diff --git a/docs/PLAN.md b/docs/PLAN.md
index 7f916b1..77b4611 100644
--- a/docs/PLAN.md
+++ b/docs/PLAN.md
@@ -382,13 +382,15 @@ program, click **Run** (or Ctrl+Return); each Run is one undo step.
   loops `x y g v` (nestable, `{}` groups), and shell filters `< > | !` via
   `sh -c`. 27 unit tests cover each.
 - **Multi-file `X`/`Y`** (`SamEngine::peelFileLoop` + Kate driver): a leading
-  `X/re/ cmd` runs `cmd` on every project file whose path matches `re` (`Y` =
-  non-match). The file set is the project index (`ProjectIndexer::cachedFiles`);
-  each matched file is opened as a Document and edited. sam permits only one
+  `X/re/ cmd` runs `cmd` on every **open buffer** whose path matches `re` (`Y` =
+  non-match). The set is the documents Kate currently has open
+  (`Application::documents()`) — acme's open-window set — matched by local file
+  path, or display name for an unsaved scratch buffer. Nothing is opened or read
+  from disk; the live `Document`s are edited in place. sam permits only one
   `X`/`Y` per command, so this is leading-token recognition, not a nested parse.
 - **Undo**: single-document Run applies all edits inside one
   `Document::EditingTransaction` → one Ctrl+Z reverts the whole Run. Multi-file
-  `X`/`Y` is undoable **per file** (KTextEditor has no global multi-file undo).
+  `X`/`Y` is undoable **per buffer** (KTextEditor has no global multi-file undo).
 - **Panel** (`src/plugin/sampanel.{h,cpp}`): program editor + Run button +
   output log; `OllieView` creates the tool view and owns the apply logic
   (`runSamProgram`, `applySamToDocument`, `runSamFileLoop`).
diff --git a/docs/SAM.md b/docs/SAM.md
index aec51a1..7c099e6 100644
--- a/docs/SAM.md
+++ b/docs/SAM.md
@@ -80,15 +80,18 @@ matches with `x`/`y`, guard with `g`/`v`, group with `{}`:
 0/start/,/end/ x/[a-z]+/ s/.*/[&]/    bracket every lowercase word in a region
 ```
 
-Multi-file `X`/`Y` applies an inner program across the project:
+Multi-file `X`/`Y` applies an inner program across the **open buffers**:
 
 ```
-X/\.cpp$/ ,s/old_api/new_api/g        rewrite every .cpp in the project
-Y/_test\./ ,x/TODO/ d                 drop TODO lines in non-test files
+X/\.cpp$/ ,s/old_api/new_api/g        rewrite every open .cpp buffer
+Y/_test\./ ,x/TODO/ d                 drop TODO lines in non-test buffers
 ```
 
-(The file set is the project index, matched by path. Edits land in buffers, not
-on disk — review and save deliberately. Undo is per file for `X`/`Y`.)
+(`X`/`Y` iterate the set of documents Kate currently has open — acme's
+open-window set — not the project on disk. The regex matches each buffer's file
+path, or its display name for an unsaved scratch buffer. Nothing is opened or
+read from disk; edits land in the live buffers, each its own undo step. Review
+and save deliberately.)
 
 ## Practical guidance
 
diff --git a/src/plugin/ollieplugin.cpp b/src/plugin/ollieplugin.cpp
index f1050c5..a1dd747 100644
--- a/src/plugin/ollieplugin.cpp
+++ b/src/plugin/ollieplugin.cpp
@@ -14,11 +14,12 @@
 #include "sampanel.h"
 #include "samengine.h"
 
-#include <KTextEditor/MainWindow>
-#include <KTextEditor/View>
+#include <KTextEditor/Application>
+#include <KTextEditor/Command>
 #include <KTextEditor/Document>
 #include <KTextEditor/Editor>
-#include <KTextEditor/Command>
+#include <KTextEditor/MainWindow>
+#include <KTextEditor/View>
 
 #include <KActionCollection>
 #include <KXMLGUIClient>
@@ -990,13 +991,8 @@ void OllieView::runSamFileLoop(bool negate, const QString &fileRegex, const QStr
     if (!m_samPanel) {
         return;
     }
-    const QString root = currentProjectRoot();
-    if (root.isEmpty()) {
-        m_samPanel->showError(i18n("X/Y needs a project; none is loaded."));
-        return;
-    }
     if (inner.trimmed().isEmpty()) {
-        m_samPanel->showError(i18n("X/Y: no command to run on matched files."));
+        m_samPanel->showError(i18n("X/Y: no command to run on matched buffers."));
         return;
     }
     QRegularExpression fileRe(fileRegex);
@@ -1005,50 +1001,50 @@ void OllieView::runSamFileLoop(bool negate, const QString &fileRegex, const QStr
         return;
     }
 
-    // Use the cached project file list; request a build if we have none yet.
-    if (!m_indexer.hasFiles(root)) {
-        m_samPanel->showOutput(i18n("Indexing project files… run X/Y again in a moment."));
-        m_indexer.requestFiles(root);
+    // X/Y iterate the set of OPEN buffers (like acme's open-window set), not the
+    // whole project on disk. Nothing is opened or read from disk: we edit the
+    // documents Kate already has loaded, in place, each as its own undo step.
+    KTextEditor::Editor *editor = KTextEditor::Editor::instance();
+    KTextEditor::Application *app = editor ? editor->application() : nullptr;
+    const QList<KTextEditor::Document *> docs =
+        app ? app->documents() : QList<KTextEditor::Document *>{};
+    if (docs.isEmpty()) {
+        m_samPanel->showError(i18n("X/Y: no open buffers."));
         return;
     }
-    const QStringList files = m_indexer.cachedFiles(root);
 
     int matched = 0;
     int changed = 0;
-    int failed = 0;
-    for (const QString &rel : files) {
-        const bool hit = fileRe.match(rel).hasMatch();
+    for (KTextEditor::Document *doc : docs) {
+        if (!doc) {
+            continue;
+        }
+        // Match the regex against the buffer's path (its local file path, or its
+        // display name for an unsaved scratch buffer).
+        const QUrl url = doc->url();
+        const QString target =
+            url.isLocalFile() ? url.toLocalFile() : doc->documentName();
+        const bool hit = fileRe.match(target).hasMatch();
         if (hit == negate) {
             continue; // X runs on hits; Y runs on misses
         }
         matched++;
-        const QString absolute = QDir(root).absoluteFilePath(rel);
-        const QUrl url = QUrl::fromLocalFile(absolute);
-        // Open (or focus) the file so the edit is a normal, undoable Document
-        // change visible to the user.
-        KTextEditor::View *view = m_mainWindow->openUrl(url);
-        if (!view || !view->document()) {
-            failed++;
-            m_samPanel->showError(i18n("could not open %1", rel));
-            continue;
-        }
-        KTextEditor::Document *doc = view->document();
         QString output;
         QString error;
         const int dotEnd = doc->text().size();
         if (applySamToDocument(doc, inner, 0, dotEnd, &output, &error)) {
             changed++;
             if (!output.isEmpty()) {
-                m_samPanel->showOutput(QStringLiteral("%1:\n%2").arg(rel, output));
+                m_samPanel->showOutput(QStringLiteral("%1:\n%2").arg(target, output));
             }
         } else {
-            // A "no match" in a given file is normal during a sweep; report it
+            // A "no match" in a given buffer is normal during a sweep; report it
             // quietly rather than as a hard error.
-            m_samPanel->showOutput(QStringLiteral("%1: %2").arg(rel, error));
+            m_samPanel->showOutput(QStringLiteral("%1: %2").arg(target, error));
         }
     }
     m_samPanel->showOutput(
-        i18n("X/Y done: %1 file(s) matched, %2 changed, %3 failed.", matched, changed, failed));
+        i18n("X/Y done: %1 open buffer(s) matched, %2 changed.", matched, changed));
 }
 
 QAction *OllieView::findActionByName(const QString &nameOrText) const