diff --git a/changelog.d/unreleased/1712.fixed.md b/changelog.d/unreleased/1712.fixed.md
new file mode 100644
index 0000000000..c2b7e17d77
--- /dev/null
+++ b/changelog.d/unreleased/1712.fixed.md
@@ -0,0 +1,16 @@
+---
+category: fixed
+issues:
+  - 1712
+affected:
+  - src/CodeIndex/Indexer/Scanning/FileIndexer.cs
+  - tests/CodeIndex.Tests/FileIndexerTests.cs
+---
+
+## English
+
+- **Per-directory `.cdidxignore` precedence is now covered by regression tests (#1712)** - child `.cdidxignore` files can further exclude paths or re-include files without leaking those rules into sibling directories.
+
+## 日本語
+
+- **ディレクトリごとの `.cdidxignore` 優先順位を回帰テストで固定しました (#1712)** - 子ディレクトリの `.cdidxignore` が追加除外や再 include を行っても、その規則が sibling ディレクトリへ漏れないことを確認します。
diff --git a/changelog.d/unreleased/1782.fixed.md b/changelog.d/unreleased/1782.fixed.md
new file mode 100644
index 0000000000..36b10a34ac
--- /dev/null
+++ b/changelog.d/unreleased/1782.fixed.md
@@ -0,0 +1,16 @@
+---
+category: fixed
+issues:
+  - 1782
+affected:
+  - src/CodeIndex/Cli/IndexCommandRunner.Update.cs
+  - tests/CodeIndex.Tests/IndexCommandRunnerTests.cs
+---
+
+## English
+
+- **Partial update ignore-file changes are now covered by regression tests (#1782)** - `--files` updates that include `.gitignore` or `.cdidxignore` fall back to a full scan so newly ignored stale rows are purged from the index.
+
+## 日本語
+
+- **部分更新で ignore file が変わった場合の挙動を回帰テストで固定しました (#1782)** - `.gitignore` や `.cdidxignore` を含む `--files` 更新は full scan に切り替わり、新たに ignore 対象になった古い行を index から削除します。
diff --git a/tests/CodeIndex.Tests/FileIndexerTests.cs b/tests/CodeIndex.Tests/FileIndexerTests.cs
index 867fe0b024..e6f2ec2511 100644
--- a/tests/CodeIndex.Tests/FileIndexerTests.cs
+++ b/tests/CodeIndex.Tests/FileIndexerTests.cs
@@ -106,6 +106,37 @@ public void ScanFiles_SkipsBuiltInDirectoriesWithCaseInsensitiveNames()
         }
     }
 
+    [Fact]
+    public void ScanFiles_PerDirectoryCdidxIgnore_AppliesChildRulesWithoutLeakingToSiblings()
+    {
+        var tempDir = Path.Combine(Path.GetTempPath(), $"cdidx-per-dir-ignore-{Guid.NewGuid():N}");
+        try
+        {
+            Directory.CreateDirectory(Path.Combine(tempDir, "left"));
+            Directory.CreateDirectory(Path.Combine(tempDir, "right"));
+            File.WriteAllText(Path.Combine(tempDir, ".cdidxignore"), "*.generated.py\n");
+            File.WriteAllText(Path.Combine(tempDir, "root.generated.py"), "print('ignored root')\n");
+            File.WriteAllText(Path.Combine(tempDir, "left", ".cdidxignore"), "!keep.generated.py\nlocal.py\n");
+            File.WriteAllText(Path.Combine(tempDir, "left", "keep.generated.py"), "print('kept child')\n");
+            File.WriteAllText(Path.Combine(tempDir, "left", "local.py"), "print('ignored child')\n");
+            File.WriteAllText(Path.Combine(tempDir, "right", "keep.generated.py"), "print('ignored sibling')\n");
+            File.WriteAllText(Path.Combine(tempDir, "right", "plain.py"), "print('kept sibling')\n");
+
+            var files = new FileIndexer(tempDir)
+                .ScanFiles()
+                .Select(path => Path.GetRelativePath(tempDir, path).Replace('\\', '/'))
+                .OrderBy(path => path, StringComparer.Ordinal)
+                .ToList();
+
+            Assert.Equal(["left/keep.generated.py", "right/plain.py"], files);
+        }
+        finally
+        {
+            if (Directory.Exists(tempDir))
+                Directory.Delete(tempDir, true);
+        }
+    }
+
     [Fact]
     public void ScanFilesDetailed_HardlinkedFiles_SkipsDuplicatePathWithWarning()
     {
diff --git a/tests/CodeIndex.Tests/IndexCommandRunnerTests.cs b/tests/CodeIndex.Tests/IndexCommandRunnerTests.cs
index 0e027c9e0f..0e68d52905 100644
--- a/tests/CodeIndex.Tests/IndexCommandRunnerTests.cs
+++ b/tests/CodeIndex.Tests/IndexCommandRunnerTests.cs
@@ -4529,6 +4529,41 @@ public void Run_FullScan_WithMalformedIgnoreRule_ReturnsSuccessWithWarningInstea
         }
     }
 
+    [Fact]
+    public void Run_UpdateMode_WhenIgnoreFileChanges_FallsBackToFullScanAndPurgesNowIgnoredRows()
+    {
+        var projectRoot = CreateTempProject();
+        try
+        {
+            File.WriteAllText(Path.Combine(projectRoot, "generated.py"), "print('generated')\n");
+            File.WriteAllText(Path.Combine(projectRoot, "keep.py"), "print('keep')\n");
+
+            var initialExitCode = IndexCommandRunner.Run([projectRoot, "--json"], _jsonOptions);
+            Assert.Equal(CommandExitCodes.Success, initialExitCode);
+
+            var dbPath = Path.Combine(projectRoot, ".cdidx", "codeindex.db");
+            Assert.Contains("generated.py", ReadIndexedPaths(dbPath));
+
+            File.WriteAllText(Path.Combine(projectRoot, ".gitignore"), "*.py\n!keep.py\n");
+
+            var (exitCode, json) = RunAndCaptureJson([projectRoot, "--files", ".gitignore", "--json"]);
+
+            Assert.Equal(CommandExitCodes.Success, exitCode);
+            Assert.Equal("success", json.GetProperty("status").GetString());
+            Assert.Equal("incremental", json.GetProperty("mode").GetString());
+
+            var indexedPaths = ReadIndexedPaths(dbPath);
+            Assert.DoesNotContain("generated.py", indexedPaths);
+            Assert.Contains("keep.py", indexedPaths);
+            Assert.Contains(".gitignore", indexedPaths);
+        }
+        finally
+        {
+            SqliteConnection.ClearAllPools();
+            DeleteDirectory(projectRoot);
+        }
+    }
+
     [Fact]
     public void Run_FullScan_SubdirectoryProjectRoot_UsesRepositoryIgnoreCaseConfigWhenTrue()
     {