diff --git a/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Core/LineNumberEditApplyPlan.cs b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Core/LineNumberEditApplyPlan.cs
new file mode 100644
index 0000000..60c35d4
--- /dev/null
+++ b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Core/LineNumberEditApplyPlan.cs
@@ -0,0 +1,41 @@
+using System.Security.Cryptography;
+using System.Text;
+using PRecAnnot.Abstractions;
+
+namespace PRecAnnot.Core;
+
+/// <summary>
+/// Produces the canonical, fixture-bound payload for the legacy line-number
+/// editing commands.  The command-specific Apply permit signs this value so a
+/// controlled session cannot turn an arbitrary selected block or prompted
+/// value into a write merely by switching runtime mode to Apply.
+/// </summary>
+public static class LineNumberEditApplyPlan
+{
+    public static string ComputeMutationHash(string commandName, string selectedObjectHandle, IReadOnlyList<LineNumberRowMutation> mutations)
+    {
+        if (string.IsNullOrWhiteSpace(commandName)) throw new ArgumentException("LINE_NUMBER_EDIT_COMMAND_REQUIRED", nameof(commandName));
+        if (string.IsNullOrWhiteSpace(selectedObjectHandle)) throw new ArgumentException("LINE_NUMBER_EDIT_SELECTION_REQUIRED", nameof(selectedObjectHandle));
+        ArgumentNullException.ThrowIfNull(mutations);
+        if (mutations.Count == 0) throw new ArgumentException("LINE_NUMBER_EDIT_MUTATIONS_REQUIRED", nameof(mutations));
+
+        var canonical = new StringBuilder()
+            .Append(commandName).Append('|')
+            .Append(selectedObjectHandle).Append('\n');
+        foreach (var mutation in mutations.OrderBy(value => value.SourceStableId, StringComparer.Ordinal)
+                     .ThenBy(value => value.PreviousMarkerNumber)
+                     .ThenBy(value => value.MarkerNumber))
+        {
+            canonical.Append(mutation.SourceStableId).Append('|')
+                .Append(mutation.PreviousMarkerNumber).Append('|')
+                .Append(mutation.MarkerNumber).Append('|')
+                .Append(mutation.Text.Replace("\r\n", "\n", StringComparison.Ordinal).Replace("\r", "\n", StringComparison.Ordinal)).Append('|');
+            if (mutation.MarkerAttributePosition is { } position)
+                canonical.Append(position.X.ToString("R", System.Globalization.CultureInfo.InvariantCulture)).Append(',')
+                    .Append(position.Y.ToString("R", System.Globalization.CultureInfo.InvariantCulture)).Append(',')
+                    .Append(position.Z.ToString("R", System.Globalization.CultureInfo.InvariantCulture));
+            canonical.Append('\n');
+        }
+        return Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(canonical.ToString())));
+    }
+}
diff --git a/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/LineNumberApplyPermit.cs b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/LineNumberApplyPermit.cs
index 58e7083..28f8fcb 100644
--- a/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/LineNumberApplyPermit.cs
+++ b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/LineNumberApplyPermit.cs
@@ -1,6 +1,7 @@
 using System.Text.Json;
 using Autodesk.AutoCAD.ApplicationServices;
 using PRecAnnot.Abstractions;
+using PRecAnnot.Core;
 
 namespace PRecAnnot.Plant3D2026;
 
@@ -12,6 +13,15 @@ internal sealed record LineNumberApplyPermit
     public required string ExpectedText { get; init; }
 }
 
+internal sealed record LineNumberEditApplyPermit
+{
+    public required bool AllowApply { get; init; }
+    public required string FixtureMarkerPath { get; init; }
+    public required string ExpectedCommandName { get; init; }
+    public required string ExpectedSelectedObjectHandle { get; init; }
+    public required string ExpectedMutationHash { get; init; }
+}
+
 internal static class LineNumberApplyPermitReader
 {
     private const string MarkerContent = "P_REC_ANNOT_TEST_FIXTURE=LINE_NUMBER_APPLY";
@@ -35,3 +45,31 @@ internal static class LineNumberApplyPermitReader
             ?? throw new InvalidOperationException("LINE_NUMBER_APPLY_PERMIT_INVALID");
     }
 }
+
+internal static class LineNumberEditApplyPermitReader
+{
+    private const string MarkerContent = "P_REC_ANNOT_TEST_FIXTURE=LINE_NUMBER_EDIT_APPLY";
+
+    public static LineNumberEditApplyPermit Read()
+    {
+        var path = Environment.GetEnvironmentVariable("P_REC_ANNOT_LINE_NUMBER_EDIT_APPLY_PERMIT_PATH");
+        if (string.IsNullOrWhiteSpace(path) || !Path.IsPathFullyQualified(path) || path.StartsWith("\\\\", StringComparison.Ordinal) || !File.Exists(path))
+            throw new InvalidOperationException("LINE_NUMBER_EDIT_APPLY_PERMIT_REQUIRED");
+        return JsonSerializer.Deserialize<LineNumberEditApplyPermit>(File.ReadAllText(path), new JsonSerializerOptions { PropertyNameCaseInsensitive = true })
+            ?? throw new InvalidOperationException("LINE_NUMBER_EDIT_APPLY_PERMIT_INVALID");
+    }
+
+    public static void Validate(Document document, LineNumberEditApplyPermit permit, string commandName, string selectedObjectHandle, IReadOnlyList<LineNumberRowMutation> mutations)
+    {
+        var mutationHash = LineNumberEditApplyPlan.ComputeMutationHash(commandName, selectedObjectHandle, mutations);
+        if (!permit.AllowApply ||
+            !string.Equals(permit.ExpectedCommandName, commandName, StringComparison.Ordinal) ||
+            !string.Equals(permit.ExpectedSelectedObjectHandle, selectedObjectHandle, StringComparison.OrdinalIgnoreCase) ||
+            !string.Equals(permit.ExpectedMutationHash, mutationHash, StringComparison.OrdinalIgnoreCase))
+            throw new InvalidOperationException("LINE_NUMBER_EDIT_APPLY_PERMIT_PLAN_MISMATCH");
+        if (!Path.IsPathFullyQualified(permit.FixtureMarkerPath) || permit.FixtureMarkerPath.StartsWith("\\\\", StringComparison.Ordinal) || !File.Exists(permit.FixtureMarkerPath) || !string.Equals(File.ReadAllText(permit.FixtureMarkerPath).Trim(), MarkerContent, StringComparison.Ordinal))
+            throw new InvalidOperationException("LINE_NUMBER_EDIT_APPLY_TEST_FIXTURE_REQUIRED");
+        var fixtureRoot = Path.GetDirectoryName(Path.GetFullPath(permit.FixtureMarkerPath))! + Path.DirectorySeparatorChar;
+        if (!Path.GetFullPath(document.Name).StartsWith(fixtureRoot, StringComparison.OrdinalIgnoreCase)) throw new InvalidOperationException("LINE_NUMBER_EDIT_APPLY_TEST_FIXTURE_REQUIRED");
+    }
+}
diff --git a/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/LineNumberEditCommands.cs b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/LineNumberEditCommands.cs
index 288f40a..d488d7f 100644
--- a/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/LineNumberEditCommands.cs
+++ b/Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/LineNumberEditCommands.cs
@@ -16,7 +16,7 @@ internal static class LineNumberEditCommands
             var start = editor.GetInteger(new PromptIntegerOptions("\nВведите новое начальное значение маркера: ") { LowerLimit = 1 });
             if (start.Status != PromptStatus.OK) return null;
             var rows = new LineNumberOwnedAnnotationReader().ReadList(document, selected);
-            return new LineNumberAnnotationWriter().ApplyEdits(document, LineNumberEditPlanner.Renumber(rows, start.Value));
+            return LineNumberEditPlanner.Renumber(rows, start.Value);
         }, "Выберите блок списка номеров линий: ");
     }
 
@@ -30,7 +30,7 @@ internal static class LineNumberEditCommands
             var row = rows.SingleOrDefault(value => value.MarkerNumber == marker.Value) ?? throw new InvalidOperationException("LINE_NUMBER_ROW_NOT_FOUND");
             var text = editor.GetString(new PromptStringOptions("\nВведите новый текст номера линии: ") { AllowSpaces = true });
             if (text.Status != PromptStatus.OK) return null;
-            return new LineNumberAnnotationWriter().ApplyEdits(document, [LineNumberEditPlanner.EditText(row, text.StringResult)]);
+            return [LineNumberEditPlanner.EditText(row, text.StringResult)];
         }, "Выберите блок списка номеров линий: ");
     }
 
@@ -40,11 +40,11 @@ internal static class LineNumberEditCommands
         {
             var row = new LineNumberOwnedAnnotationReader().ReadMarker(document, selected);
             var configured = LineNumberRuntimeConfigurationReader.Read().Assets.Marker.Texts[0].Position;
-            return new LineNumberAnnotationWriter().ApplyEdits(document, [LineNumberEditPlanner.ResetMarkerAttributePosition(row, configured)]);
+            return [LineNumberEditPlanner.ResetMarkerAttributePosition(row, configured)];
         }, "Выберите маркер номера линии: ");
     }
 
-    private static void Run(string command, Func<Document, Editor, ObjectId, LineNumberApplyResult?> operation, string prompt)
+    private static void Run(string command, Func<Document, Editor, ObjectId, IReadOnlyList<LineNumberRowMutation>?> operation, string prompt)
     {
         var document = AcadApplication.DocumentManager.MdiActiveDocument;
         if (document is null) return;
@@ -65,8 +65,11 @@ internal static class LineNumberEditCommands
             options.AddAllowedClass(typeof(BlockReference), true);
             var selected = document.Editor.GetEntity(options);
             if (selected.Status != PromptStatus.OK) return;
-            var result = operation(document, document.Editor, selected.ObjectId);
-            if (result is null) return;
+            var mutations = operation(document, document.Editor, selected.ObjectId);
+            if (mutations is null) return;
+            var selectedHandle = selected.ObjectId.Handle.ToString();
+            LineNumberEditApplyPermitReader.Validate(document, LineNumberEditApplyPermitReader.Read(), command, selectedHandle, mutations);
+            var result = new LineNumberAnnotationWriter().ApplyEdits(document, mutations);
             document.Editor.WriteMessage($"\n{command}: updated={result.Updated}; unchanged={result.Unchanged}.");
             RuntimeDiagnostics.Write("LineNumberEditCompleted", commandName: command, resultStatus: result.Updated > 0 ? "Updated" : "AlreadyCurrent", document: document,
                 details: new Dictionary<string, object?> { ["Updated"] = result.Updated, ["AlreadyCurrent"] = result.Unchanged });
diff --git a/Plant3D2026/P_Rec_Annot/tests/PRecAnnot.Core.Tests/LineNumberEditApplyPlanTests.cs b/Plant3D2026/P_Rec_Annot/tests/PRecAnnot.Core.Tests/LineNumberEditApplyPlanTests.cs
new file mode 100644
index 0000000..094b5b9
--- /dev/null
+++ b/Plant3D2026/P_Rec_Annot/tests/PRecAnnot.Core.Tests/LineNumberEditApplyPlanTests.cs
@@ -0,0 +1,30 @@
+using PRecAnnot.Abstractions;
+using PRecAnnot.Core;
+using Xunit;
+
+namespace PRecAnnot.Core.Tests;
+
+public sealed class LineNumberEditApplyPlanTests
+{
+    [Fact]
+    public void MutationHash_IsStableAcrossInputOrder()
+    {
+        var first = new LineNumberRowMutation("pipe-a", 1, 10, "A", new(1, 2, 3));
+        var second = new LineNumberRowMutation("pipe-b", 2, 11, "B", null);
+
+        var expected = LineNumberEditApplyPlan.ComputeMutationHash("PXP-ESN", "1A2B", [first, second]);
+
+        Assert.Equal(expected, LineNumberEditApplyPlan.ComputeMutationHash("PXP-ESN", "1A2B", [second, first]));
+    }
+
+    [Fact]
+    public void MutationHash_BindsCommandSelectionAndRequestedEdit()
+    {
+        var mutation = new LineNumberRowMutation("pipe-a", 1, 10, "A", null);
+        var expected = LineNumberEditApplyPlan.ComputeMutationHash("PXP-ESN", "1A2B", [mutation]);
+
+        Assert.NotEqual(expected, LineNumberEditApplyPlan.ComputeMutationHash("PXP-ELN", "1A2B", [mutation]));
+        Assert.NotEqual(expected, LineNumberEditApplyPlan.ComputeMutationHash("PXP-ESN", "2B3C", [mutation]));
+        Assert.NotEqual(expected, LineNumberEditApplyPlan.ComputeMutationHash("PXP-ESN", "1A2B", [mutation with { Text = "Changed" }]));
+    }
+}
diff --git a/Plant3D2026/P_Rec_Annot/tests/PRecAnnot.Core.Tests/LineNumberEditCommandRegistrationTests.cs b/Plant3D2026/P_Rec_Annot/tests/PRecAnnot.Core.Tests/LineNumberEditCommandRegistrationTests.cs
index bc09e63..769b82a 100644
--- a/Plant3D2026/P_Rec_Annot/tests/PRecAnnot.Core.Tests/LineNumberEditCommandRegistrationTests.cs
+++ b/Plant3D2026/P_Rec_Annot/tests/PRecAnnot.Core.Tests/LineNumberEditCommandRegistrationTests.cs
@@ -39,7 +39,10 @@ public sealed class LineNumberEditCommandRegistrationTests
     public void MutationCommands_UseOneTransactionalWriter()
     {
         var commands = File.ReadAllText(Path.Combine(ProjectRoot, "LineNumberEditCommands.cs"));
-        Assert.Equal(3, System.Text.RegularExpressions.Regex.Matches(commands, "ApplyEdits\\(document").Count);
+        Assert.Single(System.Text.RegularExpressions.Regex.Matches(commands, "ApplyEdits\\(document").Cast<System.Text.RegularExpressions.Match>());
+        Assert.Contains("LineNumberEditApplyPermitReader.Validate", commands);
+        Assert.Contains("ExpectedSelectedObjectHandle", File.ReadAllText(Path.Combine(ProjectRoot, "LineNumberApplyPermit.cs")));
+        Assert.Contains("ExpectedMutationHash", File.ReadAllText(Path.Combine(ProjectRoot, "LineNumberApplyPermit.cs")));
     }
 
     [Fact]