diff --git a/TESTING_GUIDE.md b/TESTING_GUIDE.md
index 56a8dad021..90f39433c2 100644
--- a/TESTING_GUIDE.md
+++ b/TESTING_GUIDE.md
@@ -50,6 +50,7 @@ The test project mirrors the production areas closely.
   publishes a trimmed RID-specific CLI and runs whichever entry point the SDK emits (`cdidx.dll` through `dotnet` or the native `cdidx`/`cdidx.exe` apphost). It is reported as skipped on macOS arm64 while SDK/ILLink can crash before exercising `cdidx` (#2586). Do not assume every SDK/runtime pair writes a `cdidx.dll` into self-contained publish output.
 - `QueryCommandRunnerTests.RunPublishedTrimmedCli_SearchSupportsCSharpRazorAliases`
   uses the same trimmed RID-specific publish path to verify C# Razor language aliases. It is also reported as skipped on macOS arm64 because the SDK/ILLink crash happens before the test reaches `cdidx`.
+  RID-specific publish helpers must route `NuGetLockFilePath` into the temporary publish output so local test runs do not add runtime sections to source `packages.lock.json` files (#2918).
 - `McpServerTests.cs`
   MCP JSON-RPC behavior and tool outputs.
 - `HttpMcpTransportTests.cs`
@@ -250,6 +251,7 @@ dotnet test --filter "FullyQualifiedName~GitHelperTests"
   は trimmed な RID 固有 CLI を publish し、SDK が生成した entry point（`dotnet` 経由の `cdidx.dll`、または native の `cdidx`/`cdidx.exe` apphost）を実行します。self-contained publish output に常に `cdidx.dll` が出るとは仮定しないでください。
 - `QueryCommandRunnerTests.RunPublishedTrimmedCli_SearchSupportsCSharpRazorAliases`
   は同じ trimmed RID 固有 publish 経路で C# Razor の言語 alias を検証します。このテストも macOS arm64 では、`cdidx` に到達する前に SDK/ILLink がクラッシュし得るため skipped として報告されます。
+  RID 固有 publish helper は `NuGetLockFilePath` を一時 publish 出力へ向け、ローカル test run が source の `packages.lock.json` に runtime section を追加しないようにしてください (#2918)。
 - `McpServerTests.cs`
   MCP の JSON-RPC 挙動とツール出力のテスト。
 - `GitHelperTests.cs`
diff --git a/changelog.d/unreleased/2918.fixed.md b/changelog.d/unreleased/2918.fixed.md
new file mode 100644
index 0000000000..5d327e0c12
--- /dev/null
+++ b/changelog.d/unreleased/2918.fixed.md
@@ -0,0 +1,17 @@
+---
+category: fixed
+issues:
+  - 2918
+affected:
+  - tests/CodeIndex.Tests/IndexCommandRunnerTests.cs
+  - tests/CodeIndex.Tests/QueryCommandRunnerTests.cs
+  - TESTING_GUIDE.md
+---
+
+## English
+
+- **Trimmed publish tests no longer dirty the source NuGet lock file on macOS (#2918)** - RID-specific test publishes now write their generated `packages.lock.json` to temporary publish output, so `dotnet test -p:UseSharedCompilation=false` no longer adds `net8.0/osx-arm64` to `src/CodeIndex/packages.lock.json`.
+
+## 日本語
+
+- **trimmed publish テストが macOS で source の NuGet lock file を汚さないようになりました (#2918)** - RID 固有の test publish は生成される `packages.lock.json` を一時 publish 出力へ書くため、`dotnet test -p:UseSharedCompilation=false` が `src/CodeIndex/packages.lock.json` に `net8.0/osx-arm64` を追加しなくなりました。
diff --git a/tests/CodeIndex.Tests/IndexCommandRunnerTests.cs b/tests/CodeIndex.Tests/IndexCommandRunnerTests.cs
index a42d65cc33..f458efe366 100644
--- a/tests/CodeIndex.Tests/IndexCommandRunnerTests.cs
+++ b/tests/CodeIndex.Tests/IndexCommandRunnerTests.cs
@@ -9028,6 +9028,8 @@ private static string PublishTrimmedCli(string outputDir)
         Directory.CreateDirectory(outputDir);
         var buildOutputDir = Path.Combine(outputDir, "bin", "publish") + Path.DirectorySeparatorChar;
         var intermediateDir = Path.Combine(outputDir, "obj", "publish") + Path.DirectorySeparatorChar;
+        Directory.CreateDirectory(intermediateDir);
+        var lockFilePath = Path.Combine(intermediateDir, "packages.lock.json");
 
         var psi = new System.Diagnostics.ProcessStartInfo
         {
@@ -9051,6 +9053,7 @@ private static string PublishTrimmedCli(string outputDir)
         psi.ArgumentList.Add("-p:PublishSingleFile=false");
         psi.ArgumentList.Add($"-p:OutputPath={buildOutputDir}");
         psi.ArgumentList.Add($"-p:IntermediateOutputPath={intermediateDir}");
+        psi.ArgumentList.Add($"-p:NuGetLockFilePath={lockFilePath}");
         psi.ArgumentList.Add("-p:UseSharedCompilation=false");
 
         using var process = System.Diagnostics.Process.Start(psi)
diff --git a/tests/CodeIndex.Tests/QueryCommandRunnerTests.cs b/tests/CodeIndex.Tests/QueryCommandRunnerTests.cs
index 6bb46e74c5..88509cad4b 100644
--- a/tests/CodeIndex.Tests/QueryCommandRunnerTests.cs
+++ b/tests/CodeIndex.Tests/QueryCommandRunnerTests.cs
@@ -32553,6 +32553,8 @@ private static string PublishTrimmedCli(string outputDir)
         Directory.CreateDirectory(outputDir);
         var buildOutputDir = Path.Combine(outputDir, "bin", "publish") + Path.DirectorySeparatorChar;
         var intermediateDir = Path.Combine(outputDir, "obj", "publish") + Path.DirectorySeparatorChar;
+        Directory.CreateDirectory(intermediateDir);
+        var lockFilePath = Path.Combine(intermediateDir, "packages.lock.json");
 
         var psi = new System.Diagnostics.ProcessStartInfo("dotnet")
         {
@@ -32575,6 +32577,7 @@ private static string PublishTrimmedCli(string outputDir)
         psi.ArgumentList.Add("-p:PublishSingleFile=false");
         psi.ArgumentList.Add($"-p:OutputPath={buildOutputDir}");
         psi.ArgumentList.Add($"-p:IntermediateOutputPath={intermediateDir}");
+        psi.ArgumentList.Add($"-p:NuGetLockFilePath={lockFilePath}");
         psi.ArgumentList.Add("-p:UseSharedCompilation=false");
 
         using var process = System.Diagnostics.Process.Start(psi)