Improve header setup

src/App.native.tsx

@@ -78,6 +78,7 @@ import {
   features,
   setupDeviceId,
 } from '#/analytics'
+import {useSetAnalyticsHeaders} from '#/analytics/useSetAnalyticsHeaders'
 import {IS_ANDROID, IS_IOS} from '#/env'
 import {
   prefetchLiveEvents,
@@ -117,6 +118,8 @@ function InnerApp() {
   const {_} = useLingui()
   const hasCheckedReferrer = useStarterPackEntry()
 
+  useSetAnalyticsHeaders()
+
   // init
   useEffect(() => {
     async function onLaunch(account?: SessionAccount) {

src/App.web.tsx

@@ -68,6 +68,7 @@ import {
   features,
   setupDeviceId,
 } from '#/analytics'
+import {useSetAnalyticsHeaders} from '#/analytics/useSetAnalyticsHeaders'
 import {
   prefetchLiveEvents,
   Provider as LiveEventsProvider,
@@ -93,6 +94,8 @@ function InnerApp() {
   const {_} = useLingui()
   const hasCheckedReferrer = useStarterPackEntry()
 
+  useSetAnalyticsHeaders()
+
   // init
   useEffect(() => {
     async function onLaunch(account?: SessionAccount) {

src/analytics/useSetAnalyticsHeaders.tsx

@@ -0,0 +1,36 @@
+import {useAgent} from '#/state/session'
+import {getDeviceId, useSessionId} from '#/analytics/identifiers'
+import {getIPGeolocationString} from '#/geolocation/util'
+
+/**
+ * Get anonymous identifiers and construct headers we use for requests that may
+ * trigger experiment exposures in our backend. These values are used for A/B
+ * test bucketing, in addition to the user DID, if the request is
+ * authenticated. They ensure we can consistently deliver beta features to
+ * users.
+ *
+ * This should be mounted as high as possible in the tree, _after_
+ * `setupDeviceId` has resolved and session context is available.
+ *
+ * The setters here are not wrapped in an effect because this hook does not
+ * render that often, and we want to make sure the headers are set as soon as
+ * possible after `agent` changes to ensure analytics events are properly
+ * attributed.
+ *
+ * The values here are not specific to an account. If we add new values here in
+ * the future, we should ensure that they are not account specific and handle
+ * those separately (and more carefully).
+ *
+ * These headers must stay in sync with our appview.
+ * @see https://github.com/bluesky-social/atproto/blob/39cf199df5847d3fd4a60d8cdeb604a0e07f9784/packages/bsky/src/feature-gates/utils.ts#L7-L8
+ */
+export function useSetAnalyticsHeaders() {
+  const agent = useAgent()
+  const sessionId = useSessionId()
+  agent.setHeader('X-Bsky-Device-Id', getDeviceId() ?? '')
+  agent.setHeader('X-Bsky-Session-Id', sessionId)
+  const geo = getIPGeolocationString()
+  if (geo) {
+    agent.setHeader('X-Bsky-IP-Geolocation', geo)
+  }
+}

src/analytics/utils.ts

@@ -2,12 +2,10 @@ import {useMemo} from 'react'
 
 import {BSKY_SERVICE} from '#/lib/constants'
 import {type SessionAccount} from '#/state/session'
-import {getDeviceId, getSessionId} from '#/analytics/identifiers'
 import {
   type MergeableMetadata,
   type SessionMetadata,
 } from '#/analytics/metadata'
-import {getIPGeolocationString} from '#/geolocation/util'
 
 /**
  * Thin `useMemo` wrapper that marks the metadata as memoized and provides a
@@ -33,25 +31,3 @@ export function accountToSessionMetadata(
     }
   }
 }
-
-/**
- * Get anonymous identifiers and construct headers we use for requests that may
- * trigger experiment exposures in our backend. These values are used for A/B
- * test bucketing, in addition to the user DID, if the request is
- * authenticated. They ensure we can consistently deliver beta features to
- * users.
- *
- * These headers must stay in sync with our appview.
- * @see https://github.com/bluesky-social/atproto/blob/39cf199df5847d3fd4a60d8cdeb604a0e07f9784/packages/bsky/src/feature-gates/utils.ts#L7-L8
- */
-export function getAnalyticsHeaders() {
-  return {
-    'X-Bsky-Device-Id': getDeviceId(),
-    'X-Bsky-Session-Id': getSessionId(),
-    /**
-     * This can already be inferred from server requests, but for consistency
-     * in feature bucketing, we also include it here.
-     */
-    'X-Bsky-IP-Geolocation': getIPGeolocationString(),
-  }
-}