diff --git a/.editorconfig b/.editorconfig
index 7867892e..5d51505c 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -16,6 +16,18 @@ trim_trailing_whitespace = true
 [*.ps1]
 indent_size = 4
 
+[*.py]
+charset = utf-8
+indent_size = 4
+end_of_line = lf
+
+[tests/**]
+charset = utf-8
+indent_style = space
+indent_size = 4
+end_of_line = lf
+trim_trailing_whitespace = true
+
 [*.{vcxproj,filters,props}]
 charset = utf-8
 
diff --git a/.gitattributes b/.gitattributes
index cf59f17e..03145167 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -10,6 +10,8 @@
 *.props text eol=crlf
 *.md text eol=lf
 *.ps1 text eol=lf
+*.py text eol=lf
+*.in text eol=lf
 *.sh text eol=lf
 *.yml text eol=lf
 *.yaml text eol=lf
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index bd4c6bca..2e4633bf 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -32,14 +32,16 @@ jobs:
           New-Item -ItemType Directory -Path bin -Force | Out-Null
           ./build/build.ps1 -Architecture '${{ matrix.architecture }}' -Configuration '${{ matrix.configuration }}' *> bin/build.log
           if ($LASTEXITCODE -ne 0) { Get-Content bin/build.log -Tail 80; exit 1 }
-      - name: Test editor themes
+      - uses: actions/setup-python@6d4fd22b20465ccc0f7354476588e8df7c9ca0e0 # v7.1.0
+        with:
+          python-version: '3.13'
+          architecture: ${{ matrix.architecture }}
+      - name: Install locked test dependencies
+        run: python -m pip install --require-hashes -r tests/requirements.txt
+      - name: Test native editor
         run: |
-          try {
-            ./build/test-themes.ps1 -Executable './bin/VS2022/${{ matrix.configuration }}_${{ matrix.architecture }}/Notepad2.exe' *> bin/tests.log
-          } catch {
-            Get-Content bin/tests.log -Tail 80
-            throw
-          }
+          python -m pytest --executable './bin/VS2022/${{ matrix.configuration }}_${{ matrix.architecture }}/Notepad2.exe' --architecture '${{ matrix.architecture }}' --configuration '${{ matrix.configuration }}' --junitxml bin/test-results.xml *> bin/tests.log
+          if ($LASTEXITCODE -ne 0) { Get-Content bin/tests.log -Tail 100; exit 1 }
           Get-Content bin/tests.log
       - name: Package portable release
         if: matrix.configuration == 'Release'
@@ -64,7 +66,9 @@ jobs:
         if: always()
         with:
           name: logs-${{ matrix.configuration }}-${{ matrix.architecture }}
-          path: bin/*.log
+          path: |
+            bin/*.log
+            bin/test-results.xml
           retention-days: 14
   release:
     name: Publish release
diff --git a/.gitignore b/.gitignore
index 289c2296..8201b334 100644
--- a/.gitignore
+++ b/.gitignore
@@ -26,3 +26,6 @@
 *.p12
 /.env
 /.env.*
+/.venv/
+/.pytest_cache/
+**/__pycache__/
diff --git a/AGENTS.md b/AGENTS.md
index f49a12ea..0ea366ac 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -14,6 +14,12 @@
 - Theme scope is the editor only: text, syntax colors, margins, caret, selections,
   folding and highlights. Application chrome (menus, dialogs, toolbar, status bar,
   title bar and scrollbars) is out of scope, not a planned follow-up.
+- Keep the single-document interface. Multi-tab editing and Notepad++ parity or
+  compatibility are not product goals. Standalone patches from Notepad3/Notepad4
+  may be evaluated surgically; their frameworks and feature stacks remain excluded.
+- Use pytest and pywinauto's Win32 backend for native UI regression tests, with
+  only a small adapter for Scintilla messages. Keep test dependencies separate
+  from the application. PowerShell remains appropriate for build/release scripts.
 - Finish each logical change with a granular commit after relevant validation.
   Do not ask again whether to commit completed, authorized work. Stage explicit
   paths/hunks and inspect the staged diff. Keep dependency updates, build changes,
diff --git a/ROADMAP.md b/ROADMAP.md
index ad4f6fc0..74defd56 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -66,14 +66,30 @@ demonstrates a concrete benefit.
 
 ## Fork review backlog
 
-GitHub issues hold the review notes, source commit links, acceptance criteria,
-and eventual decisions. These are candidates for selective changes, not approved
-imports; none was built or runtime-tested during the initial review.
-
-| Issue | Candidate | Review focus |
+Three independent agent reviews and a maintainer cross-check selected four
+surgical corrections, now implemented locally in separate commits. The unsaved
+buffer defect was reproduced against the pre-fix binary. Native regression tests
+cover prompting/cancellation, production MRU functions, source charset and startup
+show-state selection; actual standard-user UAC interaction remains a manual check.
+The fork review introduced no dependency upgrade or subsystem. A separately
+requested improvement adds selection-aware line copy/cut using existing Scintilla
+actions and clipboard markers. UI regression tests use pytest and pywinauto.
+
+| Priority | Accepted correction | Source |
 | --- | --- | --- |
-| [#1](https://github.com/itlezy/notepad2-mod/issues/1) | antiufo | Recovery/autosave; preserve upstream fixes and recovery buffer-fix chain. |
-| [#2](https://github.com/itlezy/notepad2-mod/issues/2) | johnwait | Selective editor fixes; exclude wholesale regex/Scintilla migration. |
-| [#3](https://github.com/itlezy/notepad2-mod/issues/3) | mercury233 | Small find/replace, reload, and context-menu improvements. |
-| [#4](https://github.com/itlezy/notepad2-mod/issues/4) | tnotstar | Initial CMake build; Debug support was explicitly unfinished. |
-| [#5](https://github.com/itlezy/notepad2-mod/issues/5) | waskosky | Aggressive reload/append merging; require data-preservation review. |
+| First | [#9: save prompting for nonempty untitled documents](https://github.com/itlezy/notepad2-mod/issues/9) | johnwait; remove C-string content sniffing that misclassifies leading NUL and whitespace. |
+| Next | [#10: skip empty MRU slots](https://github.com/itlezy/notepad2-mod/issues/10) | antiufo; one null guard before path comparison, without recovery features. |
+| Next | [#11: explicit UTF-8 source charset](https://github.com/itlezy/notepad2-mod/issues/11) | mercury233; all four app configurations, unchanged execution charset/resources/vendor code. |
+| Lower | [#12: elevated-window show-state flags](https://github.com/itlezy/notepad2-mod/issues/12) | johnwait; default to visible only when no explicit show-state flag was supplied. |
+
+Closed review decisions remain in [#1](https://github.com/itlezy/notepad2-mod/issues/1),
+[#2](https://github.com/itlezy/notepad2-mod/issues/2), and
+[#3](https://github.com/itlezy/notepad2-mod/issues/3). Recovery/autosave, regex-engine
+replacement, Scintilla migration, broad refactors, notification redesign, and
+optional context-menu/focus/shortcut changes are excluded. Several apparent fixes
+repair code introduced by those forks and do not apply here.
+
+[CMake (#4)](https://github.com/itlezy/notepad2-mod/issues/4) and
+[aggressive reload/append merging (#5)](https://github.com/itlezy/notepad2-mod/issues/5)
+are rejected and closed as not planned. Keep the existing build and file-watching
+models; revisit only if a concrete product need changes that decision.
diff --git a/Readme.md b/Readme.md
index 584993fd..be59e78d 100644
--- a/Readme.md
+++ b/Readme.md
@@ -12,6 +12,9 @@ minimal, focused patches with a clear benefit. This fork will not move to
 Notepad3/Notepad4 or adopt their feature stacks; matching newer editors or
 dependency versions is not a goal.
 
+The interface remains single-document. Multi-tab editing and Notepad++ parity
+are out of scope; isolated fixes from other editors may be evaluated surgically.
+
 The upstream repository, [XhmikosR/notepad2-mod](https://github.com/XhmikosR/notepad2-mod),
 is archived and was last updated in July 2018. Ongoing maintenance for this fork
 happens here; upstream history, licensing, and contributor credits are preserved.
@@ -80,6 +83,12 @@ Compatibility with other Windows versions has not been verified.
 
 ## Changed keyboard shortcuts compared to Notepad2:
 
+With no selection, **Ctrl+C / Ctrl+Insert** copy the current line and
+**Ctrl+X / Shift+Delete** cut it. These line operations include a line-ending and
+use Scintilla's existing line-clipboard marker: **Ctrl+V / Shift+Insert** insert
+the line above the caret's current line. With a selection, normal copy/cut/paste
+behavior is retained. Cutting is undoable and respects read-only documents.
+
 * <kbd>Ctrl+Alt+F2</kbd>       Expand selection to next match.
 * <kbd>Ctrl+Alt+Shift+F2</kbd> Expand selection to previous match.
 * <kbd>Ctrl+Shift+Enter</kbd>  New line with toggled auto indent option.
@@ -151,16 +160,24 @@ The packaging command is `./build/package.ps1 -Architecture x64` (or `x86`). It
 uses Release output and writes into ignored `bin/packages`; supply a fresh
 `-OutputDirectory` when repackaging an already-created version locally.
 
-To run the native theme integration checks against a built executable:
+Tests use Python 3.13, pytest, and pywinauto's Win32 backend. Test dependencies
+are locked with hashes and are not application dependencies. PowerShell is used
+for building, not UI automation. To test a built executable:
 
 ```powershell
-.\build\test-themes.ps1
-.\build\test-themes.ps1 -Executable .\bin\VS2022\Release_x86\Notepad2.exe
+py -3.13 -m venv .venv
+.\.venv\Scripts\python.exe -m pip install --require-hashes -r tests/requirements.txt
+.\.venv\Scripts\python.exe -m pytest
+.\.venv\Scripts\python.exe -m pytest --executable .\bin\VS2022\Release_x86\Notepad2.exe --architecture x86
 ```
 
 The checks launch isolated instances with temporary settings, exercise all 38
 schemes and customization Preview/Cancel/Reset, and verify palette/font separation,
 switching, restart persistence, invalid defaults, and disabled settings saving.
-Use `-BaselineExecutable <path>` for a seven-run small-file startup/private-memory/
-numeric edit/idle comparison. These checks do not replace visual contrast review
-or establish large-file performance.
+They also exercise save prompts with embedded NUL/whitespace, exact-byte Cancel
+preservation, production MRU functions, source charset, and startup show-state
+contracts. The latter do not replace an interactive standard-user UAC test.
+Use `--configuration Debug` for the corresponding native helper runtime. A
+pre-fix binary can be checked with `-m pytest tests/test_save_prompts.py
+--legacy-save-behavior --executable <path>` to reproduce the nine loss paths.
+These tests do not replace visual review or establish large-file performance.
diff --git a/build/publish-release.ps1 b/build/publish-release.ps1
index 496aaeeb..2fb72123 100644
--- a/build/publish-release.ps1
+++ b/build/publish-release.ps1
@@ -31,13 +31,17 @@ $notes = Join-Path $PackageDirectory 'release-notes.txt'
 @"
 Native Original/Dark editor palettes on Scintilla 3.7.6, with a VS 2022 build.
 
+Focused corrections protect nonempty untitled documents during save prompting, skip empty recent-file slots, make application source encoding deterministic, and honor elevated-launch show-state flags.
+
+With no selection, Ctrl+C / Ctrl+Insert copy the current line and Ctrl+X / Shift+Delete cut it. Ctrl+V / Shift+Insert paste line-marked clipboard content above the current line. Normal selected-text behavior is retained.
+
 Choose View > Editor Theme > Dark. Existing Original colors and font preferences are retained. Application chrome is unchanged.
 
 Download the portable ZIP for your architecture and extract it into a writable folder. Preserve your existing Notepad2.ini when upgrading. These binaries are unsigned. SHA256SUMS.txt provides archive integrity checks.
 
 Source commit: $commit
 Executable version: $version
-Validation: Release/Debug x86/x64 builds and native theme integration tests, including all 38 schemes and customization/persistence checks.
+Validation: Release/Debug x86/x64 builds with pytest and pywinauto, including all 38 schemes, customization/persistence, save-prompt data preservation, line shortcuts, and native helper contracts. Actual standard-user UAC interaction remains a manual check.
 "@ | Set-Content $notes -Encoding utf8
 $existing = & gh release view $Tag --json isDraft 2>$null
 if ($LASTEXITCODE -eq 0) {
diff --git a/build/test-fork-helpers.c b/build/test-fork-helpers.c
new file mode 100644
index 00000000..e1caf750
--- /dev/null
+++ b/build/test-fork-helpers.c
@@ -0,0 +1,65 @@
+// Exercises production MRU/path functions, plus compiler and startup contracts.
+#include <windows.h>
+#include <shlwapi.h>
+#include <stdio.h>
+#include "Scintilla.h"
+#include "Helpers.h"
+#include "Version.h"
+#include "fork-contracts.h"
+
+HINSTANCE g_hInstance;
+UINT16 g_uWinVer;
+HMODULE hModUxTheme;
+WCHAR szIniFile[MAX_PATH];
+
+#define CHECK(condition) do { if (!(condition)) { printf("Failed at line %d\n",__LINE__); return 1; } } while (0)
+
+int main(void)
+{
+  WCHAR path[MAX_PATH],second[MAX_PATH],relative[] = L"test-file.txt";
+  LPMRULIST list = MRU_Create(L"Test",MRU_NOCASE,3);
+  STARTUPINFO si = {0};
+  int i;
+  g_hInstance = GetModuleHandle(NULL);
+  GetModuleFileName(NULL,path,MAX_PATH);
+  PathRemoveFileSpec(path);
+  lstrcpy(second,path);
+  PathAppend(path,L"test-file.txt");
+  PathAppend(second,L"second.txt");
+  CHECK(MRU_AddFile(list,path,FALSE,FALSE)); // Initially every slot is NULL.
+  CHECK(lstrcmpi(list->pszItems[0],path) == 0);
+  CHECK(MRU_AddFile(list,second,FALSE,FALSE)); // Partial list.
+  CHECK(MRU_AddFile(list,path,FALSE,FALSE)); // Existing absolute duplicate.
+  CHECK(lstrcmpi(list->pszItems[0],path) == 0 && lstrcmpi(list->pszItems[1],second) == 0);
+  MRU_Empty(list);
+  list->pszItems[1] = StrDup(relative); // Null gap before a relative duplicate.
+  CHECK(MRU_AddFile(list,path,FALSE,FALSE));
+  CHECK(lstrcmpi(list->pszItems[0],path) == 0);
+  MRU_Empty(list);
+  SetEnvironmentVariable(L"NP2_MRU_TEST",second);
+  list->pszItems[1] = StrDup(L"%NP2_MRU_TEST%");
+  CHECK(MRU_AddFile(list,second,FALSE,FALSE));
+  CHECK(lstrcmpi(list->pszItems[0],second) == 0);
+  MRU_Empty(list);
+  for (i = 0; i < 5; ++i) {
+    WCHAR name[MAX_PATH];
+    wsprintf(name,L"C:\\test-%d.txt",i);
+    CHECK(MRU_AddFile(list,name,FALSE,FALSE));
+  }
+  CHECK(lstrcmp(list->pszItems[0],L"C:\\test-4.txt") == 0);
+  CHECK(lstrcmp(list->pszItems[2],L"C:\\test-2.txt") == 0);
+  MRU_Destroy(list);
+  CHECK(VERSION_LEGALCOPYRIGHT_LONG[0] == 0x00A9);
+  CHECK(wcschr(titlePunctuation,0x0384) && wcschr(titlePunctuation,0x2019));
+  CHECK(StartupShowState(si) == SW_SHOWNORMAL);
+  si.wShowWindow = SW_SHOWMAXIMIZED;
+  CHECK(StartupShowState(si) == SW_SHOWNORMAL); // Value irrelevant without flag.
+  si.dwFlags = STARTF_USESHOWWINDOW;
+  CHECK(StartupShowState(si) == SW_SHOWMAXIMIZED);
+  si.wShowWindow = SW_HIDE;
+  CHECK(StartupShowState(si) == SW_HIDE);
+  si.wShowWindow = SW_SHOWMINIMIZED;
+  CHECK(StartupShowState(si) == SW_SHOWMINIMIZED);
+  puts("MRU, UTF-8 source and startup show-state contracts passed.");
+  return 0;
+}
diff --git a/build/test-themes.ps1 b/build/test-themes.ps1
deleted file mode 100644
index 44113876..00000000
--- a/build/test-themes.ps1
+++ /dev/null
@@ -1,227 +0,0 @@
-[CmdletBinding()]
-param(
-    [string]$Executable = "$PSScriptRoot/../bin/VS2022/Release_x64/Notepad2.exe",
-    [string]$BaselineExecutable
-)
-
-$ErrorActionPreference = 'Stop'
-Add-Type @'
-using System;
-using System.Text;
-using System.Runtime.InteropServices;
-public static class ThemeTestNative {
-    public delegate bool Callback(IntPtr hwnd, IntPtr state);
-    [DllImport("user32.dll")] public static extern bool EnumWindows(Callback cb, IntPtr state);
-    [DllImport("user32.dll")] public static extern bool EnumChildWindows(IntPtr hwnd, Callback cb, IntPtr state);
-    [DllImport("user32.dll")] public static extern uint GetWindowThreadProcessId(IntPtr hwnd, out uint pid);
-    [DllImport("user32.dll", CharSet=CharSet.Unicode)] public static extern int GetClassName(IntPtr hwnd, StringBuilder text, int size);
-    [DllImport("user32.dll")] public static extern IntPtr SendMessage(IntPtr hwnd, uint msg, IntPtr w, IntPtr l);
-    [DllImport("user32.dll")] public static extern bool PostMessage(IntPtr hwnd, uint msg, IntPtr w, IntPtr l);
-    [DllImport("user32.dll")] public static extern IntPtr GetDlgItem(IntPtr hwnd, int id);
-    [DllImport("user32.dll", CharSet=CharSet.Unicode, EntryPoint="SendMessageW")] public static extern IntPtr SendText(IntPtr hwnd, uint msg, IntPtr w, string text);
-}
-'@
-
-function Assert($condition, $message) { if (-not $condition) { throw $message } }
-function Sci($message, $w = 0, $l = 0) {
-    [ThemeTestNative]::SendMessage($script:editor, $message, [IntPtr]$w, [IntPtr]$l).ToInt64()
-}
-function Select-Theme($dark) {
-    $command = if ($dark) { 40981 } else { 40980 }
-    $null = [ThemeTestNative]::SendMessage($script:window, 0x111, [IntPtr]$command, [IntPtr]::Zero)
-}
-function Start-Editor($ini, $document, $scheme = 'cpp') {
-    $script:app = Start-Process -FilePath $Executable -ArgumentList @('/n', '/f', ('"'+$ini+'"'), '/s', $scheme, ('"'+$document+'"')) -WindowStyle Hidden -PassThru
-    # Hosted Windows runners can stall process initialization under scanner/load.
-    # Keep assertions strict, but allow a bounded CI startup window.
-    Assert ($script:app.WaitForInputIdle(60000)) "Editor startup timed out after 60s: $Executable (PID $($script:app.Id))"
-    $script:window = [IntPtr]::Zero
-    $script:editor = [IntPtr]::Zero
-    $processId = $script:app.Id
-    $callback = [ThemeTestNative+Callback]{ param($handle, $state)
-        [uint32]$owner = 0
-        $null = [ThemeTestNative]::GetWindowThreadProcessId($handle, [ref]$owner)
-        $name = New-Object Text.StringBuilder 128
-        $null = [ThemeTestNative]::GetClassName($handle, $name, 128)
-        if ($owner -eq $processId -and $name.ToString() -like 'Notepad2*') { $script:window = $handle }
-        return $true
-    }
-    $null = [ThemeTestNative]::EnumWindows($callback, [IntPtr]::Zero)
-    Assert ($script:window -ne [IntPtr]::Zero) 'Main window missing'
-    $child = [ThemeTestNative+Callback]{ param($handle, $state)
-        $name = New-Object Text.StringBuilder 128
-        $null = [ThemeTestNative]::GetClassName($handle, $name, 128)
-        if ($name.ToString() -eq 'Scintilla') { $script:editor = $handle }
-        return $true
-    }
-    $null = [ThemeTestNative]::EnumChildWindows($script:window, $child, [IntPtr]::Zero)
-    Assert ($script:editor -ne [IntPtr]::Zero) 'Scintilla window missing'
-}
-function Stop-Editor {
-    $null = Sci 2014
-    $null = [ThemeTestNative]::PostMessage($script:window, 0x10, [IntPtr]::Zero, [IntPtr]::Zero)
-    Assert ($script:app.WaitForExit(10000)) 'Editor did not exit normally'
-}
-
-function Open-Customization {
-    $null = [ThemeTestNative]::PostMessage($script:window, 0x111, [IntPtr]40402, [IntPtr]::Zero)
-    $script:dialog = [IntPtr]::Zero
-    $processId = $script:app.Id
-    $callback = [ThemeTestNative+Callback]{ param($handle, $state)
-        [uint32]$owner = 0
-        $null = [ThemeTestNative]::GetWindowThreadProcessId($handle, [ref]$owner)
-        $name = New-Object Text.StringBuilder 128
-        $null = [ThemeTestNative]::GetClassName($handle, $name, 128)
-        if ($owner -eq $processId -and $name.ToString() -eq '#32770') { $script:dialog = $handle }
-        return $true
-    }
-    for ($attempt = 0; $attempt -lt 50 -and $script:dialog -eq [IntPtr]::Zero; ++$attempt) {
-        Start-Sleep -Milliseconds 20
-        $null = [ThemeTestNative]::EnumWindows($callback, [IntPtr]::Zero)
-    }
-    Assert ($script:dialog -ne [IntPtr]::Zero) 'Customize Schemes dialog missing'
-    # Window enumeration can see the dialog before WM_INITDIALOG populates it.
-    $first = [IntPtr]::Zero
-    for ($attempt = 0; $attempt -lt 500 -and $first -eq [IntPtr]::Zero; ++$attempt) {
-        $tree = [ThemeTestNative]::GetDlgItem($script:dialog, 100)
-        $root = [ThemeTestNative]::SendMessage($tree, 0x110A, [IntPtr]::Zero, [IntPtr]::Zero)
-        if ($root -ne [IntPtr]::Zero) { $first = [ThemeTestNative]::SendMessage($tree, 0x110A, [IntPtr]4, $root) }
-        if ($first -eq [IntPtr]::Zero) { Start-Sleep -Milliseconds 20 }
-    }
-    Assert ($first -ne [IntPtr]::Zero) 'Customize Schemes tree was not populated'
-    $null = [ThemeTestNative]::SendMessage($tree, 0x110B, [IntPtr]9, $first)
-}
-
-$Executable = (Resolve-Path $Executable).Path
-$testDir = Join-Path ([IO.Path]::GetTempPath()) ('np2-themes-' + [Guid]::NewGuid().ToString('N'))
-$null = New-Item -ItemType Directory -Path $testDir
-$ini = Join-Path $testDir 'settings.ini'
-$document = Join-Path $testDir 'sample.cpp'
-[IO.File]::WriteAllText($document, "// comment`r`nint main() { return 42; }`r`n")
-$settings = "[Settings]`r`nSaveSettings=1`r`n[Default Text]`r`nDefault Style=font:Consolas; size:13; fore:#123456; back:#EEDDCC`r`n"
-[IO.File]::WriteAllText($ini, $settings, [Text.Encoding]::Unicode)
-try {
-    Start-Editor $ini $document
-    $original = Sci 2482 32
-    $fontSize = Sci 2485 32
-    $lexer = Sci 4002
-    $null = Sci 2645 0 1 # Create a real undo record, with numeric-only cross-process messages.
-    $null = Sci 2160 2 7
-    $snapshot = @((Sci 2006), (Sci 2008), (Sci 2009), (Sci 2152), (Sci 2174))
-    $timer = [Diagnostics.Stopwatch]::StartNew()
-    for ($i = 0; $i -lt 20; ++$i) {
-        Select-Theme $true
-        Assert ((Sci 2482 32) -eq 0x1E1E1E) 'Dark background not applied'
-        Assert ((Sci 2485 32) -eq $fontSize) 'Theme changed font size'
-        Select-Theme $false
-        Assert ((Sci 2482 32) -eq $original) 'Original custom background lost'
-    }
-    $timer.Stop()
-    Assert ((Sci 4002) -eq $lexer) 'Theme changed lexer'
-    $after = @((Sci 2006), (Sci 2008), (Sci 2009), (Sci 2152), (Sci 2174))
-    Assert (($snapshot -join ',') -eq ($after -join ',')) 'Theme changed document/selection/viewport/undo state'
-    Select-Theme $true
-    Stop-Editor
-    Start-Editor $ini $document
-    Assert ((Sci 2482 32) -eq 0x1E1E1E) 'Theme selection did not persist'
-    Select-Theme $false
-    Assert ((Sci 2482 32) -eq $original) 'Original settings changed after restart'
-    Stop-Editor
-    [IO.File]::WriteAllText($ini, $settings.Replace('SaveSettings=1','SaveSettings=0'), [Text.Encoding]::Unicode)
-    Start-Editor $ini $document
-    Select-Theme $true
-    Stop-Editor
-    Start-Editor $ini $document
-    Assert ((Sci 2482 32) -eq $original) 'Disabled settings saving was ignored'
-    Stop-Editor
-    # Saved Dark colors are independent; typography embedded in a color section is ignored.
-    $custom = $settings + "[Styles]`r`nEditorTheme=1`r`n[Theme.Dark.Default Text]`r`nDefault Style=font:Ignored; size:99; fore:#ABCDEF; back:#222222`r`n"
-    [IO.File]::WriteAllText($ini, $custom, [Text.Encoding]::Unicode)
-    Start-Editor $ini $document
-    Assert ((Sci 2482 32) -eq 0x222222) 'Custom Dark color not loaded'
-    Assert ((Sci 2485 32) -eq $fontSize) 'Dark color section changed shared typography'
-    Select-Theme $false
-    Assert ((Sci 2482 32) -eq $original) 'Dark customization overwrote Original'
-    Select-Theme $true
-    Assert ((Sci 2482 32) -eq 0x222222) 'Dark customization lost on round trip'
-    Stop-Editor
-    [IO.File]::WriteAllText($ini, $settings + "[Styles]`r`nEditorTheme=99`r`n", [Text.Encoding]::Unicode)
-    Start-Editor $ini $document
-    Assert ((Sci 2482 32) -eq $original) 'Unknown theme did not fall back to Original'
-    Stop-Editor
-    [IO.File]::WriteAllText($ini, $settings + "[Styles]`r`nEditorTheme=1`r`n[Theme.Dark.Default Text]`r`nDefault Style=back:invalid`r`n", [Text.Encoding]::Unicode)
-    Start-Editor $ini $document
-    Assert ((Sci 2482 32) -eq 0x1E1E1E) 'Invalid saved Dark default did not fall back safely'
-    Stop-Editor
-    $source = [IO.File]::ReadAllText((Join-Path $PSScriptRoot '../src/Styles.c'))
-    $lexers = [regex]::Matches($source, 'EDITLEXER\s+\w+\s*=\s*\{[^\r\n]*?L"([^"]+)",\s*L"([^"]*)"')
-    Assert ($lexers.Count -eq 38) 'Lexer coverage inventory changed'
-    foreach ($entry in $lexers) {
-        [IO.File]::WriteAllText($ini, $settings, [Text.Encoding]::Unicode)
-        $scheme = $entry.Groups[2].Value.Split(';')[0].Trim()
-        Start-Editor $ini $document $scheme
-        Select-Theme $true
-        Assert ((Sci 2482 32) -eq 0x1E1E1E) "Dark background failed for $scheme"
-        Select-Theme $false
-        Stop-Editor
-    }
-    [IO.File]::WriteAllText($ini, $settings, [Text.Encoding]::Unicode)
-    Start-Editor $ini $document
-    Select-Theme $true
-    Open-Customization
-    $field = [ThemeTestNative]::GetDlgItem($script:dialog, 102)
-    $null = [ThemeTestNative]::SendText($field, 0xC, [IntPtr]::Zero, 'font:Consolas; size:15; fore:#EEEEEE; back:#111111')
-    $null = [ThemeTestNative]::SendMessage($script:dialog, 0x111, [IntPtr]106, [IntPtr]::Zero)
-    Assert ((Sci 2482 32) -eq 0x111111) 'Customization preview did not apply'
-    $null = [ThemeTestNative]::SendMessage($script:dialog, 0x111, [IntPtr]107, [IntPtr]::Zero)
-    $null = [ThemeTestNative]::SendMessage($script:dialog, 0x111, [IntPtr]106, [IntPtr]::Zero)
-    Assert ((Sci 2482 32) -eq 0x1E1E1E) 'Reset restored light colors in Dark'
-    $null = [ThemeTestNative]::SendMessage($script:dialog, 0x111, [IntPtr]2, [IntPtr]::Zero)
-    Assert ((Sci 2482 32) -eq 0x1E1E1E -and (Sci 2485 32) -eq $fontSize) 'Cancel did not restore preview'
-    Open-Customization
-    $field = [ThemeTestNative]::GetDlgItem($script:dialog, 102)
-    $null = [ThemeTestNative]::SendText($field, 0xC, [IntPtr]::Zero, 'font:Consolas; size:15; fore:#EEEEEE; back:#111111')
-    $null = [ThemeTestNative]::SendMessage($script:dialog, 0x111, [IntPtr]1, [IntPtr]::Zero)
-    Select-Theme $false
-    Assert ((Sci 2485 32) -eq 15 -and (Sci 2482 32) -eq $original) 'Customization did not share typography and isolate colors'
-    Select-Theme $true
-    $null = [ThemeTestNative]::SendMessage($script:window, 0x111, [IntPtr]40401, [IntPtr]::Zero)
-    Assert ((Sci 2482 32) -eq 0x1E1E1E) 'Second default was not themed'
-    $null = [ThemeTestNative]::SendMessage($script:window, 0x111, [IntPtr]40401, [IntPtr]::Zero)
-    Stop-Editor
-    Start-Editor $ini $document
-    Assert ((Sci 2482 32) -eq 0x111111 -and (Sci 2485 32) -eq 15) 'Customized theme did not persist'
-    Stop-Editor
-    Write-Output "Theme integration passed. 40 switches: $($timer.ElapsedMilliseconds) ms. Fixtures: $testDir"
-    if ($BaselineExecutable) {
-        $currentExecutable = $Executable
-        foreach ($mode in @('Baseline', 'Original', 'Dark')) {
-            $Executable = if ($mode -eq 'Baseline') { (Resolve-Path $BaselineExecutable).Path } else { $currentExecutable }
-            $samples = for ($run = 0; $run -lt 7; ++$run) {
-                $theme = if ($mode -eq 'Dark') { 1 } else { 0 }
-                [IO.File]::WriteAllText($ini, $settings + "[Styles]`r`nEditorTheme=$theme`r`n", [Text.Encoding]::Unicode)
-                $startup = [Diagnostics.Stopwatch]::StartNew()
-                Start-Editor $ini $document
-                $startup.Stop()
-                $script:app.Refresh()
-                $privateBytes = $script:app.PrivateMemorySize64
-                $editing = [Diagnostics.Stopwatch]::StartNew()
-                for ($op = 0; $op -lt 100; ++$op) { $null = Sci 2645 0 1; $null = Sci 2176 }
-                $editing.Stop()
-                $cpuBefore = $script:app.TotalProcessorTime.TotalMilliseconds
-                Start-Sleep -Milliseconds 200
-                $script:app.Refresh()
-                $idle = $script:app.TotalProcessorTime.TotalMilliseconds - $cpuBefore
-                Stop-Editor
-                [pscustomobject]@{ StartupMs=$startup.Elapsed.TotalMilliseconds; PrivateKiB=$privateBytes/1024; Edit100Ms=$editing.Elapsed.TotalMilliseconds; Idle200Ms=$idle }
-            }
-            $median = [ordered]@{ Mode=$mode }
-            foreach ($metric in @('StartupMs','PrivateKiB','Edit100Ms','Idle200Ms')) {
-                $median[$metric] = [Math]::Round(($samples.$metric | Sort-Object)[3], 2)
-            }
-            [pscustomobject]$median
-        }
-    }
-} finally {
-    if ($script:app -and -not $script:app.HasExited) { Stop-Process -Id $script:app.Id }
-}
diff --git a/conftest.py b/conftest.py
new file mode 100644
index 00000000..d843d637
--- /dev/null
+++ b/conftest.py
@@ -0,0 +1,11 @@
+"""Register CLI options before pytest resolves test paths."""
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent
+
+
+def pytest_addoption(parser):
+    parser.addoption("--executable", default=str(ROOT / "bin/VS2022/Release_x64/Notepad2.exe"))
+    parser.addoption("--architecture", choices=("x86", "x64"), default="x64")
+    parser.addoption("--configuration", choices=("Release", "Debug"), default="Release")
+    parser.addoption("--legacy-save-behavior", action="store_true")
diff --git a/pytest.ini b/pytest.ini
new file mode 100644
index 00000000..0bc51309
--- /dev/null
+++ b/pytest.ini
@@ -0,0 +1,3 @@
+[pytest]
+testpaths = tests
+addopts = -ra
diff --git a/src/Helpers.c b/src/Helpers.c
index 3870c26e..950b2ef2 100644
--- a/src/Helpers.c
+++ b/src/Helpers.c
@@ -1656,6 +1656,7 @@ BOOL MRU_AddFile(LPMRULIST pmru,LPCWSTR pszFile,BOOL bRelativePath,BOOL bUnexpan
 
   int i;
   for (i = 0; i < pmru->iSize; i++) {
+    if (!pmru->pszItems[i]) continue;
     if (lstrcmpi(pmru->pszItems[i],pszFile) == 0) {
       LocalFree(pmru->pszItems[i]);
       break;
diff --git a/src/Notepad2.c b/src/Notepad2.c
index dfed1cdb..9c6916b4 100644
--- a/src/Notepad2.c
+++ b/src/Notepad2.c
@@ -2108,8 +2108,8 @@ void MsgInitMenu(HWND hwnd,WPARAM wParam,LPARAM lParam)
   i  = (int)SendMessage(hwndEdit,SCI_GETSELECTIONEND,0,0) - (int)SendMessage(hwndEdit,SCI_GETSELECTIONSTART,0,0);
   i2 = (int)SendMessage(hwndEdit,SCI_CANPASTE,0,0);
 
-  EnableCmd(hmenu,IDM_EDIT_CUT,i /*&& !bReadOnly*/);
-  EnableCmd(hmenu,IDM_EDIT_COPY,i /*&& !bReadOnly*/);
+  EnableCmd(hmenu,IDM_EDIT_CUT,SendMessage(hwndEdit,SCI_GETLENGTH,0,0));
+  EnableCmd(hmenu,IDM_EDIT_COPY,SendMessage(hwndEdit,SCI_GETLENGTH,0,0));
   EnableCmd(hmenu,IDM_EDIT_COPYALL,SendMessage(hwndEdit,SCI_GETLENGTH,0,0) /*&& !bReadOnly*/);
   EnableCmd(hmenu,IDM_EDIT_COPYADD,i /*&& !bReadOnly*/);
   EnableCmd(hmenu,IDM_EDIT_PASTE,i2 /*&& !bReadOnly*/);
@@ -2845,14 +2845,21 @@ LRESULT MsgCommand(HWND hwnd,WPARAM wParam,LPARAM lParam)
     case IDM_EDIT_CUT:
       if (flagPasteBoard)
         bLastCopyFromMe = TRUE;
-      SendMessage(hwndEdit,SCI_CUT,0,0);
+      if (SendMessage(hwndEdit,SCI_GETSELECTIONEMPTY,0,0)) {
+        if (!SendMessage(hwndEdit,SCI_GETREADONLY,0,0) && SendMessage(hwndEdit,SCI_GETLENGTH,0,0)) {
+          SendMessage(hwndEdit,SCI_COPYALLOWLINE,0,0);
+          SendMessage(hwndEdit,SCI_LINEDELETE,0,0);
+        }
+      }
+      else
+        SendMessage(hwndEdit,SCI_CUT,0,0);
       break;
 
 
     case IDM_EDIT_COPY:
       if (flagPasteBoard)
         bLastCopyFromMe = TRUE;
-      SendMessage(hwndEdit,SCI_COPY,0,0);
+      SendMessage(hwndEdit,SCI_COPYALLOWLINE,0,0);
       UpdateToolbar();
       break;
 
@@ -7021,13 +7028,6 @@ BOOL FileSave(BOOL bSaveAlways,BOOL bAsk,BOOL bSaveAs,BOOL bSaveCopy)
     int cchText = (int)SendMessage(hwndEdit,SCI_GETLENGTH,0,0);
     if (cchText == 0)
       bIsEmptyNewFile = TRUE;
-    else if (cchText < 1023) {
-      char tchText[2048];
-      SendMessage(hwndEdit,SCI_GETTEXT,(WPARAM)2047,(LPARAM)tchText);
-      StrTrimA(tchText," \t\n\r");
-      if (lstrlenA(tchText) == 0)
-        bIsEmptyNewFile = TRUE;
-    }
   }
 
   if (!bSaveAlways && (!bModified && iEncoding == iOriginalEncoding || bIsEmptyNewFile) && !bSaveAs)
@@ -7618,7 +7618,7 @@ BOOL RelaunchElevated() {
       sei.lpFile = lpArg1;
       sei.lpParameters = lpArg2;
       sei.lpDirectory = g_wchWorkingDirectory;
-      sei.nShow = si.wShowWindow;
+      sei.nShow = (si.dwFlags & STARTF_USESHOWWINDOW) ? si.wShowWindow : SW_SHOWNORMAL;
 
       ShellExecuteEx(&sei);
     }
diff --git a/src/Notepad2.rc b/src/Notepad2.rc
index 73d65ece..999eb5e7 100644
Binary files a/src/Notepad2.rc and b/src/Notepad2.rc differ
diff --git a/src/Notepad2.vcxproj b/src/Notepad2.vcxproj
index ccd68ebd..0b066a48 100644
--- a/src/Notepad2.vcxproj
+++ b/src/Notepad2.vcxproj
@@ -102,6 +102,7 @@
       <PreprocessorDefinitions>WIN32;STATIC_BUILD;SCI_LEXER;BOOKMARK_EDITION;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
       <WarningLevel>Level3</WarningLevel>
+      <AdditionalOptions>/source-charset:utf-8 %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <AdditionalDependencies>comctl32.lib;imm32.lib;shlwapi.lib;msimg32.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -128,6 +129,7 @@
       <PreprocessorDefinitions>_WIN64;STATIC_BUILD;SCI_LEXER;BOOKMARK_EDITION;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
       <WarningLevel>Level3</WarningLevel>
+      <AdditionalOptions>/source-charset:utf-8 %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <AdditionalDependencies>comctl32.lib;imm32.lib;shlwapi.lib;msimg32.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -152,6 +154,7 @@
       <PreprocessorDefinitions>WIN32;STATIC_BUILD;SCI_LEXER;BOOKMARK_EDITION;NDEBUG;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
       <WarningLevel>Level3</WarningLevel>
+      <AdditionalOptions>/source-charset:utf-8 %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <AdditionalDependencies>comctl32.lib;imm32.lib;shlwapi.lib;msimg32.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -179,6 +182,7 @@
       <PreprocessorDefinitions>_WIN64;STATIC_BUILD;SCI_LEXER;BOOKMARK_EDITION;NDEBUG;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
       <WarningLevel>Level3</WarningLevel>
+      <AdditionalOptions>/source-charset:utf-8 %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <AdditionalDependencies>comctl32.lib;imm32.lib;shlwapi.lib;msimg32.lib;%(AdditionalDependencies)</AdditionalDependencies>
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 00000000..91cdd231
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,37 @@
+from contextlib import contextmanager
+from pathlib import Path
+import sys
+
+# OLE clipboard preservation requires STA; select it before importing pywinauto.
+sys.coinit_flags = 2
+
+import pytest
+
+from windows_app import Editor
+
+@pytest.fixture
+def legacy_save_behavior(request):
+    return request.config.getoption("--legacy-save-behavior")
+
+
+@pytest.fixture
+def editor_factory(request, tmp_path):
+    serial = 0
+
+    @contextmanager
+    def factory(named=False, settings=None, scheme="cpp", content=None):
+        nonlocal serial
+        serial += 1
+        folder = tmp_path / str(serial)
+        folder.mkdir()
+        ini = folder / "settings.ini"
+        ini.write_text(settings or "[Settings]\nSaveSettings=1\n", encoding="utf-16")
+        document = folder / "sample.cpp"
+        document.write_bytes(content if content is not None else b"// comment\r\nint main() { return 42; }\r\n")
+        editor = Editor(Path(request.config.getoption("--executable")).resolve(), ini, document if named else None, scheme)
+        try:
+            yield editor
+        finally:
+            editor.close()
+
+    return factory
diff --git a/tests/requirements.in b/tests/requirements.in
new file mode 100644
index 00000000..b79da906
--- /dev/null
+++ b/tests/requirements.in
@@ -0,0 +1,2 @@
+pytest
+pywinauto
diff --git a/tests/requirements.txt b/tests/requirements.txt
new file mode 100644
index 00000000..b3655a61
--- /dev/null
+++ b/tests/requirements.txt
@@ -0,0 +1,61 @@
+# This file was autogenerated by uv via the following command:
+#    uv pip compile tests/requirements.in --generate-hashes -o tests/requirements.txt
+colorama==0.4.6 \
+    --hash=sha256:08695f5cb7ed6e0531a20572697297273c47b8cae5a63ffc6d6ed5c201be6e44 \
+    --hash=sha256:4f1d9991f5acc0ca119f9d443620b77f9d6b33703e51011c16baf57afb285fc6
+    # via pytest
+comtypes==1.4.17 \
+    --hash=sha256:3d9c1e92ad8daf7600d371e76ee16161a627a5fb70c3144f6e52e78af6034363 \
+    --hash=sha256:4e0a221dde2c589b82977bed802efd71cd5eb67a380347b732e02735e597f586
+    # via pywinauto
+iniconfig==2.3.1 \
+    --hash=sha256:67f4b9c50da0dedf52af349e7749a80a9057a5031199791b906c3bb3ae878960 \
+    --hash=sha256:9121e2c1fdb355232495be3194c8dfe87ccc2d5dee45947b78e68f499790d7a7
+    # via pytest
+packaging==26.3 \
+    --hash=sha256:94edc256424af38762eb31306eed28beb9f0efc50a8837492c9d6fd6004aed79 \
+    --hash=sha256:d7193f7c8e4e93f444fde0262bf90af30e16fa0ad0ad44cb553c87339b23cd1c
+    # via pytest
+pluggy==1.7.0 \
+    --hash=sha256:7dd7b0d8832ba3cb632c306926ded123429211b83641b35dc5c41ad2d34f9bec \
+    --hash=sha256:d1eaa46ebb595891b860ab086b4d09c8588af65ebd4361b8e8f4bb8920b90ba8
+    # via pytest
+pygments==2.21.0 \
+    --hash=sha256:2363c69b61c4a97c838da3b130dcd6468f4848992b21a82f2a63ec34377137d9 \
+    --hash=sha256:610ca751c9bc2492b38eb9a38a7fbc93edbbb2d7182edaf34e66ae493dee5c8c
+    # via pytest
+pytest==9.2.0 \
+    --hash=sha256:07acdcf88ec174f907dc01af70bf52d49b014bbab03faeeade31c96b18c2e588 \
+    --hash=sha256:97c4f3b1f3c7414aa36465e09b8220f1d03627993bd51b1282e193753c80557b
+    # via -r tests/requirements.in
+pywin32==312 \
+    --hash=sha256:02ebca0f0242b75292e218065004310d6a477407c09fa449bfe4f6022bc0c0fc \
+    --hash=sha256:17948aeadbdb091f0ced6ef0841620794e68327b94ee415571c1203594b7215c \
+    --hash=sha256:3020656e34f1cf7faeb7bccd2b84653a607c6ff0c55ada85e6487d61716deabd \
+    --hash=sha256:59aba5d5940842075343a5ddc6b11f1cdf0d1567fe745290359dfbcc7c2eb831 \
+    --hash=sha256:5c1fbe4a937a73ae9297384a3da38518cbc694c68ad8a809b2e19acd350f03ed \
+    --hash=sha256:5dbc35d2b5320dc07f25fa31269cfb767471002b17de5eb067d03da68c7cb2db \
+    --hash=sha256:6017c58e12f6809fbb0555b75df144c2922a9ffd18e4b9b5afa863b6c1a9d950 \
+    --hash=sha256:772235332b5d1024c696f11cea1ae4be7930f0a8b894bb43db14e3f435f1ff7e \
+    --hash=sha256:7a27df850933d16a8eabfbaeb73d52b273e2da667f80d70b01a89d1f6828d02c \
+    --hash=sha256:9fce94568364e0155e6dfb781ac5d95903be8baf28670632beab1b523f300daa \
+    --hash=sha256:a4dd3a848290ef724347b19f301045831d8e802fa4464f491b98b1e0a081432e \
+    --hash=sha256:a77a90fbb6881238d2ca9c6fd797b25817f3768fe78d214a90137ff055a75f5b \
+    --hash=sha256:a8597d28f267b39074aef51fa593530082b39cbe5a074226096857b1fed2dfb9 \
+    --hash=sha256:b2200a054ca6d6625c4842fc56a4976a4b47f96b73dbe5538c3f813a80359f47 \
+    --hash=sha256:b457f6d628a47e8a7346ce22acb7e1a46a4a78b52e1d17e1af56871bd19a93bc \
+    --hash=sha256:c2f03a0f73f804a13c2735b99392b0cd426bb4f2c4d0178e5ac966a0f21618d5 \
+    --hash=sha256:c53e878d15a1c44788082bfe712a905433473aa38f86375b7cf8b45e3acbaaf9 \
+    --hash=sha256:d11417d84412f859b722fad0841b3614459ed0047f7542d8362e77884f6b6e8a \
+    --hash=sha256:d620900033cc7531e50727c3c8333091df5dd3ffe6d68cdca38c03f5821408d5 \
+    --hash=sha256:dab4f65ac9c4e48400a2a0530c46c3c579cd5905ecd11b80692373915269208b \
+    --hash=sha256:dc90147579a905b8635e1b0ec6514967dcb07e6e0d9c42f1477feef14cac23bb
+    # via pywinauto
+pywinauto==0.6.9 \
+    --hash=sha256:5924b3072864a1d730c5546bbeb17cf4063ba518b618dbc5e43c18276c7c9356 \
+    --hash=sha256:94d710bfa796df245250f952ffa65d97233d9807bcd42e052b71b81af469b6de
+    # via -r tests/requirements.in
+six==1.17.0 \
+    --hash=sha256:4721f391ed90541fddacab5acf947aa0d3dc7d27b2e1e8eda2be8970586c3274 \
+    --hash=sha256:ff70335d468e7eb6ec65b95b99d3a2836546063f63acc5171de367e834932a81
+    # via pywinauto
diff --git a/tests/test_line_shortcuts.py b/tests/test_line_shortcuts.py
new file mode 100644
index 00000000..b71a22a4
--- /dev/null
+++ b/tests/test_line_shortcuts.py
@@ -0,0 +1,127 @@
+"""Current-line shortcuts use existing Scintilla actions, without a new subsystem."""
+import ctypes
+import pythoncom
+import pytest
+import win32clipboard
+from pywinauto.timings import wait_until, wait_until_passes
+
+
+def clipboard_text(value=None):
+    def access():
+        win32clipboard.OpenClipboard()
+        try:
+            if value is None:
+                return win32clipboard.GetClipboardData(win32clipboard.CF_UNICODETEXT)
+            win32clipboard.EmptyClipboard()
+            win32clipboard.SetClipboardText(value, win32clipboard.CF_UNICODETEXT)
+        finally:
+            win32clipboard.CloseClipboard()
+    return wait_until_passes(5, 0.05, access)
+
+
+@pytest.fixture(autouse=True)
+def preserve_clipboard():
+    # OLE retains the original data object, including non-text formats.
+    pythoncom.OleInitialize()
+    original = wait_until_passes(5, 0.05, pythoncom.OleGetClipboard)
+    try:
+        clipboard_text("np2-test-sentinel")
+        yield
+    finally:
+        try:
+            wait_until_passes(5, 0.05, lambda: pythoncom.OleSetClipboard(original))
+            wait_until_passes(5, 0.05, pythoncom.OleFlushClipboard)
+        finally:
+            ctypes.windll.ole32.OleUninitialize()
+
+
+@pytest.mark.parametrize("eol", [b"\r\n", b"\n", b"\r"])
+@pytest.mark.parametrize("last", [False, True])
+@pytest.mark.parametrize("keys", ["^c", "^{INSERT}"])
+def test_ctrl_c_copies_line_without_selection(editor_factory, eol, last, keys):
+    content = b"first" + eol + "βeta".encode()
+    with editor_factory(named=True, content=content) as e:
+        e.sci(2031, {b"\r\n": 0, b"\r": 1, b"\n": 2}[eol])
+        position = len(b"first" + eol) + 2 if last else 2
+        e.sci(2160, position, position)
+        before, undo = e.read_bytes(), e.sci(2174)
+        e.editor.send_keystrokes(keys)
+        expected = ("βeta" if last else "first") + eol.decode()
+        wait_until(5, 0.05, lambda: clipboard_text() == expected)
+        assert e.read_bytes() == before
+        assert e.sci(2008) == e.sci(2009) == position
+        assert e.sci(2174) == undo
+
+
+@pytest.mark.parametrize("selection", [False, True])
+@pytest.mark.parametrize("keys", ["^x", "+{DELETE}"])
+def test_shift_delete_cuts_line_or_selection_and_undoes(editor_factory, selection, keys):
+    original = b"first\r\nsecond\r\nthird"
+    with editor_factory(named=True, content=original) as e:
+        e.sci(2160, 1 if selection else 2, 4 if selection else 2)
+        e.editor.send_keystrokes(keys)
+        expected = b"ft\r\nsecond\r\nthird" if selection else b"second\r\nthird"
+        wait_until(5, 0.05, lambda: e.read_bytes() == expected)
+        assert clipboard_text() == ("irs" if selection else "first\r\n")
+        e.sci(2176)
+        assert e.read_bytes() == original
+
+
+def test_ctrl_c_keeps_selected_text_behavior(editor_factory):
+    with editor_factory(named=True, content=b"first\r\nsecond") as e:
+        e.sci(2160, 1, 4)
+        e.editor.send_keystrokes("^c")
+        wait_until(5, 0.05, lambda: clipboard_text() == "irs")
+        assert e.read_bytes() == b"first\r\nsecond"
+
+
+def test_read_only_cut_preserves_text_and_clipboard(editor_factory):
+    with editor_factory(named=True, content=b"read only\r\n") as e:
+        e.sci(2171, 1)
+        e.command(40302)
+        assert e.read_bytes() == b"read only\r\n"
+        assert clipboard_text() == "np2-test-sentinel"
+
+
+@pytest.mark.parametrize("original,position,remaining,copied", [
+    (b"last", 2, b"", "last\r\n"),
+    (b"first\r\nlast", 9, b"first\r\n", "last\r\n"),
+    (b"first\r\n\r\nthird", 7, b"first\r\nthird", "\r\n"),
+])
+def test_cut_line_edges(editor_factory, original, position, remaining, copied):
+    with editor_factory(named=True, content=original) as e:
+        e.sci(2160, position, position)
+        e.editor.send_keystrokes("+{DELETE}")
+        wait_until(5, 0.05, lambda: e.read_bytes() == remaining)
+        assert clipboard_text() == copied
+        e.sci(2176)
+        assert e.read_bytes() == original
+
+
+def test_empty_cut_does_not_replace_clipboard(editor_factory):
+    with editor_factory() as e:
+        e.command(40302)
+        assert e.read_bytes() == b""
+        assert clipboard_text() == "np2-test-sentinel"
+
+
+@pytest.mark.parametrize("copy_keys", ["^c", "^{INSERT}", "^x", "+{DELETE}"])
+@pytest.mark.parametrize("paste_keys", ["^v", "+{INSERT}"])
+def test_line_clipboard_pastes_above_current_line(editor_factory, copy_keys, paste_keys):
+    original = b"first\r\nsecond\r\nthird"
+    cutting = copy_keys in ("^x", "+{DELETE}")
+    with editor_factory(named=True, content=original) as e:
+        e.sci(2160, 2, 2)
+        e.editor.send_keystrokes(copy_keys)
+        wait_until(5, 0.05, lambda: clipboard_text() == "first\r\n")
+        marker = win32clipboard.RegisterClipboardFormat("MSDEVLineSelect")
+        assert win32clipboard.IsClipboardFormatAvailable(marker)
+        # Paste while the caret is inside 'third', not at column zero.
+        before_paste = b"second\r\nthird" if cutting else original
+        caret = len(before_paste) - 2
+        e.sci(2160, caret, caret)
+        e.editor.send_keystrokes(paste_keys)
+        expected = b"second\r\nfirst\r\nthird" if cutting else b"first\r\nsecond\r\nfirst\r\nthird"
+        wait_until(5, 0.05, lambda: e.read_bytes() == expected)
+        e.sci(2176)
+        assert e.read_bytes() == before_paste
diff --git a/tests/test_native_contracts.py b/tests/test_native_contracts.py
new file mode 100644
index 00000000..2e7e8376
--- /dev/null
+++ b/tests/test_native_contracts.py
@@ -0,0 +1,54 @@
+"""Compile production MRU functions and source-linked Unicode/startup contracts."""
+import os
+from pathlib import Path
+import re
+import subprocess
+import xml.etree.ElementTree as ET
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def test_native_contracts(request, tmp_path):
+    arch = request.config.getoption("--architecture")
+    config = request.config.getoption("--configuration")
+    for source in (ROOT / "src").iterdir():
+        if source.suffix in (".c", ".cpp", ".h"):
+            source.read_bytes().decode("utf-8", errors="strict")
+    ns = {"m": "http://schemas.microsoft.com/developer/msbuild/2003"}
+    project = ET.parse(ROOT / "src/Notepad2.vcxproj")
+    compilers = project.findall("m:ItemDefinitionGroup/m:ClCompile", ns)
+    assert len(compilers) == 4
+    for compiler in compilers:
+        options = compiler.findtext("m:AdditionalOptions", namespaces=ns)
+        assert "/source-charset:utf-8" in options
+        assert "/execution-charset" not in options and "/utf-8" not in options
+    source = (ROOT / "src/Notepad2.c").read_text(encoding="utf-8")
+    elevation = source[source.index("BOOL RelaunchElevated() {"):]
+    show = re.search(r"sei\.nShow\s*=\s*([^;]+);", elevation).group(1)
+    edit = (ROOT / "src/Edit.c").read_text(encoding="utf-8")
+    punctuation = re.search(r'StrChr\((L"[^"]+"),pszTextW\[i\]\)', edit).group(1)
+    (tmp_path / "fork-contracts.h").write_text(
+        f"static int StartupShowState(STARTUPINFO si) {{ return {show}; }}\n"
+        f"static const wchar_t titlePunctuation[] = {punctuation};\n", encoding="utf-8"
+    )
+    vswhere = Path(os.environ["ProgramFiles(x86)"]) / "Microsoft Visual Studio/Installer/vswhere.exe"
+    vs = subprocess.check_output([
+        str(vswhere), "-latest", "-version", "[17.0,18.0)", "-products", "*",
+        "-requires", "Microsoft.VisualStudio.Component.VC.Tools.x86.x64", "-property", "installationPath"
+    ], text=True).strip()
+    assert vs
+    runtime = "/MTd" if config == "Debug" else "/MT"
+    batch = tmp_path / "run.bat"
+    batch.write_text(
+        f'@echo off\nchcp 65001 >nul\ncall "{vs}\\Common7\\Tools\\VsDevCmd.bat" -no_logo -arch={arch}\n'
+        'if errorlevel 1 exit /b 1\n'
+        f'cd /d "{tmp_path}"\n'
+        f'cl /nologo /TC {runtime} /Gy /DUNICODE /D_UNICODE /D_CRT_SECURE_NO_WARNINGS /source-charset:utf-8 '
+        f'/I"{ROOT / "src"}" /I"{ROOT / "scintilla/include"}" /I"{tmp_path}" '
+        f'"{ROOT / "build/test-fork-helpers.c"}" "{ROOT / "src/Helpers.c"}" /Fe:contracts.exe '
+        '/link /OPT:REF /INCREMENTAL:NO shlwapi.lib shell32.lib user32.lib comctl32.lib ole32.lib comdlg32.lib gdi32.lib advapi32.lib\n'
+        'if errorlevel 1 exit /b 1\ncontracts.exe\nexit /b %errorlevel%\n',
+        encoding="utf-8", newline="\r\n"
+    )
+    result = subprocess.run(["cmd.exe", "/d", "/c", str(batch)], capture_output=True, timeout=60)
+    assert result.returncode == 0, (result.stdout + result.stderr).decode("utf-8", errors="replace")
diff --git a/tests/test_save_prompts.py b/tests/test_save_prompts.py
new file mode 100644
index 00000000..455d80e1
--- /dev/null
+++ b/tests/test_save_prompts.py
@@ -0,0 +1,69 @@
+"""Exercise save prompting through the native UI, including embedded NUL data."""
+
+import pytest
+from pywinauto.timings import wait_until
+
+
+CASES = [
+    pytest.param(b"\0AB", False, True, id="leading-nul"),
+    pytest.param(b" \t\r\n", False, True, id="whitespace"),
+    pytest.param(b"\0A" + bytes(1020), False, True, id="1022-byte-nul"),
+    pytest.param(b"\0A" + bytes(1021), False, False, id="1023-byte-nul"),
+    pytest.param(b"", False, False, id="empty"),
+    pytest.param(b"\0AB", True, False, id="named-nul"),
+]
+
+
+@pytest.mark.parametrize("payload,named,legacy_drops", CASES)
+@pytest.mark.parametrize("operation", ["new", "open", "close"])
+def test_nonempty_document_prompts_before_discard(
+    editor_factory, legacy_save_behavior, payload, named, legacy_drops, operation
+):
+    with editor_factory(named=named) as editor:
+        editor.add_bytes(payload)
+        before = editor.read_bytes()
+        if operation == "close":
+            editor.post_close()
+        else:
+            editor.post_command(40000 if operation == "new" else 40001)
+
+        result = {}
+
+        def operation_reached_ui():
+            if not editor.is_running():
+                result["state"] = "closed"
+                return True
+            dialog = editor.dialog()
+            if dialog is not None and dialog.is_visible():
+                buttons = {
+                    child.control_id()
+                    for child in dialog.descendants(class_name="Button")
+                }
+                if {6, 7}.issubset(buttons):
+                    result.update(state="save", dialog=dialog)
+                    return True
+                if {1, 2}.issubset(buttons):
+                    result["state"] = "open-dialog"
+                    return True
+            if operation == "new" and editor.sci(2006) == 0:
+                result["state"] = "cleared"
+                return True
+            return False
+
+        wait_until(10, 0.05, operation_reached_ui)
+        should_prompt = bool(before) and not (
+            legacy_save_behavior and legacy_drops
+        )
+        assert (result["state"] == "save") is should_prompt, (
+            f"{operation}: observed {result['state']}; "
+            f"save prompt expected={should_prompt}"
+        )
+        if should_prompt:
+            result["dialog"].child_window(control_id=2).wrapper_object().click()
+            wait_until(5, 0.05, lambda: editor.dialog() is None)
+            assert editor.read_bytes() == before, "Cancel changed document bytes"
+        elif legacy_save_behavior and legacy_drops:
+            expected_state = {
+                "new": "cleared", "open": "open-dialog", "close": "closed"
+            }[operation]
+            assert result["state"] == expected_state
diff --git a/tests/test_themes.py b/tests/test_themes.py
new file mode 100644
index 00000000..78445832
--- /dev/null
+++ b/tests/test_themes.py
@@ -0,0 +1,87 @@
+import re
+from pathlib import Path
+
+import pytest
+
+SETTINGS = "[Settings]\nSaveSettings=1\n[Default Text]\nDefault Style=font:Consolas; size:13; fore:#123456; back:#EEDDCC\n"
+SOURCE = (Path(__file__).resolve().parents[1] / "src/Styles.c").read_text(encoding="utf-8")
+SCHEMES = re.findall(r'EDITLEXER\s+\w+\s*=\s*\{[^\r\n]*?L"([^"]+)",\s*L"([^"]*)"', SOURCE)
+
+
+@pytest.mark.parametrize("name,extensions", SCHEMES, ids=[entry[0] for entry in SCHEMES])
+def test_scheme_round_trip(editor_factory, name, extensions):
+    assert len(SCHEMES) == 38
+    with editor_factory(named=True, settings=SETTINGS, scheme=extensions.split(";")[0].strip()) as e:
+        original = e.sci(2482, 32)
+        e.theme(True)
+        assert e.sci(2482, 32) == 0x1E1E1E
+        e.theme(False)
+        assert e.sci(2482, 32) == original
+
+
+def test_switching_preserves_document_and_preferences(editor_factory):
+    with editor_factory(named=True, settings=SETTINGS) as e:
+        e.sci(2645, 0, 1)
+        e.sci(2160, 2, 7)
+        before = e.read_bytes()
+        state = [e.sci(m) for m in (2008, 2009, 2152, 2174, 4002)]
+        original, font = e.sci(2482, 32), e.sci(2485, 32)
+        for _ in range(20):
+            e.theme(True)
+            assert e.sci(2482, 32) == 0x1E1E1E
+            assert e.sci(2485, 32) == font
+            e.theme(False)
+            assert e.sci(2482, 32) == original
+        assert e.read_bytes() == before
+        assert [e.sci(m) for m in (2008, 2009, 2152, 2174, 4002)] == state
+
+
+@pytest.mark.parametrize("save", [True, False])
+def test_selection_persistence(editor_factory, save):
+    with editor_factory(named=True, settings=SETTINGS.replace("SaveSettings=1", f"SaveSettings={int(save)}")) as e:
+        original = e.sci(2482, 32)
+        e.theme(True)
+        e.exit()
+        e.launch()
+        assert e.sci(2482, 32) == (0x1E1E1E if save else original)
+        e.theme(False)
+        assert e.sci(2482, 32) == original
+
+
+@pytest.mark.parametrize("extra,expected", [
+    ("[Styles]\nEditorTheme=99\n", 0xCCDDEE),
+    ("[Styles]\nEditorTheme=1\n[Theme.Dark.Default Text]\nDefault Style=back:invalid\n", 0x1E1E1E),
+    ("[Styles]\nEditorTheme=1\n[Theme.Dark.Default Text]\nDefault Style=font:Ignored; size:99; fore:#ABCDEF; back:#222222\n", 0x222222),
+])
+def test_saved_palette_defaults(editor_factory, extra, expected):
+    with editor_factory(named=True, settings=SETTINGS + extra) as e:
+        assert e.sci(2482, 32) == expected
+        assert e.sci(2485, 32) == 13
+        e.theme(False)
+        assert e.sci(2482, 32) == 0xCCDDEE
+
+
+def test_customize_preview_cancel_reset_and_save(editor_factory):
+    with editor_factory(named=True, settings=SETTINGS) as e:
+        e.theme(True)
+        dialog = e.customize()
+        dialog.child_window(control_id=102).set_edit_text("font:Consolas; size:15; fore:#EEEEEE; back:#111111")
+        dialog.child_window(control_id=106).click()
+        assert e.sci(2482, 32) == 0x111111
+        dialog.child_window(control_id=107).click()
+        dialog.child_window(control_id=106).click()
+        assert e.sci(2482, 32) == 0x1E1E1E
+        dialog.child_window(control_id=2).click()
+        assert e.sci(2482, 32) == 0x1E1E1E and e.sci(2485, 32) == 13
+        dialog = e.customize()
+        dialog.child_window(control_id=102).set_edit_text("font:Consolas; size:15; fore:#EEEEEE; back:#111111")
+        dialog.child_window(control_id=1).click()
+        e.theme(False)
+        assert e.sci(2485, 32) == 15 and e.sci(2482, 32) == 0xCCDDEE
+        e.theme(True)
+        e.command(40401)
+        assert e.sci(2482, 32) == 0x1E1E1E
+        e.command(40401)
+        e.exit()
+        e.launch()
+        assert e.sci(2482, 32) == 0x111111 and e.sci(2485, 32) == 15
diff --git a/tests/windows_app.py b/tests/windows_app.py
new file mode 100644
index 00000000..620ee96f
--- /dev/null
+++ b/tests/windows_app.py
@@ -0,0 +1,97 @@
+"""pywinauto owns window/control automation; this adapter handles Scintilla messages."""
+import ctypes
+import subprocess
+
+from pywinauto import Application
+from pywinauto.remote_memory_block import RemoteMemoryBlock
+from pywinauto.timings import wait_until
+
+
+class Editor:
+    def __init__(self, executable, ini, document=None, scheme="cpp"):
+        self.executable, self.ini, self.document, self.scheme = executable, ini, document, scheme
+        self.launch()
+
+    def launch(self):
+        args = [str(self.executable), "/n", "/f", str(self.ini), "/s", self.scheme]
+        if self.document:
+            args.append(str(self.document))
+        startup = subprocess.STARTUPINFO()
+        startup.dwFlags = subprocess.STARTF_USESHOWWINDOW
+        startup.wShowWindow = 0
+        self.process = subprocess.Popen(args, startupinfo=startup)
+        try:
+            self.app = Application(backend="win32").connect(process=self.process.pid, timeout=60)
+            self.main = self.app.window(class_name_re="Notepad2.*", visible_only=False)
+            self.main.wait("exists", timeout=60)
+            control = self.main.child_window(class_name="Scintilla")
+            control.wait("exists", timeout=60)
+            self.editor = control.wrapper_object()
+        except BaseException:
+            self.close()
+            raise
+
+    def sci(self, message, w=0, l=0):
+        return self.editor.send_message_timeout(message, w, l, timeout=10)
+
+    def add_bytes(self, data):
+        if data:
+            buffer = ctypes.create_string_buffer(data)
+            remote = RemoteMemoryBlock(self.editor, size=len(buffer))
+            try:
+                remote.Write(buffer)
+                self.sci(2001, len(data), remote.Address())
+            finally:
+                remote.CleanUp()
+
+    def read_bytes(self):
+        size = self.sci(2006)
+        buffer = ctypes.create_string_buffer(size + 1)
+        remote = RemoteMemoryBlock(self.editor, size=size + 1)
+        try:
+            self.sci(2182, size + 1, remote.Address())
+            remote.Read(buffer)
+            return buffer.raw[:size]
+        finally:
+            remote.CleanUp()
+
+    def command(self, command):
+        self.main.send_message_timeout(0x111, command, 0, timeout=10)
+
+    def post_command(self, command):
+        self.main.post_message(0x111, command, 0)
+
+    def post_close(self):
+        self.main.post_message(0x10)
+
+    def dialog(self):
+        if not self.is_running():
+            return None
+        windows = self.app.windows(class_name="#32770", visible_only=False)
+        return self.app.window(handle=windows[0].handle) if windows else None
+
+    def is_running(self):
+        return self.process.poll() is None
+
+    def theme(self, dark):
+        self.command(40981 if dark else 40980)
+
+    def customize(self):
+        self.post_command(40402)
+        wait_until(10, 0.05, lambda: self.dialog() is not None and self.dialog().is_visible())
+        dialog = self.dialog()
+        tree = dialog.child_window(control_id=100).wrapper_object()
+        wait_until(10, 0.05, lambda: tree.item_count() > 38)
+        tree.get_item([0, 0]).select()
+        return dialog
+
+    def exit(self):
+        self.sci(2014)  # Tests decide what to save; never leave an unsaved prompt.
+        self.post_close()
+        self.process.wait(timeout=10)
+        assert self.process.returncode == 0
+
+    def close(self):
+        if self.is_running():
+            self.process.terminate()
+            self.process.wait(timeout=10)