Send beta user state with AppView requests (#11474)

src/state/session/clients.ts

@@ -7,8 +7,33 @@ import {
   PUBLIC_BSKY_SERVICE,
 } from '#/lib/constants'
 import {createLexClient} from '#/lib/lexClient'
+import {getCachedIsBetaUser} from '#/state/preferences/beta-user-cache'
 import {networkAwareFetch} from './network'
 
+const IS_BETA_USER_HEADER = 'X-Bsky-Is-Beta-User'
+
+/**
+ * Add account-scoped headers to appview requests.
+ *
+ * Values are read from memory per request so preference changes are reflected
+ * immediately without rebuilding the session bundle.
+ */
+function withAppviewRequestHeaders(agent: Agent): Agent {
+  return {
+    get did() {
+      return agent.did
+    },
+    fetchHandler(path, init) {
+      const headers = new Headers(init?.headers)
+      const isBetaUser = agent.did ? getCachedIsBetaUser(agent.did) : undefined
+      if (isBetaUser !== undefined) {
+        headers.set(IS_BETA_USER_HEADER, String(isBetaUser))
+      }
+      return agent.fetchHandler(path, {...init, headers})
+    },
+  }
+}
+
 /**
  * Build the signed-in appview {@link Client}.
  *
@@ -28,7 +53,9 @@ import {networkAwareFetch} from './network'
  * fetch, which is `networkAwareFetch` wrapped in the disposal kill switch.
  */
 export function buildAppviewClient(agent: Agent): Client {
-  return createLexClient(agent, {service: BLUESKY_PROXY_HEADER.get()})
+  return createLexClient(withAppviewRequestHeaders(agent), {
+    service: BLUESKY_PROXY_HEADER.get(),
+  })
 }
 
 /**