fix(memory): tokenize query and events alike in InMemoryMemoryService

Matches adk-python: both sides are split with a Unicode-aware \w+, so a query
word followed by punctuation, a word with accented letters and a number now
match. Before, the query was split on whitespace only and events kept only
ASCII letters.

Author: Laurianti

core/src/main/java/com/google/adk/memory/InMemoryMemoryService.java

@@ -44,8 +44,9 @@
  */
 public final class InMemoryMemoryService implements BaseMemoryService {
 
-  // Pattern to extract words, matching the Python version.
-  private static final Pattern WORD_PATTERN = Pattern.compile("[A-Za-z]+");
+  // Pattern to extract words, matching Python's Unicode-aware \w+.
+  private static final Pattern WORD_PATTERN =
+      Pattern.compile("\\w+", Pattern.UNICODE_CHARACTER_CLASS);
 
   /** Keys are "app_name/user_id", values are maps of "session_id" to a list of events. */
   private final Map<String, Map<String, List<Event>>> sessionEvents;
@@ -91,8 +92,7 @@ public Single<SearchMemoryResponse> searchMemory(String appName, String userId,
 
           Map<String, List<Event>> userSessions = sessionEvents.get(key);
 
-          ImmutableSet<String> wordsInQuery =
-              ImmutableSet.copyOf(query.toLowerCase(Locale.ROOT).split("\\s+"));
+          ImmutableSet<String> wordsInQuery = extractWordsLower(query);
 
           List<MemoryEntry> matchingMemories = new ArrayList<>();
 
@@ -105,12 +105,7 @@ public Single<SearchMemoryResponse> searchMemory(String appName, String userId,
               Set<String> wordsInEvent = new HashSet<>();
               for (Part part : event.content().get().parts().get()) {
                 String text = part.text().orElse("");
-                if (!text.isEmpty()) {
-                  Matcher matcher = WORD_PATTERN.matcher(text);
-                  while (matcher.find()) {
-                    wordsInEvent.add(matcher.group().toLowerCase(Locale.ROOT));
-                  }
-                }
+                wordsInEvent.addAll(extractWordsLower(text));
               }
 
               if (wordsInEvent.isEmpty()) {
@@ -135,6 +130,16 @@ public Single<SearchMemoryResponse> searchMemory(String appName, String userId,
         });
   }
 
+  /** Extracts words from a string and converts them to lowercase. */
+  private static ImmutableSet<String> extractWordsLower(String text) {
+    ImmutableSet.Builder<String> words = ImmutableSet.builder();
+    Matcher matcher = WORD_PATTERN.matcher(text);
+    while (matcher.find()) {
+      words.add(matcher.group().toLowerCase(Locale.ROOT));
+    }
+    return words.build();
+  }
+
   private String formatTimestamp(long timestamp) {
     return Instant.ofEpochMilli(timestamp).toString();
   }

core/src/test/java/com/google/adk/memory/InMemoryMemoryServiceTest.java

@@ -137,4 +137,41 @@ public void searchMemory_textAndFunctionCallInOneEvent_stillMatchesOnTheText() {
     assertThat(response.memories().get(0).content())
         .isEqualTo(Content.fromParts(Part.fromText("weather in Seoul"), functionCall));
   }
+
+  @Test
+  public void searchMemory_queryWithPunctuation_matchesWord() {
+    InMemoryMemoryService service = new InMemoryMemoryService();
+    service
+        .addSessionToMemory(sessionWith(event(Part.fromText("weather in Seoul"))))
+        .blockingAwait();
+
+    SearchMemoryResponse response =
+        service.searchMemory(APP_NAME, USER_ID, "weather?").blockingGet();
+
+    assertThat(response.memories()).hasSize(1);
+  }
+
+  @Test
+  public void searchMemory_nonAsciiWord_matchesWholeWord() {
+    InMemoryMemoryService service = new InMemoryMemoryService();
+    service
+        .addSessionToMemory(sessionWith(event(Part.fromText("Meet me at the café"))))
+        .blockingAwait();
+
+    SearchMemoryResponse response = service.searchMemory(APP_NAME, USER_ID, "café").blockingGet();
+
+    assertThat(response.memories()).hasSize(1);
+  }
+
+  @Test
+  public void searchMemory_digits_matchWord() {
+    InMemoryMemoryService service = new InMemoryMemoryService();
+    service
+        .addSessionToMemory(sessionWith(event(Part.fromText("Order 12345 shipped"))))
+        .blockingAwait();
+
+    SearchMemoryResponse response = service.searchMemory(APP_NAME, USER_ID, "12345").blockingGet();
+
+    assertThat(response.memories()).hasSize(1);
+  }
 }