diff --git a/.github/actions/contract-tests/action.yml b/.github/actions/contract-tests/action.yml
index fc3a9829..00fce260 100644
--- a/.github/actions/contract-tests/action.yml
+++ b/.github/actions/contract-tests/action.yml
@@ -1,17 +1,21 @@
 name: Contract Tests
-description: Runs Contract Tests
+description: Runs Contract Tests (builds, starts service, runs SDK contract test harness)
 inputs:
   workspace_path:
-    description: 'Path to the package.'
+    description: 'Path to the package (e.g. lib/sdk/server).'
     required: true
   token:
     description: 'Github token, used for contract tests'
     required: false
     default: ''
+  test_harness_params:
+    description: 'Optional extra parameters for the SDK test harness (e.g. -enable-long-running-tests). Passed as TEST_HARNESS_PARAMS to make.'
+    required: false
+    default: ''
 
 runs:
   using: composite
   steps:
     - name: Run contract tests
       shell: bash
-      run: make contract-tests -C ${{ inputs.workspace_path }}
+      run: make contract-tests -C ${{ inputs.workspace_path }} TEST_HARNESS_PARAMS="${{ inputs.test_harness_params }}"
diff --git a/.github/workflows/nightly-contract-tests.yml b/.github/workflows/nightly-contract-tests.yml
new file mode 100644
index 00000000..aac2977a
--- /dev/null
+++ b/.github/workflows/nightly-contract-tests.yml
@@ -0,0 +1,99 @@
+name: Nightly Contract Tests
+
+on:
+  schedule:
+    - cron: "0 4 * * *" # every day at 4am UTC
+  workflow_dispatch:
+    inputs:
+      branch:
+        description: 'Branch to run contract tests on'
+        required: false
+        default: ''
+      test_slack_notification:
+        description: 'Also send a test Slack notification (to verify Slack integration)'
+        required: false
+        type: boolean
+        default: false
+
+jobs:
+  nightly-contract-tests:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          ref: ${{ inputs.branch || github.ref }}
+
+      - name: Shared CI Steps
+        uses: ./.github/actions/ci
+        with:
+          workspace_path: 'lib/sdk/server'
+          java_version: 8
+
+      - name: Contract Tests (with long-running tests)
+        uses: ./.github/actions/contract-tests
+        with:
+          workspace_path: 'lib/sdk/server'
+          token: ${{ secrets.GITHUB_TOKEN }}
+          test_harness_params: '-enable-long-running-tests'
+
+  notify-slack-on-failure:
+    runs-on: ubuntu-latest
+    if: ${{ always() && needs.nightly-contract-tests.result == 'failure' }}
+    needs:
+      - nightly-contract-tests
+    steps:
+      - name: Send Slack notification
+        uses: slackapi/slack-github-action@91efab103c0de0a537f72a35f6b8cda0ee76bf0a # v2.1.1
+        with:
+          webhook: ${{ secrets.SLACK_WEBHOOK_URL }}
+          webhook-type: incoming-webhook
+          payload: |
+            {
+              "blocks": [
+                {
+                  "type": "section",
+                  "text": {
+                    "type": "mrkdwn",
+                    "text": ":warning: *Nightly Contract Tests Failed* :warning:\nThe nightly contract tests (with long-running tests enabled) failed on `${{ github.ref_name }}`."
+                  },
+                  "accessory": {
+                    "type": "button",
+                    "text": {
+                      "type": "plain_text",
+                      "text": "View failed run"
+                    },
+                    "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}"
+                  }
+                }
+              ]
+            }
+
+  test-slack-notification:
+    runs-on: ubuntu-latest
+    if: ${{ inputs.test_slack_notification == true || inputs.test_slack_notification == 'true' }}
+    steps:
+      - name: Send test Slack notification
+        uses: slackapi/slack-github-action@91efab103c0de0a537f72a35f6b8cda0ee76bf0a # v2.1.1
+        with:
+          webhook: ${{ secrets.SLACK_WEBHOOK_URL }}
+          webhook-type: incoming-webhook
+          payload: |
+            {
+              "blocks": [
+                {
+                  "type": "section",
+                  "text": {
+                    "type": "mrkdwn",
+                    "text": ":white_check_mark: *Nightly Contract Tests – Slack test*\nThis is a test notification to verify Slack integration is working. Triggered manually from the Nightly Contract Tests workflow."
+                  },
+                  "accessory": {
+                    "type": "button",
+                    "text": {
+                      "type": "plain_text",
+                      "text": "View workflow run"
+                    },
+                    "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}"
+                  }
+                }
+              ]
+            }
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 99890e78..10bb9741 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
@@ -27,6 +27,7 @@ public static class SdkConfigParams {
     Long startWaitTimeMs;
     boolean initCanFail;
     SdkConfigStreamParams streaming;
+    SdkConfigPollingParams polling;
     SdkConfigEventParams events;
     SdkConfigBigSegmentsParams bigSegments;
     SdkConfigTagParams tags;
@@ -170,6 +171,7 @@ public static class SdkConfigSynchronizerParams {
   public static class SdkConfigPollingParams {
     URI baseUri;
     Long pollIntervalMs;
+    String filter;
   }
 
   public static class SdkConfigStreamingParams {
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 ced6e3fb..70280ed2 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
@@ -401,6 +401,16 @@ private LDConfig buildSdkConfig(SdkConfigParams params, String tag) {
       }
       dataSource.payloadFilter(params.streaming.filter);
       builder.dataSource(dataSource);
+    } else if (params.polling != null && params.dataSystem == null) {
+      // v2 harness: top-level polling only (no dataSystem); use FDv1 polling data source
+      PollingDataSourceBuilder pollingDataSource = Components.pollingDataSource();
+      if (params.polling.pollIntervalMs != null) {
+        pollingDataSource.pollInterval(Duration.ofMillis(params.polling.pollIntervalMs));
+      }
+      if (params.polling.filter != null && !params.polling.filter.isEmpty()) {
+        pollingDataSource.payloadFilter(params.polling.filter);
+      }
+      builder.dataSource(pollingDataSource);
     }
 
     if (params.events == null) {
@@ -463,6 +473,11 @@ private LDConfig buildSdkConfig(SdkConfigParams params, String tag) {
         endpoints.events(params.serviceEndpoints.events);
       }
     }
+
+    if (params.polling != null && params.polling.baseUri != null && !params.polling.baseUri.toString().trim().isEmpty()) {
+      endpoints.polling(params.polling.baseUri);
+    }
+
     builder.serviceEndpoints(endpoints);
 
     if (params.hooks != null && params.hooks.hooks != null) {
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 84bbb3e5..9f16f387 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
@@ -41,6 +41,7 @@ public class TestService {
     "service-endpoints",
     "strongly-typed",
     "tags",
+    "server-side-polling"
   };
 
   static final Gson gson = new GsonBuilder().serializeNulls().create();
diff --git a/lib/sdk/server/contract-tests/test-suppressions-fdv2.txt b/lib/sdk/server/contract-tests/test-suppressions-fdv2.txt
index e69de29b..9765a098 100644
--- a/lib/sdk/server/contract-tests/test-suppressions-fdv2.txt
+++ b/lib/sdk/server/contract-tests/test-suppressions-fdv2.txt
@@ -0,0 +1,3 @@
+streaming/fdv2/recoverable fallback to secondary synchronizer
+streaming/fdv2/recoverable fallback with recovery
+streaming/fdv2/permanent fallback with recovery