diff --git a/lib/shared/dm-ops/dm-op-specs.js b/lib/shared/dm-ops/dm-op-specs.js
--- a/lib/shared/dm-ops/dm-op-specs.js
+++ b/lib/shared/dm-ops/dm-op-specs.js
@@ -18,6 +18,7 @@
 import { sendMultimediaMessageSpec } from './send-multimedia-message-spec.js';
 import { sendReactionMessageSpec } from './send-reaction-message-spec.js';
 import { sendTextMessageSpec } from './send-text-message-spec.js';
+import { updateRelationshipSpec } from './update-relationship-spec.js';
 import { type DMOperationType, dmOperationTypes } from '../../types/dm-ops.js';
 
 export const dmOpSpecs: {
@@ -40,4 +41,5 @@
   [dmOperationTypes.CREATE_ENTRY]: createEntrySpec,
   [dmOperationTypes.DELETE_ENTRY]: deleteEntrySpec,
   [dmOperationTypes.EDIT_ENTRY]: editEntrySpec,
+  [dmOperationTypes.UPDATE_RELATIONSHIP]: updateRelationshipSpec,
 });
diff --git a/lib/shared/dm-ops/update-relationship-spec.js b/lib/shared/dm-ops/update-relationship-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/dm-ops/update-relationship-spec.js
@@ -0,0 +1,110 @@
+// @flow
+
+import type {
+  DMOperationSpec,
+  ProcessDMOperationUtilities,
+} from './dm-op-spec.js';
+import type { DMUpdateRelationshipOperation } from '../../types/dm-ops.js';
+import { messageTypes } from '../../types/message-types-enum.js';
+import { rawMessageInfoFromMessageData } from '../message-utils.js';
+
+async function createMessageDataFromDMOperation(
+  dmOperation: DMUpdateRelationshipOperation,
+  viewerID: string,
+  utilities: ProcessDMOperationUtilities,
+) {
+  const { threadID, creatorID, time, operation } = dmOperation;
+  if (operation !== 'farcaster_mutual') {
+    return {
+      type: messageTypes.UPDATE_RELATIONSHIP,
+      threadID,
+      creatorID,
+      targetID: viewerID,
+      time,
+      operation,
+    };
+  }
+  const { findUserIdentities } = utilities;
+  const { identities: userIdentities } = await findUserIdentities([
+    creatorID,
+    viewerID,
+  ]);
+  const creatorFID = userIdentities[creatorID]?.farcasterID;
+  const targetFID = userIdentities[viewerID]?.farcasterID;
+  if (!creatorFID || !targetFID) {
+    const errorMap = { creatorID: creatorFID, viewerID: targetFID };
+    throw new Error(
+      'could not fetch FID for either creator or target: ' +
+        JSON.stringify(errorMap),
+    );
+  }
+  return {
+    type: messageTypes.UPDATE_RELATIONSHIP,
+    threadID,
+    creatorID,
+    creatorFID,
+    targetID: viewerID,
+    targetFID,
+    time,
+    operation,
+  };
+}
+
+const updateRelationshipSpec: DMOperationSpec<DMUpdateRelationshipOperation> =
+  Object.freeze({
+    notificationsCreationData: async (
+      dmOperation: DMUpdateRelationshipOperation,
+      viewerID: string,
+      utilities: ProcessDMOperationUtilities,
+    ) => {
+      const messageData = await createMessageDataFromDMOperation(
+        dmOperation,
+        viewerID,
+        utilities,
+      );
+      return { messageDatas: [messageData] };
+    },
+    processDMOperation: async (
+      dmOperation: DMUpdateRelationshipOperation,
+      viewerID: string,
+      utilities: ProcessDMOperationUtilities,
+    ) => {
+      const { messageID } = dmOperation;
+      const messageData = await createMessageDataFromDMOperation(
+        dmOperation,
+        viewerID,
+        utilities,
+      );
+      const rawMessageInfos = [
+        rawMessageInfoFromMessageData(messageData, messageID),
+      ];
+      return {
+        rawMessageInfos,
+        updateInfos: [],
+      };
+    },
+    canBeProcessed: async (
+      dmOperation: DMUpdateRelationshipOperation,
+      viewerID: string,
+      utilities: ProcessDMOperationUtilities,
+    ) => {
+      try {
+        await createMessageDataFromDMOperation(
+          dmOperation,
+          viewerID,
+          utilities,
+        );
+        return {
+          isProcessingPossible: true,
+        };
+      } catch (e) {
+        return {
+          isProcessingPossible: false,
+          reason: { type: 'invalid' },
+        };
+      }
+    },
+    supportsAutoRetry: true,
+  });
+
+export { updateRelationshipSpec };