Meldungsbereich: Button linksbündig; leeren bei Validieren und Techn. Tests

- clearMessagesButton ist jetzt linksbündig (CENTER_LEFT statt CENTER_RIGHT)
- pendingMessages.clear() wird auch am Anfang von runValidationAction() und
  runTechnicalTestsAction() aufgerufen; jeder Durchlauf zeigt nur seine eigenen
  Befunde
- GuiValidateActionSmokeTest: Erwartung von 2 auf 1 Bestätigungsmeldung nach
  zwei Klicks angepasst (Replace- statt Akkumulierungsverhalten)
- Zwei neue Smoke-Tests: validationAction_clearsPreviousMessages und
  technicalTestsAction_clearsPreviousMessages
- Dokumentation in docs/gui-bedienanleitung.md ergänzt

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pdf-umbenenner-adapter-in-gui/src/main/java/de/gecheckt/pdf/umbenenner/adapter/in/gui/GuiConfigurationEditorWorkspace.java

@@ -1501,6 +1501,7 @@ public final class GuiConfigurationEditorWorkspace {
      */
     private void runTechnicalTestsAction() {
         LOG.info("Aktion Technische Tests ausführen gestartet.");
+        pendingMessages.clear();
         technicalTestsButton.setDisable(true);
         technicalTestCoordinator.triggerTechnicalTests();
     }
@@ -1569,7 +1570,7 @@ public final class GuiConfigurationEditorWorkspace {
 
         clearMessagesButton.setOnAction(e -> clearMessages());
         HBox clearButtonRow = new HBox(clearMessagesButton);
-        clearButtonRow.setAlignment(Pos.CENTER_RIGHT);
+        clearButtonRow.setAlignment(Pos.CENTER_LEFT);
         card.getChildren().add(clearButtonRow);
 
         // Populate immediately so the area is not blank before the first validation run.
@@ -1739,6 +1740,7 @@ public final class GuiConfigurationEditorWorkspace {
      */
     private void runValidationAction() {
         LOG.info("Aktion Validieren ausgeführt.");
+        pendingMessages.clear();
 
         EditorValidationInput input = buildValidationInput();
         EditorValidationReport report = editorValidator.validate(input);

pdf-umbenenner-adapter-in-gui/src/test/java/de/gecheckt/pdf/umbenenner/adapter/in/gui/GuiMessageAreaSmokeTest.java

@@ -680,6 +680,75 @@ class GuiMessageAreaSmokeTest {
         });
     }
 
+    // =========================================================================
+    // Scenario: "Validieren" clears previous messages before showing results
+    // =========================================================================
+
+    /**
+     * Smoke test: invoking {@code runValidationAction()} via the validate button removes
+     * pre-existing messages so that results from a previous action do not accumulate.
+     */
+    @Test
+    void validationAction_clearsPreviousMessages() throws Exception {
+        runOnFx(() -> {
+            GuiConfigurationEditorWorkspace ws = new GuiConfigurationEditorWorkspace(Optional.empty());
+            ws.requestNewConfiguration();
+
+            // Seed a stale message that must not survive the validation action.
+            ws.pendingMessages.add(
+                    GuiMessageEntry.of(GuiMessageSeverity.ERROR, "Alter Befund", "Test"));
+            assertFalse(ws.pendingMessages.isEmpty(),
+                    "Pre-condition: pending messages must not be empty before Validieren");
+
+            ws.validateButton.fire();
+
+            assertFalse(
+                    ws.pendingMessages.stream()
+                            .anyMatch(m -> "Alter Befund".equals(m.text())),
+                    "The stale message must have been removed after Validieren");
+        });
+    }
+
+    // =========================================================================
+    // Scenario: "Technische Tests ausführen" clears previous messages before starting
+    // =========================================================================
+
+    /**
+     * Smoke test: invoking the technical-tests action removes pre-existing messages so that
+     * results from a previous action do not accumulate.
+     * <p>
+     * The clear happens synchronously on the FX thread before the background worker starts.
+     * The thread factory is replaced with a no-op so no background thread is actually
+     * started, which prevents native dialog calls that are not supported under Monocle.
+     */
+    @Test
+    void technicalTestsAction_clearsPreviousMessages() throws Exception {
+        runOnFx(() -> {
+            GuiConfigurationEditorWorkspace ws = new GuiConfigurationEditorWorkspace(Optional.empty());
+            ws.requestNewConfiguration();
+
+            // Replace thread factory with a no-op so no background work runs in Monocle.
+            ws.technicalTestCoordinator.testThreadFactory = task -> new Thread(() -> { }) {
+                @Override
+                public void start() {
+                    // Do not start — we only verify the synchronous clear, not the test result.
+                }
+            };
+
+            ws.pendingMessages.add(
+                    GuiMessageEntry.of(GuiMessageSeverity.WARNING, "Alte Warnung", "Test"));
+            assertFalse(ws.pendingMessages.isEmpty(),
+                    "Pre-condition: pending messages must not be empty before technical tests");
+
+            ws.technicalTestsButton.fire();
+
+            assertFalse(
+                    ws.pendingMessages.stream()
+                            .anyMatch(m -> "Alte Warnung".equals(m.text())),
+                    "The stale message must have been removed after Technische Tests ausführen");
+        });
+    }
+
     // =========================================================================
     // Scenario: ai.provider.active field-error label is registered and shown
     // =========================================================================

pdf-umbenenner-adapter-in-gui/src/test/java/de/gecheckt/pdf/umbenenner/adapter/in/gui/GuiValidateActionSmokeTest.java

@@ -244,13 +244,13 @@ class GuiValidateActionSmokeTest {
     }
 
     // =========================================================================
-    // Scenario: clicking twice → message appears exactly once (replace semantics)
+    // Scenario: clicking twice → exactly one message present (replace semantics)
     // =========================================================================
 
     /**
-     * Smoke test: clicking "Validieren" twice must leave two action-confirmation
-     * INFO messages in the message list (accumulation semantics — each click appends
-     * a fresh snapshot of findings).
+     * Smoke test: clicking "Validieren" twice must leave exactly one action-confirmation
+     * INFO message in the message list. Each click clears the previous messages before
+     * adding the new result, so messages from an earlier click do not accumulate.
      *
      * @throws Exception if the FX thread task fails or times out
      */
@@ -267,8 +267,9 @@ class GuiValidateActionSmokeTest {
                             && ACTION_SOURCE.equals(m.source().get()))
                     .filter(m -> m.text().startsWith("Aktion Validieren wurde ausgeführt."))
                     .count();
-            assertEquals(2, confirmationCount,
-                    "After two clicks two action-confirmation INFO messages must be present");
+            assertEquals(1, confirmationCount,
+                    "After two clicks exactly one action-confirmation INFO message must be present"
+                    + " (second click replaces messages from the first click)");
         });
     }