Fix git fixture signing and stderr tee failures

TESTING_GUIDE.md

@@ -170,6 +170,7 @@ For boundary tests, use the smallest fixture that still crosses the boundary. If
 
 - Never assume global git identity exists.
 - Configure repo-local `user.name` and `user.email` inside the test setup.
+- Disable repo-local commit/tag signing for fixture repositories so global signing settings cannot prompt or fail non-interactively.
 - Use helper methods or `ProcessStartInfo.ArgumentList`; do not depend on shell-specific quoting behavior.
 
 ### Database tests
@@ -366,6 +367,7 @@ dotnet test --filter "FullyQualifiedName~GitHelperTests"
 
 - global の git identity がある前提にしない。
 - テストセットアップ内で repo-local の `user.name` と `user.email` を設定する。
+- fixture リポジトリでは repo-local の commit/tag signing を無効化し、global signing 設定が非対話実行でプロンプトや失敗を起こさないようにする。
 - shell 依存の quoting ではなく、ヘルパーや `ProcessStartInfo.ArgumentList` を使う。
 
 ### DB 系テスト

changelog.d/unreleased/2729.fixed.md

@@ -0,0 +1,19 @@
+---
+category: fixed
+issues:
+  - 2729
+affected:
+  - tests/CodeIndex.Tests/TestProjectHelper.cs
+  - tests/CodeIndex.Tests/GitHelperTests.cs
+  - tests/CodeIndex.Tests/IndexCommandRunnerTests.cs
+  - tests/CodeIndex.Tests/GitTestProjectHelperTests.cs
+  - TESTING_GUIDE.md
+---
+
+## English
+
+- **Git-backed test fixtures no longer inherit commit signing (#2729)** — temporary repositories created by test helpers now disable commit and tag signing locally so fixture commits do not prompt for signing-key passphrases.
+
+## 日本語
+
+- **Git を使うテスト fixture が commit signing を引き継がなくなりました (#2729)** — テストヘルパーが作る一時リポジトリでは commit / tag signing を repo-local に無効化し、fixture commit が署名キーのパスフレーズ入力を要求しないようにしました。

changelog.d/unreleased/2730.fixed.md

@@ -0,0 +1,16 @@
+---
+category: fixed
+issues:
+  - 2730
+affected:
+  - src/CodeIndex/Cli/GlobalToolLog.cs
+  - tests/CodeIndex.Tests/GlobalToolLogTests.cs
+---
+
+## English
+
+- **Persistent stderr mirroring no longer cascades disposed-writer failures (#2730)** — the global tool log tee now treats closed console/log writers as best-effort failures instead of throwing `ObjectDisposedException` back into test or CLI callers.
+
+## 日本語
+
+- **永続 stderr mirror が閉じた writer の失敗を連鎖させなくなりました (#2730)** — global tool log の tee は、閉じた console/log writer をベストエフォートの失敗として扱い、`ObjectDisposedException` をテストや CLI 呼び出し元へ投げ返さないようになりました。

src/CodeIndex/Cli/GlobalToolLog.cs

@@ -638,26 +638,39 @@ private sealed class TeeTextWriter(TextWriter primary, TextWriter secondary) : T
 
         public override void Flush()
         {
-            primary.Flush();
-            secondary.Flush();
+            TryWrite(primary.Flush);
+            TryWrite(secondary.Flush);
         }
 
         public override void Write(char value)
         {
-            primary.Write(value);
-            secondary.Write(value);
+            TryWrite(() => primary.Write(value));
+            TryWrite(() => secondary.Write(value));
         }
 
         public override void Write(string? value)
         {
-            primary.Write(value);
-            secondary.Write(value);
+            TryWrite(() => primary.Write(value));
+            TryWrite(() => secondary.Write(value));
         }
 
         public override void WriteLine(string? value)
         {
-            primary.WriteLine(value);
-            secondary.WriteLine(value);
+            TryWrite(() => primary.WriteLine(value));
+            TryWrite(() => secondary.WriteLine(value));
+        }
+
+        private static void TryWrite(Action write)
+        {
+            try
+            {
+                write();
+            }
+            catch (Exception ex) when (ex is IOException or ObjectDisposedException)
+            {
+                // Best-effort mirror: a disposed console writer must not cascade into callers.
+                // mirror はベストエフォート。閉じた console writer が呼び出し側へ波及しないようにする。
+            }
         }
     }
 }

tests/CodeIndex.Tests/GitHelperTests.cs

@@ -699,6 +699,8 @@ private string CreateGitRepo()
         RunGit(repoDir, "init");
         RunGit(repoDir, "config", "user.name", "CodeIndex Tests");
         RunGit(repoDir, "config", "user.email", "tests@example.com");
+        RunGit(repoDir, "config", "commit.gpgsign", "false");
+        RunGit(repoDir, "config", "tag.gpgsign", "false");
 
         return repoDir;
     }

tests/CodeIndex.Tests/GitTestProjectHelperTests.cs

@@ -0,0 +1,41 @@
+namespace CodeIndex.Tests;
+
+public class GitTestProjectHelperTests
+{
+    [Fact]
+    public void InitializeGitRepo_DisablesCommitSigningForFixtureCommits()
+    {
+        var projectRoot = TestProjectHelper.CreateTempProject("cdidx_git_signing");
+        var globalConfig = Path.Combine(projectRoot, "global-gitconfig");
+        try
+        {
+            File.WriteAllText(
+                globalConfig,
+                """
+                [commit]
+                    gpgsign = true
+                [gpg]
+                    format = ssh
+                [user]
+                    signingkey = /definitely/missing/signing-key
+                """);
+            using var env = EnvironmentVariableScope.Capture("GIT_CONFIG_GLOBAL");
+            env.Set("GIT_CONFIG_GLOBAL", globalConfig);
+
+            TestProjectHelper.InitializeGitRepo(projectRoot);
+            File.WriteAllText(Path.Combine(projectRoot, "app.cs"), "class App {}\n");
+
+            TestProjectHelper.RunGit(projectRoot, "add", "app.cs");
+            var commitSigning = TestProjectHelper.RunGit(projectRoot, "config", "--get", "commit.gpgsign").Trim();
+            var tagSigning = TestProjectHelper.RunGit(projectRoot, "config", "--get", "tag.gpgsign").Trim();
+            TestProjectHelper.RunGit(projectRoot, "commit", "-m", "fixture");
+
+            Assert.Equal("false", commitSigning);
+            Assert.Equal("false", tagSigning);
+        }
+        finally
+        {
+            TestProjectHelper.DeleteDirectory(projectRoot);
+        }
+    }
+}

tests/CodeIndex.Tests/GlobalToolLogTests.cs

@@ -1,4 +1,5 @@
 using System.Globalization;
+using System.Text;
 using System.Text.RegularExpressions;
 using CodeIndex.Cli;
 
@@ -117,6 +118,52 @@ public void TryStart_WritesInvariantUtcTimestampAndStackTrace()
         }
     }
 
+    [Fact]
+    public void TryStart_ErrorMirrorIgnoresDisposedOriginalConsoleWriter()
+    {
+        var logRoot = Path.Combine(Path.GetTempPath(), $"cdidx_global_log_disposed_{Guid.NewGuid():N}");
+        var originalError = Console.Error;
+        try
+        {
+            using var env = EnvironmentVariableScope.Capture(
+                "CDIDX_FORCE_GLOBAL_TOOL_LOG",
+                "CDIDX_DISABLE_PERSISTENT_LOG",
+                "CDIDX_GLOBAL_TOOL_LOG_DIR");
+            env.Set("CDIDX_FORCE_GLOBAL_TOOL_LOG", "1");
+            env.Set("CDIDX_DISABLE_PERSISTENT_LOG", null);
+            env.Set("CDIDX_GLOBAL_TOOL_LOG_DIR", logRoot);
+
+            using var session = GlobalToolLog.TryStartForTesting(
+                ["status"],
+                "test",
+                afterWriterCreated: () => Console.SetError(new ThrowingTextWriter()));
+
+            var exception = Record.Exception(() => Console.Error.WriteLine("mirrored error"));
+
+            Assert.NotNull(session);
+            Assert.Null(exception);
+        }
+        finally
+        {
+            Console.SetError(originalError);
+            if (Directory.Exists(logRoot))
+                Directory.Delete(logRoot, recursive: true);
+        }
+    }
+
     private static void ThrowForGlobalToolLogTest() =>
         throw new InvalidOperationException("global log stack trace test");
+
+    private sealed class ThrowingTextWriter : TextWriter
+    {
+        public override Encoding Encoding => Encoding.UTF8;
+
+        public override void Flush() => throw new ObjectDisposedException(nameof(ThrowingTextWriter));
+
+        public override void Write(char value) => throw new ObjectDisposedException(nameof(ThrowingTextWriter));
+
+        public override void Write(string? value) => throw new ObjectDisposedException(nameof(ThrowingTextWriter));
+
+        public override void WriteLine(string? value) => throw new ObjectDisposedException(nameof(ThrowingTextWriter));
+    }
 }

tests/CodeIndex.Tests/IndexCommandRunnerTests.cs

@@ -8844,6 +8844,8 @@ private static void RunGit(string workDir, params string[] args)
         {
             RunGit(workDir, "config", "user.name", "CodeIndex Tests");
             RunGit(workDir, "config", "user.email", "tests@codeindex.local");
+            RunGit(workDir, "config", "commit.gpgsign", "false");
+            RunGit(workDir, "config", "tag.gpgsign", "false");
         }
     }
 

tests/CodeIndex.Tests/TestProjectHelper.cs

@@ -21,6 +21,8 @@ internal static void InitializeGitRepo(string projectRoot)
         RunGit(projectRoot, "init");
         RunGit(projectRoot, "config", "user.name", "CodeIndex Tests");
         RunGit(projectRoot, "config", "user.email", "tests@codeindex.local");
+        RunGit(projectRoot, "config", "commit.gpgsign", "false");
+        RunGit(projectRoot, "config", "tag.gpgsign", "false");
 
         var excludePath = Path.Combine(projectRoot, ".git", "info", "exclude");
         Directory.CreateDirectory(Path.GetDirectoryName(excludePath)!);