Windows-Zeichenbehandlung im finalen Basis-Dateinamen explizit umgesetzt

pdf-umbenenner-application/src/main/java/de/gecheckt/pdf/umbenenner/application/service/TargetFilenameBuildingService.java

@@ -97,6 +97,11 @@ public final class TargetFilenameBuildingService {
      * If any rule is violated, the state is treated as an
      * {@link InconsistentProposalState}.
      * <p>
+     * Windows compatibility: The final filename is cleaned of Windows-incompatible characters
+     * (e.g., {@code < > : " / \ | ? *}) to ensure the resulting filename can be created on
+     * Windows systems. This is a defensive measure; the validated title is already expected
+     * to contain only letters, digits, and spaces.
+     * <p>
      * The 20-character limit applies exclusively to the base title. A duplicate-avoidance
      * suffix (e.g., {@code (1)}) may be appended by the target folder adapter after this
      * method returns and is not counted against the 20 characters.
@@ -134,8 +139,16 @@ public final class TargetFilenameBuildingService {
                             + title + "'");
         }
 
+        // Defensive Windows compatibility: remove Windows-incompatible characters
+        String cleanedTitle = removeWindowsIncompatibleCharacters(title);
+        if (cleanedTitle.isBlank()) {
+            return new InconsistentProposalState(
+                    "Title becomes empty after Windows-compatibility cleaning: '"
+                            + title + "'");
+        }
+
         // Build: YYYY-MM-DD - Titel.pdf
-        String baseFilename = date + " - " + title + ".pdf";
+        String baseFilename = date + " - " + cleanedTitle + ".pdf";
         return new BaseFilenameReady(baseFilename);
     }
 
@@ -156,4 +169,21 @@ public final class TargetFilenameBuildingService {
         }
         return true;
     }
+
+    /**
+     * Removes characters that are incompatible with Windows filenames.
+     * <p>
+     * Windows-incompatible characters are: {@code < > : " / \ | ? *}
+     * <p>
+     * This is a defensive measure for ensuring Windows compatibility. The characters are
+     * simply removed; no replacement is performed. Unicode letters (including Umlauts and ß)
+     * and spaces are retained.
+     *
+     * @param title the title to clean; must not be null
+     * @return the cleaned title with Windows-incompatible characters removed
+     */
+    private static String removeWindowsIncompatibleCharacters(String title) {
+        // Windows-incompatible characters: < > : " / \ | ? *
+        return title.replaceAll("[<>:\"/\\\\|?*]", "");
+    }
 }

pdf-umbenenner-application/src/test/java/de/gecheckt/pdf/umbenenner/application/service/TargetFilenameBuildingServiceTest.java

@@ -21,8 +21,9 @@ import static org.assertj.core.api.Assertions.assertThatNullPointerException;
  * Unit tests for {@link TargetFilenameBuildingService}.
  * <p>
  * Covers the verbindliches Zielformat {@code YYYY-MM-DD - Titel.pdf}, the 20-character
- * base-title rule, the fachliche Titelregel (only letters, digits, and spaces), and the
+ * base-title rule, the fachliche Titelregel (only letters, digits, and spaces),
- * detection of inconsistent persistence states.
+ * Windows-compatibility character removal, and the detection of inconsistent persistence
+ * states.
  */
 class TargetFilenameBuildingServiceTest {
 
@@ -218,6 +219,86 @@ class TargetFilenameBuildingServiceTest {
         assertThat(result).isInstanceOf(InconsistentProposalState.class);
     }
 
+    // -------------------------------------------------------------------------
+    // Windows compatibility – removal of incompatible characters
+    // (defensive measure; characters should not appear in validated title)
+    // -------------------------------------------------------------------------
+
+    @Test
+    void buildBaseFilename_validTitleProducesWindowsCompatibleFilename() {
+        // Valid titles containing only letters, digits, and spaces should produce
+        // correct Windows-compatible filenames
+        ProcessingAttempt attempt = proposalAttempt(LocalDate.of(2026, 5, 20), "Versicherung");
+
+        BaseFilenameResult result = TargetFilenameBuildingService.buildBaseFilename(attempt);
+
+        assertThat(result).isInstanceOf(BaseFilenameReady.class);
+        assertThat(((BaseFilenameReady) result).baseFilename())
+                .isEqualTo("2026-05-20 - Versicherung.pdf");
+    }
+
+    @Test
+    void buildBaseFilename_germanUmlautsAreRetainedInFilename() {
+        // German Umlauts (ä, ö, ü) and ß are valid filename characters on Windows
+        // and must be retained in the output filename
+        ProcessingAttempt attempt = proposalAttempt(LocalDate.of(2026, 6, 15), "Überprüfung");
+
+        BaseFilenameResult result = TargetFilenameBuildingService.buildBaseFilename(attempt);
+
+        assertThat(result).isInstanceOf(BaseFilenameReady.class);
+        assertThat(((BaseFilenameReady) result).baseFilename())
+                .isEqualTo("2026-06-15 - Überprüfung.pdf");
+    }
+
+    @Test
+    void buildBaseFilename_germanSzligIsRetainedInFilename() {
+        // German ß is a valid filename character on Windows and must be retained
+        ProcessingAttempt attempt = proposalAttempt(LocalDate.of(2026, 3, 10), "Straße");
+
+        BaseFilenameResult result = TargetFilenameBuildingService.buildBaseFilename(attempt);
+
+        assertThat(result).isInstanceOf(BaseFilenameReady.class);
+        assertThat(((BaseFilenameReady) result).baseFilename())
+                .isEqualTo("2026-03-10 - Straße.pdf");
+    }
+
+    @Test
+    void buildBaseFilename_completeFormatIsWindowsCompatible() {
+        // The complete filename format (YYYY-MM-DD - Titel.pdf) is Windows-compatible
+        // The hyphen in the date and the dot in the extension are valid Windows characters
+        ProcessingAttempt attempt = proposalAttempt(LocalDate.of(2026, 12, 31), "Bericht");
+
+        BaseFilenameResult result = TargetFilenameBuildingService.buildBaseFilename(attempt);
+
+        assertThat(result).isInstanceOf(BaseFilenameReady.class);
+        String filename = ((BaseFilenameReady) result).baseFilename();
+        assertThat(filename).matches("\\d{4}-\\d{2}-\\d{2} - .+\\.pdf");
+        // Verify no Windows-incompatible characters: < > : " / \ | ? *
+        assertThat(filename).doesNotContain("<");
+        assertThat(filename).doesNotContain(">");
+        assertThat(filename).doesNotContain(":");
+        assertThat(filename).doesNotContain("\"");
+        assertThat(filename).doesNotContain("/");
+        assertThat(filename).doesNotContain("\\");
+        assertThat(filename).doesNotContain("|");
+        assertThat(filename).doesNotContain("?");
+        assertThat(filename).doesNotContain("*");
+    }
+
+    @Test
+    void buildBaseFilename_twentyCharacterRuleUnaffectedByWindowsCompatibility() {
+        // The 20-character rule applies to the base title only.
+        // Windows-compatibility cleaning does not change the length counting mechanism.
+        String title = "Stromabrechnung 2026"; // exactly 20 characters
+        ProcessingAttempt attempt = proposalAttempt(LocalDate.of(2026, 3, 31), title);
+
+        BaseFilenameResult result = TargetFilenameBuildingService.buildBaseFilename(attempt);
+
+        assertThat(result).isInstanceOf(BaseFilenameReady.class);
+        assertThat(((BaseFilenameReady) result).baseFilename())
+                .startsWith("2026-03-31 - Stromabrechnung 2026");
+    }
+
     // -------------------------------------------------------------------------
     // InconsistentProposalState reason field is non-null
     // -------------------------------------------------------------------------