Release v0.6.43: fix forwarded input and verify snippet pastes

CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.24)
-project(KSwitcher VERSION 0.6.38 LANGUAGES CXX RC)
+project(KSwitcher VERSION 0.6.43 LANGUAGES CXX RC)
 if(NOT WIN32)
   message(FATAL_ERROR "KSwitcher uses native Windows APIs")
 endif()
@@ -66,6 +66,29 @@ else()
   target_link_options(KSwitcherOcrTests PRIVATE -static -static-libgcc -static-libstdc++)
 endif()
 enable_testing()
+add_executable(KSwitcherHistoryHostTests tests/history_host.cpp)
+target_link_libraries(KSwitcherHistoryHostTests PRIVATE kscore psapi)
+set_target_properties(KSwitcherHistoryHostTests PROPERTIES RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/history-host-fixture-$<CONFIG>")
+add_dependencies(KSwitcherHistoryHostTests KSwitcher KSwitcherScreenshot)
+add_custom_command(TARGET KSwitcherHistoryHostTests POST_BUILD
+  COMMAND ${CMAKE_COMMAND} -E copy "$<TARGET_FILE:KSwitcher>" "$<TARGET_FILE_DIR:KSwitcherHistoryHostTests>/KSwitcher.exe"
+  COMMAND ${CMAKE_COMMAND} -E copy "$<TARGET_FILE:KSwitcherScreenshot>" "$<TARGET_FILE_DIR:KSwitcherHistoryHostTests>/KSwitcher.Screenshot.exe"
+  COMMAND ${CMAKE_COMMAND} -E touch "$<TARGET_FILE_DIR:KSwitcherHistoryHostTests>/.local-dev")
+if(MSVC)
+  target_compile_options(KSwitcherHistoryHostTests PRIVATE /utf-8)
+  set_property(TARGET KSwitcherHistoryHostTests PROPERTY MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
+else()
+  target_link_options(KSwitcherHistoryHostTests PRIVATE -static -static-libgcc -static-libstdc++)
+endif()
+add_executable(KSwitcherClipboardSnapshotTests tests/clipboard_snapshot.cpp)
+target_link_libraries(KSwitcherClipboardSnapshotTests PRIVATE kscore psapi)
+add_dependencies(KSwitcherClipboardSnapshotTests KSwitcherScreenshot)
+if(MSVC)
+  target_compile_options(KSwitcherClipboardSnapshotTests PRIVATE /utf-8)
+  set_property(TARGET KSwitcherClipboardSnapshotTests PROPERTY MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
+else()
+  target_link_options(KSwitcherClipboardSnapshotTests PRIVATE -static -static-libgcc -static-libstdc++)
+endif()
 add_executable(KSwitcherImageCaptureTests tests/image_capture.cpp)
 target_link_libraries(KSwitcherImageCaptureTests PRIVATE kscore)
 add_dependencies(KSwitcherImageCaptureTests KSwitcherScreenshot)

README.md

@@ -75,6 +75,9 @@ Ctrl+Alt+Delete and Win+L; these cannot be assigned.
 
 Keyboard and mouse input forwarded by Microsoft Mouse Without Borders follows the same input
 path as a local keyboard/mouse, including shortcuts, recent-word conversion and snippets.
+On the sending computer, KSwitcher ignores keyboard events consumed by another keyboard hook
+(including Mouse Without Borders forwarding). The receiving computer still processes delivered
+input normally, so both computers can run KSwitcher without starting duplicate snippet operations.
 KSwitcher marks its own generated input so copy/paste, selection, modifier releases and shell-mask
 keys cannot trigger recursive commands or overwrite the recorded typing run. Other injected input
 is accepted, including key-up events and VK-only keyboard events. Unicode packets do not provide
@@ -274,10 +277,18 @@ thumbnails and source labels aligned with the scaled fonts and spacing.
   of the complete expected text. Browser/editor compatibility depends on its handling of simulated input.
 - Selection conversion and verified recent input (physical scan codes, 2-second typing-run boundary).
 - Same-process clipboard ownership plus verified WebView2 descendants, including the Teams fix.
+  Clipboard synchronizers such as Mouse Without Borders may republish a copy only when
+  KSwitcher first observed it owned by the target application and the selection text and
+  editor selection metadata remain identical. Unobserved or altered foreign copies are rejected.
+  Snippets require accessibility verification of their selected trigger and pasted text,
+  even with logging disabled. If verification is unavailable or the paste differs, expansion
+  stops without running cursor or Enter actions. Clipboard changes during paste also cancel actions.
 - Teams recent-word conversion uses a single word-selection command and validates the copied range.
   If the editor's word boundary differs from the recorded typing, it falls back to paced character
   selection: Teams can coalesce a burst of Shift+Left events into just one character.
 - Clipboard snapshot/restoration with concurrent-copy, foreground and input-version checks.
+  A snapshot interrupted by a concurrent clipboard publication is retried up to three total
+  attempts before selection starts, provided the foreground and input context remain unchanged.
   A silently dropped copy is retried up to three total attempts while the clipboard and input
   context remain unchanged. Temporary transaction contents are excluded from Windows clipboard
   history and cloud synchronization. Paste is not blindly retried: with manual paste readback
@@ -720,8 +731,14 @@ Consecutive duplicates use SHA-256 fingerprints inside the encrypted history ind
 
 Moving OCR isolates its temporary memory rather than reducing the combined processing peak. A controlled three-run comparison retained about 0.8 MiB less private RAM in the caller after recognition; combined peak RAM was about 55.6 MiB before and 56.6 MiB with the helper. Results depend on the image, OCR engine and system.
 
-### History previews and Escape — v0.6.38
+### Pinned history checkbox — v0.6.42
 
-History initializes RichEdit only for HTML/RTF previews. Plain text keeps Unicode and line breaks without RTF conversion; empty history and image-only previews do not load RichEdit unnecessarily. Plain and formatted text previews share the existing bounded text-preview cache.
+Check **★ Pinned only** beside the history search box to show only pinned entries; uncheck it to show all entries. The checkbox sits on the left, immediately followed by the search box; its right edge stays aligned with the history list when resizing. The text search applies within that filter. Unpinning an item removes it from the pinned view immediately. The checkbox state and search are remembered after closing and reopening history. **Clear history…** still deletes the entire history after confirmation, including entries hidden by the filter.
 
-Esc clears hidden rows/caches and cancels obsolete queued preview work, while retaining the selected/top entry for reopening. Already-needed RichEdit controls are cleared and reused. Clipboard contents, paste formatting, OCR, settings and shortcuts are unchanged. A local isolated comparison saved approximately 0.48–0.72 MiB private working set after Esc depending on content; this is not a fixed application footprint or a guarantee that all UI memory returns to the startup level.
+### History process and clipboard memory — v0.6.40
+
+History opens in a separate, short-lived instance of **KSwitcher.exe**. **Esc** closes it even when focus is on the window or an action button, releasing Windows UI allocations with the process. The resident keeps keyboard hooks, clipboard capture and history storage. Search, selection and the top entry are preserved in encrypted view state. If a full-text item viewer is still open, the helper stays alive until the last viewer closes. Pin/delete, formatted/plain paste and OCR remain available; settings and default shortcuts are unchanged.
+
+Image thumbnails are decoded in **KSwitcher.Screenshot.exe**, returning only bounded preview pixels. Image clipboard backup/restore also uses that helper and encrypted temporary files, with clipboard-sequence checks before restoring. Selection reads avoid loading image formats. Keep all three executables together; no fourth executable is required. Paste allows a brief foreground handoff after history closes while preserving cancellation checks. UI Automation remains in the resident.
+
+A live development-build test measured **4.37 MiB before history and 4.35 MiB after two open/Esc cycles**, compared with an earlier roughly 8–9 MiB plateau. A same-image clipboard-backup benchmark retained **12.78 MiB before versus 0.05 MiB after**. These measure private working set, not a guaranteed total footprint. Include all helpers when measuring active use: combined memory can be higher while history is open. No forced working-set trimming is used. Existing screenshots and shortcuts remain applicable. The v0.6.38 approach of retaining a hidden history window/RichEdit control is superseded by process termination.

Release/README.md

@@ -1,22 +1,23 @@
 # Latest Windows release
 
-## v0.6.38 — 2026-11-04
+## v0.6.43 — 2026-11-04
 
 ## Changes
-- Clipboard history loads RichEdit only when an HTML/RTF preview actually needs it. Empty history, plain text and image-only previews no longer initialize it unnecessarily.
+- Respect downstream keyboard-hook suppression before tracking input or starting snippets. This prevents source-side expansion of keys forwarded by Mouse Without Borders. Update KSwitcher on both computers, especially the keyboard-sharing source.
-- Plain text previews retain Unicode and line breaks without converting the text to RTF. Plain and formatted preview payloads share the existing bounded text-preview cache.
+- Verify snippet selection and pasted text through accessibility even with logging disabled. Unavailable verification, incorrect text or clipboard changes cancel further cursor/Enter actions. No snippet syntax, shortcut or default changed.
-- Esc still clears hidden history rows and preview caches while preserving the remembered selection/top item. Closing or replacing a search now cancels obsolete preview work before loading/decoding where possible, and discards completed stale results.
+- Accept identical clipboard relays only after observing target-owned content, preserving text and editor selection metadata checks. Unicode allocation padding and format order do not cause false mismatches; changed content remains rejected.
-- A RichEdit control that was needed for formatted text is cleared and reused, not repeatedly destroyed/recreated. This avoids additional initialization on reopening. Settings, shortcuts, stored clipboard contents, formatting on paste and OCR behavior are unchanged.
+- Retry clipboard snapshots interrupted by concurrent publication up to three times before selection, while input context remains unchanged.
+- Clicking a warning notification opens Logs. Copy rejection diagnostics include observed/current text, clipboard sequences and the sentinel for troubleshooting.
 
 ## Validation
-Staged build and tests cover dictionary equivalence for 140,939 words, 105 sync checks, wheel batching, 315 native checks, 561 input checks, screenshot UI/PNG/notification registration, 48 updater checks and updater progress UI. Added checks for plain previews without RichEdit, retained HTML rendering, lazy control creation and cleanup through Esc. Isolated real-window tests also verified formatted previews after reopening.
+Release regression checks cover dictionary equivalence (140,939 words), 105 sync checks, 319 native checks, 569 input checks, screenshot UI/save/registration, 48 updater checks and updater progress UI. The isolated snippet suite exercises an actual downstream forwarding hook, verifies no source-side copy or text changes, and checks normal expansion, Enter, buffered typing, copy retries and suppression of Enter after incorrect pasted text.
 
-A controlled local comparison measured 0.72 MiB less private working set after Esc for empty history, 0.66 MiB for plain text, 0.48 MiB for formatted text and 0.53 MiB for images. These are isolated test-process comparisons, not the application's total RAM or a guaranteed reduction on another computer. The reported 7 MiB plateau on a different laptop was not reproduced. No working-set trimming was used; closing the history window does not promise an exact return to startup memory.
+Live two-computer validation with both instances updated remains outstanding. An older instance on either computer can still interfere; the fix does not accept unrelated clipboard contents.
 
 ## Upgrade
-Choose **Update** in the tray menu. Legacy v0.3.0–v0.4.1 clients first receive the v0.4.2 compatibility bridge, then the current full release. v0.2.3 and earlier require manual installation.
+Choose **Update** in the tray menu on both computers. Legacy v0.3.0–v0.4.1 clients first receive the v0.4.2 compatibility bridge, then the current full release. v0.2.3 and earlier require manual installation.
-For manual installation, exit KSwitcher, close screenshot editors and extract the entire ZIP into its installation folder. Keep personal `data/` and customized dictionaries.
+For manual installation, exit KSwitcher, close its configurator and screenshot editors, and extract the entire ZIP into its installation folder. Keep personal `data/` and customized dictionaries.
 
-Download **KSwitcher-win-x64.zip** with **SHA256SUMS.txt**. Keep all three executables together. The package contains no personal settings, credentials or clipboard history.
+Download **KSwitcher-win-x64.zip** with **SHA256SUMS.txt**. Keep all three executables together; history uses another instance of KSwitcher.exe. The package contains no personal settings, credentials or clipboard history.
 
 Publish stable `release-vX.Y.Z` tags matching the executable version. Keep `v0.4.2` as the last legacy tag.

Release/SHA256SUMS.txt

@@ -1 +1 @@
-f430767d440581018e6adb33c153fb332318fa1eee5a162ddf32690d0b5a3391  KSwitcher-win-x64.zip
+008f34a2a4a875acb07d21a39c0fad3a0cb63371edbcb91d393edf72543aea5e  KSwitcher-win-x64.zip

build.ps1

@@ -81,6 +81,20 @@ try {
         if ($LASTEXITCODE) { throw 'Updater progress UI tests failed' }
     }
     if ($Integration) {
+        $historyFixture = Join-Path (Resolve-Path build) ('history-host-fixture-' + [guid]::NewGuid().ToString('N'))
+        New-Item -ItemType Directory $historyFixture | Out-Null
+        Copy-Item $executablePath,(Join-Path (Split-Path $executablePath) 'KSwitcher.Screenshot.exe') -Destination $historyFixture
+        Set-Content (Join-Path $historyFixture '.local-dev') 'Isolated history integration test'
+        $historyTest = Join-Path $historyFixture 'KSwitcherHistoryHostTests.exe'
+        & $compiler @common tests/history_host.cpp build/core.o build/platform.o build/storage.o build/ocr.o @libs -lpsapi -static -s -o $historyTest
+        if ($LASTEXITCODE) { throw 'History host test build failed' }
+        & $historyTest
+        if ($LASTEXITCODE) { throw 'History host tests failed' }
+        $snapshotTest = Join-Path (Split-Path $executablePath) 'KSwitcherClipboardSnapshotTests.exe'
+        & $compiler @common tests/clipboard_snapshot.cpp build/core.o build/platform.o build/storage.o build/ocr.o @libs -lpsapi -static -s -o $snapshotTest
+        if ($LASTEXITCODE) { throw 'Clipboard snapshot test build failed' }
+        & $snapshotTest
+        if ($LASTEXITCODE) { throw 'Clipboard snapshot tests failed' }
         $captureTest = Join-Path (Split-Path $executablePath) 'KSwitcherImageCaptureTests.exe'
         & $compiler @common tests/image_capture.cpp build/core.o build/platform.o build/storage.o build/ocr.o @libs -static -s -o $captureTest
         if ($LASTEXITCODE) { throw 'Image capture test build failed' }

resources/app.rc

@@ -9,8 +9,8 @@ IDC_SCREENSHOT_PENCIL CURSOR "icons/lucide/pencil.cur"
 1 RT_MANIFEST "app.manifest"
 201 RCDATA "update.ps1"
 1 VERSIONINFO
- FILEVERSION 0,6,38,0
+ FILEVERSION 0,6,43,0
- PRODUCTVERSION 0,6,38,0
+ PRODUCTVERSION 0,6,43,0
  FILEOS VOS_NT_WINDOWS32
  FILETYPE VFT_APP
 BEGIN
@@ -20,7 +20,7 @@ BEGIN
   BEGIN
    VALUE "FileDescription", "KSwitcher — native keyboard and clipboard utility"
    VALUE "ProductName", "KSwitcher"
-   VALUE "FileVersion", "0.6.38"
+   VALUE "FileVersion", "0.6.43"
   END
  END
  BLOCK "VarFileInfo"

src/app.cpp

@@ -15,6 +15,7 @@ namespace ks
 {
 #include "app_sync.inl"
 App *App::current = nullptr;
+#include "app_history.inl"
 namespace
 {
 const char *transformCommandName(int command)
@@ -71,12 +72,14 @@ class Transaction
     App &app;
     HWND target;
     uint64_t version;
-    Clip snapshot;
+    ClipboardSnapshot snapshot;
     DWORD expected{};
     bool captured{};
     mutable bool invalidLogged{};
     unsigned copyNumber{};
     std::wstring adopted;
+    Bytes adoptedFormats;
+    bool trustedContentsObserved{};
     std::unique_ptr<PasteProbe> selectionProof;
     std::wstring provenSelection;
 
@@ -85,11 +88,27 @@ class Transaction
     {
         app.suspended = true;
         try
+        {
+            for (unsigned attempt = 0; ; ++attempt)
             {
                 expected = GetClipboardSequenceNumber();
-            snapshot = readClipboard(app.window, 64 * 1024 * 1024);
+                try
+                {
+                    snapshot.capture(app.window, expected);
                     if (expected != GetClipboardSequenceNumber())
                         throw std::runtime_error("Clipboard changed while taking snapshot");
+                    break;
+                }
+                catch (...)
+                {
+                    // No selection or clipboard write has happened yet. Recapture
+                    // the latest clipboard after a concurrent publisher settles.
+                    if (attempt >= 2 || !valid() || expected == GetClipboardSequenceNumber())
+                        throw;
+                    diagnosticEvent(L"Snapshot retry: clipboard changed during capture");
+                    Sleep(20);
+                }
+            }
             captured = true;
         }
         catch (...)
@@ -103,7 +122,7 @@ class Transaction
         if (captured && GetClipboardSequenceNumber() == expected)
             try
             {
-                app.ownSequence = writeClipboard(app.window, snapshot);
+                app.ownSequence = snapshot.restore(app.window, expected);
             }
             catch (...)
             {
@@ -131,9 +150,19 @@ class Transaction
         if (GetClipboardSequenceNumber() != expected)
         {
             auto now = GetClipboardSequenceNumber();
-            if (adopted.empty() || !ownsClipboard(target) || readClipboard(app.window).text() != adopted ||
+            auto current = readClipboard(app.window, 32 * 1024 * 1024, ClipboardRead::Selection);
-                GetClipboardSequenceNumber() != now)
+            const bool sameContents = selectionClipboardIdentity(current) == adoptedFormats;
+            if (adopted.empty() || (!trustedContentsObserved && !ownsClipboard(target)) ||
+                !sameContents || GetClipboardSequenceNumber() != now)
+            {
+                diagnosticEvent(L"Clipboard check rejected: expectedSequence=" + std::to_wstring(expected) +
+                    L" readSequence=" + std::to_wstring(now) + L" currentSequence=" +
+                    std::to_wstring(GetClipboardSequenceNumber()) + L" owner=" +
+                    std::to_wstring((uintptr_t)GetClipboardOwner()) + L" sameContents=" +
+                    std::to_wstring(sameContents) + L" expectedText=" + diagnosticText(adopted) +
+                    L" currentText=" + diagnosticText(current.text()));
                 throw std::runtime_error("Operation cancelled: another application changed the clipboard");
+            }
             expected = now;
         }
     }
@@ -141,6 +170,8 @@ class Transaction
     {
         check();
         adopted.clear();
+        adoptedFormats.clear();
+        trustedContentsObserved = false;
         // These are temporary transaction contents, not a user's clipboard entry.
         // In particular, do not invite the Windows history service to read our
         // sentinel while the target editor is trying to open the clipboard.
@@ -153,7 +184,7 @@ class Transaction
         if (GetClipboardOwner() != app.window)
             throw std::runtime_error("Clipboard changed immediately after writing");
         auto text = c.text();
-        if ((!text.empty() && readClipboard(app.window).text() != text) ||
+        if ((!text.empty() && readClipboard(app.window, 32 * 1024 * 1024, ClipboardRead::Selection).text() != text) ||
             GetClipboardSequenceNumber() != expected)
             throw std::runtime_error("Clipboard changed while verifying our write");
     }
@@ -163,10 +194,12 @@ class Transaction
         const auto number = ++copyNumber;
         if (!valid())
             return {};
-        write(textClip(L"\x2063KSwitcher-" + std::to_wstring(GetTickCount64())));
+        const auto sentinel = L"\x2063KSwitcher-" + std::to_wstring(GetTickCount64());
+        write(textClip(sentinel));
         DWORD before = expected;
         diagnosticEvent(L"Copy begin number=" + std::to_wstring(number) + L" sentinelSequence=" +
-            std::to_wstring(before) + L" target=" + std::to_wstring((uintptr_t)target));
+            std::to_wstring(before) + L" target=" + std::to_wstring((uintptr_t)target) +
+            L" sentinel=" + diagnosticText(sentinel));
         if (!valid() || !chord(L'C', MOD_CONTROL))
         {
             diagnosticEvent(L"Copy failed: context changed or simulated Ctrl+C blocked");
@@ -178,6 +211,7 @@ class Transaction
         DWORD changed = before;
         ULONGLONG stable = 0;
         bool changedAgain = false;
+        std::optional<Bytes> observedTargetCopy;
         while (GetTickCount64() < deadline)
         {
             if (!valid())
@@ -192,6 +226,18 @@ class Transaction
                 changedAgain |= changed != before;
                 changed = now;
                 stable = GetTickCount64();
+                // Clipboard synchronizers can republish a legitimate copy under
+                // their own HWND. Record provenance before that handoff; an
+                // unobserved or altered foreign copy must still be rejected.
+                if (ownsClipboard(target))
+                {
+                    auto candidate = readClipboard(app.window, 32 * 1024 * 1024, ClipboardRead::Selection);
+                    if (GetClipboardSequenceNumber() == now && ownsClipboard(target) && !candidate.text().empty())
+                    {
+                        observedTargetCopy = selectionClipboardIdentity(candidate);
+                        diagnosticEvent(L"Copy: target-owned selection observed number=" + std::to_wstring(number));
+                    }
+                }
             }
             if (changed != before && GetTickCount64() - stable >= 60)
                 break;
@@ -223,16 +269,31 @@ class Transaction
                                     L"Copy failed: context changed");
             return {};
         }
-        if ((GetClipboardOwner() ? !ownsClipboard(target) : changedAgain) ||
+        const bool targetOwned = ownsClipboard(target);
+        auto clip = readClipboard(app.window, 32 * 1024 * 1024, ClipboardRead::Selection);
+        const auto formats = selectionClipboardIdentity(clip);
+        const bool verifiedRelay = observedTargetCopy && *observedTargetCopy == formats;
+        if (((GetClipboardOwner() ? !targetOwned : changedAgain) && !verifiedRelay) ||
             changed != GetClipboardSequenceNumber())
+        {
+            diagnosticEvent(L"Copy rejected: observedTarget=" + std::to_wstring(observedTargetCopy.has_value()) +
+                L" verifiedRelay=" + std::to_wstring(verifiedRelay) + L" expectedSequence=" +
+                std::to_wstring(changed) + L" currentSequence=" + std::to_wstring(GetClipboardSequenceNumber()) +
+                L" owner=" + std::to_wstring((uintptr_t)GetClipboardOwner()) + L" targetText=" +
+                diagnosticText(observedTargetCopy ? decodeClip(*observedTargetCopy).text() : L"") +
+                L" currentText=" + diagnosticText(clip.text()));
             throw std::runtime_error("Operation cancelled: copy did not belong to the target application");
+        }
+        if (!targetOwned && verifiedRelay)
+            diagnosticEvent(L"Copy: identical target selection republished by clipboard synchronizer");
         expected = changed;
-        auto clip = readClipboard(app.window);
         auto text = clip.text();
         diagnosticEvent(L"Copy result number=" + std::to_wstring(number) + L" attempts=" +
             std::to_wstring(attempts) + L" elapsedMs=" + std::to_wstring(GetTickCount64() - started) +
             L" text=" + diagnosticText(text));
         adopted = text;
+        adoptedFormats = formats;
+        trustedContentsObserved = targetOwned || verifiedRelay;
         check();
         for (auto &f : clip.formats)
         {
@@ -358,6 +419,14 @@ class Transaction
         if (!valid())
             return false;
         write(clip);
+        // Our verified payload is also trusted across an identical relay. The
+        // sentinel written by copy() deliberately does not get this allowance.
+        if (clip.formats.size() == 1 && clip.formats.front().id == CF_UNICODETEXT)
+        {
+            adopted = clip.text();
+            adoptedFormats = selectionClipboardIdentity(clip);
+            trustedContentsObserved = true;
+        }
         // Viber's Qt editor observes clipboard changes asynchronously. Give it
         // a chance to discard the data object from Ctrl+C before requesting paste.
         // Recheck ownership and input below; never retry a possibly applied paste.
@@ -375,6 +444,10 @@ class Transaction
         if (!chord(L'V', MOD_CONTROL))
             throw std::runtime_error("Windows blocked simulated input; check application privilege levels");
         Sleep(300);
+        // A clipboard synchronizer may replace our payload after Ctrl+V is
+        // queued but before the editor consumes it. Do not run snippet actions
+        // (especially Enter) after such a race.
+        check();
         return true;
     }
     bool nativeSelectionIs(const std::wstring &original) const
@@ -405,7 +478,8 @@ class Transaction
     }
 };
 } // namespace
-App::App(HINSTANCE h, bool test, const std::filesystem::path &dataRoot) : instance(h), smoke(test)
+App::App(HINSTANCE h, bool test, const std::filesystem::path &dataRoot, HWND service)
+    : historyService(service), instance(h), smoke(test)
 {
     updateNotifier = notifyUpdateAvailable;
     current = this;
@@ -422,7 +496,7 @@ App::App(HINSTANCE h, bool test, const std::filesystem::path &dataRoot) : instan
         registrationWarning = L"Settings were not loaded: " + wide(e.what());
     }
     setLoggingEnabled(settings.writeLog);
-    if (settings.autoCorrect)
+    if (settings.autoCorrect && !historyService)
         try { autoPredictor.configure(std::filesystem::path(executable()).parent_path() / L"dictionaries", settings.autoLanguages); }
         catch (const std::exception &e)
         {
@@ -441,6 +515,8 @@ App::App(HINSTANCE h, bool test, const std::filesystem::path &dataRoot) : instan
 }
 App::~App()
 {
+    if (auto host = historyController(historyProcess)) PostMessageW(host, WM_CLOSE, 0, 0);
+    if (historyProcess) CloseHandle(historyProcess);
     if (notificationRegistration) CloseHandle(notificationRegistration);
     if (syncWorker.joinable()) syncWorker.join();
     if (updateWorker.joinable())
@@ -688,6 +764,7 @@ void App::reloadLayouts()
 }
 void App::clearHistory()
 {
+    if (historyService) { remoteHistory("clear"); history->reload(); return; }
     if (busy) throw std::runtime_error("Wait for the current operation to finish.");
     if (history) history->clear();
     if (historyWindow) refreshHistory(*this);
@@ -950,6 +1027,15 @@ void App::replayTyping()
 }
 LRESULT CALLBACK App::keyProc(int code, WPARAM wp, LPARAM lp)
 {
+    // MWB suppresses source-machine events that it forwards elsewhere. Let
+    // downstream hooks route the event before tracking it or starting a snippet.
+    // Call the chain exactly once; a local event can still be consumed below.
+    const auto routed = CallNextHookEx(nullptr, code, wp, lp);
+    return keyboardAfterHooks(code, wp, lp, routed);
+}
+LRESULT App::keyboardAfterHooks(int code, WPARAM wp, LPARAM lp, LRESULT routed)
+{
+    if (routed) return routed;
     if (code == HC_ACTION && current &&
         (wp == WM_KEYDOWN || wp == WM_SYSKEYDOWN || wp == WM_KEYUP || wp == WM_SYSKEYUP))
     {
@@ -964,7 +1050,7 @@ LRESULT CALLBACK App::keyProc(int code, WPARAM wp, LPARAM lp)
                                     wp == WM_KEYDOWN || wp == WM_SYSKEYDOWN, mods))
             return 1;
     }
-    return CallNextHookEx(nullptr, code, wp, lp);
+    return routed;
 }
 LRESULT CALLBACK App::mouseProc(int code, WPARAM wp, LPARAM lp)
 {
@@ -1393,11 +1479,11 @@ void App::transform(int command, int snippet)
                     }
                 }
                 bool sent = false;
-                const bool requireReadback = tx.recoveredSelection();
+                const bool requireReadback = tx.recoveredSelection() || snippet >= 0;
                 PasteProbe probe(((config.writeLog && manual) || requireReadback) && result != text, text, target);
                 if (requireReadback && result != text && probe.status != L"ready")
                 {
-                    reason = L"recovered-selection-unavailable";
+                    reason = snippet >= 0 ? L"snippet-verification-unavailable" : L"recovered-selection-unavailable";
                     std::lock_guard lock(stateMutex);
                     last.reset();
                     run.reset();
@@ -1411,7 +1497,7 @@ void App::transform(int command, int snippet)
                     chord(VK_RIGHT);
                 if (requireReadback && result != text && !sent)
                 {
-                    reason = L"recovered-selection-paste-cancelled";
+                    reason = snippet >= 0 ? L"snippet-paste-cancelled" : L"recovered-selection-paste-cancelled";
                     std::lock_guard lock(stateMutex);
                     last.reset();
                     run.reset();
@@ -1523,6 +1609,7 @@ void App::transform(int command, int snippet)
 }
 void App::pasteEntry(std::wstring id, bool plain)
 {
+    if (historyService) { remoteHistory("paste", id, plain); return; }
     if (installingUpdate) return;
     if (!history || busy.exchange(true))
         return;
@@ -1544,10 +1631,20 @@ void App::pasteEntry(std::wstring id, bool plain)
             } reset{busy};
             try
             {
-                for (int i = 0; i < 20 && !modifiersReleased(); ++i)
+                // Foreground activation crosses a process boundary when the
+                // history UI closes. Let the destination finish activation,
+                // while retaining the same input-version cancellation guard.
+                for (int i = 0; i < 20 && inputVersion == version &&
+                     (!modifiersReleased() || GetForegroundWindow() != target); ++i)
                     Sleep(10);
                 if (!modifiersReleased() || GetForegroundWindow() != target || inputVersion != version)
+                {
+                    log(L"History paste cancelled before transaction: foreground=" +
+                        std::to_wstring(GetForegroundWindow() == target) + L" modifiers=" +
+                        std::to_wstring(modifiersReleased()) + L" expectedVersion=" + std::to_wstring(version) +
+                        L" actualVersion=" + std::to_wstring(inputVersion.load()));
                     return;
+                }
                 auto clip = history->load(id);
                 if (plain)
                 {
@@ -1557,7 +1654,7 @@ void App::pasteEntry(std::wstring id, bool plain)
                     clip = textClip(text);
                 }
                 Transaction tx(*this, target, version);
-                tx.paste(clip);
+                log(tx.paste(clip) ? L"History paste: simulated paste completed" : L"History paste cancelled before simulated paste");
             }
             catch (const std::exception &e)
             {
@@ -1599,7 +1696,8 @@ void App::captureHistory()
                     }
                     return;
                 }
-                auto clip = readClipboard(window, (size_t)config.maxImageMiB * 1024 * 1024);
+                auto clip = readClipboard(window, (size_t)config.maxImageMiB * 1024 * 1024,
+                                          ClipboardRead::WithoutImages, sequence);
                 if (sequence != GetClipboardSequenceNumber())
                     return;
                 for (auto &f : clip.formats)
@@ -1618,6 +1716,7 @@ void App::captureHistory()
 }
 void App::recognizeEntry(std::wstring id)
 {
+    if (historyService) { remoteHistory("ocr", id); return; }
     if (!history || busy.exchange(true))
         return;
     auto sequence = GetClipboardSequenceNumber();
@@ -1788,7 +1887,37 @@ LRESULT CALLBACK App::windowProc(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp)
     auto *app = current;
     if (!app)
         return DefWindowProcW(hwnd, msg, wp, lp);
-    if (msg == app->taskbarCreated && app->taskbarCreated)
+    if (app->historyService) {
+        if (msg == HistoryHostShow || msg == HistoryHostRefresh) {
+            try {
+                app->history->reload();
+                if (msg == HistoryHostShow) showHistory(*app);
+                else if (IsWindowVisible(app->historyWindow)) refreshHistory(*app);
+            } catch (const std::exception &e) { app->report(wide(e.what())); }
+            return 0;
+        }
+        if (msg == WM_TIMER) {
+            if (!IsWindow(app->historyService)) PostMessageW(hwnd, WM_CLOSE, 0, 0);
+            return 0;
+        }
+        if (msg == WM_CLOSE) {
+            EnumThreadWindows(GetCurrentThreadId(), [](HWND child, LPARAM) -> BOOL {
+                wchar_t name[64]{}; GetClassNameW(child, name, 64);
+                if (std::wstring(name) == L"KSwitcher.Entry" || std::wstring(name) == L"KSwitcher.History")
+                    DestroyWindow(child);
+                return TRUE;
+            }, 0);
+            DestroyWindow(hwnd);
+            return 0;
+        }
+        if (msg == WM_DESTROY) { PostQuitMessage(0); return 0; }
+        if (msg == ErrorMessage) {
+            std::unique_ptr<std::wstring> text(reinterpret_cast<std::wstring *>(lp));
+            MessageBoxW(app->historyWindow, text->c_str(), L"Clipboard history", MB_OK | MB_ICONWARNING);
+            return 0;
+        }
+    }
+    if (!app->historyService && msg == app->taskbarCreated && app->taskbarCreated)
     {
         app->addTray();
         return 0;
@@ -1852,7 +1981,9 @@ LRESULT CALLBACK App::windowProc(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp)
         app->replayTyping();
         return 0;
     case TrayMessage:
-        if (LOWORD(lp) == WM_CONTEXTMENU)
+        if (LOWORD(lp) == NIN_BALLOONUSERCLICK)
+            showLogs(*app);
+        else if (LOWORD(lp) == WM_CONTEXTMENU)
             app->trayMenu();
         else if (LOWORD(lp) == WM_LBUTTONDBLCLK)
             // The shell still owns the mouse gesture on the second button-down.
@@ -1902,6 +2033,7 @@ LRESULT CALLBACK App::windowProc(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp)
     case WM_COPYDATA:
     {
         auto *data = (COPYDATASTRUCT *)lp;
+        if (data && data->dwData == HistoryRequest) return app->historyRequest((HWND)wp, *data);
         if (data && data->dwData >= ConfigRead && data->dwData < ConfigEnd)
         {
             if (app->installingUpdate) return FALSE;
@@ -1988,7 +2120,7 @@ int App::execute()
     WNDCLASSW cls{};
     cls.hInstance = instance;
     cls.lpfnWndProc = windowProc;
-    cls.lpszClassName = L"KSwitcher.Main";
+    cls.lpszClassName = historyService ? HistoryHostClass : L"KSwitcher.Main";
     cls.hIcon = LoadIconW(instance, MAKEINTRESOURCEW(IDI_KSWITCHER));
     RegisterClassW(&cls);
     window = CreateWindowExW(WS_EX_TOOLWINDOW, cls.lpszClassName, L"KSwitcher", WS_POPUP, 0, 0, 0, 0, nullptr,
@@ -2022,6 +2154,30 @@ int App::execute()
             }
             CoUninitialize();
         });
+    if (historyService) {
+        try {
+            auto bytes = unprotect(readFile(data / L"history-view.bin", 4 * 1024 * 1024));
+            auto state = HistoryJson::parse(bytes);
+            historySelection = wide(state.value("selection", std::string{}));
+            historyTop = wide(state.value("top", std::string{}));
+            historyQuery = wide(state.value("query", std::string{}));
+            historyPinnedOnly = state.value("pinnedOnly", false);
+        } catch (...) {}
+        showHistory(*this);
+        remoteHistory("ready", std::to_wstring(reinterpret_cast<uintptr_t>(historyWindow)));
+        SetTimer(window, 1, 1000, nullptr);
+        MSG message{};
+        while (GetMessageW(&message, nullptr, 0, 0) > 0) {
+            if (message.message == WM_KEYDOWN && message.wParam == VK_ESCAPE && historyWindow &&
+                (message.hwnd == historyWindow || IsChild(historyWindow, message.hwnd))) {
+                SendMessageW(historyWindow, WM_CLOSE, 0, 0);
+                continue;
+            }
+            if (historyWindow && message.message == WM_SYSCHAR && IsDialogMessageW(historyWindow, &message)) continue;
+            TranslateMessage(&message); DispatchMessageW(&message);
+        }
+        return int(message.wParam);
+    }
     keyboardHook = SetWindowsHookExW(WH_KEYBOARD_LL, keyProc, instance, 0);
     mouseHook = SetWindowsHookExW(WH_MOUSE_LL, mouseProc, instance, 0);
     registerHotkeys(settings);
@@ -2058,7 +2214,7 @@ int App::execute()
                 continue;
         }
         // Preserve history-specific Enter/Shift+Enter and Ctrl+digit handling.
-        if (historyWindow && msg.message == WM_SYSCHAR && IsDialogMessageW(historyWindow, &msg))
+        if (!isolateHistory && historyWindow && msg.message == WM_SYSCHAR && IsDialogMessageW(historyWindow, &msg))
             continue;
         if (settingsWindow && IsDialogMessageW(settingsWindow, &msg))
             continue;

src/app.h

@@ -33,6 +33,11 @@ class App
 {
   public:
     HWND window{}, historyWindow{}, settingsWindow{}, snippetsWindow{};
+    HWND historyService{}; // Non-null only in the short-lived history UI process.
+    bool isolateHistory{};
+    unsigned historyEntryWindows{};
+    std::wstring historySelection, historyTop, historyQuery;
+    bool historyPinnedOnly{};
     HINSTANCE instance{};
     std::filesystem::path data;
     std::vector<Layout> layouts;
@@ -55,7 +60,7 @@ class App
     bool smoke{};
     int startCommand{};
     std::wstring updateStartupEvent;
-    App(HINSTANCE, bool = false, const std::filesystem::path &dataRoot = {});
+    App(HINSTANCE, bool = false, const std::filesystem::path &dataRoot = {}, HWND historyService = nullptr);
     ~App();
     int execute();
     void dispatch(int);
@@ -72,6 +77,11 @@ class App
     void applySettings(const Settings &);
     void reloadLayouts();
     void clearHistory();
+    void openHistoryProcess();
+    void refreshHistoryProcess();
+    void remoteHistory(const char *action, const std::wstring &id = {}, bool plain = false);
+    LRESULT historyRequest(HWND, const COPYDATASTRUCT &);
+    void saveHistoryView(const std::wstring &, const std::wstring &, const std::wstring &, bool);
     void clearLog(bool previous);
     void setHotkeyCapture(HWND);
     bool isHotkey(DWORD, UINT);
@@ -88,6 +98,7 @@ class App
     friend struct InputRegressionAccess;
     void releaseIdleMemory(ULONGLONG now);
     HHOOK keyboardHook{}, mouseHook{};
+    HANDLE historyProcess{};
     std::mutex jobsMutex;
     std::condition_variable jobsReady;
     std::deque<std::function<void()>> jobs;
@@ -132,6 +143,7 @@ class App
     void replayTyping();
     static LRESULT CALLBACK windowProc(HWND, UINT, WPARAM, LPARAM);
     static LRESULT CALLBACK keyProc(int, WPARAM, LPARAM);
+    static LRESULT keyboardAfterHooks(int, WPARAM, LPARAM, LRESULT);
     static LRESULT CALLBACK mouseProc(int, WPARAM, LPARAM);
 };
 void showHistory(App &, bool visible = true);

src/app_history.inl

@@ -0,0 +1,100 @@
+// History UI has no clipboard listener or hooks. The resident remains the only writer.
+namespace {
+constexpr ULONG_PTR HistoryRequest = 0x4b530200;
+constexpr UINT HistoryHostShow = WM_APP + 71, HistoryHostRefresh = WM_APP + 72;
+constexpr wchar_t HistoryHostClass[] = L"KSwitcher.HistoryHost";
+using HistoryJson = nlohmann::json;
+HWND historyController(HANDLE process)
+{
+    if (!process || WaitForSingleObject(process, 0) == WAIT_OBJECT_0) return nullptr;
+    auto window = FindWindowW(HistoryHostClass, nullptr);
+    DWORD pid{}; GetWindowThreadProcessId(window, &pid);
+    return pid == GetProcessId(process) ? window : nullptr;
+}
+}
+void App::openHistoryProcess()
+{
+    auto foreground = GetForegroundWindow();
+    if (foreground != window && foreground != historyWindow) pasteTarget = foreground;
+    if (historyProcess && WaitForSingleObject(historyProcess, 0) == WAIT_OBJECT_0) {
+        CloseHandle(historyProcess); historyProcess = nullptr; historyWindow = nullptr;
+    }
+    if (historyProcess) {
+        if (auto host = historyController(historyProcess)) {
+            AllowSetForegroundWindow(GetProcessId(historyProcess));
+            PostMessageW(host, HistoryHostShow, 0, 0);
+        }
+        return;
+    }
+    auto path = executable();
+    auto command = L"\"" + path + L"\" --history-host=" + std::to_wstring(reinterpret_cast<uintptr_t>(window));
+    STARTUPINFOW startup{sizeof(startup)};
+    startup.dwFlags = STARTF_USESHOWWINDOW; startup.wShowWindow = SW_HIDE;
+    PROCESS_INFORMATION child{};
+    if (!CreateProcessW(path.c_str(), command.data(), nullptr, nullptr, FALSE, CREATE_NO_WINDOW,
+                        nullptr, std::filesystem::path(path).parent_path().c_str(), &startup, &child))
+        throw std::runtime_error("Cannot start clipboard history window");
+    CloseHandle(child.hThread);
+    historyProcess = child.hProcess;
+    AllowSetForegroundWindow(child.dwProcessId);
+}
+void App::refreshHistoryProcess()
+{
+    if (auto host = historyController(historyProcess)) PostMessageW(host, HistoryHostRefresh, 0, 0);
+}
+void App::remoteHistory(const char *action, const std::wstring &id, bool plain)
+{
+    if (!historyService || !configurationPeer(historyService, L"KSwitcher.exe"))
+        throw std::runtime_error("KSwitcher has stopped. Reopen clipboard history.");
+    auto text = HistoryJson{{"action", action}, {"id", utf8(id)}, {"plain", plain}}.dump();
+    if (std::string_view(action) == "paste") {
+        DWORD residentPid{}; GetWindowThreadProcessId(historyService, &residentPid);
+        AllowSetForegroundWindow(residentPid);
+    }
+    COPYDATASTRUCT message{HistoryRequest, DWORD(text.size()), text.data()};
+    DWORD_PTR result{};
+    if (!SendMessageTimeoutW(historyService, WM_COPYDATA, reinterpret_cast<WPARAM>(window),
+                             reinterpret_cast<LPARAM>(&message), SMTO_ABORTIFHUNG | SMTO_ERRORONEXIT,
+                             15000, &result) || result != 1)
+        throw std::runtime_error("KSwitcher could not complete the history request. Reopen history and retry.");
+}
+LRESULT App::historyRequest(HWND sender, const COPYDATASTRUCT &message)
+{
+    DWORD pid{}; GetWindowThreadProcessId(sender, &pid);
+    if (!historyProcess || pid != GetProcessId(historyProcess) ||
+        !configurationPeer(sender, L"KSwitcher.exe") || message.cbData > 4096 ||
+        !message.cbData || !message.lpData || installingUpdate) return FALSE;
+    try {
+        const auto *first = static_cast<const char *>(message.lpData);
+        auto job = HistoryJson::parse(first, first + message.cbData);
+        auto action = job.at("action").get<std::string>();
+        auto id = wide(job.at("id").get<std::string>());
+        if (id.size() > 128) return FALSE;
+        if (action == "ready") {
+            auto ui = reinterpret_cast<HWND>(uintptr_t(std::stoull(id)));
+            DWORD uiPid{}; GetWindowThreadProcessId(ui, &uiPid);
+            wchar_t name[64]{}; GetClassNameW(ui, name, 64);
+            if (uiPid != pid || std::wstring(name) != L"KSwitcher.History") return FALSE;
+            historyWindow = ui;
+        } else if (action == "paste") {
+            if (busy || !history) return FALSE;
+            pasteEntry(id, job.at("plain").get<bool>());
+        } else if (action == "ocr") {
+            if (busy || !history) return FALSE;
+            recognizeEntry(id);
+        } else if (action == "clear") clearHistory();
+        else if (action == "pin" || action == "remove") {
+            if (busy || !history) return FALSE;
+            if (action == "pin") history->pin(id); else history->remove(id);
+        } else return FALSE;
+        return TRUE;
+    } catch (...) { return FALSE; }
+}
+void App::saveHistoryView(const std::wstring &selection, const std::wstring &top, const std::wstring &query, bool pinnedOnly)
+{
+    if (!historyService) return;
+    try {
+        auto text = HistoryJson{{"selection", utf8(selection)}, {"top", utf8(top)}, {"query", utf8(query)}, {"pinnedOnly", pinnedOnly}}.dump();
+        atomicWrite(data / L"history-view.bin", protect(Bytes(text.begin(), text.end())));
+    } catch (...) {} // Closing the UI must still release its process if state cannot be saved.
+}

src/config_main.cpp

@@ -79,7 +79,7 @@ LRESULT CALLBACK controller(HWND window, UINT message, WPARAM wp, LPARAM lp)
 }
 // The configurator owns no history store, dictionaries, worker or input hooks.
 // All mutations are validated and committed by the resident process.
-App::App(HINSTANCE h, bool, const std::filesystem::path &) : instance(h)
+App::App(HINSTANCE h, bool, const std::filesystem::path &, HWND) : instance(h)
 {
     current = this;
     data = dataDirectory();

src/main.cpp

@@ -1,12 +1,27 @@
 #include "app.h"
 #include <shellapi.h>
 #include <shlobj.h>
+#include "configuration.h"
 int WINAPI wWinMain(HINSTANCE instance, HINSTANCE, PWSTR, int)
 {
     CoInitializeEx(nullptr, COINIT_APARTMENTTHREADED);
     int argc{};
     auto argv = CommandLineToArgvW(GetCommandLineW(), &argc);
     std::wstring arg = argc > 1 ? argv[1] : L"";
+    if (argc == 2 && arg.starts_with(L"--history-host=")) {
+        LocalFree(argv);
+        int result = 1;
+        try {
+            auto service = reinterpret_cast<HWND>(uintptr_t(std::stoull(arg.substr(15))));
+            wchar_t name[64]{}; GetClassNameW(service, name, 64);
+            if (std::wstring(name) != L"KSwitcher.Main" || !ks::configurationPeer(service, L"KSwitcher.exe"))
+                throw std::runtime_error("Invalid history service");
+            ks::App app(instance, true, {}, service);
+            result = app.execute();
+        } catch (...) {}
+        CoUninitialize();
+        return result;
+    }
     if (arg.starts_with(L"--configure-autostart="))
     {
         int result = 1;
@@ -72,6 +87,7 @@ int WINAPI wWinMain(HINSTANCE instance, HINSTANCE, PWSTR, int)
     try
     {
         ks::App app(instance, arg == L"--smoke-test");
+        app.isolateHistory = !app.smoke;
         if (arg.starts_with(L"--update-ready-event="))
             app.updateStartupEvent = arg.substr(std::wstring(L"--update-ready-event=").size());
         else if (!arg.empty() && arg != L"--smoke-test")

src/platform.cpp

@@ -265,15 +265,27 @@ std::wstring processName(HWND window)
     CloseHandle(h);
     return ok ? std::filesystem::path(std::wstring(path, n)).stem().wstring() : L"";
 }
-Clip readClipboard(HWND window, size_t limit)
+Clip readClipboard(HWND window, size_t limit, ClipboardRead mode, std::optional<DWORD> expected)
 {
     ClipboardLock lock(window);
+    if (expected && *expected != GetClipboardSequenceNumber())
+        throw std::runtime_error("Clipboard changed while taking snapshot");
+    if (mode == ClipboardRead::WithoutImages &&
+        (IsClipboardFormatAvailable(CF_DIB) || IsClipboardFormatAvailable(CF_DIBV5) ||
+         IsClipboardFormatAvailable(CF_BITMAP) || IsClipboardFormatAvailable(RegisterClipboardFormatW(L"PNG"))))
+        throw std::runtime_error("Clipboard changed to an image");
     Clip c;
     size_t total = 0;
     for (UINT f = EnumClipboardFormats(0); f; f = EnumClipboardFormats(f))
     {
         if (!globalFormat(f))
             continue;
+        wchar_t name[256]{};
+        if (f >= 0xc000) GetClipboardFormatNameW(f, name, 256);
+        if (mode == ClipboardRead::Selection && f != CF_UNICODETEXT &&
+            std::wstring_view(name) != L"VisualStudioEditorOperationsLineCutCopyClipboardTag" &&
+            std::wstring_view(name) != L"MSDEVLineSelect" && std::wstring_view(name) != L"vscode-editor-data")
+            continue;
         HANDLE handle = GetClipboardData(f);
         if (!handle)
             continue;
@@ -291,8 +303,6 @@ Clip readClipboard(HWND window, size_t limit)
         GlobalUnlock(handle);
         if (f >= 0xc000)
         {
-            wchar_t name[256]{};
-            GetClipboardFormatNameW(f, name, 256);
             format.name = name;
         }
         total += size;
@@ -300,7 +310,8 @@ Clip readClipboard(HWND window, size_t limit)
     }
     return c;
 }
-DWORD writeClipboard(HWND window, const Clip &c)
+DWORD writeClipboard(HWND window, const Clip &c) { return writeClipboardGuarded(window, c, {}); }
+DWORD writeClipboardGuarded(HWND window, const Clip &c, std::optional<DWORD> expected)
 {
     // Allocate all blocks before replacing any existing data.
     std::vector<std::pair<UINT, HGLOBAL>> blocks;
@@ -327,6 +338,8 @@ DWORD writeClipboard(HWND window, const Clip &c)
             blocks.emplace_back(id, h);
         }
         ClipboardLock lock(window);
+        if (expected && *expected != GetClipboardSequenceNumber())
+            throw std::runtime_error("Clipboard changed before restoring snapshot");
         if (!EmptyClipboard())
             throw std::runtime_error("Cannot replace clipboard");
         for (auto &[id, h] : blocks)

src/platform.h

@@ -43,8 +43,11 @@ bool ownsClipboard(HWND);
 bool webViewDescendant(DWORD owner, DWORD host,
                        const std::function<std::optional<std::pair<DWORD, std::wstring>>(DWORD)> &read);
 std::wstring processName(HWND);
-Clip readClipboard(HWND, size_t limit = 32 * 1024 * 1024);
+enum class ClipboardRead { All, Selection, WithoutImages };
+Clip readClipboard(HWND, size_t limit = 32 * 1024 * 1024,
+                   ClipboardRead = ClipboardRead::All, std::optional<DWORD> expected = {});
 DWORD writeClipboard(HWND, const Clip &);
+DWORD writeClipboardGuarded(HWND, const Clip &, std::optional<DWORD> expected);
 Clip textClip(const std::wstring &);
 bool chord(WORD key, UINT modifiers = 0);
 // Process-local marker, shared by every KSwitcher input producer (not an authentication token).

src/screenshot_main.cpp

@@ -50,6 +50,10 @@ int WINAPI wWinMain(HINSTANCE instance,HINSTANCE,PWSTR,int)
     std::wstring token;
     bool autoOpenEditor=false, writeLog=false;
     int argc{}; auto argv=CommandLineToArgvW(GetCommandLineW(),&argc);
+    if(argc==3 && std::wstring(argv[1])==L"--clipboard-snapshot") {
+        std::filesystem::path request=argv[2]; LocalFree(argv);
+        return ks::runClipboardSnapshot(request);
+    }
     if(argc==3 && (std::wstring(argv[1])==L"--capture-history" || std::wstring(argv[1])==L"--history-ocr")) {
         bool ocr=std::wstring(argv[1])==L"--history-ocr";
         std::filesystem::path request=argv[2]; LocalFree(argv);

src/storage.cpp

@@ -344,6 +344,20 @@ Bytes encodeClip(const Clip &clip)
     }
     return b;
 }
+Bytes selectionClipboardIdentity(const Clip &clip)
+{
+    auto normalized = clip;
+    // GlobalSize includes allocation slack. A clipboard relay may allocate a
+    // different-sized block for the same NUL-terminated Unicode string.
+    for (auto &format : normalized.formats)
+        if (format.id == CF_UNICODETEXT)
+            format = textClip(clip.text()).formats.front();
+    std::sort(normalized.formats.begin(), normalized.formats.end(), [](const Format &a, const Format &b)
+    {
+        return std::tie(a.name, a.id) < std::tie(b.name, b.id);
+    });
+    return encodeClip(normalized);
+}
 Clip decodeClip(const Bytes &b)
 {
     size_t p = 0;
@@ -410,6 +424,87 @@ void History::loadIndex()
     }
     entries_ = std::move(loaded);
 }
+void History::reload() { std::lock_guard lock(mutex_); loadIndex(); }
+void ClipboardSnapshot::cleanup() noexcept
+{
+    if (request_.empty()) return;
+    std::error_code ignored;
+    for (const auto *suffix : {L"", L".snapshot", L".result"})
+        std::filesystem::remove(std::filesystem::path(request_.wstring() + suffix), ignored);
+    request_.clear();
+}
+ClipboardSnapshot::~ClipboardSnapshot() { cleanup(); }
+DWORD ClipboardSnapshot::run(bool restore, DWORD sequence)
+{
+    atomicWrite(request_, protect(jsonBytes(Json{{"schema", 1}, {"restore", restore}, {"sequence", sequence}})));
+    auto helper = std::filesystem::path(executable()).parent_path() / L"KSwitcher.Screenshot.exe";
+    auto command = L"\"" + helper.wstring() + L"\" --clipboard-snapshot \"" + request_.wstring() + L"\"";
+    STARTUPINFOW startup{sizeof(startup)};
+    startup.dwFlags = STARTF_USESHOWWINDOW; startup.wShowWindow = SW_HIDE;
+    PROCESS_INFORMATION process{};
+    if (!CreateProcessW(helper.c_str(), command.data(), nullptr, nullptr, FALSE, CREATE_NO_WINDOW,
+                        nullptr, helper.parent_path().c_str(), &startup, &process))
+        throw std::runtime_error("Cannot start clipboard snapshot helper");
+    CloseHandle(process.hThread);
+    auto wait = WaitForSingleObject(process.hProcess, 10000);
+    DWORD result = ERROR_GEN_FAILURE;
+    if (wait != WAIT_OBJECT_0)
+    {
+        TerminateProcess(process.hProcess, ERROR_TIMEOUT);
+        WaitForSingleObject(process.hProcess, INFINITE);
+    }
+    GetExitCodeProcess(process.hProcess, &result);
+    CloseHandle(process.hProcess);
+    if (wait != WAIT_OBJECT_0 || result) throw std::runtime_error("Clipboard snapshot helper failed");
+    return parse(unprotect(readFile(request_.wstring() + L".result", 4096))).at("sequence").get<DWORD>();
+}
+void ClipboardSnapshot::capture(HWND window, DWORD sequence)
+{
+    cleanup();
+    clip_ = {};
+    if (!IsClipboardFormatAvailable(CF_DIB) && !IsClipboardFormatAvailable(CF_DIBV5) &&
+        !IsClipboardFormatAvailable(CF_BITMAP) && !IsClipboardFormatAvailable(RegisterClipboardFormatW(L"PNG")))
+    {
+        clip_ = readClipboard(window, 64 * 1024 * 1024, ClipboardRead::WithoutImages, sequence);
+        return;
+    }
+    request_ = std::filesystem::temp_directory_path() / (L"ks-clipboard-" + newSnippetId() + L".request");
+    try { run(false, sequence); }
+    catch (...) { cleanup(); throw; }
+}
+DWORD ClipboardSnapshot::restore(HWND window, DWORD sequence)
+{
+    return request_.empty() ? writeClipboardGuarded(window, clip_, sequence) : run(true, sequence);
+}
+int runClipboardSnapshot(const std::filesystem::path &request)
+{
+    try
+    {
+        if (!request.is_absolute() || !request.filename().wstring().starts_with(L"ks-clipboard-") ||
+            request.extension() != L".request") return 1;
+        auto job = parse(unprotect(readFile(request, 4096)));
+        if (job.at("schema") != 1) return 1;
+        auto sequence = job.at("sequence").get<DWORD>();
+        const auto snapshot = request.wstring() + L".snapshot";
+        if (job.at("restore").get<bool>())
+        {
+            auto clip = decodeClip(unprotect(readFile(snapshot, 70 * 1024 * 1024)));
+            HWND window = CreateWindowExW(0, L"STATIC", L"", 0, 0, 0, 0, 0, HWND_MESSAGE, nullptr, nullptr, nullptr);
+            if (!window) return 1;
+            struct WindowCleanup { HWND window; ~WindowCleanup() { DestroyWindow(window); } } cleanup{window};
+            sequence = writeClipboardGuarded(window, clip, sequence);
+        }
+        else
+        {
+            auto clip = readClipboard(nullptr, 64 * 1024 * 1024, ClipboardRead::All, sequence);
+            if (sequence != GetClipboardSequenceNumber()) return 2;
+            atomicWrite(snapshot, protect(encodeClip(clip)));
+        }
+        atomicWrite(request.wstring() + L".result", protect(jsonBytes(Json{{"sequence", sequence}})));
+        return 0;
+    }
+    catch (...) { return 1; }
+}
 bool History::captureImage(DWORD sequence, const std::wstring &app, const Settings &settings)
 {
     // Serialize helper index changes with all resident history mutations. Only
@@ -706,12 +801,12 @@ void History::clear()
         std::filesystem::remove(folder_ / (e.id + L".ocr"), ec);
     }
 }
-std::wstring History::recognizeImage(const std::wstring &id, const Settings &settings,
+static Bytes historyImageJob(const std::filesystem::path &folder, const std::wstring &id,
-                                    const std::function<bool()> &cancelled) const
+                             const Json &job, const std::function<bool()> &cancelled)
 {
     if (!validId(id)) throw std::runtime_error("Invalid history ID");
     if (cancelled && cancelled()) throw std::runtime_error("History OCR cancelled");
-    auto request = std::filesystem::absolute(folder_) / (L"ocr-" + newSnippetId() + L".request");
+    auto request = std::filesystem::absolute(folder) / (L"ocr-" + newSnippetId() + L".request");
     auto response = request; response += L".result";
     struct Cleanup {
         std::filesystem::path request, response;
@@ -721,9 +816,6 @@ std::wstring History::recognizeImage(const std::wstring &id, const Settings &set
             std::filesystem::remove(response, ignored);
         }
     } cleanup{request, response};
-    // Send only OCR options and the entry ID. The resident never loads image bytes.
-    Json job{{"schema", 1}, {"id", utf8(id)}, {"tesseract", settings.useTesseract},
-             {"path", utf8(settings.tesseractPath)}, {"languages", utf8(settings.tesseractLanguages)}};
     atomicWrite(request, protect(jsonBytes(job)));
     auto helper = std::filesystem::path(executable()).parent_path() / L"KSwitcher.Screenshot.exe";
     auto command = L"\"" + helper.wstring() + L"\" --history-ocr \"" + request.wstring() + L"\"";
@@ -755,11 +847,28 @@ std::wstring History::recognizeImage(const std::wstring &id, const Settings &set
     DWORD result{};
     if (!GetExitCodeProcess(child.handle, &result) || result)
         throw std::runtime_error("History OCR helper failed: " + std::to_string(result));
-    auto reply = parse(unprotect(readFile(response, 8 * 1024 * 1024)));
+    return unprotect(readFile(response, 8 * 1024 * 1024));
+}
+std::wstring History::recognizeImage(const std::wstring &id, const Settings &settings,
+                                    const std::function<bool()> &cancelled) const
+{
+    Json job{{"schema", 1}, {"id", utf8(id)}, {"tesseract", settings.useTesseract},
+             {"path", utf8(settings.tesseractPath)}, {"languages", utf8(settings.tesseractLanguages)}};
+    auto reply = parse(historyImageJob(folder_, id, job, cancelled));
     if (reply.at("schema") != 1 || str(reply, "id") != id)
         throw std::runtime_error("Invalid history OCR response");
     return str(reply, "text");
 }
+Pixels History::thumbnail(const std::wstring &id, const std::function<bool()> &cancelled) const
+{
+    auto bytes = historyImageJob(folder_, id, Json{{"schema", 1}, {"id", utf8(id)}, {"thumbnail", true}}, cancelled);
+    size_t at = 0;
+    auto width = get32(bytes, at), height = get32(bytes, at);
+    if (!width || !height || width > 208 || height > 128 || bytes.size() - at != width * height * 4)
+        throw std::runtime_error("Invalid history thumbnail response");
+    bytes.erase(bytes.begin(), bytes.begin() + at);
+    return Pixels{width, height, std::move(bytes)};
+}
 int runHistoryOcr(const std::filesystem::path &request)
 {
     try {
@@ -768,11 +877,20 @@ int runHistoryOcr(const std::filesystem::path &request)
         auto job = parse(unprotect(readFile(request, 1024 * 1024)));
         auto id = str(job, "id");
         if (job.at("schema") != 1 || !validId(id)) return 1;
+        auto clip = decodeClip(unprotect(readFile(request.parent_path() / (id + L".dat"), 80 * 1024 * 1024)));
+        if (job.value("thumbnail", false)) {
+            auto pixels = decodeImage(clip, 208, 128);
+            if (!pixels.width || !pixels.height) return 1;
+            Bytes reply;
+            put32(reply, pixels.width); put32(reply, pixels.height);
+            reply.insert(reply.end(), pixels.bgra.begin(), pixels.bgra.end());
+            atomicWrite(request.wstring() + L".result", protect(reply));
+            return 0;
+        }
         Settings settings;
         settings.useTesseract = job.at("tesseract").get<bool>();
         settings.tesseractPath = str(job, "path");
         settings.tesseractLanguages = str(job, "languages");
-        auto clip = decodeClip(unprotect(readFile(request.parent_path() / (id + L".dat"), 80 * 1024 * 1024)));
         auto text = utf8(recognizeText(clip, settings));
         if (text.size() > 1024 * 1024) return 1;
         auto response = request; response += L".result";
@@ -820,9 +938,10 @@ std::optional<std::wstring> History::ocrText(const std::wstring &id, const std::
     if (bytes.empty() || bytes.front() != 1) throw std::runtime_error("Invalid OCR text format");
     return wide(std::string(bytes.begin() + 1, bytes.end()));
 }
-std::vector<Entry> History::search(const std::wstring &query) const
+std::vector<Entry> History::search(const std::wstring &query, bool pinnedOnly) const
 {
     auto items = entries();
+    if (pinnedOnly) std::erase_if(items, [](const Entry &entry) { return !entry.pinned; });
     if (query.empty())
         return items;
     auto q = lower(query);

src/storage.h

@@ -4,6 +4,7 @@
 #include <functional>
 namespace ks
 {
+struct Pixels;
 Settings loadSettings(const std::filesystem::path &, const std::vector<Layout> &);
 Settings decodeSettings(const Bytes &, const std::vector<Layout> &);
 Bytes encodeSettings(const Settings &);
@@ -29,22 +30,41 @@ class History
 
   public:
     explicit History(const std::filesystem::path &);
+    void reload();
     std::vector<Entry> entries() const;
     Clip load(const std::wstring &id) const;
     void add(const Clip &, const std::wstring &app, const Settings &);
     bool captureImage(DWORD sequence, const std::wstring &app, const Settings &);
     std::wstring recognizeImage(const std::wstring &id, const Settings &,
                                 const std::function<bool()> &cancelled = {}) const;
+    Pixels thumbnail(const std::wstring &id, const std::function<bool()> &cancelled = {}) const;
     bool saveOcr(const std::wstring &id, const std::optional<std::wstring> &, const Settings &);
     std::optional<std::wstring> ocrText(const std::wstring &id, const std::wstring &profile = L"") const;
     void remove(const std::wstring &);
     void pin(const std::wstring &);
     void clear();
-    std::vector<Entry> search(const std::wstring &) const;
+    std::vector<Entry> search(const std::wstring &, bool pinnedOnly = false) const;
 };
 Bytes encodeClip(const Clip &);
+Bytes selectionClipboardIdentity(const Clip &);
 Clip decodeClip(const Bytes &);
 bool sameClipboardImage(const Clip &, const Clip &);
 int runImageHistoryCapture(const std::filesystem::path &request);
 int runHistoryOcr(const std::filesystem::path &request);
+// Image backups stay encrypted on disk and are read/written only by a short-lived helper.
+class ClipboardSnapshot
+{
+    Clip clip_;
+    std::filesystem::path request_;
+    void cleanup() noexcept;
+    DWORD run(bool restore, DWORD sequence);
+  public:
+    ClipboardSnapshot() = default;
+    ClipboardSnapshot(const ClipboardSnapshot &) = delete;
+    ClipboardSnapshot &operator=(const ClipboardSnapshot &) = delete;
+    ~ClipboardSnapshot();
+    void capture(HWND, DWORD sequence);
+    DWORD restore(HWND, DWORD sequence);
+};
+int runClipboardSnapshot(const std::filesystem::path &request);
 } // namespace ks

src/ui.cpp

@@ -514,15 +514,16 @@ void search(HWND w, HistoryView *v)
     v->previewActive = std::make_shared<std::atomic<bool>>(true);
     v->closed = false;
     auto q = value(w, 101);
+    const bool pinnedOnly = SendDlgItemMessageW(w, 117, BM_GETCHECK, 0, 0) == BST_CHECKED;
     auto generation = ++v->generation;
     v->pending.clear();
     auto *app = v->app;
     app->enqueueHistorySearch(
-        [w, app, q, generation]
+        [w, app, q, generation, pinnedOnly]
         {
             try
             {
-                auto result = new SearchResult{generation, app->history->search(q)};
+                auto result = new SearchResult{generation, app->history->search(q, pinnedOnly)};
                 if (!PostMessageW(w, ResultsMessage, 0, (LPARAM)result))
                     delete result;
             }
@@ -549,11 +550,11 @@ void requestPreview(HWND w, HistoryView *v, const Entry &entry)
             auto result = new PreviewResult{generation, id, {}, {}};
             try
             {
+                if (image)
+                    result->pixels = app->history->thumbnail(id, [active] { return !active->load(); });
+                else {
                     auto clip = app->history->load(id);
                     if (!active->load()) { delete result; return; }
-                if (image)
-                    result->pixels = decodeImage(clip, 208, 128);
-                else {
                     result->text.rtf = richPreview(clip, false);
                     if (result->text.rtf.empty()) {
                         result->text.plain = clip.text();
@@ -739,6 +740,12 @@ LRESULT CALLBACK historyProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
         case WM_COMMAND:
         {
             int id = LOWORD(wp);
+            if (id == 117 && HIWORD(wp) == BN_CLICKED)
+            {
+                KillTimer(w, 1);
+                search(w, v);
+                return 0;
+            }
             if (id == 101 && HIWORD(wp) == EN_CHANGE)
             {
                 // Reject an older result even during the debounce interval.
@@ -771,7 +778,10 @@ LRESULT CALLBACK historyProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
             {
                 if (!entry.empty())
                 {
-                    if (id == 112)
+                    if (v->app->historyService) {
+                        v->app->remoteHistory(id == 112 ? "pin" : "remove", entry);
+                        v->app->history->reload();
+                    } else if (id == 112)
                         v->app->history->pin(entry);
                     else
                         v->app->history->remove(entry);
@@ -907,6 +917,8 @@ LRESULT CALLBACK historyProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
             v->rememberedSelection = selected(w, v);
             int top = (int)SendDlgItemMessageW(w,102,LB_GETTOPINDEX,0,0);
             v->rememberedTop = top >= 0 && top < (int)v->items.size() ? v->items[top].id : L"";
+            v->app->saveHistoryView(v->rememberedSelection, v->rememberedTop, value(w, 101),
+                                   SendDlgItemMessageW(w, 117, BM_GETCHECK, 0, 0) == BST_CHECKED);
             KillTimer(w, 1);
             v->closed = true;
             v->previewActive->store(false);
@@ -918,6 +930,8 @@ LRESULT CALLBACK historyProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
             v->richTexts.clear();
             if (v->rich) SetWindowTextW(v->rich, L"");
             v->pending.clear();
+            if (v->app->historyService && !v->app->historyEntryWindows)
+                PostMessageW(v->app->window, WM_CLOSE, 0, 0);
             return 0;
         }
         case WM_NCDESTROY:
@@ -1681,13 +1695,19 @@ LRESULT CALLBACK snippetProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
 #ifndef KS_CONFIG_APP
 LRESULT CALLBACK entryProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
 {
+    if (msg == WM_NCCREATE)
+        SetWindowLongPtrW(w, GWLP_USERDATA, (LONG_PTR)((CREATESTRUCTW *)lp)->lpCreateParams);
     if (msg == WM_SIZE)
     {
         MoveWindow(GetDlgItem(w, 1), 10, 10, LOWORD(lp) - 20, HIWORD(lp) - 20, TRUE);
         return 0;
     }
-    if (msg == WM_NCDESTROY)
+    if (msg == WM_NCDESTROY) {
         disposeFont(w);
+        auto *app = (App *)GetWindowLongPtrW(w, GWLP_USERDATA);
+        if (app && app->historyService && app->historyEntryWindows && !--app->historyEntryWindows &&
+            !IsWindowVisible(app->historyWindow)) PostMessageW(app->window, WM_CLOSE, 0, 0);
+    }
     return DefWindowProcW(w, msg, wp, lp);
 }
 #endif
@@ -1695,6 +1715,7 @@ LRESULT CALLBACK entryProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
 #ifndef KS_CONFIG_APP
 void refreshHistory(App &app)
 {
+    if (app.isolateHistory) { app.refreshHistoryProcess(); return; }
     if (app.historyWindow)
     {
         auto *v = (HistoryView *)GetWindowLongPtrW(app.historyWindow, GWLP_USERDATA);
@@ -1703,6 +1724,7 @@ void refreshHistory(App &app)
 }
 void showHistory(App &app, bool visible)
 {
+    if (app.isolateHistory) { if (visible) app.openHistoryProcess(); return; }
     if (!app.history)
     {
         app.report(L"Clipboard history is unavailable. See the log in the data folder.");
@@ -1723,8 +1745,11 @@ void showHistory(App &app, bool visible)
         HWND w = makeWindow(app, L"KSwitcher.History", L"Clipboard history", historyProc, 760, 500);
         app.historyWindow = w;
         windowLayoutState(w)->history = true;
-        label(w, L"&Search clipboard history", 16, 12, 500);
+        auto filter = control(w, L"BUTTON", L"★ Pinned only", WS_TABSTOP | BS_AUTOCHECKBOX,
-        edit(w, 101, 16, 38, 728);
+                              117, 16, 38, 112, 25);
+        SendMessageW(filter, BM_SETCHECK, app.historyPinnedOnly ? BST_CHECKED : BST_UNCHECKED, 0);
+        label(w, L"&Search clipboard history", 136, 12, 500);
+        edit(w, 101, 136, 38, 608);
         auto list = control(w, L"LISTBOX", L"",
                             WS_TABSTOP | WS_VSCROLL | LBS_NOTIFY | LBS_NOINTEGRALHEIGHT | WS_BORDER |
                                 LBS_OWNERDRAWFIXED | LBS_HASSTRINGS,
@@ -1738,6 +1763,12 @@ void showHistory(App &app, bool visible)
         button(w, L"Clear &history…", 116, 546, 452, 150);
         SetWindowSubclass(list, historyKey, 1, (DWORD_PTR)w);
         SetWindowSubclass(GetDlgItem(w, 101), historyKey, 1, (DWORD_PTR)w);
+        if (app.historyService) {
+            auto *v = (HistoryView *)GetWindowLongPtrW(w, GWLP_USERDATA);
+            v->rememberedSelection = app.historySelection;
+            v->rememberedTop = app.historyTop;
+            SetDlgItemTextW(w, 101, app.historyQuery.c_str());
+        }
     }
     if (!visible) return;
     POINT cursor;
@@ -1894,6 +1925,7 @@ void showEntry(App &app, const std::wstring &id)
         }
         HWND w = makeWindow(app, L"KSwitcher.Entry", L"Clipboard item", entryProc, 720, 500,
                             WS_THICKFRAME | WS_MAXIMIZEBOX);
+        if (app.historyService) ++app.historyEntryWindows;
         auto field = edit(w, 1, 10, 10, 700, 480, ES_MULTILINE | ES_READONLY | ES_AUTOVSCROLL | WS_VSCROLL);
         SetWindowTextW(field, text.c_str());
         showRequestedWindow(w);

src/update.h

@@ -2,7 +2,7 @@
 #include "platform.h"
 namespace ks
 {
-inline constexpr wchar_t AppVersion[] = L"0.6.38";
+inline constexpr wchar_t AppVersion[] = L"0.6.43";
 inline constexpr UINT UpdateMessage = WM_APP + 7;
 inline constexpr UINT UpdateCheckIntervalMs = 6 * 60 * 60 * 1000;
 inline constexpr UINT UpdateNotificationRetryMs = 5 * 60 * 1000;

tests/clipboard_snapshot.cpp

@@ -0,0 +1,108 @@
+// Run with the resident stopped. The suite restores the original clipboard.
+#include "storage.h"
+#include "ocr.h"
+#include <psapi.h>
+#include <iostream>
+#include <algorithm>
+static void require(bool ok, const char *name) {
+    if (!ok) throw std::runtime_error(name);
+    std::cout << "PASS " << name << '\n';
+}
+static HWND owner() {
+    return CreateWindowExW(0,L"STATIC",L"Snapshot test",0,0,0,0,0,HWND_MESSAGE,nullptr,nullptr,nullptr);
+}
+static void child(const std::wstring &argument) {
+    auto exe=ks::executable(), command=L"\""+exe+L"\" "+argument;
+    STARTUPINFOW startup{sizeof(startup)}; startup.dwFlags=STARTF_USESHOWWINDOW; startup.wShowWindow=SW_HIDE;
+    PROCESS_INFORMATION p{};
+    if(!CreateProcessW(exe.c_str(),command.data(),nullptr,nullptr,FALSE,CREATE_NO_WINDOW,nullptr,nullptr,&startup,&p))
+        throw std::runtime_error("start fixture process");
+    CloseHandle(p.hThread);
+    auto wait=WaitForSingleObject(p.hProcess,30000); DWORD code=1;
+    if(wait!=WAIT_OBJECT_0) {TerminateProcess(p.hProcess,1);WaitForSingleObject(p.hProcess,INFINITE);}
+    GetExitCodeProcess(p.hProcess,&code); CloseHandle(p.hProcess);
+    if(code) throw std::runtime_error("fixture process failed");
+}
+static size_t resident() {
+    ks::Bytes b(1024*1024); auto ws=reinterpret_cast<PSAPI_WORKING_SET_INFORMATION*>(b.data());
+    if(!QueryWorkingSet(GetCurrentProcess(),ws,DWORD(b.size()))) throw std::runtime_error("working set query");
+    size_t pages=0; for(size_t i=0;i<ws->NumberOfEntries;++i) if(!ws->WorkingSetInfo[i].Shared) ++pages;
+    return pages*4096;
+}
+static void verifyImage(HWND w) {
+    auto c=ks::readClipboard(w,64*1024*1024);
+    for(auto id:{CF_DIB,CF_DIBV5}) {
+        auto it=std::find_if(c.formats.begin(),c.formats.end(),[&](const auto &f){return f.id==UINT(id);});
+        require(it!=c.formats.end(),"restores image representation");
+        auto pixels=ks::decodeImage(ks::Clip{{*it}});
+        require(pixels.width==1566 && pixels.height==1068 && pixels.bgra.front()==77,"preserves image pixels");
+    }
+    require(c.text()==L"Snapshot mixed text","preserves accompanying text");
+}
+int main(int argc,char**argv) {
+    CoInitializeEx(nullptr,COINIT_MULTITHREADED);
+    HWND w=owner(); int result=0; ks::Clip original; bool saved=false;
+    try {
+        std::string mode=argc>1?argv[1]:"suite";
+        if(mode=="publish") {
+            ks::Pixels p{1566,1068,ks::Bytes(1566*1068*4,255)}; p.bgra[0]=77;
+            auto dib=ks::imageDib(p); auto v5=dib;
+            BITMAPV5HEADER h{}; h.bV5Size=sizeof(h); h.bV5Width=p.width; h.bV5Height=-p.height;
+            h.bV5Planes=1; h.bV5BitCount=32; h.bV5Compression=BI_BITFIELDS;
+            h.bV5RedMask=0xff0000; h.bV5GreenMask=0xff00; h.bV5BlueMask=0xff; h.bV5AlphaMask=0xff000000;
+            v5.id=CF_DIBV5; v5.data.resize(sizeof(h)+p.bgra.size());
+            memcpy(v5.data.data(),&h,sizeof(h)); memcpy(v5.data.data()+sizeof(h),p.bgra.data(),p.bgra.size());
+            auto clip=ks::textClip(L"Snapshot mixed text"); clip.formats.push_back(dib); clip.formats.push_back(v5);
+            ks::writeClipboard(w,clip);
+        } else if(mode=="old" || mode=="new") {
+            child(L"publish"); auto baseline=resident();
+            if(mode=="old") {
+                auto clip=ks::readClipboard(w,64*1024*1024);
+                ks::writeClipboard(w,ks::textClip(L"temporary")); ks::writeClipboard(w,clip);
+            } else {
+                ks::ClipboardSnapshot snapshot; snapshot.capture(w,GetClipboardSequenceNumber());
+                auto seq=ks::writeClipboard(w,ks::textClip(L"temporary"));
+                require(snapshot.restore(w,seq)==GetClipboardSequenceNumber(),"helper returns current sequence");
+            }
+            auto after=resident();
+            auto report="baseline="+std::to_string(baseline)+" after="+std::to_string(after)+" delta="+std::to_string(int64_t(after)-int64_t(baseline))+"\n";
+            auto path=std::filesystem::path(ks::executable()).parent_path()/(L"snapshot-memory-"+ks::wide(mode)+L".txt");
+            ks::atomicWrite(path,ks::Bytes(report.begin(),report.end()));
+            verifyImage(w); // Only after measuring: verification intentionally reads images.
+        } else {
+            original=ks::readClipboard(w,128*1024*1024); saved=true;
+            child(L"old"); child(L"new"); child(L"publish");
+            auto seq=GetClipboardSequenceNumber();
+            auto selected=ks::readClipboard(w,32*1024*1024,ks::ClipboardRead::Selection);
+            require(selected.formats.size()==1 && selected.text()==L"Snapshot mixed text","selection read excludes image data");
+            bool rejected=false;
+            try {ks::readClipboard(w,32*1024*1024,ks::ClipboardRead::WithoutImages,seq);} catch(...) {rejected=true;}
+            require(rejected,"resident rejects images before reading their data");
+            {
+                ks::ClipboardSnapshot snapshot; snapshot.capture(w,seq);
+                auto stale=ks::writeClipboard(w,ks::textClip(L"temporary"));
+                ks::writeClipboard(w,ks::textClip(L"external copy")); rejected=false;
+                try {snapshot.restore(w,stale);} catch(...) {rejected=true;}
+                require(rejected && ks::readClipboard(w).text()==L"external copy","stale image restore preserves external copy");
+            }
+            {
+                ks::ClipboardSnapshot snapshot; snapshot.capture(w,GetClipboardSequenceNumber());
+                auto temporary=ks::writeClipboard(w,ks::textClip(L"temporary"));
+                snapshot.restore(w,temporary);
+                require(ks::readClipboard(w).text()==L"external copy","text snapshot fast path restores clipboard");
+            }
+            {
+                ks::Clip empty; auto seqEmpty=ks::writeClipboard(w,empty);
+                ks::ClipboardSnapshot snapshot; snapshot.capture(w,seqEmpty);
+                snapshot.restore(w,ks::writeClipboard(w,ks::textClip(L"temporary")));
+                require(ks::readClipboard(w).formats.empty(),"empty clipboard restored");
+            }
+            auto marked=ks::textClip(L"line"); marked.formats.push_back({0,L"MSDEVLineSelect",ks::Bytes{1}});
+            ks::writeClipboard(w,marked);
+            require(ks::readClipboard(w,1024,ks::ClipboardRead::Selection).formats.size()==2,"selection reader preserves editor guard metadata");
+            std::cout<<"PASS clipboard snapshot suite\n";
+        }
+    } catch(const std::exception &e) {std::cerr<<"FAIL "<<e.what()<<'\n';result=1;}
+    if(saved) try {ks::writeClipboard(w,original);} catch(...) {result=1;}
+    DestroyWindow(w); CoUninitialize(); return result;
+}

tests/history_host.cpp

@@ -0,0 +1,184 @@
+// Run from an isolated fixture folder containing KSwitcher.exe and Screenshot.exe,
+// with the normal resident stopped. Never points at the installed user's data.
+#include "storage.h"
+#include "ocr.h"
+#include "json.hpp"
+#include <commctrl.h>
+#include <psapi.h>
+#include <iostream>
+static HWND editor{};
+static bool pastedImage{};
+static LRESULT CALLBACK targetProc(HWND w,UINT message,WPARAM wp,LPARAM lp) {
+    if(message==WM_SETFOCUS && editor) {SetFocus(editor);return 0;}
+    return DefWindowProcW(w,message,wp,lp);
+}
+static void require(bool ok,const char *what) {if(!ok)throw std::runtime_error(what);std::cout<<"PASS "<<what<<'\n';}
+static void pump() {MSG m;while(PeekMessageW(&m,nullptr,0,0,PM_REMOVE)){TranslateMessage(&m);DispatchMessageW(&m);}}
+template<class F> static void until(F condition,const char *what,DWORD timeout=10000) {
+    auto end=GetTickCount64()+timeout;
+    while(!condition()){if(GetTickCount64()>=end)throw std::runtime_error(what);pump();Sleep(10);}
+}
+static LRESULT send(HWND w,UINT message,WPARAM wp=0,LPARAM lp=0) {
+    DWORD_PTR result{};
+    if(!SendMessageTimeoutW(w,message,wp,lp,SMTO_ABORTIFHUNG,5000,&result))throw std::runtime_error("window request timed out");
+    return LRESULT(result);
+}
+static void command(HWND resident,int cmd) {
+    COPYDATASTRUCT data{1,sizeof(cmd),&cmd};send(resident,WM_COPYDATA,0,LPARAM(&data));
+}
+static size_t memory(HANDLE process) {
+    ks::Bytes bytes(1024*1024);auto ws=reinterpret_cast<PSAPI_WORKING_SET_INFORMATION*>(bytes.data());
+    if(!QueryWorkingSet(process,ws,DWORD(bytes.size())))throw std::runtime_error("memory query failed");
+    size_t pages=0;for(size_t i=0;i<ws->NumberOfEntries;++i)if(!ws->WorkingSetInfo[i].Shared)++pages;
+    return pages*4096;
+}
+static std::wstring editorText() {wchar_t text[256]{};GetWindowTextW(editor,text,256);return text;}
+static LRESULT CALLBACK editProc(HWND w,UINT message,WPARAM wp,LPARAM lp,UINT_PTR,DWORD_PTR) {
+    if(message==WM_PASTE && IsClipboardFormatAvailable(CF_DIB)) {pastedImage=true;return 0;}
+    return DefSubclassProc(w,message,wp,lp);
+}
+static ks::Clip excluded(ks::Clip clip) {
+    clip.formats.push_back({0,L"ExcludeClipboardContentFromMonitorProcessing",ks::Bytes{0}});return clip;
+}
+int main() {
+    CoInitializeEx(nullptr,COINIT_APARTMENTTHREADED);
+    PROCESS_INFORMATION process{};HWND resident{},target{};ks::Clip saved;bool captured=false;int result=0;
+    try {
+        auto folder=std::filesystem::path(ks::executable()).parent_path();
+        require(folder.filename().wstring().starts_with(L"history-host-fixture-"),"isolated fixture directory");
+        require(!FindWindowW(L"KSwitcher.Main",nullptr),"normal resident is stopped");
+        WNDCLASSW targetClass{};targetClass.lpfnWndProc=targetProc;targetClass.hInstance=GetModuleHandleW(nullptr);
+        targetClass.lpszClassName=L"KSwitcher.HistoryTestDestination";RegisterClassW(&targetClass);
+        target=CreateWindowExW(0,targetClass.lpszClassName,L"KSwitcher history test destination",WS_OVERLAPPEDWINDOW|WS_VISIBLE,
+                               50,50,500,250,nullptr,nullptr,nullptr,nullptr);
+        editor=CreateWindowExW(0,L"EDIT",L"",WS_CHILD|WS_VISIBLE|ES_MULTILINE,10,10,450,180,target,nullptr,nullptr,nullptr);
+        SetWindowSubclass(editor,editProc,1,0);
+        saved=ks::readClipboard(target,128*1024*1024);captured=true;
+        ks::writeClipboard(target,excluded(ks::textClip(L"fixture clipboard")));
+        auto settings=ks::loadSettings(folder/L"missing.json",ks::readLayouts());
+        settings.autoCorrect=false;settings.writeLog=true;settings.history=true;settings.maxItems=500;settings.maxMiB=100;
+        std::filesystem::create_directories(folder/L"data");
+        ks::saveSettings(folder/L"data/settings.json",settings);
+        ks::History history(folder/L"data/history");
+        history.clear(); // This executable only runs in its dedicated fixture directory.
+        ks::Pixels pixels{1566,1068,ks::Bytes(1566*1068*4,255)};
+        auto image=ks::Clip{{ks::imageDib(pixels)}};
+        history.add(image,L"test",settings);
+        auto imageId=history.entries().front().id;
+        // Seed once rather than rewriting the encrypted index 500 times. This
+        // also avoids measuring fixture creation in the resident under test.
+        auto indexPath=folder/L"data/history/index.dat";
+        auto rows=nlohmann::json::parse(ks::unprotect(ks::readFile(indexPath,1024*1024)));
+        for(int i=0;i<499;++i) {
+            auto id=ks::lower(ks::newSnippetId().substr(1,36)),text=L"History fixture "+std::to_wstring(i);
+            auto bytes=ks::protect(ks::encodeClip(ks::textClip(text)));
+            ks::atomicWrite(folder/L"data/history"/(id+L".dat"),bytes);
+            rows.insert(rows.begin(),nlohmann::json{{"id",ks::utf8(id)},{"preview",ks::utf8(text)},
+                {"app","test"},{"bytes",bytes.size()},{"at",i+1},{"pinned",false},{"image",false},{"files",false}});
+        }
+        auto encoded=rows.dump();ks::atomicWrite(indexPath,ks::protect(ks::Bytes(encoded.begin(),encoded.end())));
+        history.reload();
+        auto textId=history.entries().front().id;
+        auto exe=folder/L"KSwitcher.exe";auto line=L"\""+exe.wstring()+L"\"";
+        STARTUPINFOW startup{sizeof(startup)};startup.dwFlags=STARTF_USESHOWWINDOW;startup.wShowWindow=SW_HIDE;
+        require(CreateProcessW(exe.c_str(),line.data(),nullptr,nullptr,FALSE,CREATE_NO_WINDOW,nullptr,folder.c_str(),&startup,&process),"start isolated resident");
+        CloseHandle(process.hThread);process.hThread=nullptr;
+        until([&]{resident=FindWindowW(L"KSwitcher.Main",nullptr);return resident!=nullptr;},"resident startup");
+        auto base=memory(process.hProcess);
+        std::string forged="{\"action\":\"clear\",\"id\":\"\",\"plain\":false}";
+        COPYDATASTRUCT forgedRequest{0x4b530200,DWORD(forged.size()),forged.data()};
+        require(send(resident,WM_COPYDATA,WPARAM(target),LPARAM(&forgedRequest))==0,
+                "history rejects requests from an untrusted process");
+        auto open=[&] {
+            require(ks::activateWindow(target),"destination foreground");SetFocus(editor);command(resident,5);
+            HWND window{};
+            until([&]{window=FindWindowW(L"KSwitcher.History",nullptr);return window&&IsWindowVisible(window);},"history startup");
+            until([&]{return send(GetDlgItem(window,102),LB_GETCOUNT)>0;},"history rows");
+            DWORD pid{};GetWindowThreadProcessId(window,&pid);
+            require(pid!=process.dwProcessId,"history belongs to a separate process");
+            return window;
+        };
+        auto close=[&](HWND window) {
+            DWORD pid{};GetWindowThreadProcessId(window,&pid);HANDLE child=OpenProcess(SYNCHRONIZE,FALSE,pid);
+            PostMessageW(window,WM_KEYDOWN,VK_ESCAPE,0); // Escape also works with focus on the window itself.
+            until([&]{return WaitForSingleObject(child,0)==WAIT_OBJECT_0;},"history helper exits after Escape");
+            CloseHandle(child);
+            require(!FindWindowW(L"KSwitcher.History",nullptr),"Escape destroys history window");
+        };
+        for(int i=0;i<3;++i){auto w=open();until([&]{return send(GetDlgItem(w,102),LB_GETCOUNT)==500;},"all history rows loaded");require(true,"all history entries visible");close(w);}
+        auto idle=memory(process.hProcess);
+        std::cout<<"MEMORY resident_before="<<base<<" after_three_closes="<<idle<<'\n';
+        require(idle<base+2*1024*1024,"repeated history does not retain UI heap in resident");
+        auto w=open();send(w,WM_COMMAND,112);
+        until([&]{history.reload();return history.entries().front().pinned;},"resident pin mutation");
+        require(history.entries().front().id==textId,"pin preserves history identity");
+        auto filter=[&](HWND window,int index) {
+            auto checkbox=GetDlgItem(window,117);
+            if(send(checkbox,BM_GETCHECK)!=(index ? BST_CHECKED : BST_UNCHECKED)) send(checkbox,BM_CLICK);
+        };
+        filter(w,1);
+        until([&]{return send(GetDlgItem(w,102),LB_GETCOUNT)==1;},"pinned filter hides unpinned entries");
+        send(GetDlgItem(w,101),WM_SETTEXT,0,LPARAM(L"History fixture 497"));
+        until([&]{return send(GetDlgItem(w,102),LB_GETCOUNT)==0;},"search cannot match an unpinned item in pinned view");
+        send(GetDlgItem(w,101),WM_SETTEXT,0,LPARAM(L"History fixture 498"));
+        until([&]{return send(GetDlgItem(w,102),LB_GETCOUNT)==1;},"history search");
+        send(w,WM_COMMAND,112);
+        until([&]{return send(GetDlgItem(w,102),LB_GETCOUNT)==0;},"unpin removes the last pinned result");
+        filter(w,0);
+        until([&]{return send(GetDlgItem(w,102),LB_GETCOUNT)==1;},"all items restores the matching unpinned entry");
+        send(w,WM_COMMAND,112);
+        filter(w,1);
+        close(w);w=open();
+        require(send(GetDlgItem(w,117),BM_GETCHECK)==BST_CHECKED,"pinned checkbox survives helper restart");
+        wchar_t query[100]{};send(GetDlgItem(w,101),WM_GETTEXT,100,LPARAM(query));
+        require(std::wstring(query)==L"History fixture 498","search survives helper restart");
+        send(w,WM_COMMAND,114);
+        HWND entry{};until([&]{entry=FindWindowW(L"KSwitcher.Entry",nullptr);return entry!=nullptr;},"full item opens");
+        DWORD childPid{};GetWindowThreadProcessId(w,&childPid);HANDLE child=OpenProcess(SYNCHRONIZE,FALSE,childPid);
+        send(GetDlgItem(w,101),WM_KEYDOWN,VK_ESCAPE);
+        require(WaitForSingleObject(child,0)==WAIT_TIMEOUT && IsWindow(entry),"full item remains usable after closing history");
+        send(entry,WM_CLOSE);
+        until([&]{return WaitForSingleObject(child,0)==WAIT_OBJECT_0;},"helper exits after last full item closes");CloseHandle(child);
+        w=open();filter(w,0);send(GetDlgItem(w,101),WM_SETTEXT,0,LPARAM(L""));
+        until([&]{return send(GetDlgItem(w,102),LB_GETCOUNT)==500;},"clear search");close(w);
+        ks::writeClipboard(target,excluded(image));
+        w=open();send(w,WM_COMMAND,111);
+        until([&]{return editorText()==L"History fixture 498";},"paste plain text into native editor");
+        until([&]{return IsClipboardFormatAvailable(CF_DIB)&&!FindWindowW(L"KSwitcher.HistoryHost",nullptr);},"image clipboard restored after paste");
+        require(ks::decodeImage(ks::readClipboard(target,64*1024*1024)).width==pixels.width,"image clipboard survives history paste");
+        auto afterPaste=memory(process.hProcess);
+        std::cout<<"MEMORY after_paste_with_image_backup="<<afterPaste<<'\n';
+        require(afterPaste<base+2*1024*1024,"image clipboard backup stays outside resident");
+        ks::writeClipboard(target,excluded(ks::textClip(L"keep clipboard")));
+        w=open();send(GetDlgItem(w,101),WM_SETTEXT,0,LPARAM(L"Image"));
+        until([&]{return send(GetDlgItem(w,102),LB_GETCOUNT)==1;},"image search");
+        pastedImage=false;send(w,WM_COMMAND,110);
+        until([&]{return pastedImage;},"image paste reaches destination");
+        until([&]{return ks::readClipboard(target).text()==L"keep clipboard";},"clipboard restored after image paste");
+        std::cout<<"MEMORY after_image_paste="<<memory(process.hProcess)<<'\n';
+        require(memory(process.hProcess)<base+2*1024*1024,"image paste does not retain full bitmap in resident");
+        until([&]{return !FindWindowW(L"KSwitcher.HistoryHost",nullptr);},"image paste helper exits");
+        w=open();send(w,WM_COMMAND,113);
+        until([&]{history.reload();return history.entries().size()==499;},"resident removes selected image");
+        GetWindowThreadProcessId(w,&childPid);child=OpenProcess(SYNCHRONIZE,FALSE,childPid);
+        // Startup update checks temporarily reject exit; retry after that
+        // operation finishes instead of treating its guard as a host leak.
+        ULONGLONG nextExit{};
+        until([&]{
+            if(WaitForSingleObject(process.hProcess,0)==WAIT_OBJECT_0) return true;
+            if(GetTickCount64()>=nextExit) {
+                command(resident,99);nextExit=GetTickCount64()+500;
+            }
+            return false;
+        },"resident accepts exit after startup update check",30000);
+        until([&]{return WaitForSingleObject(child,0)==WAIT_OBJECT_0;},"resident shutdown closes history helper");
+        CloseHandle(child);resident=nullptr;
+        std::cout<<"PASS isolated history host suite\n";
+    } catch(const std::exception &e){std::cerr<<"FAIL "<<e.what()<<" editor="<<ks::utf8(editorText())<<" foreground="<<(GetForegroundWindow()==target)<<'\n';result=1;}
+    if(resident)try{command(resident,99);}catch(...){}
+    if(process.hProcess){if(WaitForSingleObject(process.hProcess,10000)!=WAIT_OBJECT_0){TerminateProcess(process.hProcess,1);WaitForSingleObject(process.hProcess,INFINITE);}CloseHandle(process.hProcess);}
+    if(captured)try{ks::writeClipboard(target,saved);}catch(...){result=1;}
+    if(target) DestroyWindow(target);
+    CoUninitialize();
+    return result;
+}

tests/image_capture.cpp

@@ -29,6 +29,12 @@ int main() {
                 "helper persists fingerprints and resident reloads them");
         require(entries.back().id==pinned && entries.back().pinned,"helper preserves existing pinned entry");
         auto restored=history.load(entries.front().id);
+        auto thumbnail=history.thumbnail(entries.front().id);
+        require(thumbnail.width==pixels.width && thumbnail.height==pixels.height && thumbnail.bgra==pixels.bgra,
+                "helper thumbnail preserves small image pixels");
+        bool thumbnailCancelled=false;
+        try {history.thumbnail(entries.front().id,[]{return true;});} catch(...) {thumbnailCancelled=true;}
+        require(thumbnailCancelled,"closed history cancels thumbnail work");
         auto has=[&](const ks::Format &expected) {
             return std::any_of(restored.formats.begin(),restored.formats.end(),[&](const ks::Format &actual) {
                 return (expected.name.empty()?actual.id==expected.id:actual.name==expected.name) && actual.data==expected.data;
@@ -55,6 +61,16 @@ int main() {
         }
         require(rejected && history.entries().size()==2,"oversized image is rejected without changing index");
         require(GetClipboardSequenceNumber()==sequence,"rejection leaves clipboard unchanged");
+        settings.maxImageMiB=20;
+        history.add(ks::Clip{{ks::imageDib(pixels)}},L"thumbnail fixture",settings);
+        auto largeId=history.entries().front().id;
+        thumbnail=history.thumbnail(largeId);
+        require(thumbnail.width==208 && thumbnail.height==104 && thumbnail.bgra.size()==208*104*4,
+                "large image returns only bounded thumbnail pixels");
+        history.remove(largeId);
+        bool missingRejected=false;
+        try {history.thumbnail(largeId);} catch(...) {missingRejected=true;}
+        require(missingRejected,"deleted image cannot be previewed or recreated");
         for(const auto &file:std::filesystem::directory_iterator(folder))
             require(file.path().extension()!=L".request","encrypted capture request is cleaned up");
     } catch(const std::exception &e) {std::cerr << "FAIL " << e.what() << '\n';result=1;}

tests/input.cpp

@@ -94,6 +94,9 @@ struct InputRegressionAccess {
     }
     static void notificationSetup(App &a) { a.updateNotifier = notify; }
     static void setup(App &a) { a.hookBindings = {{Toggle,{MOD_CONTROL,VK_F12}}, {Case,{MOD_CONTROL|MOD_SHIFT,'U'}}}; }
+    static LRESULT routedKey(int code, UINT message, const KBDLLHOOKSTRUCT &key, LRESULT routed) {
+        return App::keyboardAfterHooks(code,message,(LPARAM)&key,routed);
+    }
     static bool updateTimer(App &a) {
         a.updateRunning=true; // Exercise timer scheduling without launching a network request.
         App::windowProc(a.window,WM_TIMER,5,0);
@@ -648,6 +651,22 @@ int main(int argc, char **argv) {
             };
             auto commands=[&] { MSG m{}; int n=0; while(PeekMessageW(&m,app.window,WM_HOTKEY,WM_HOTKEY,PM_REMOVE)) ++n; return n; };
             auto f12=event(VK_F12);
+            {
+                const auto before = app.inputVersion.load();
+                const auto recorded = app.run.keys;
+                for (UINT message : {WM_KEYDOWN, WM_KEYUP, WM_SYSKEYDOWN, WM_SYSKEYUP})
+                    require(ks::InputRegressionAccess::routedKey(HC_ACTION,message,event('A',30),7)==7,
+                            "forwarded keyboard events preserve downstream suppression");
+                require(app.inputVersion==before && app.run.keys==recorded && commands()==0,
+                        "forwarded events never track text, invalidate transactions or dispatch shortcuts");
+                require(ks::InputRegressionAccess::routedKey(-1,WM_KEYDOWN,event('A',30),0)==0 &&
+                        app.inputVersion==before,"negative hook codes do not process keyboard input");
+                require(ks::InputRegressionAccess::routedKey(HC_ACTION,WM_KEYDOWN,event('A',30,true),0)==0 &&
+                        app.inputVersion==before,"own input remains excluded after downstream routing");
+                require(ks::InputRegressionAccess::routedKey(HC_ACTION,WM_KEYDOWN,event('A',30),0)==0 &&
+                        app.inputVersion>before,"delivered remote input is still processed on the receiver");
+                app.run.reset();
+            }
             require(!app.handleKeyboard(event(VK_LCONTROL),true,0),"remote modifier passes through");
             require(app.handleKeyboard(f12,true,MOD_CONTROL),"remote Ctrl+F12 handled");
             require(app.handleKeyboard(f12,true,MOD_CONTROL),"remote repeat suppressed");

tests/integration.cpp

@@ -33,6 +33,17 @@ bool trimCopiedSpaces = false;
 int trimmedCopies = 0;
 bool temporaryClipboardExcluded = true;
 bool clipboardAccessTimedOut = false;
+uint64_t forwardedVersion{};
+int forwardedEvents{};
+LRESULT CALLBACK forwardingHook(int code, WPARAM wp, LPARAM lp)
+{
+    if (code == HC_ACTION && reinterpret_cast<KBDLLHOOKSTRUCT *>(lp)->dwExtraInfo == 456)
+    {
+        ++forwardedEvents;
+        return 1; // Model MWB consuming source input routed to another machine.
+    }
+    return CallNextHookEx(nullptr, code, wp, lp);
+}
 LRESULT CALLBACK observeEnter(HWND w, UINT message, WPARAM wp, LPARAM lp, UINT_PTR, DWORD_PTR)
 {
     if (message == WM_KEYDOWN && wp == VK_LEFT && droppedSelectionKeys > 0 &&
@@ -309,6 +320,8 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 app->settings.autoCorrect = true;
                 app->settings.switchLayout = true;
                 app->settings.autoLanguages = {L"en", L"ru"};
+                // Direct fixture mutations bypass applySettings' dictionary preload.
+                app->autoPredictor.configure(L"dictionaries", app->settings.autoLanguages);
                 app->settings.cycle = {app->layouts[en].id, app->layouts[ru].id};
                 ActivateKeyboardLayout(app->layouts[en].handle, 0);
                 prepare(L"ghbdtn ", false);
@@ -575,10 +588,41 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 require(ks::readClipboard(app->window).text() == sentinel, "selected and repeated conversions restore clipboard");
                 finish();
                 break;
+            case 62:
+                saved = ks::readClipboard(app->window, 64 * 1024 * 1024);
+                captured = true;
+                app->ownSequence = ks::writeClipboard(app->window, ks::textClip(sentinel));
+                app->settings.snippets = {{L";r", L"unexpected{enter}"}};
+                ActivateKeyboardLayout(app->layouts[en].handle, 0);
+                prepare(L"prefix ", false);
+                forwardedVersion = app->inputVersion.load();
+                copyRequests = forwardedEvents = 0;
+                {
+                    std::vector<INPUT> inputs;
+                    for (WORD key : {WORD(VK_OEM_1), WORD('R')})
+                        for (DWORD flags : {DWORD(0), DWORD(KEYEVENTF_KEYUP)})
+                        {
+                            auto input = ks::keyboardInput(key, flags);
+                            input.ki.dwExtraInfo = 456;
+                            inputs.push_back(input);
+                        }
+                    require(SendInput((UINT)inputs.size(),inputs.data(),sizeof(INPUT))==inputs.size(),
+                            "forwarded snippet input submitted to real hook chain");
+                }
+                break;
+            case 63:
+                require(forwardedEvents==4,"downstream forwarding hook consumed every key event");
+                require(app->inputVersion==forwardedVersion && copyRequests==0,
+                        "forwarded snippet does not start tracking or clipboard work on source computer");
+                require(text()==L"prefix " && ks::readClipboard(app->window).text()==sentinel,
+                        "forwarded snippet leaves source editor and clipboard untouched");
+                stage = 30;
+                break;
             case 30:
             case 32:
             case 34:
             case 37:
+            case 60:
                 // Earlier password/word tests replace the original multiline
                 // editor with a single-line EDIT. Restore the snippet fixture:
                 // a single-line control cannot insert the tested Enter action.
@@ -607,6 +651,11 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 enterPresses = 0;
                 copyRequests = 0;
                 copyFailuresRemaining = stage == 38 ? 10 : stage == 33 ? 1 : 0;
+                if (stage == 61)
+                {
+                    pasteBehavior = 2; // Editor inserts unrelated clipboard text.
+                    app->settings.writeLog = false;
+                }
                 temporaryClipboardExcluded = true;
                 ActivateKeyboardLayout(app->layouts[en].handle, 0);
                 prepare(L"prefix ", false);
@@ -670,6 +719,13 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 require(ks::readClipboard(app->window).text() == sentinel,
                         "exhausted copy retries restore the clipboard");
                 copyFailuresRemaining = 0;
+                stage = 60;
+                break;
+            case 61:
+                require(text() == L"prefix other! x", "incorrect snippet paste preserves following typing");
+                require(enterPresses == 0, "unverified snippet never submits Enter even without logging");
+                require(ks::readClipboard(app->window).text() == sentinel, "rejected snippet restores clipboard");
+                pasteBehavior = 0;
                 finish();
                 break;
             case 20:
@@ -682,6 +738,7 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 app->settings.autoCorrect = true;
                 app->settings.switchLayout = true;
                 app->settings.autoLanguages = {L"en", L"ru"};
+                app->autoPredictor.configure(L"dictionaries", app->settings.autoLanguages);
                 app->settings.cycle = {app->layouts[en].id, app->layouts[ru].id};
                 app->autoCorrector = ks::AutoCorrector{};
                 ActivateKeyboardLayout(app->layouts[en].handle, 0);
@@ -731,6 +788,7 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 });
                 require(uk != app->layouts.end(), "Ukrainian layout available for punctuation-key regression");
                 app->settings.autoLanguages = {L"en", L"uk"};
+                app->autoPredictor.configure(L"dictionaries", app->settings.autoLanguages);
                 app->settings.cycle = {app->layouts[en].id, uk->id};
                 app->settings.autoWords[L"uk"] = {L"робить"};
                 app->autoCorrector = ks::AutoCorrector{};
@@ -981,9 +1039,12 @@ int main(int argc, char **argv)
             if (typosOnly || (argc > 1 && std::string(argv[1]) == "--typing-only"))
                 stage = 20;
             if (argc > 1 && std::string(argv[1]) == "--snippets-only")
-                stage = 30;
+                stage = 62;
             SetTimer(host, 1, 100, nullptr);
+            auto forwarding = SetWindowsHookExW(WH_KEYBOARD_LL,forwardingHook,GetModuleHandleW(nullptr),0);
+            require(forwarding!=nullptr,"downstream forwarding fixture installed before application hook");
             app->execute();
+            UnhookWindowsHookEx(forwarding);
         }
         std::filesystem::remove_all(root);
     }

tests/tests.cpp

@@ -517,6 +517,24 @@ int main(int argc, char **argv)
         auto encoded = ks::encodeClip(clip);
         require(ks::decodeClip(encoded).text() == clip.text(), "clipboard Unicode roundtrip");
         require(ks::decodeClip(encoded).formats[1].name == L"HTML Format", "registered format identity");
+        auto selection = ks::textClip(L";pa");
+        selection.formats.push_back({0, L"vscode-editor-data", {1, 2, 3}});
+        auto relayed = selection;
+        relayed.formats.front().data.resize(128, 0xab);
+        std::reverse(relayed.formats.begin(), relayed.formats.end());
+        require(ks::selectionClipboardIdentity(selection) == ks::selectionClipboardIdentity(relayed),
+                "clipboard relay tolerates Unicode allocation slack and format order");
+        relayed.formats.front().data[0] ^= 1;
+        require(ks::selectionClipboardIdentity(selection) != ks::selectionClipboardIdentity(relayed),
+                "clipboard relay rejects changed editor metadata");
+        relayed = selection;
+        relayed.formats.pop_back();
+        require(ks::selectionClipboardIdentity(selection) != ks::selectionClipboardIdentity(relayed),
+                "clipboard relay rejects missing editor metadata");
+        relayed = selection;
+        relayed.formats.front() = ks::textClip(L";pb").formats.front();
+        require(ks::selectionClipboardIdentity(selection) != ks::selectionClipboardIdentity(relayed),
+                "clipboard relay rejects changed Unicode text");
         auto encrypted = ks::protect(encoded);
         require(encrypted != encoded, "history ciphertext differs");
         require(ks::unprotect(encrypted) == encoded, "Windows DPAPI roundtrip");