From 6a4232dbac951b00ee5dfcc48d0c23a0dba070e5 Mon Sep 17 00:00:00 2001
From: vineyardbovines <spencerfpope@gmail.com>
Date: Wed, 26 Aug 2026 11:48:57 -0400
Subject: [PATCH] Handle transient errors during PDS detection

---
 .../queries/__tests__/pds-detection.test.ts   | 43 +++++++++++++++++++
 src/state/queries/pds-detection.ts            | 21 ++++-----
 2 files changed, 54 insertions(+), 10 deletions(-)
 create mode 100644 src/state/queries/__tests__/pds-detection.test.ts

diff --git a/src/state/queries/__tests__/pds-detection.test.ts b/src/state/queries/__tests__/pds-detection.test.ts
new file mode 100644
index 0000000000..c664fedcff
--- /dev/null
+++ b/src/state/queries/__tests__/pds-detection.test.ts
@@ -0,0 +1,43 @@
+import {getMain, XrpcResponseError} from '@atproto/lex'
+import {beforeEach, describe, expect, it, jest} from '@jest/globals'
+
+import {com} from '#/lexicons'
+
+const mockCall = jest.fn<(...args: unknown[]) => Promise<unknown>>()
+
+jest.mock('#/state/session/clients', () => ({
+  getPublicAppviewClient: () => ({call: mockCall}),
+}))
+
+import {resolvePdsForIdentifier} from '../pds-detection'
+
+function responseError(status: number) {
+  return new XrpcResponseError(
+    getMain(com.atproto.identity.resolveHandle),
+    new Response(null, {status}),
+    undefined,
+  )
+}
+
+describe('resolvePdsForIdentifier', () => {
+  beforeEach(() => {
+    mockCall.mockReset()
+  })
+
+  it.each([429, 500, 502, 503])(
+    'surfaces a transient resolveHandle %s response as a network failure',
+    async status => {
+      mockCall.mockRejectedValueOnce(responseError(status))
+
+      await expect(resolvePdsForIdentifier('samuel.fm')).rejects.toThrow(
+        `Network request failed: resolveHandle returned ${status}`,
+      )
+    },
+  )
+
+  it('treats a permanent resolveHandle 4xx response as unresolved', async () => {
+    mockCall.mockRejectedValueOnce(responseError(400))
+
+    await expect(resolvePdsForIdentifier('missing.test')).resolves.toBeNull()
+  })
+})
diff --git a/src/state/queries/pds-detection.ts b/src/state/queries/pds-detection.ts
index 424cc404f0..3d72d495c7 100644
--- a/src/state/queries/pds-detection.ts
+++ b/src/state/queries/pds-detection.ts
@@ -3,12 +3,13 @@ import {type DidDocument, getPdsEndpoint} from '@atproto/common-web'
 import {type HandleString} from '@atproto/syntax'
 import {useQuery, useQueryClient} from '@tanstack/react-query'
 
-import {DEFAULT_SERVICE, PUBLIC_BSKY_SERVICE} from '#/lib/constants'
+import {DEFAULT_SERVICE} from '#/lib/constants'
 import {useDebouncedValue} from '#/lib/hooks/useDebouncedValue'
-import {createServiceClient} from '#/lib/lexClient'
 import {isNetworkError} from '#/lib/strings/errors'
+import {getErrorStatus} from '#/lib/xrpc-error'
 import {logger} from '#/logger'
 import {STALE} from '#/state/queries'
+import {getPublicAppviewClient} from '#/state/session/clients'
 import {com} from '#/lexicons'
 
 const RQKEY_ROOT = 'pds-detection'
@@ -149,14 +150,7 @@ export async function resolvePdsForIdentifier(
   identifier: string,
 ): Promise<{did: string; pdsUrl: string | null} | null> {
   const norm = normalizeIdentifier(identifier)
-  /*
-   * This is a pre-auth request. Use an isolated service client rather than the
-   * shared public appview client, whose global moderation configuration is
-   * intended for appview content reads and can change independently of this
-   * login flow. This also matches the pre-auth handle resolution used during
-   * signup.
-   */
-  const client = createServiceClient(PUBLIC_BSKY_SERVICE)
+  const client = getPublicAppviewClient()
   try {
     let did: string
     if (norm.startsWith('did:')) {
@@ -194,6 +188,13 @@ export async function resolvePdsForIdentifier(
       isNetworkError: isNetworkError(err),
     })
     if (isNetworkError(err)) throw err
+    const status = getErrorStatus(err)
+    if (status !== undefined && isTransientHttpStatus(status)) {
+      throw new Error(
+        `Network request failed: resolveHandle returned ${status}`,
+        {cause: err},
+      )
+    }
     return null
   }
 }