Fix interrupted rebuild rollback preserving index

changelog.d/unreleased/2642.fixed.md

@@ -0,0 +1,16 @@
+---
+category: fixed
+issues:
+  - 2642
+affected:
+  - src/CodeIndex/Cli/IndexCommandRunner.cs
+  - tests/CodeIndex.Tests/IndexCommandRunnerTests.cs
+---
+
+## English
+
+- **Interrupted full-scan and rebuild indexing no longer demote or empty a healthy index after rollback (#2642)** — the full-scan batch marker is now written inside the same rollback boundary as readiness demotion and file updates, and `--rebuild` no longer drops the existing index before the transactional write phase while still removing rows for files that become non-indexable.
+
+## 日本語
+
+- **full-scan / rebuild index の中断後に rollback 済みの正常な index が degraded や空にならないようにしました (#2642)** — full-scan の batch marker を readiness 降格や file 更新と同じ rollback 境界内で書くようにし、`--rebuild` は transactional な書き込み phase より前に既存 index を drop しない一方で、非 index 対象になったファイルの行は削除します。

src/CodeIndex/Cli/IndexCommandRunner.cs

@@ -492,15 +492,6 @@ void RecordDryRunScanErrors(IEnumerable<FileIndexer.ScanError> scanErrors)
         // まだ clear しない。update モードの preflight が失敗しただけで healthy な DB を
         // 縮退状態に落とさないよう、clear は実際に書き込み直前で行う。
 
-        if (options.Rebuild)
-        {
-            db.ClearReadyFlags();
-            var rebuildWriter = new DbWriter(db);
-            rebuildWriter.ClearHotspotFamilyReady();
-            rebuildWriter.ClearMetadataTargetReady();
-            db.DropAll();
-        }
-
         db.InitializeSchema();
         AddToGitExclude(options.ProjectPath, dbPath);
 
@@ -3218,13 +3209,14 @@ void ThrowIfFullScanCancelled(int filesProcessed, int? filesTotal)
         }
 
         // Full-scan commits to mutating the DB from here on. Keep the whole write phase in
-        // one outer transaction so Ctrl-C/SIGTERM can roll back the readiness demotion,
-        // stale-file purge, and per-file writes instead of leaving a half-cleared index.
-        // full-scan の書き込み全体を outer transaction に入れ、中断時に readiness clear /
-        // purge / per-file write をまとめて rollback する。
+        // one outer transaction so Ctrl-C/SIGTERM can roll back the batch marker,
+        // readiness demotion, stale-file purge, and per-file writes instead of leaving a
+        // half-cleared index.
+        // full-scan の書き込み全体を outer transaction に入れ、中断時に batch marker /
+        // readiness clear / purge / per-file write をまとめて rollback する。
         ThrowIfFullScanCancelled(0, files.Count);
-        writer.MarkBatchInProgress();
         using var fullScanTxn = writer.BeginTransaction();
+        writer.MarkBatchInProgress();
         writer.ClearReadyFlags();
         writer.ClearHotspotFamilyReady();
         writer.ClearMetadataTargetReady();
@@ -3609,7 +3601,7 @@ void StopJsonHeartbeat()
                             ResumeIndexSpinnerAfterConsoleWrite();
                         }
 
-                        if (!options.Rebuild && writer.HasFileAtPath(currentJsonIndexFile))
+                        if (writer.HasFileAtPath(currentJsonIndexFile))
                         {
                             using var deleteTxn = writer.BeginTransaction();
                             if (writer.DeleteFileByPath(currentJsonIndexFile))

tests/CodeIndex.Tests/IndexCommandRunnerTests.cs

@@ -3642,13 +3642,14 @@ public void Run_FullScan_CancelledAfterReadinessDemotion_RollsBackExistingIndex(
 
             Assert.True(hookInvoked);
             Assert.Equal(CommandExitCodes.Interrupted, interruptedExitCode);
-            var recoveryWarning = ConsoleCapture.CaptureError(() =>
+            var reopenWarning = ConsoleCapture.CaptureError(() =>
             {
                 using var db = new DbContext(dbPath);
-                Assert.Equal(0, db.GetUserVersion());
+                Assert.Equal(initialReadiness, db.GetUserVersion());
             });
-            Assert.Contains("Last batch did not complete", recoveryWarning);
+            Assert.DoesNotContain("Last batch did not complete", reopenWarning);
             Assert.DoesNotContain("later.cs", ReadIndexedPaths(dbPath));
+            Assert.Contains("app.cs", ReadIndexedPaths(dbPath));
         }
         finally
         {
@@ -3658,6 +3659,98 @@ public void Run_FullScan_CancelledAfterReadinessDemotion_RollsBackExistingIndex(
         }
     }
 
+    [Fact]
+    public void Run_Rebuild_CancelledAfterReadinessDemotion_PreservesExistingIndex()
+    {
+        var projectRoot = CreateTempProject();
+        try
+        {
+            File.WriteAllText(Path.Combine(projectRoot, "app.cs"), "public class App { public void Run() { } }\n");
+
+            var initialExitCode = IndexCommandRunner.Run([projectRoot, "--json"], _jsonOptions);
+            Assert.Equal(CommandExitCodes.Success, initialExitCode);
+
+            var dbPath = Path.Combine(projectRoot, ".cdidx", "codeindex.db");
+            int initialReadiness;
+            using (var db = new DbContext(dbPath))
+                initialReadiness = db.GetUserVersion();
+            Assert.Equal(DbContext.CurrentSchemaVersion, initialReadiness);
+            Assert.Contains("app.cs", ReadIndexedPaths(dbPath));
+
+            File.WriteAllText(Path.Combine(projectRoot, "later.cs"), "public class Later { }\n");
+            using var cancellation = new CancellationTokenSource();
+            var hookInvoked = false;
+            IndexCommandRunner.FullScanWritePhaseStartedForTesting = () =>
+            {
+                hookInvoked = true;
+                cancellation.Cancel();
+            };
+
+            int interruptedExitCode;
+            lock (TestConsoleLock.Gate)
+            {
+                var originalOut = Console.Out;
+                using var stdout = new StringWriter();
+                try
+                {
+                    Console.SetOut(stdout);
+                    interruptedExitCode = IndexCommandRunner.Run([projectRoot, "--rebuild", "--yes", "--json"], _jsonOptions, cancellation);
+                }
+                finally
+                {
+                    Console.SetOut(originalOut);
+                    IndexCommandRunner.FullScanWritePhaseStartedForTesting = null;
+                }
+            }
+
+            Assert.True(hookInvoked);
+            Assert.Equal(CommandExitCodes.Interrupted, interruptedExitCode);
+            var reopenWarning = ConsoleCapture.CaptureError(() =>
+            {
+                using var db = new DbContext(dbPath);
+                Assert.Equal(initialReadiness, db.GetUserVersion());
+            });
+            Assert.DoesNotContain("Last batch did not complete", reopenWarning);
+            Assert.DoesNotContain("later.cs", ReadIndexedPaths(dbPath));
+            Assert.Contains("app.cs", ReadIndexedPaths(dbPath));
+        }
+        finally
+        {
+            IndexCommandRunner.FullScanWritePhaseStartedForTesting = null;
+            SqliteConnection.ClearAllPools();
+            DeleteDirectory(projectRoot);
+        }
+    }
+
+    [Fact]
+    public void Run_Rebuild_WhenIndexedFileBecomesBinary_RemovesStaleRow()
+    {
+        var projectRoot = CreateTempProject();
+        try
+        {
+            var sourcePath = Path.Combine(projectRoot, "app.py");
+            File.WriteAllText(sourcePath, "def run():\n    return 1\n");
+
+            var initialExitCode = IndexCommandRunner.Run([projectRoot, "--json"], _jsonOptions);
+            Assert.Equal(CommandExitCodes.Success, initialExitCode);
+
+            var dbPath = Path.Combine(projectRoot, ".cdidx", "codeindex.db");
+            Assert.Contains("app.py", ReadIndexedPaths(dbPath));
+
+            File.WriteAllBytes(sourcePath, [0, 1, 2, 3]);
+
+            var rebuildExitCode = IndexCommandRunner.Run([projectRoot, "--rebuild", "--yes", "--json"], _jsonOptions);
+
+            Assert.Equal(CommandExitCodes.Success, rebuildExitCode);
+            Assert.DoesNotContain("app.py", ReadIndexedPaths(dbPath));
+        }
+        finally
+        {
+            SqliteConnection.ClearAllPools();
+            DeleteDirectory(projectRoot);
+        }
+    }
+
     [Fact]
     public void Run_UpdateMode_WithOversizedFile_PrintsSkipWarningWithoutRecoveryWarning()
     {