diff --git a/docs/pages/api-reference/liveblocks-client.mdx b/docs/pages/api-reference/liveblocks-client.mdx
index c221ec8465..7af81f12a4 100644
--- a/docs/pages/api-reference/liveblocks-client.mdx
+++ b/docs/pages/api-reference/liveblocks-client.mdx
@@ -6639,6 +6639,12 @@ declare global {
     // Custom metadata set on comments
     CommentMetadata: {};
 
+    // Custom metadata set on feeds
+    FeedMetadata: {};
+
+    // The shape of the data stored in each feed message
+    FeedMessageData: {};
+
     // Custom room info set with resolveRoomsInfo
     RoomInfo: {};
 
@@ -6701,6 +6707,22 @@ declare global {
       spam: boolean;
     };
 
+    // Custom metadata set on feeds
+    FeedMetadata: {
+      // Example, a title and a type for each feed
+      title: string;
+      type: "chat" | "thread";
+    };
+
+    // The shape of the data stored in each feed message
+    FeedMessageData: {
+      // Example, a message with an author, content, status, and reactions
+      userId: string;
+      content: string;
+      status: "streaming" | "complete";
+      reactions?: { emoji: string; userId: string; createdAt: number }[];
+    };
+
     // Custom room info set with resolveRoomsInfo
     RoomInfo: {
       // Example, rooms with a title and url
diff --git a/docs/pages/api-reference/liveblocks-react.mdx b/docs/pages/api-reference/liveblocks-react.mdx
index 98bf4de8a7..81da209274 100644
--- a/docs/pages/api-reference/liveblocks-react.mdx
+++ b/docs/pages/api-reference/liveblocks-react.mdx
@@ -7135,6 +7135,12 @@ declare global {
     // Custom metadata set on comments, for useCreateThread, useCreateComment, etc.
     CommentMetadata: {};
 
+    // Custom metadata set on feeds, for useFeeds, useUpdateFeedMetadata, etc.
+    FeedMetadata: {};
+
+    // The shape of the data stored in each feed message, for useFeedMessages, etc.
+    FeedMessageData: {};
+
     // Custom room info set with resolveRoomsInfo, for useRoomInfo
     RoomInfo: {};
 
@@ -7197,6 +7203,22 @@ declare global {
       spam: boolean;
     };
 
+    // Custom metadata set on feeds, for useFeeds, useUpdateFeedMetadata, etc.
+    FeedMetadata: {
+      // Example, a title and a type for each feed
+      title: string;
+      type: "chat" | "thread";
+    };
+
+    // The shape of the data stored in each feed message, for useFeedMessages, etc.
+    FeedMessageData: {
+      // Example, a message with an author, content, status, and reactions
+      userId: string;
+      content: string;
+      status: "streaming" | "complete";
+      reactions?: { emoji: string; userId: string; createdAt: number }[];
+    };
+
     // Custom room info set with resolveRoomsInfo, for useRoomInfo
     RoomInfo: {
       // Example, rooms with a title and url
diff --git a/docs/pages/errors/FeedMessageData.mdx b/docs/pages/errors/FeedMessageData.mdx
new file mode 100644
index 0000000000..6f8563159e
--- /dev/null
+++ b/docs/pages/errors/FeedMessageData.mdx
@@ -0,0 +1,86 @@
+---
+meta:
+  title: "The type you provided for 'FeedMessageData' is not a valid JSON value"
+  parentTitle: "Error"
+  description:
+    "Your 'FeedMessageData' type is incorrect and needs to be updated"
+---
+
+## Why this error occurred
+
+You have provided a custom `FeedMessageData` type for your application, but the
+type you provided isn’t a (completely) valid JSON value. Values like `Date`,
+`Map`, `Set`, functions, classes, or `unknown` aren’t valid JSON.
+
+```ts highlight="4-8"
+declare global {
+  interface Liveblocks {
+    FeedMessageData: {
+      // Your own fields go here…
+      userId: string;
+      content: string;
+      status: "streaming" | "complete";
+      sentAt: Date; // ❌ The issue is here
+    };
+  }
+}
+```
+
+In the example above, the problem is in the `sentAt` field, because a `Date`
+isn’t a valid JSON value.
+
+## How to fix it
+
+You’ll need to figure out what part of your provided `FeedMessageData` type
+definition isn’t valid JSON. Sometimes this is immediately obvious, like in the
+example above.
+
+Sometimes the issue may be a bit less obvious:
+
+```ts highlight="6-7"
+import type { Json } from "@liveblocks/client";
+
+declare global {
+  interface Liveblocks {
+    FeedMessageData: {
+      content: unknown; // ❌ Unknowns could contain non-JSON
+      content: Json; // ✅ Prefer using Json
+    };
+  }
+}
+```
+
+By using `Json`, you can still work with unknown or unspecified values, but
+still ensure they will be valid JSON.
+
+## If you cannot find the root cause
+
+Sometimes types can be complex and the root cause is still unclear. In those
+cases, there is a small trick you can use. Try to assign your type to the
+required base type, with this line:
+
+```ts highlight="9-10"
+import type { Json } from "@liveblocks/client";
+
+declare global {
+  interface Liveblocks {
+    FeedMessageData: MyFeedMessageData;
+  }
+}
+
+// Quick debugging snippet to find root cause
+const xxx: Json = {} as MyFeedMessageData;
+//    ^?
+//    The error will appear here
+```
+
+Now TypeScript will explain why it thinks your type isn’t valid JSON:
+
+```error showLineNumbers={false}
+Type 'MyFeedMessageData' is not assignable to type 'Json'.
+  Type 'MyFeedMessageData' is not assignable to type 'JsonObject'.
+    Property 'sentAt' is incompatible with index signature.
+      Type 'Date' is not assignable to type 'Json | undefined'.
+        Type 'Date' is not assignable to type 'JsonObject'.
+          Index signature for type 'string' is missing in type 'Date'.
+```
diff --git a/docs/pages/errors/FeedMetadata.mdx b/docs/pages/errors/FeedMetadata.mdx
new file mode 100644
index 0000000000..49a57828e8
--- /dev/null
+++ b/docs/pages/errors/FeedMetadata.mdx
@@ -0,0 +1,84 @@
+---
+meta:
+  title: "The type you provided for 'FeedMetadata' is not a valid JSON value"
+  parentTitle: "Error"
+  description: "Your 'FeedMetadata' type is incorrect and needs to be updated"
+---
+
+## Why this error occurred
+
+You have provided a custom `FeedMetadata` type for your application, but the
+type you provided isn’t a (completely) valid JSON value. Values like `Date`,
+`Map`, `Set`, functions, classes, or `unknown` aren’t valid JSON.
+
+```ts highlight="4-7"
+declare global {
+  interface Liveblocks {
+    FeedMetadata: {
+      // Your own fields go here…
+      title: string;
+      type: "chat" | "thread";
+      createdAt: Date; // ❌ The issue is here
+    };
+  }
+}
+```
+
+In the example above, the problem is in the `createdAt` field, because a `Date`
+isn’t a valid JSON value.
+
+## How to fix it
+
+You’ll need to figure out what part of your provided `FeedMetadata` type
+definition isn’t valid JSON. Sometimes this is immediately obvious, like in the
+example above.
+
+Sometimes the issue may be a bit less obvious:
+
+```ts highlight="6-7"
+import type { Json } from "@liveblocks/client";
+
+declare global {
+  interface Liveblocks {
+    FeedMetadata: {
+      custom: unknown; // ❌ Unknowns could contain non-JSON
+      custom: Json; // ✅ Prefer using Json
+    };
+  }
+}
+```
+
+By using `Json`, you can still work with unknown or unspecified values, but
+still ensure they will be valid JSON.
+
+## If you cannot find the root cause
+
+Sometimes types can be complex and the root cause is still unclear. In those
+cases, there is a small trick you can use. Try to assign your type to the
+required base type, with this line:
+
+```ts highlight="9-10"
+import type { Json } from "@liveblocks/client";
+
+declare global {
+  interface Liveblocks {
+    FeedMetadata: MyFeedMetadata;
+  }
+}
+
+// Quick debugging snippet to find root cause
+const xxx: Json = {} as MyFeedMetadata;
+//    ^?
+//    The error will appear here
+```
+
+Now TypeScript will explain why it thinks your type isn’t valid JSON:
+
+```error showLineNumbers={false}
+Type 'MyFeedMetadata' is not assignable to type 'Json'.
+  Type 'MyFeedMetadata' is not assignable to type 'JsonObject'.
+    Property 'createdAt' is incompatible with index signature.
+      Type 'Date' is not assignable to type 'Json | undefined'.
+        Type 'Date' is not assignable to type 'JsonObject'.
+          Index signature for type 'string' is missing in type 'Date'.
+```
diff --git a/docs/routes.json b/docs/routes.json
index 9bb067afc4..9e0ecf2cd8 100644
--- a/docs/routes.json
+++ b/docs/routes.json
@@ -777,6 +777,14 @@
         "title": "The type you provided for 'ThreadMetadata' does not match its requirements",
         "path": "/errors/ThreadMetadata"
       },
+      {
+        "title": "The type you provided for 'FeedMetadata' is not a valid JSON value",
+        "path": "/errors/FeedMetadata"
+      },
+      {
+        "title": "The type you provided for 'FeedMessageData' is not a valid JSON value",
+        "path": "/errors/FeedMessageData"
+      },
       {
         "title": "The type you provided for 'RoomInfo' does not match its requirements",
         "path": "/errors/RoomInfo"