First attempt at declaring rules from main site (not working)

package.json

@@ -34,5 +34,10 @@
     "eslint-import-resolver-typescript": "^3.6.1",
     "eslint-plugin-import": "^2.29.1",
     "eslint-plugin-prettier": "^5.1.1"
+  },
+  "manifest": {
+    "permissions": [
+      "declarativeNetRequest"
+    ]
   }
 }

src/background/messages/declarative-net-request.ts

@@ -0,0 +1,71 @@
+import type { PlasmoMessaging } from '@plasmohq/messaging';
+
+interface RequestBody {
+  ruleId: number;
+  domain: string;
+  requestHeaders?: Record<string, string>;
+  responseHeaders?: Record<string, string>;
+}
+
+const mapHeadersToDeclarativeNetRequestHeaders = (
+  headers: Record<string, string>,
+): chrome.declarativeNetRequest.ModifyHeaderInfo[] => {
+  return Object.entries(headers).map(([name, value]) => ({
+    header: name,
+    operation: chrome.declarativeNetRequest.HeaderOperation.SET,
+    value,
+  }));
+};
+
+const handler: PlasmoMessaging.MessageHandler<RequestBody> = async (req, res) => {
+  console.log('declarative-net-request: ', req.body);
+  try {
+    await chrome.declarativeNetRequest.updateDynamicRules({
+      removeRuleIds: [req.body.ruleId],
+      addRules: [
+        {
+          id: req.body.ruleId,
+          condition: {
+            initiatorDomains: [req.body.domain],
+          },
+          action: {
+            type: chrome.declarativeNetRequest.RuleActionType.MODIFY_HEADERS,
+            requestHeaders: mapHeadersToDeclarativeNetRequestHeaders(req.body.requestHeaders ?? {}),
+            responseHeaders: [
+              {
+                header: 'Access-Control-Allow-Origin',
+                operation: chrome.declarativeNetRequest.HeaderOperation.SET,
+                value: '*',
+              },
+              {
+                header: 'Access-Control-Allow-Methods',
+                operation: chrome.declarativeNetRequest.HeaderOperation.SET,
+                value: 'GET, POST, PUT, DELETE, PATCH, OPTIONS',
+              },
+              {
+                header: 'Access-Control-Allow-Headers',
+                operation: chrome.declarativeNetRequest.HeaderOperation.SET,
+                value: '*',
+              },
+              ...mapHeadersToDeclarativeNetRequestHeaders(req.body.responseHeaders ?? {}),
+            ],
+          },
+        },
+      ],
+    });
+
+    if (chrome.runtime.lastError?.message) throw new Error(chrome.runtime.lastError.message);
+
+    res.send({
+      success: true,
+      body: req.body,
+    });
+  } catch (err) {
+    res.send({
+      success: false,
+      error: err.message,
+    });
+  }
+};
+
+export default handler;

src/contents/movie-web.ts

@@ -7,5 +7,9 @@ export const config: PlasmoCSConfig = {
 };
 
 relayMessage({
-  name: 'proxy',
+  name: 'proxy-request',
+});
+
+relayMessage({
+  name: 'declarative-net-request',
 });