Stabilize parallel batch snapshot refresh tests

TESTING_GUIDE.md

@@ -696,7 +696,7 @@ Use `docs/test-doc-maintenance-plan.md` before moving oversized suites or adding
 - `QueryCommandRunnerBatchIssue4723Tests.cs`
   CLI batch coverage for structured command objects, configurable input/output budgets, bounded parallel read overlap, input-order result emission, per-item failure isolation, and cancellation/console restoration. The deterministic overlap test blocks the first worker until the second finishes through batch-only test seams; keep those seams reset in `finally` and do not replace the signal with timing assertions.
 - `QueryCommandRunnerBatchIssue4872Tests.cs`
-  Parallel batch session-reuse coverage. Keep the exact worker-slot session bound, serial/parallel result and input-order parity, between-item checkpointed-WAL snapshot and direct-session refresh, validation/reader-construction failure cleanup, hot-WAL snapshot fixture, warmup, and the generous 12-item/3-item ratio guard together. The checkpointed-WAL snapshot refresh gives each status wave two minutes of headroom for the loaded net9 full suite; keep its completion signals and result/session assertions intact rather than weakening the concurrency contract. The benchmark injects deterministic database-open/schema work through a test seam; its fixed delay models phase cost only, while worker coordination remains signal-driven.
+  Parallel batch session-reuse coverage. Keep the exact worker-slot session bound, serial/parallel result and input-order parity, between-item checkpointed-WAL snapshot and direct-session refresh, validation/reader-construction failure cleanup, hot-WAL snapshot fixture, warmup, and the generous 12-item/3-item ratio guard together. The interactive refresh fixtures run the synchronous batch loop on a dedicated thread, await worker completion without blocking a thread-pool thread, and query only the lightweight JSON file count needed to observe the database generation; do not restore `Task.Run`, synchronous waits, or broad `status` diagnostics there. The checkpointed-WAL snapshot refresh retains two minutes of headroom for the loaded net9 full suite; keep its completion and result/session assertions intact rather than weakening the concurrency contract. The benchmark injects deterministic database-open/schema work through a test seam; its fixed delay models phase cost only, while worker coordination remains signal-driven.
 - `PropertyBasedParserTests.cs`
   FsCheck-driven property tests for parser-heavy paths called out in issue #1572: `ArgHelper.WantsHelp` and `ProgramRunner.IsProjectPathArg` never throw on arbitrary inputs; `FileIndexer.NormalizePathSeparators` is idempotent under double application; the literal-safe FTS5 sanitizer (`DbReader.SanitizeFtsQuery`) always emits a query that a real in-memory FTS5 virtual table can parse. They complement, not replace, the example-based tests in `ArgHelperTests.cs` / `QueryCommandRunnerTests.cs`.
 - `TestProjectHelper.cs`, `TestDeterminism.cs`, `RepositoryTestPaths.cs`, `TestConsoleLock.cs`
@@ -1649,7 +1649,7 @@ dotnet test --filter "FullyQualifiedName~GitHelperTests"
 - `QueryCommandRunnerBatchIssue4723Tests.cs`
   structured command object、設定可能な input / output budget、上限付き parallel read の重複実行、入力順の result 出力、item ごとの failure isolation、cancellation / console 復元を対象とする CLI batch test です。決定的な overlap test は batch 専用 test seam を通じて第 1 worker を第 2 worker の完了まで block します。seam は `finally` で必ず reset し、signal を timing assertion に置き換えないでください。
 - `QueryCommandRunnerBatchIssue4872Tests.cs`
-  parallel batch の session 再利用を検証します。worker slot 数と一致する厳密な session 上限、serial / parallel の result と入力順 parity、item 間の checkpoint 済み WAL snapshot / direct session 更新、validation / reader 構築失敗時の cleanup、hot-WAL snapshot fixture、warmup、十分に余裕を持たせた 12-item / 3-item ratio guard を一緒に維持してください。checkpoint 済み WAL snapshot の refresh test は、負荷がかかる net9 full suite に備えて各 status wave に 2 分の余裕を持たせます。completion signal と result / session assertion は concurrency 契約を弱めず維持してください。benchmark は test seam から決定的な database-open / schema 作業を注入します。固定 delay は phase cost のモデル化だけに使い、worker coordination は引き続き signal で制御します。
+  parallel batch の session 再利用を検証します。worker slot 数と一致する厳密な session 上限、serial / parallel の result と入力順 parity、item 間の checkpoint 済み WAL snapshot / direct session 更新、validation / reader 構築失敗時の cleanup、hot-WAL snapshot fixture、warmup、十分に余裕を持たせた 12-item / 3-item ratio guard を一緒に維持してください。interactive refresh fixture は同期 batch loop を専用 thread で実行し、thread-pool thread を block せず worker 完了を await し、database generation の観測に必要な軽量 JSON file count だけを query します。この箇所に `Task.Run`、同期 wait、広範な `status` diagnostics を戻さないでください。checkpoint 済み WAL snapshot の refresh test は、負荷がかかる net9 full suite に備えて 2 分の余裕を維持します。completion と result / session assertion は concurrency 契約を弱めず維持してください。benchmark は test seam から決定的な database-open / schema 作業を注入します。固定 delay は phase cost のモデル化だけに使い、worker coordination は引き続き signal で制御します。
 - `PropertyBasedParserTests.cs`
   issue #1572 で挙げられたパーサー系経路に対する FsCheck 駆動の property テスト: `ArgHelper.WantsHelp` と `ProgramRunner.IsProjectPathArg` が任意入力で例外を投げないこと、`FileIndexer.NormalizePathSeparators` が二重適用で idempotent であること、literal-safe な FTS5 サニタイザ (`DbReader.SanitizeFtsQuery`) が常にインメモリ FTS5 仮想テーブルで parse 可能なクエリを出力すること。`ArgHelperTests.cs` / `QueryCommandRunnerTests.cs` の例ベーステストを置き換えるものではなく補完します。
 - `TestProjectHelper.cs`、`TestDeterminism.cs`、`RepositoryTestPaths.cs`、`TestConsoleLock.cs`

changelog.d/unreleased/5033.internal.md

@@ -0,0 +1,16 @@
+---
+category: internal
+issues:
+  - 5033
+affected:
+  - tests/CodeIndex.Tests/QueryCommandRunnerBatchIssue4872Tests.cs
+  - TESTING_GUIDE.md
+---
+
+## English
+
+- **The parallel detached-snapshot fixture no longer depends on thread-pool timing or broad status diagnostics (#5033)** — its interactive batch loop now runs on a dedicated test thread, uses asynchronous completion signals, and checks generation refresh through lightweight file-count queries so the net8 test remains deterministic under suite load.
+
+## 日本語
+
+- **parallel detached-snapshot fixture が thread-pool timing や広範な status diagnostics に依存しなくなりました (#5033)** — interactive batch loop を専用 test thread で実行し、非同期 completion signal と軽量な file-count query で generation refresh を確認するため、suite 負荷下でも net8 test が安定して完了します。

tests/CodeIndex.Tests/QueryCommandRunnerBatchIssue4872Tests.cs

@@ -119,34 +119,38 @@ INSERT INTO files(path, lang, size, lines, checksum, modified)
         using var input = new InteractiveBatchTextReader();
         using var stdout = new StringWriter();
         using var stderr = new StringWriter();
-        using var firstWaveCompleted = new CountdownEvent(2);
+        var firstWaveCompleted = new TaskCompletionSource(
+            TaskCreationOptions.RunContinuationsAsynchronously);
         using var cancellation = new CancellationTokenSource();
         var statusWaveTimeout = TimeSpan.FromMinutes(2);
         Task<int>? runTask = null;
         var openedSessions = 0;
+        var completedFirstWaveCommands = 0;
         QueryCommandRunner.BatchParallelSessionOpenedForTesting =
             () => Interlocked.Increment(ref openedSessions);
         QueryCommandRunner.BatchParallelCommandCompletedForTesting = lineNumber =>
         {
-            if (lineNumber <= 2)
-                firstWaveCompleted.Signal();
+            if (lineNumber <= 2
+                && Interlocked.Increment(ref completedFirstWaveCommands) == 2)
+            {
+                firstWaveCompleted.TrySetResult();
+            }
         };
 
         try
         {
-            runTask = Task.Run(() =>
-            {
-                using var capture = ConsoleCapture.Start(stdout, stderr, input);
-                return QueryCommandRunner.RunBatch(
-                    ["--db", dbPath, "--json-summary", "--parallel", "2"],
-                    _jsonOptions,
-                    cancellationToken: cancellation.Token);
-            });
-            input.WriteLine("""{"command":"status","args":["--json"]}""");
-            input.WriteLine("""{"command":"status","args":["--json"]}""");
-            Assert.True(
-                firstWaveCompleted.Wait(statusWaveTimeout),
-                "The first parallel batch wave did not complete.");
+            runTask = StartIssue4872InteractiveBatch(
+                dbPath,
+                input,
+                stdout,
+                stderr,
+                cancellation.Token);
+            input.WriteLine("""{"command":"files","args":["--format","count","--json"]}""");
+            input.WriteLine("""{"command":"files","args":["--format","count","--json"]}""");
+            await WaitForIssue4872FirstWaveAsync(
+                firstWaveCompleted.Task,
+                runTask,
+                statusWaveTimeout);
 
             using (var update = writer.CreateCommand())
             {
@@ -160,22 +164,24 @@ INSERT INTO files(path, lang, size, lines, checksum, modified)
             Assert.Equal(initialDbLength, new FileInfo(dbPath).Length);
             Assert.Equal(0, new FileInfo(dbPath + "-wal").Length);
 
-            input.WriteLine("""{"command":"status","args":["--json"]}""");
-            input.WriteLine("""{"command":"status","args":["--json"]}""");
+            input.WriteLine("""{"command":"files","args":["--format","count","--json"]}""");
+            input.WriteLine("""{"command":"files","args":["--format","count","--json"]}""");
             input.Complete();
 
             var exitCode = await runTask.WaitAsync(statusWaveTimeout);
-            Assert.Equal(CommandExitCodes.Success, exitCode);
+            Assert.True(
+                exitCode == CommandExitCodes.Success,
+                $"Parallel batch exited with code {exitCode}: {stdout}");
             Assert.Equal(string.Empty, stderr.ToString());
 
             var lines = ParseJsonLines(stdout.ToString());
             try
             {
                 Assert.Equal(5, lines.Count);
-                Assert.Equal(1, lines[0].RootElement.GetProperty("result").GetProperty("files").GetInt32());
-                Assert.Equal(1, lines[1].RootElement.GetProperty("result").GetProperty("files").GetInt32());
-                Assert.Equal(2, lines[2].RootElement.GetProperty("result").GetProperty("files").GetInt32());
-                Assert.Equal(2, lines[3].RootElement.GetProperty("result").GetProperty("files").GetInt32());
+                Assert.Equal(1, lines[0].RootElement.GetProperty("result").GetProperty("count").GetInt32());
+                Assert.Equal(1, lines[1].RootElement.GetProperty("result").GetProperty("count").GetInt32());
+                Assert.Equal(2, lines[2].RootElement.GetProperty("result").GetProperty("count").GetInt32());
+                Assert.Equal(2, lines[3].RootElement.GetProperty("result").GetProperty("count").GetInt32());
                 Assert.Equal(4, Volatile.Read(ref openedSessions));
             }
             finally
@@ -199,6 +205,12 @@ INSERT INTO files(path, lang, size, lines, checksum, modified)
                 catch (OperationCanceledException) when (cancellation.IsCancellationRequested)
                 {
                 }
+                catch (TimeoutException exception)
+                {
+                    throw new TimeoutException(
+                        "The dedicated parallel batch test thread did not drain after cancellation.",
+                        exception);
+                }
             }
         }
     }
@@ -240,33 +252,37 @@ INSERT INTO files(path, lang, size, lines, checksum, modified)
         using var input = new InteractiveBatchTextReader();
         using var stdout = new StringWriter();
         using var stderr = new StringWriter();
-        using var firstWaveCompleted = new CountdownEvent(2);
+        var firstWaveCompleted = new TaskCompletionSource(
+            TaskCreationOptions.RunContinuationsAsynchronously);
         using var cancellation = new CancellationTokenSource();
         Task<int>? runTask = null;
         var openedSessions = 0;
+        var completedFirstWaveCommands = 0;
         QueryCommandRunner.BatchParallelSessionOpenedForTesting =
             () => Interlocked.Increment(ref openedSessions);
         QueryCommandRunner.BatchParallelCommandCompletedForTesting = lineNumber =>
         {
-            if (lineNumber <= 2)
-                firstWaveCompleted.Signal();
+            if (lineNumber <= 2
+                && Interlocked.Increment(ref completedFirstWaveCommands) == 2)
+            {
+                firstWaveCompleted.TrySetResult();
+            }
         };
 
         try
         {
-            runTask = Task.Run(() =>
-            {
-                using var capture = ConsoleCapture.Start(stdout, stderr, input);
-                return QueryCommandRunner.RunBatch(
-                    ["--db", dbPath, "--json-summary", "--parallel", "2"],
-                    _jsonOptions,
-                    cancellationToken: cancellation.Token);
-            });
-            input.WriteLine("""{"command":"status","args":["--json"]}""");
-            input.WriteLine("""{"command":"status","args":["--json"]}""");
-            Assert.True(
-                firstWaveCompleted.Wait(TimeSpan.FromSeconds(60)),
-                "The first parallel batch wave did not complete.");
+            runTask = StartIssue4872InteractiveBatch(
+                dbPath,
+                input,
+                stdout,
+                stderr,
+                cancellation.Token);
+            input.WriteLine("""{"command":"files","args":["--format","count","--json"]}""");
+            input.WriteLine("""{"command":"files","args":["--format","count","--json"]}""");
+            await WaitForIssue4872FirstWaveAsync(
+                firstWaveCompleted.Task,
+                runTask,
+                TimeSpan.FromSeconds(60));
 
             using (var update = writer.CreateCommand())
             {
@@ -277,22 +293,24 @@ INSERT INTO files(path, lang, size, lines, checksum, modified)
                 Assert.Equal(1, update.ExecuteNonQuery());
             }
 
-            input.WriteLine("""{"command":"status","args":["--json"]}""");
-            input.WriteLine("""{"command":"status","args":["--json"]}""");
+            input.WriteLine("""{"command":"files","args":["--format","count","--json"]}""");
+            input.WriteLine("""{"command":"files","args":["--format","count","--json"]}""");
             input.Complete();
 
             var exitCode = await runTask.WaitAsync(TimeSpan.FromSeconds(60));
-            Assert.Equal(CommandExitCodes.Success, exitCode);
+            Assert.True(
+                exitCode == CommandExitCodes.Success,
+                $"Parallel batch exited with code {exitCode}: {stdout}");
             Assert.Equal(string.Empty, stderr.ToString());
 
             var lines = ParseJsonLines(stdout.ToString());
             try
             {
                 Assert.Equal(5, lines.Count);
-                Assert.Equal(1, lines[0].RootElement.GetProperty("result").GetProperty("files").GetInt32());
-                Assert.Equal(1, lines[1].RootElement.GetProperty("result").GetProperty("files").GetInt32());
-                Assert.Equal(2, lines[2].RootElement.GetProperty("result").GetProperty("files").GetInt32());
-                Assert.Equal(2, lines[3].RootElement.GetProperty("result").GetProperty("files").GetInt32());
+                Assert.Equal(1, lines[0].RootElement.GetProperty("result").GetProperty("count").GetInt32());
+                Assert.Equal(1, lines[1].RootElement.GetProperty("result").GetProperty("count").GetInt32());
+                Assert.Equal(2, lines[2].RootElement.GetProperty("result").GetProperty("count").GetInt32());
+                Assert.Equal(2, lines[3].RootElement.GetProperty("result").GetProperty("count").GetInt32());
                 Assert.Equal(4, Volatile.Read(ref openedSessions));
             }
             finally
@@ -316,6 +334,12 @@ INSERT INTO files(path, lang, size, lines, checksum, modified)
                 catch (OperationCanceledException) when (cancellation.IsCancellationRequested)
                 {
                 }
+                catch (TimeoutException exception)
+                {
+                    throw new TimeoutException(
+                        "The dedicated parallel batch test thread did not drain after cancellation.",
+                        exception);
+                }
             }
         }
     }
@@ -529,4 +553,52 @@ private static string ReadJournalMode(SqliteConnection connection)
         command.CommandText = "PRAGMA journal_mode";
         return Assert.IsType<string>(command.ExecuteScalar());
     }
+
+    private Task<int> StartIssue4872InteractiveBatch(
+        string dbPath,
+        InteractiveBatchTextReader input,
+        StringWriter stdout,
+        StringWriter stderr,
+        CancellationToken cancellationToken)
+        => Task.Factory.StartNew(
+            () =>
+            {
+                using (var capture = ConsoleCapture.Start(stdout, stderr, input))
+                {
+                    return QueryCommandRunner.RunBatch(
+                        ["--db", dbPath, "--json-summary", "--parallel", "2"],
+                        _jsonOptions,
+                        cancellationToken: cancellationToken);
+                }
+            },
+            CancellationToken.None,
+            TaskCreationOptions.LongRunning | TaskCreationOptions.DenyChildAttach,
+            TaskScheduler.Default);
+
+    private static async Task WaitForIssue4872FirstWaveAsync(
+        Task firstWaveCompleted,
+        Task<int> runTask,
+        TimeSpan timeout)
+    {
+        Task boundary;
+        try
+        {
+            boundary = await Task.WhenAny(firstWaveCompleted, runTask)
+                .WaitAsync(timeout);
+        }
+        catch (TimeoutException exception)
+        {
+            throw new TimeoutException(
+                "The first parallel batch wave did not complete before its synchronization boundary.",
+                exception);
+        }
+        if (ReferenceEquals(boundary, runTask))
+        {
+            var exitCode = await runTask;
+            Assert.Fail(
+                $"The parallel batch exited with code {exitCode} before the first wave completed.");
+        }
+
+        await firstWaveCompleted;
+    }
 }