diff --git a/lib/sdk/server/contract-tests/service/src/main/java/sdktest/Representations.java b/lib/sdk/server/contract-tests/service/src/main/java/sdktest/Representations.java
index cd7593e7..a2e03b1c 100644
--- a/lib/sdk/server/contract-tests/service/src/main/java/sdktest/Representations.java
+++ b/lib/sdk/server/contract-tests/service/src/main/java/sdktest/Representations.java
@@ -34,6 +34,21 @@ public static class SdkConfigParams {
     SdkConfigServiceEndpointParams serviceEndpoints;
     SdkConfigHookParams hooks;
     SdkConfigDataSystemParams dataSystem;
+    SdkConfigOverridesParams overrides;
+  }
+
+  /**
+   * Configuration for the SDK's file-based flag overrides (the "flag-overrides" capability).
+   */
+  public static class SdkConfigOverridesParams {
+    /** Absolute paths of the override files, in precedence order. */
+    String[] filePaths;
+    /** "fail" (the default) or "ignore". */
+    String duplicateKeysHandling;
+    /** "polling" or "watching"; null means the SDK default. */
+    String changeDetection;
+    /** The polling interval in milliseconds; the SDK may raise it to its minimum. */
+    Long pollIntervalMs;
   }
   
   public static class SdkConfigStreamParams {
diff --git a/lib/sdk/server/contract-tests/service/src/main/java/sdktest/SdkClientEntity.java b/lib/sdk/server/contract-tests/service/src/main/java/sdktest/SdkClientEntity.java
index f6bb9d96..53da61ac 100644
--- a/lib/sdk/server/contract-tests/service/src/main/java/sdktest/SdkClientEntity.java
+++ b/lib/sdk/server/contract-tests/service/src/main/java/sdktest/SdkClientEntity.java
@@ -32,6 +32,9 @@
 import com.launchdarkly.sdk.server.integrations.FDv2PollingInitializerBuilder;
 import com.launchdarkly.sdk.server.integrations.FDv2PollingSynchronizerBuilder;
 import com.launchdarkly.sdk.server.integrations.FDv2StreamingSynchronizerBuilder;
+import com.launchdarkly.sdk.server.integrations.FileData;
+import com.launchdarkly.sdk.server.integrations.FileOverrideSourceBuilder;
+import com.launchdarkly.sdk.server.integrations.FileOverrides;
 import com.launchdarkly.sdk.server.interfaces.BigSegmentStoreStatusProvider;
 import com.launchdarkly.sdk.server.subsystems.DataSourceBuilder;
 import com.launchdarkly.sdk.server.datasources.Initializer;
@@ -68,6 +71,7 @@
 import sdktest.Representations.SdkConfigParams;
 import sdktest.Representations.SdkConfigDataSystemParams;
 import sdktest.Representations.SdkConfigDataInitializerParams;
+import sdktest.Representations.SdkConfigOverridesParams;
 import sdktest.Representations.SdkConfigSynchronizerParams;
 import sdktest.Representations.SdkConfigPollingParams;
 import sdktest.Representations.SdkConfigStreamingParams;
@@ -587,12 +591,53 @@ private LDConfig buildSdkConfig(SdkConfigParams params, String tag) {
         dataSystemBuilder.fDv1FallbackSynchronizer(fdv1Polling);
       }
 
+      if (params.overrides != null) {
+        dataSystemBuilder.overrides(makeOverridesConfig(params.overrides));
+      }
+
       builder.dataSystem(dataSystemBuilder);
+    } else if (params.overrides != null) {
+      throw new IllegalArgumentException("flag overrides require the data system to be configured");
     }
 
     return builder.build();
   }
 
+  private static FileOverrideSourceBuilder makeOverridesConfig(SdkConfigOverridesParams params) {
+    FileOverrideSourceBuilder overrides = FileOverrides.source();
+    if (params.filePaths != null) {
+      overrides.filePaths(params.filePaths);
+    }
+    if (params.duplicateKeysHandling != null) {
+      switch (params.duplicateKeysHandling) {
+      case "fail":
+        overrides.duplicateKeysHandling(FileData.DuplicateKeysHandling.FAIL);
+        break;
+      case "ignore":
+        overrides.duplicateKeysHandling(FileData.DuplicateKeysHandling.IGNORE);
+        break;
+      default:
+        throw new IllegalArgumentException("unknown duplicate keys handling: " + params.duplicateKeysHandling);
+      }
+    }
+    if (params.changeDetection != null) {
+      switch (params.changeDetection) {
+      case "polling":
+        overrides.changeDetection(FileOverrides.ChangeDetection.POLLING);
+        break;
+      case "watching":
+        overrides.changeDetection(FileOverrides.ChangeDetection.WATCHING);
+        break;
+      default:
+        throw new IllegalArgumentException("unknown change detection mode: " + params.changeDetection);
+      }
+    }
+    if (params.pollIntervalMs != null) {
+      overrides.pollInterval(Duration.ofMillis(params.pollIntervalMs));
+    }
+    return overrides;
+  }
+
   private DataSourceBuilder<Synchronizer> createSynchronizer(
       SdkConfigSynchronizerParams synchronizer,
       String payloadFilter) {
diff --git a/lib/sdk/server/contract-tests/service/src/main/java/sdktest/TestService.java b/lib/sdk/server/contract-tests/service/src/main/java/sdktest/TestService.java
index 45eeead7..51f9fb4e 100644
--- a/lib/sdk/server/contract-tests/service/src/main/java/sdktest/TestService.java
+++ b/lib/sdk/server/contract-tests/service/src/main/java/sdktest/TestService.java
@@ -21,7 +21,7 @@
 import sdktest.Representations.Status;
 
 public class TestService {
-  private static final int PORT = 8000;
+  private static final int DEFAULT_PORT = 8000;
   private static final String[] CAPABILITIES = new String[]{
     "all-flags-client-side-only",
     "all-flags-details-only-for-tracked-flags",
@@ -47,7 +47,8 @@ public class TestService {
     "fdv1-fallback",
     "instance-id",
     "retry-conformance-fdv1-streaming",
-    "retry-conformance-fdv1-polling"
+    "retry-conformance-fdv1-polling",
+    "flag-overrides"
   };
 
   static final Gson gson = new GsonBuilder().serializeNulls().create();
@@ -83,10 +84,15 @@ public static void main(String[] args) throws Exception {
         .addRegex("POST", Pattern.compile("/clients/(.*)"), ctx -> service.postClientCommand(diableKeepAlive(ctx)))
         .addRegex("DELETE", Pattern.compile("/clients/(.*)"), ctx -> service.deleteClient(diableKeepAlive(ctx)));
 
-    HttpServer server = HttpServer.start(PORT, router);
+    int port = DEFAULT_PORT;
+    String portEnv = System.getenv("PORT");
+    if (portEnv != null && !portEnv.isEmpty()) {
+      port = Integer.parseInt(portEnv);
+    }
+    HttpServer server = HttpServer.start(port, router);
     server.getRecorder().setEnabled(false); // don't accumulate a request log
 
-    System.out.println("Listening on port " + PORT);
+    System.out.println("Listening on port " + port);
 
     // need to explicitly sleep because HttpServer now starts as a daemon thread
     while (true) {