fix(workspace): reject impossible calendar dates in memory snapshot import

mateclaw-server/src/main/java/vip/mate/workspace/document/WorkspaceMemoryArchiveService.java

@@ -17,6 +17,8 @@ import java.nio.charset.StandardCharsets;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.time.Instant;
+import java.time.LocalDate;
+import java.time.format.DateTimeParseException;
 import java.util.ArrayList;
 import java.util.Comparator;
 import java.util.LinkedHashMap;
@@ -210,7 +212,23 @@ public class WorkspaceMemoryArchiveService {
     }
 
     private static boolean isAllowedFilename(String name) {
-        return TOP_LEVEL_WHITELIST.contains(name) || DAILY_FILENAME.matcher(name).matches();
+        if (TOP_LEVEL_WHITELIST.contains(name)) {
+            return true;
+        }
+        if (!DAILY_FILENAME.matcher(name).matches()) {
+            return false;
+        }
+        // The regex only constrains digit shape, so structurally-valid but
+        // non-existent dates (memory/2026-13-99.md, memory/2026-02-30.md)
+        // would slip through. Parse the date to reject calendar dates that
+        // cannot occur, keeping the daily ledger namespace clean.
+        String date = name.substring("memory/".length(), name.length() - ".md".length());
+        try {
+            LocalDate.parse(date);
+            return true;
+        } catch (DateTimeParseException e) {
+            return false;
+        }
     }
 
     /**

mateclaw-server/src/test/java/vip/mate/workspace/document/WorkspaceMemoryArchiveServiceTest.java

@@ -173,6 +173,33 @@ class WorkspaceMemoryArchiveServiceTest {
                 org.mockito.ArgumentMatchers.anyString(), org.mockito.ArgumentMatchers.anyString());
     }
 
+    @Test
+    @DisplayName("Daily filename matching the digit shape but not a real date is rejected")
+    void impossibleCalendarDateRejected() throws Exception {
+        wireAgent(1L, 10L);
+        when(workspaceFileService.getFile(1L, "memory/2026-05-12.md"))
+                .thenReturn(null);
+
+        byte[] zip = makeZip(Map.of(
+                "memory/2026-05-12.md", "real date → create",
+                "memory/2026-13-99.md", "month 13 / day 99 → reject",
+                "memory/2026-02-30.md", "feb 30 does not exist → reject"));
+
+        WorkspaceMemoryArchiveService.ImportPreview preview =
+                service.previewImport(1L, 10L, zip);
+
+        assertThat(preview.willCreate()).containsExactlyInAnyOrder("memory/2026-05-12.md");
+        assertThat(preview.willSkip())
+                .extracting(WorkspaceMemoryArchiveService.SkipEntry::filename,
+                        WorkspaceMemoryArchiveService.SkipEntry::reason)
+                .contains(
+                        org.assertj.core.groups.Tuple.tuple("memory/2026-13-99.md", "not in whitelist"),
+                        org.assertj.core.groups.Tuple.tuple("memory/2026-02-30.md", "not in whitelist"));
+
+        verify(workspaceFileService, never()).saveFile(org.mockito.ArgumentMatchers.anyLong(),
+                org.mockito.ArgumentMatchers.anyString(), org.mockito.ArgumentMatchers.anyString());
+    }
+
     @Test
     @DisplayName("Preview surfaces old vs new hash + size for updated files")
     void previewExposesDiffMetadata() throws Exception {