"AA6\0"</c> → <c>"AA6"</c>, <c>"S1\0N"</c> → <c>"S1"</c>.
     /// </summary>
-    /// <param name="bytes">The bytes to decode.</param>
-    /// <returns>The decoded name record.</returns>
+    /// <remarks>
+    ///     <para><b>All four bytes are name bytes.</b> This used to read only the first two, which
+    ///     collapsed the real 31i-B's paired axes <c>"AA6"</c>/<c>"AA7"</c> (live capture
+    ///     <c>ref-axisname-0x0089.bin</c>) to two axes both called <c>"AA"</c> — the duplicate Gitea
+    ///     #548 then had to disambiguate as <c>AA_1</c>/<c>AA_2</c>.</para>
+    ///     <para><b>The first NUL terminates, not trailing-NUL trimming.</b> A control writes only the
+    ///     bytes its name needs and leaves the rest of the buffer as it found it: Makino Z-34184's
+    ///     <c>cnc_rdspdlname</c> answered <c>53 31 00 4e</c> — <c>"S1"</c> plus the <c>'N'</c> of an
+    ///     earlier <c>"CNC"</c> response. Both rules are ported from the sister ignitionoee FOCAS
+    ///     driver (Focas.Wire-001 / Focas.Wire-022).</para>
+    /// </remarks>
+    /// <param name="bytes">The record bytes (4 on the wire; a shorter span is read as far as it goes).</param>
+    /// <returns>The decoded name; empty for a blank record.</returns>
     public static string ReadNameRecord(ReadOnlySpan<byte> bytes)
     {
-        if (bytes.Length < 2) return string.Empty;
-        var buffer = bytes.Slice(0, Math.Min(2, bytes.Length)).ToArray();
-        return Encoding.ASCII.GetString(buffer).TrimEnd(' ', '\0');
+        var record = bytes.Slice(0, Math.Min(NameRecordLength, bytes.Length));
+        var nul = record.IndexOf((byte)0);
+        if (nul >= 0) record = record.Slice(0, nul);
+        return Encoding.ASCII.GetString(record).TrimEnd(' ');
     }
 
+    /// <summary>Byte length of one axis/spindle name record.</summary>
+    public const int NameRecordLength = 4;
+
     private static byte[] BuildRequestBlock(RequestBlock request)
     {
         var extra = request.ExtraPayload ?? Array.Empty<byte>();