diff --git a/.dockerignore b/.dockerignore
index 28069318613..cf10e8046c0 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -105,6 +105,7 @@ blocks/**/.env
 **/dist
 **/build
 **/target
+**/pkg
 
 # vscode config
 **/.vscode/settings.json
diff --git a/.gitignore b/.gitignore
index 4c9d2ab525d..8c0a51f5ad3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -88,6 +88,7 @@ blocks/**/.env
 **/dist
 **/build
 **/target
+**/pkg
 
 # vscode config
 **/.vscode/settings.json
diff --git a/.yarn/patches/@types-webextension-polyfill-npm-0.10.4-291152c615.patch b/.yarn/patches/@types-webextension-polyfill-npm-0.10.4-291152c615.patch
deleted file mode 100644
index 5a34a7e4cb9..00000000000
--- a/.yarn/patches/@types-webextension-polyfill-npm-0.10.4-291152c615.patch
+++ /dev/null
@@ -1,22 +0,0 @@
-diff --git a/namespaces/runtime.d.ts b/namespaces/runtime.d.ts
-index eaeaf9110a189d77894844591c5d575f10585f97..54b2b4ea914139affa3d772a49a60b057df41b76 100644
---- a/namespaces/runtime.d.ts
-+++ b/namespaces/runtime.d.ts
-@@ -448,7 +448,7 @@ export namespace Runtime {
-          * will keep the message channel open to the other end until <code>sendResponse</code> is called).
-          */
-         onMessage: Events.Event<
--            (message: any, sender: MessageSender, sendResponse: () => void) => Promise<any> | true | void
-+            (message: any, sender: MessageSender, sendResponse: (response: any) => void) => Promise<any> | true | void
-         >;
- 
-         /**
-@@ -463,7 +463,7 @@ export namespace Runtime {
-          * will keep the message channel open to the other end until <code>sendResponse</code> is called).
-          */
-         onMessageExternal: Events.Event<
--            (message: any, sender: MessageSender, sendResponse: () => void) => Promise<any> | true | void
-+            (message: any, sender: MessageSender, sendResponse: (response: any) => void) => Promise<any> | true | void
-         >;
- 
-         /**
diff --git a/apps/plugin-browser/package.json b/apps/plugin-browser/package.json
index 4cc21f47074..dbe40ab4b8c 100755
--- a/apps/plugin-browser/package.json
+++ b/apps/plugin-browser/package.json
@@ -45,7 +45,7 @@
     "react": "19.0.0",
     "react-dom": "19.0.0",
     "uuid": "11.0.3",
-    "webextension-polyfill": "0.10.0",
+    "webextension-polyfill": "0.12.0",
     "ws": "8.18.0"
   },
   "devDependencies": {
@@ -65,7 +65,7 @@
     "@types/lodash.debounce": "4.0.9",
     "@types/react": "19.0.1",
     "@types/react-dom": "19.0.2",
-    "@types/webextension-polyfill": "patch:@types/webextension-polyfill@npm%3A0.10.4#~/.yarn/patches/@types-webextension-polyfill-npm-0.10.4-291152c615.patch",
+    "@types/webextension-polyfill": "0.12.0",
     "@types/ws": "8.5.13",
     "babel-loader": "9.2.1",
     "babel-preset-react-app": "10.0.1",
diff --git a/apps/plugin-browser/src/pages/popup/popup-contents/action-center/one-off/infer-entities-action.tsx b/apps/plugin-browser/src/pages/popup/popup-contents/action-center/one-off/infer-entities-action.tsx
index dd487e0024a..1563a121ebd 100644
--- a/apps/plugin-browser/src/pages/popup/popup-contents/action-center/one-off/infer-entities-action.tsx
+++ b/apps/plugin-browser/src/pages/popup/popup-contents/action-center/one-off/infer-entities-action.tsx
@@ -62,10 +62,10 @@ export const InferEntitiesAction = ({
     };
 
     try {
-      const sourceWebPage = await (browser.tabs.sendMessage(
-        activeTab.id,
-        message,
-      ) as Promise<GetTabContentReturn>);
+      const sourceWebPage = await browser.tabs.sendMessage<
+        GetTabContentRequest,
+        GetTabContentReturn
+      >(activeTab.id, message);
 
       void sendMessageToBackground({
         createAs,
diff --git a/apps/plugin-browser/src/scripts/background.ts b/apps/plugin-browser/src/scripts/background.ts
index 6dd14195db0..fc7adda01ce 100644
--- a/apps/plugin-browser/src/scripts/background.ts
+++ b/apps/plugin-browser/src/scripts/background.ts
@@ -5,8 +5,8 @@ import { getUser } from "../shared/get-user";
 import type {
   GetTabContentRequest,
   GetTabContentReturn,
-  Message,
 } from "../shared/messages";
+import { isWellFormattedMessage } from "../shared/messages";
 import {
   clearLocalStorage,
   getFromLocalStorage,
@@ -36,7 +36,11 @@ browser.runtime.onInstalled.addListener(({ reason }) => {
   }
 });
 
-browser.runtime.onMessage.addListener(async (message: Message, sender) => {
+browser.runtime.onMessage.addListener(async (message, sender) => {
+  if (!isWellFormattedMessage(message)) {
+    return `Unrecognised message format ${String(message)}`;
+  }
+
   if (sender.tab) {
     // We are not expecting any messages from the content script
     return;
@@ -63,9 +67,12 @@ browser.tabs.onUpdated.addListener((tabId, changeInfo) => {
             setTimeout(resolve, 2_000);
           });
 
-          const webPage = await (browser.tabs.sendMessage(tabId, {
+          const webPage = await browser.tabs.sendMessage<
+            GetTabContentRequest,
+            GetTabContentReturn
+          >(tabId, {
             type: "get-tab-content",
-          } satisfies GetTabContentRequest) as Promise<GetTabContentReturn>);
+          });
 
           const applicableRules = automaticInferenceConfig.rules.filter(
             ({ restrictToDomains }) => {
diff --git a/apps/plugin-browser/src/scripts/background/infer-entities/get-website-content.ts b/apps/plugin-browser/src/scripts/background/infer-entities/get-website-content.ts
index 331e9bbf5f4..56b7aa8ca2b 100644
--- a/apps/plugin-browser/src/scripts/background/infer-entities/get-website-content.ts
+++ b/apps/plugin-browser/src/scripts/background/infer-entities/get-website-content.ts
@@ -45,9 +45,12 @@ export const getWebsiteContent = async (urls: string[]) => {
       browser.tabs.onUpdated.addListener(tabChangeListener);
     });
 
-    const webPage = await (browser.tabs.sendMessage(tab.id, {
+    const webPage = await browser.tabs.sendMessage<
+      GetTabContentRequest,
+      GetTabContentReturn
+    >(tab.id, {
       type: "get-tab-content",
-    } satisfies GetTabContentRequest) as Promise<GetTabContentReturn>);
+    });
 
     webPages.push(webPage);
 
diff --git a/apps/plugin-browser/src/scripts/content.ts b/apps/plugin-browser/src/scripts/content.ts
index 19fe32bb204..50679f092b6 100644
--- a/apps/plugin-browser/src/scripts/content.ts
+++ b/apps/plugin-browser/src/scripts/content.ts
@@ -1,6 +1,12 @@
 import browser from "webextension-polyfill";
 
+import {
+  type GetTabContentReturn,
+  isWellFormattedMessage,
+} from "../shared/messages";
+
 /**
+ * @file
  * Content scripts operate in the context of the webpage itself, for reading and manipulating context.
  *
  * They have access to a limited set of browser APIs
@@ -10,11 +16,15 @@ import browser from "webextension-polyfill";
  *
  * You must update the extension if you amend this file, from the extensions manager page in the browser.
  */
-import type { GetTabContentReturn, Message } from "../shared/messages";
 
-// Promise based API (see: https://github.com/mozilla/webextension-polyfill/?tab=readme-ov-file#using-the-promise-based-apis)
+// Promise based API (see:
+// https://github.com/mozilla/webextension-polyfill/?tab=readme-ov-file#using-the-promise-based-apis)
 // eslint-disable-next-line @typescript-eslint/require-await
-browser.runtime.onMessage.addListener(async (message: Message, _sender) => {
+browser.runtime.onMessage.addListener(async (message) => {
+  if (!isWellFormattedMessage(message)) {
+    return `Unrecognised message format ${String(message)}`;
+  }
+
   if (message.type === "get-tab-content") {
     const docContent =
       document.querySelector("main") ?? document.querySelector("body");
diff --git a/apps/plugin-browser/src/shared/messages.ts b/apps/plugin-browser/src/shared/messages.ts
index acb8d5c1e24..ab3adeec31a 100644
--- a/apps/plugin-browser/src/shared/messages.ts
+++ b/apps/plugin-browser/src/shared/messages.ts
@@ -27,3 +27,8 @@ export type Message =
   | InferEntitiesRequest
   | CancelInferEntitiesRequest
   | GetTabContentRequest;
+
+export const isWellFormattedMessage = (message: unknown): message is Message =>
+  typeof message === "object" &&
+  message !== null &&
+  typeof (message as { type: unknown }).type === "string";
diff --git a/libs/@local/status/typescript/README.md b/libs/@local/status/typescript/README.md
index fab1a370869..eb52767b484 100644
--- a/libs/@local/status/typescript/README.md
+++ b/libs/@local/status/typescript/README.md
@@ -84,9 +84,9 @@ This process works through code-generation using the [`quicktype`](https://githu
 
 This package is structured into two main areas:
 
-- [`pkg`](./pkg) contains the TypeScript package that exports the `Status`, `StatusCode` types, and helper functions.
 - [`rust`](./rust) contains the Rust crate that defines the `Status` and `StatusCode` types.
-- [`type-defs`](./type-defs) contains the plain type definitions for `Status`, `StatusCode`, and associated status payloads. These types are defined in TypeScript at the moment but could easily be represented in another schema format.
+- [`typescript`](./src) contains the TypeScript package that exports the `Status`, `StatusCode` types, and helper functions.
+- [`typescript/type-defs`](./type-defs) contains the plain type definitions for `Status`, `StatusCode`, and associated status payloads. These types are defined in TypeScript at the moment but could easily be represented in another schema format.
 
 Note: despite the `type-defs` being in TypeScript, we define them separately to keep a better separation of concerns, and to avoid `quicktype` breaking when it encounters non-type code (e.g. `const` definitions).
 
diff --git a/libs/@local/status/typescript/package.json b/libs/@local/status/typescript/package.json
index b9e373ffc5d..c69bcd48c9a 100644
--- a/libs/@local/status/typescript/package.json
+++ b/libs/@local/status/typescript/package.json
@@ -5,10 +5,10 @@
   "license": "(MIT OR Apache-2.0)",
   "type": "module",
   "exports": {
-    ".": "./dist/pkg/src/main.js",
+    ".": "./dist/src/main.js",
     "./type-defs/*": "./dist/type-defs/*.js"
   },
-  "types": "./dist/pkg/src/main.d.ts",
+  "types": "./dist/src/main.d.ts",
   "scripts": {
     "build": "rimraf dist && tsc --build tsconfig.build.json",
     "fix:eslint": "eslint --fix .",
diff --git a/libs/@local/status/typescript/pkg/src/main.ts b/libs/@local/status/typescript/src/main.ts
similarity index 87%
rename from libs/@local/status/typescript/pkg/src/main.ts
rename to libs/@local/status/typescript/src/main.ts
index 4cfbd8bd692..ffc0d056921 100644
--- a/libs/@local/status/typescript/pkg/src/main.ts
+++ b/libs/@local/status/typescript/src/main.ts
@@ -3,10 +3,10 @@
  * and RPC APIs.
  */
 
-import type { Status } from "../../type-defs/status.js";
+import type { Status } from "../type-defs/status.js";
 import { StatusCode } from "./status-code.js";
 
-export type { Status } from "../../type-defs/status.js";
+export type { Status } from "../type-defs/status.js";
 export {
   convertHttpCodeToStatusCode,
   convertStatusCodeToHttpCode,
diff --git a/libs/@local/status/typescript/pkg/src/status-code.ts b/libs/@local/status/typescript/src/status-code.ts
similarity index 98%
rename from libs/@local/status/typescript/pkg/src/status-code.ts
rename to libs/@local/status/typescript/src/status-code.ts
index 05a0ac284cc..459ce488326 100644
--- a/libs/@local/status/typescript/pkg/src/status-code.ts
+++ b/libs/@local/status/typescript/src/status-code.ts
@@ -1,6 +1,6 @@
-import { StatusCode } from "../../type-defs/status-code.js";
+import { StatusCode } from "../type-defs/status-code.js";
 
-export { StatusCode } from "../../type-defs/status-code.js";
+export { StatusCode } from "../type-defs/status-code.js";
 
 const STATUS_CODE_TO_HTTP_CODE: Record<StatusCode, number> = {
   OK: 200,
diff --git a/libs/@local/status/typescript/tsconfig.build.json b/libs/@local/status/typescript/tsconfig.build.json
index df24c1073a1..21689d29105 100644
--- a/libs/@local/status/typescript/tsconfig.build.json
+++ b/libs/@local/status/typescript/tsconfig.build.json
@@ -1,6 +1,6 @@
 {
   "extends": "./tsconfig.json",
-  "include": ["pkg", "type-defs"],
+  "include": ["src", "type-defs"],
   "compilerOptions": {
     "declaration": true,
     "outDir": "dist",
diff --git a/libs/@local/status/typescript/tsconfig.json b/libs/@local/status/typescript/tsconfig.json
index ab95f2df657..b2d3cc538e3 100644
--- a/libs/@local/status/typescript/tsconfig.json
+++ b/libs/@local/status/typescript/tsconfig.json
@@ -1,6 +1,6 @@
 {
   "extends": "@local/tsconfig/legacy-base-tsconfig-to-refactor.json",
-  "include": ["./pkg/src/", "./scripts", "./type-defs", "eslint.config.js"],
+  "include": ["./src/", "./scripts", "./type-defs", "eslint.config.js"],
   "compilerOptions": {
     "module": "NodeNext",
     "moduleResolution": "NodeNext"
diff --git a/libs/@local/tsconfig/legacy-base-tsconfig-to-refactor.json b/libs/@local/tsconfig/legacy-base-tsconfig-to-refactor.json
index cbfe08d45c5..a975c50143a 100644
--- a/libs/@local/tsconfig/legacy-base-tsconfig-to-refactor.json
+++ b/libs/@local/tsconfig/legacy-base-tsconfig-to-refactor.json
@@ -30,7 +30,8 @@
       "@local/hash-graph-sdk/*": ["../graph/sdk/typescript/src/*.ts"],
       "@local/hash-graph-types/*": ["../graph/types/typescript/src/*.ts"],
       "@local/hash-isomorphic-utils/*": ["../hash-isomorphic-utils/src/*.ts"],
-      "@local/status": ["../status/typescript/pkg/src/main.ts"],
+      "@local/status": ["../status/typescript/src/main.ts"],
+      "@local/status/type-defs/*": ["../status/typescript/src/type-defs/*.ts"],
       "@local/hash-subgraph": ["../hash-subgraph/src/main.ts"],
       "@local/hash-subgraph/*": ["../hash-subgraph/src/*.ts"],
       "@local/harpc-client": ["../harpc/client/typescript/src/index.ts"],
diff --git a/yarn.lock b/yarn.lock
index 4a0add8a2bd..c65d633368d 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -813,7 +813,7 @@ __metadata:
     "@types/lodash.debounce": "npm:4.0.9"
     "@types/react": "npm:19.0.1"
     "@types/react-dom": "npm:19.0.2"
-    "@types/webextension-polyfill": "patch:@types/webextension-polyfill@npm%3A0.10.4#~/.yarn/patches/@types-webextension-polyfill-npm-0.10.4-291152c615.patch"
+    "@types/webextension-polyfill": "npm:0.12.0"
     "@types/ws": "npm:8.5.13"
     babel-loader: "npm:9.2.1"
     babel-preset-react-app: "npm:10.0.1"
@@ -847,7 +847,7 @@ __metadata:
     type-fest: "npm:3.13.1"
     typescript: "npm:5.7.2"
     uuid: "npm:11.0.3"
-    webextension-polyfill: "npm:0.10.0"
+    webextension-polyfill: "npm:0.12.0"
     webpack: "npm:5.97.1"
     webpack-cli: "npm:4.10.0"
     webpack-dev-server: "npm:4.15.2"
@@ -18613,17 +18613,10 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@types/webextension-polyfill@npm:0.10.4":
-  version: 0.10.4
-  resolution: "@types/webextension-polyfill@npm:0.10.4"
-  checksum: 10c0/6ae62b0d0b61878c0c7f65ac484b436d8a07e3561ade441a12e363bdc7db7b2675db9f94e3d1e7efd5ad2c0a5ee0818ea5942f06246cc18384b14ec698371253
-  languageName: node
-  linkType: hard
-
-"@types/webextension-polyfill@patch:@types/webextension-polyfill@npm%3A0.10.4#~/.yarn/patches/@types-webextension-polyfill-npm-0.10.4-291152c615.patch":
-  version: 0.10.4
-  resolution: "@types/webextension-polyfill@patch:@types/webextension-polyfill@npm%3A0.10.4#~/.yarn/patches/@types-webextension-polyfill-npm-0.10.4-291152c615.patch::version=0.10.4&hash=ff32d6"
-  checksum: 10c0/86fb2c10a438117d9310f3924a5d64f1ce0100a7f539bd6208864af4b7f5a795d8bf27fd25587cb939ea35689ba9daacd15bd07aed4241ec711a7db5812065ad
+"@types/webextension-polyfill@npm:0.12.0":
+  version: 0.12.0
+  resolution: "@types/webextension-polyfill@npm:0.12.0"
+  checksum: 10c0/d8b69620e9af41802a144ddbefcaf1f627856ed1b1ccf42af0b4d546906a738fea01f45efcf4eb9c2e08761e1b3333105026eb7fd4b51cafb5b4e591079faa8c
   languageName: node
   linkType: hard
 
@@ -47734,10 +47727,10 @@ __metadata:
   languageName: node
   linkType: hard
 
-"webextension-polyfill@npm:0.10.0":
-  version: 0.10.0
-  resolution: "webextension-polyfill@npm:0.10.0"
-  checksum: 10c0/6a45278f1fed8fbd5355f9b19a7b0b3fadc91fa3a6eef69125a1706bb3efa2181235eefbfb3f538443bb396cfcb97512361551888ce8465c08914431cb2d5b6d
+"webextension-polyfill@npm:0.12.0":
+  version: 0.12.0
+  resolution: "webextension-polyfill@npm:0.12.0"
+  checksum: 10c0/5ace2aaaf6a203515bdd2fb948622f186a5fbb50099b539ce9c0ad54896f9cc1fcc3c0e2a71d1f7071dd7236d7daebba1e0cbcf43bfdfe54361addf0333ee7d1
   languageName: node
   linkType: hard