diff --git a/agent-memory-client/agent-memory-client-java/src/main/java/com/redis/agentmemory/models/common/TagFilter.java b/agent-memory-client/agent-memory-client-java/src/main/java/com/redis/agentmemory/models/common/TagFilter.java
new file mode 100644
index 00000000..cf2cc694
--- /dev/null
+++ b/agent-memory-client/agent-memory-client-java/src/main/java/com/redis/agentmemory/models/common/TagFilter.java
@@ -0,0 +1,97 @@
+package com.redis.agentmemory.models.common;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Filter for tag-style string fields (user_id, session_id, namespace, topics, entities).
+ * Match the server-side TagFilter; supports eq, ne, any, all, and startswith operators.
+ *
+ * <p>
+ * Example — match any of several user IDs in one search:
+ * <pre>{@code
+ * SearchRequest.builder()
+ *     .userId(TagFilter.any("user-123", "__account__"))
+ *     .build()
+ * }</pre>
+ */
+@JsonInclude(JsonInclude.Include.NON_NULL)
+public class TagFilter {
+
+    @Nullable
+    private String eq;
+
+    @Nullable
+    private String ne;
+
+    @Nullable
+    @JsonProperty("any")
+    private List<String> any;
+
+    @Nullable
+    @JsonProperty("all")
+    private List<String> all;
+
+    @Nullable
+    private String startswith;
+
+    private TagFilter() {}
+
+    public static TagFilter eq(@NotNull String value) {
+        TagFilter f = new TagFilter();
+        f.eq = value;
+        return f;
+    }
+
+    public static TagFilter ne(@NotNull String value) {
+        TagFilter f = new TagFilter();
+        f.ne = value;
+        return f;
+    }
+
+    public static TagFilter any(@NotNull List<String> values) {
+        TagFilter f = new TagFilter();
+        f.any = List.copyOf(values);
+        return f;
+    }
+
+    public static TagFilter any(@NotNull String... values) {
+        return any(Arrays.asList(values));
+    }
+
+    public static TagFilter all(@NotNull List<String> values) {
+        TagFilter f = new TagFilter();
+        f.all = List.copyOf(values);
+        return f;
+    }
+
+    public static TagFilter all(@NotNull String... values) {
+        return all(Arrays.asList(values));
+    }
+
+    public static TagFilter startsWith(@NotNull String prefix) {
+        TagFilter f = new TagFilter();
+        f.startswith = prefix;
+        return f;
+    }
+
+    @Nullable
+    public String getEq() { return eq; }
+
+    @Nullable
+    public String getNe() { return ne; }
+
+    @Nullable
+    public List<String> getAny() { return any; }
+
+    @Nullable
+    public List<String> getAll() { return all; }
+
+    @Nullable
+    public String getStartswith() { return startswith; }
+}
diff --git a/agent-memory-client/agent-memory-client-java/src/main/java/com/redis/agentmemory/models/longtermemory/SearchRequest.java b/agent-memory-client/agent-memory-client-java/src/main/java/com/redis/agentmemory/models/longtermemory/SearchRequest.java
index 2e0c9ef9..5168d15c 100644
--- a/agent-memory-client/agent-memory-client-java/src/main/java/com/redis/agentmemory/models/longtermemory/SearchRequest.java
+++ b/agent-memory-client/agent-memory-client-java/src/main/java/com/redis/agentmemory/models/longtermemory/SearchRequest.java
@@ -2,6 +2,7 @@
 
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.redis.agentmemory.models.common.TagFilter;
 import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
@@ -29,20 +30,20 @@ public class SearchRequest {
 
     @Nullable
     @JsonProperty("session_id")
-    private String sessionId;
+    private TagFilter sessionId;
 
     @Nullable
-    private String namespace;
+    private TagFilter namespace;
 
     @Nullable
-    private List<String> topics;
+    private TagFilter topics;
 
     @Nullable
-    private List<String> entities;
+    private TagFilter entities;
 
     @Nullable
     @JsonProperty("user_id")
-    private String userId;
+    private TagFilter userId;
 
     @Nullable
     @JsonProperty("distance_threshold")
@@ -125,47 +126,69 @@ public void setTextScorer(@Nullable String textScorer) {
     }
 
     @Nullable
-    public String getSessionId() {
+    public TagFilter getSessionId() {
         return sessionId;
     }
 
     public void setSessionId(@Nullable String sessionId) {
+        this.sessionId = sessionId != null ? TagFilter.eq(sessionId) : null;
+    }
+
+    public void setSessionId(@Nullable TagFilter sessionId) {
         this.sessionId = sessionId;
     }
 
     @Nullable
-    public String getNamespace() {
+    public TagFilter getNamespace() {
         return namespace;
     }
 
     public void setNamespace(@Nullable String namespace) {
+        this.namespace = namespace != null ? TagFilter.eq(namespace) : null;
+    }
+
+    public void setNamespace(@Nullable TagFilter namespace) {
         this.namespace = namespace;
     }
 
     @Nullable
-    public List<String> getTopics() {
+    public TagFilter getTopics() {
         return topics;
     }
 
     public void setTopics(@Nullable List<String> topics) {
+        var present = topics != null && !topics.isEmpty();
+        this.topics = present ? TagFilter.any(topics) : null;
+    }
+
+    public void setTopics(@Nullable TagFilter topics) {
         this.topics = topics;
     }
 
     @Nullable
-    public List<String> getEntities() {
+    public TagFilter getEntities() {
         return entities;
     }
 
     public void setEntities(@Nullable List<String> entities) {
+        var present = entities != null && !entities.isEmpty();
+        this.entities = present ? TagFilter.any(entities) : null;
+    }
+
+    public void setEntities(@Nullable TagFilter entities) {
         this.entities = entities;
     }
 
     @Nullable
-    public String getUserId() {
+    public TagFilter getUserId() {
         return userId;
     }
 
     public void setUserId(@Nullable String userId) {
+        this.userId = userId != null ? TagFilter.eq(userId) : null;
+    }
+
+    public void setUserId(@Nullable TagFilter userId) {
         this.userId = userId;
     }
 
@@ -273,11 +296,11 @@ public String toString() {
                 ", searchMode='" + searchMode + '\'' +
                 ", hybridAlpha=" + hybridAlpha +
                 ", textScorer='" + textScorer + '\'' +
-                ", sessionId='" + sessionId + '\'' +
-                ", namespace='" + namespace + '\'' +
+                ", sessionId=" + sessionId +
+                ", namespace=" + namespace +
                 ", topics=" + topics +
                 ", entities=" + entities +
-                ", userId='" + userId + '\'' +
+                ", userId=" + userId +
                 ", distanceThreshold=" + distanceThreshold +
                 ", limit=" + limit +
                 ", offset=" + offset +
@@ -327,26 +350,53 @@ public Builder textScorer(@Nullable String textScorer) {
         }
 
         public Builder sessionId(@Nullable String sessionId) {
+            request.sessionId = sessionId != null ? TagFilter.eq(sessionId) : null;
+            return this;
+        }
+
+        public Builder sessionId(@Nullable TagFilter sessionId) {
             request.sessionId = sessionId;
             return this;
         }
 
         public Builder namespace(@Nullable String namespace) {
+            request.namespace = namespace != null ? TagFilter.eq(namespace) : null;
+            return this;
+        }
+
+        public Builder namespace(@Nullable TagFilter namespace) {
             request.namespace = namespace;
             return this;
         }
 
         public Builder topics(@Nullable List<String> topics) {
+            var present = topics != null && !topics.isEmpty();
+            request.topics = present ? TagFilter.any(topics) : null;
+            return this;
+        }
+
+        public Builder topics(@Nullable TagFilter topics) {
             request.topics = topics;
             return this;
         }
 
         public Builder entities(@Nullable List<String> entities) {
+            var present = entities != null && !entities.isEmpty();
+            request.entities = present ? TagFilter.any(entities) : null;
+            return this;
+        }
+
+        public Builder entities(@Nullable TagFilter entities) {
             request.entities = entities;
             return this;
         }
 
         public Builder userId(@Nullable String userId) {
+            request.userId = userId != null ? TagFilter.eq(userId) : null;
+            return this;
+        }
+
+        public Builder userId(@Nullable TagFilter userId) {
             request.userId = userId;
             return this;
         }
diff --git a/agent-memory-client/agent-memory-client-java/src/main/java/com/redis/agentmemory/services/LongTermMemoryService.java b/agent-memory-client/agent-memory-client-java/src/main/java/com/redis/agentmemory/services/LongTermMemoryService.java
index faeaf090..b9a66906 100644
--- a/agent-memory-client/agent-memory-client-java/src/main/java/com/redis/agentmemory/services/LongTermMemoryService.java
+++ b/agent-memory-client/agent-memory-client-java/src/main/java/com/redis/agentmemory/services/LongTermMemoryService.java
@@ -3,6 +3,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.redis.agentmemory.exceptions.MemoryClientException;
 import com.redis.agentmemory.models.common.AckResponse;
+import com.redis.agentmemory.models.common.TagFilter;
 import com.redis.agentmemory.models.longtermemory.*;
 import okhttp3.*;
 import org.jetbrains.annotations.NotNull;
@@ -86,22 +87,22 @@ public MemoryRecordResults searchLongTermMemories(@NotNull SearchRequest request
 
         // Add filters if present
         if (request.getSessionId() != null) {
-            payload.put("session_id", Map.of("eq", request.getSessionId()));
+            payload.put("session_id", request.getSessionId());
         }
         if (request.getUserId() != null) {
-            payload.put("user_id", Map.of("eq", request.getUserId()));
+            payload.put("user_id", request.getUserId());
         }
         if (request.getNamespace() != null) {
-            payload.put("namespace", Map.of("eq", request.getNamespace()));
+            payload.put("namespace", request.getNamespace());
         } else if (defaultNamespace != null) {
-            payload.put("namespace", Map.of("eq", defaultNamespace));
+            payload.put("namespace", TagFilter.eq(defaultNamespace));
         }
 
-        if (request.getTopics() != null && !request.getTopics().isEmpty()) {
-            payload.put("topics", Map.of("any", request.getTopics()));
+        if (request.getTopics() != null) {
+            payload.put("topics", request.getTopics());
         }
-        if (request.getEntities() != null && !request.getEntities().isEmpty()) {
-            payload.put("entities", Map.of("any", request.getEntities()));
+        if (request.getEntities() != null) {
+            payload.put("entities", request.getEntities());
         }
         if (request.getDistanceThreshold() != null) {
             payload.put("distance_threshold", request.getDistanceThreshold());
diff --git a/agent-memory-client/agent-memory-client-java/src/test/java/com/redis/agentmemory/models/common/TagFilterTest.java b/agent-memory-client/agent-memory-client-java/src/test/java/com/redis/agentmemory/models/common/TagFilterTest.java
new file mode 100644
index 00000000..43f834e3
--- /dev/null
+++ b/agent-memory-client/agent-memory-client-java/src/test/java/com/redis/agentmemory/models/common/TagFilterTest.java
@@ -0,0 +1,55 @@
+package com.redis.agentmemory.models.common;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class TagFilterTest {
+
+    private ObjectMapper objectMapper;
+
+    @BeforeEach
+    void setUp() {
+        objectMapper = new ObjectMapper();
+    }
+
+    @Test
+    void eq_serializesToEqOperator() throws Exception {
+        String json = objectMapper.writeValueAsString(TagFilter.eq("user-123"));
+        assertEquals("{\"eq\":\"user-123\"}", json);
+    }
+
+    @Test
+    void ne_serializesToNeOperator() throws Exception {
+        String json = objectMapper.writeValueAsString(TagFilter.ne("user-123"));
+        assertEquals("{\"ne\":\"user-123\"}", json);
+    }
+
+    @Test
+    void any_varargs_serializesToAnyOperator() throws Exception {
+        String json = objectMapper.writeValueAsString(TagFilter.any("user-123", "__account__"));
+        assertEquals("{\"any\":[\"user-123\",\"__account__\"]}", json);
+    }
+
+    @Test
+    void any_list_serializesToAnyOperator() throws Exception {
+        String json = objectMapper.writeValueAsString(TagFilter.any(List.of("a", "b", "c")));
+        assertEquals("{\"any\":[\"a\",\"b\",\"c\"]}", json);
+    }
+
+    @Test
+    void all_serializesToAllOperator() throws Exception {
+        String json = objectMapper.writeValueAsString(TagFilter.all("x", "y"));
+        assertEquals("{\"all\":[\"x\",\"y\"]}", json);
+    }
+
+    @Test
+    void startsWith_serializesToStartswithOperator() throws Exception {
+        String json = objectMapper.writeValueAsString(TagFilter.startsWith("tenant-"));
+        assertEquals("{\"startswith\":\"tenant-\"}", json);
+    }
+}
diff --git a/agent-memory-client/agent-memory-client-java/src/test/java/com/redis/agentmemory/services/LongTermMemoryServiceTest.java b/agent-memory-client/agent-memory-client-java/src/test/java/com/redis/agentmemory/services/LongTermMemoryServiceTest.java
index 6ffea49a..bc3fef01 100644
--- a/agent-memory-client/agent-memory-client-java/src/test/java/com/redis/agentmemory/services/LongTermMemoryServiceTest.java
+++ b/agent-memory-client/agent-memory-client-java/src/test/java/com/redis/agentmemory/services/LongTermMemoryServiceTest.java
@@ -4,6 +4,7 @@
 import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 import com.redis.agentmemory.MemoryAPIClient;
 import com.redis.agentmemory.models.common.AckResponse;
+import com.redis.agentmemory.models.common.TagFilter;
 import com.redis.agentmemory.models.longtermemory.*;
 import okhttp3.mockwebserver.MockResponse;
 import okhttp3.mockwebserver.MockWebServer;
@@ -435,6 +436,162 @@ void testSearchLongTermMemories_WithDistanceThreshold() throws Exception {
         assertTrue(requestBody.contains("\"distance_threshold\":0.35"));
     }
 
+    @Test
+    void testSearchLongTermMemories_WithUserIdString() throws Exception {
+        // backward compat: plain String userId still serializes {"eq": "..."}
+        mockServer.enqueue(new MockResponse()
+                .setBody(objectMapper.writeValueAsString(emptyResults()))
+                .addHeader("Content-Type", "application/json"));
+
+        SearchRequest request = SearchRequest.builder()
+                .text("query")
+                .userId("user-123")
+                .build();
+        client.longTermMemory().searchLongTermMemories(request);
+
+        RecordedRequest recorded = mockServer.takeRequest();
+        String body = recorded.getBody().readUtf8();
+        assertTrue(body.contains("\"user_id\":{\"eq\":\"user-123\"}"));
+    }
+
+
+    @Test
+    void testSearchLongTermMemories_WithUserIdAny() throws Exception {
+        mockServer.enqueue(new MockResponse()
+                .setBody(objectMapper.writeValueAsString(emptyResults()))
+                .addHeader("Content-Type", "application/json"));
+
+        SearchRequest request = SearchRequest.builder()
+                .text("query")
+                .userId(TagFilter.any("user-123", "__account__"))
+                .build();
+        client.longTermMemory().searchLongTermMemories(request);
+
+        RecordedRequest recorded = mockServer.takeRequest();
+        String body = recorded.getBody().readUtf8();
+        assertTrue(body.contains("\"user_id\":{\"any\":[\"user-123\",\"__account__\"]}"));
+        assertFalse(body.contains("\"eq\""));
+    }
+
+    @Test
+    void testSearchLongTermMemory_WithNamespaceTagFilter() throws Exception {
+        mockServer.enqueue(new MockResponse()
+                .setBody(objectMapper.writeValueAsString(emptyResults()))
+                .addHeader("Content-Type", "application/json"));
+
+        SearchRequest request = SearchRequest.builder()
+                .text("query")
+                .namespace(TagFilter.startsWith("tenant-"))
+                .build();
+        client.longTermMemory().searchLongTermMemories(request);
+
+        RecordedRequest recorded = mockServer.takeRequest();
+        String body = recorded.getBody().readUtf8();
+        assertTrue(body.contains("\"namespace\":{\"startswith\":\"tenant-\"}"));
+    }
+
+    @Test
+    void testSearchLongTermMemory_WithSessionIdAny() throws Exception {
+        mockServer.enqueue(new MockResponse()
+                .setBody(objectMapper.writeValueAsString(emptyResults()))
+                .addHeader("Content-Type", "application/json"));
+
+        SearchRequest request = SearchRequest.builder()
+                .text("query")
+                .sessionId(TagFilter.any("session-a", "session-b"))
+                .build();
+        client.longTermMemory().searchLongTermMemories(request);
+
+        RecordedRequest recorded = mockServer.takeRequest();
+        String body = recorded.getBody().readUtf8();
+        assertTrue(body.contains("\"session_id\":{\"any\":[\"session-a\",\"session-b\"]}"));
+    }
+
+    @Test
+    void testSearchLongTermMemory_WithTopicsList() throws Exception {
+        // backward compat: List<String> convenience API still serializes {"any": [...]}
+        mockServer.enqueue(new MockResponse()
+                .setBody(objectMapper.writeValueAsString(emptyResults()))
+                .addHeader("Content-Type", "application/json"));
+
+        SearchRequest request = SearchRequest.builder()
+                .text("query")
+                .topics(List.of("finance", "real-estate"))
+                .build();
+        client.longTermMemory().searchLongTermMemories(request);
+
+        RecordedRequest recorded = mockServer.takeRequest();
+        String body = recorded.getBody().readUtf8();
+        assertTrue(body.contains("\"topics\":{\"any\":[\"finance\",\"real-estate\"]}"));
+    }
+
+    @Test
+    void testSearchLongTermMemory_WithTopicsAllFilter() throws Exception {
+        mockServer.enqueue(new MockResponse()
+                .setBody(objectMapper.writeValueAsString(emptyResults()))
+                .addHeader("Content-Type", "application/json"));
+
+        SearchRequest request = SearchRequest.builder()
+                .text("query")
+                .topics(TagFilter.all("finance", "real-estate"))
+                .build();
+        client.longTermMemory().searchLongTermMemories(request);
+
+        RecordedRequest recorded = mockServer.takeRequest();
+        String body = recorded.getBody().readUtf8();
+        assertTrue(body.contains("\"topics\":{\"all\":[\"finance\",\"real-estate\"]}"));
+    }
+
+    @Test
+    void testSearchLongTermMemory_WithEntitiesTagFilter() throws Exception {
+        mockServer.enqueue(new MockResponse()
+                .setBody(objectMapper.writeValueAsString(emptyResults()))
+                .addHeader("Content-Type", "application/json"));
+
+        SearchRequest request = SearchRequest.builder()
+                .text("query")
+                .entities(TagFilter.any("Google", "Apple"))
+                .build();
+        client.longTermMemory().searchLongTermMemories(request);
+
+        RecordedRequest recorded = mockServer.takeRequest();
+        String body = recorded.getBody().readUtf8();
+        assertTrue(body.contains("\"entities\":{\"any\":[\"Google\",\"Apple\"]}"));
+    }
+
+    @Test
+    void testSearchLongTermMemory_WithEmptyTopicsList() throws Exception {
+        mockServer.enqueue(new MockResponse()
+                .setBody(objectMapper.writeValueAsString(emptyResults()))
+                .addHeader("Content-Type", "application/json"));
+
+        SearchRequest request = SearchRequest.builder()
+                .text("query")
+                .topics(List.of())
+                .build();
+        client.longTermMemory().searchLongTermMemories(request);
+
+        RecordedRequest recorded = mockServer.takeRequest();
+        String body = recorded.getBody().readUtf8();
+        assertFalse(body.contains("\"topics\""));
+    }
+
+    @Test
+    void testSearchLongTermMemory_WithNoUserId() throws Exception {
+        mockServer.enqueue(new MockResponse()
+                .setBody(objectMapper.writeValueAsString(emptyResults()))
+                .addHeader("Content-Type", "application/json"));
+
+        SearchRequest request = SearchRequest.builder()
+                .text("query")
+                .build();
+        client.longTermMemory().searchLongTermMemories(request);
+
+        RecordedRequest recorded = mockServer.takeRequest();
+        String body = recorded.getBody().readUtf8();
+        assertFalse(body.contains("\"user_id\""));
+    }
+
     @Test
     void testSearchRequestBuilder_AllRecencyFields() {
         // Test that all recency fields can be set via builder
@@ -461,4 +618,10 @@ void testSearchRequestBuilder_AllRecencyFields() {
         assertFalse(request.getServerSideRecency());
     }
 
+    private MemoryRecordResults emptyResults() {
+        MemoryRecordResults r = new MemoryRecordResults();
+        r.setMemories(new ArrayList<>());
+        r.setTotal(0);
+        return r;
+    }
 }