From 7e07ed6fe0b80f24c5c1c660d2c993094f4e1dc7 Mon Sep 17 00:00:00 2001
From: Daniel Roe <daniel@roe.dev>
Date: Sat, 15 Aug 2026 00:02:35 +0100
Subject: [PATCH] fix: normalise blob refs to json lex encoding

---
 server/api/admin/blobs.post.ts   |  4 +++-
 server/utils/admin/ama-record.ts |  5 ++++-
 server/utils/admin/crud.ts       | 16 +++++++++++++---
 shared/cms/blob.ts               | 10 ++++++----
 test/unit/blob.spec.ts           |  8 ++++++++
 5 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/server/api/admin/blobs.post.ts b/server/api/admin/blobs.post.ts
index d84c1e24..b5d59836 100644
--- a/server/api/admin/blobs.post.ts
+++ b/server/api/admin/blobs.post.ts
@@ -1,3 +1,5 @@
+import { lexToJson } from '@atproto/lex'
+
 import { requireAdminClient } from '../../utils/admin/client'
 
 /**
@@ -26,7 +28,7 @@ export default defineEventHandler(async event => {
     probeAspectRatio(bytes, contentType),
   ])
   return {
-    blob: res.body.blob,
+    blob: lexToJson(res.body.blob),
     ...(aspectRatio ? { aspectRatio } : {}),
   }
 })
diff --git a/server/utils/admin/ama-record.ts b/server/utils/admin/ama-record.ts
index 0f493c16..f827ccc1 100644
--- a/server/utils/admin/ama-record.ts
+++ b/server/utils/admin/ama-record.ts
@@ -274,7 +274,10 @@ export async function prepareAmaImage (
 
   const cid = cidFromBlob(body.image)
   if (!cid) {
-    throw createError({ statusCode: 422, statusMessage: 'Invalid AMA image blob.' })
+    throw createError({
+      statusCode: 422,
+      statusMessage: `Invalid AMA image blob: ${JSON.stringify(body.image)}`,
+    })
   }
 
   const service = useRuntimeConfig(event).public.atproto.service
diff --git a/server/utils/admin/crud.ts b/server/utils/admin/crud.ts
index 875d7991..b25ce607 100644
--- a/server/utils/admin/crud.ts
+++ b/server/utils/admin/crud.ts
@@ -1,5 +1,5 @@
 import type { H3Event } from 'h3'
-import { LexValidationError, XrpcResponseError, jsonToLex } from '@atproto/lex'
+import { LexValidationError, XrpcResponseError, jsonToLex, lexToJson } from '@atproto/lex'
 import type { AtUriString, CidString, CreateOptions, DeleteOptions, GetOptions, Infer, JsonValue, PutOptions, RecordSchema } from '@atproto/lex'
 
 import { requireAdminClient } from './client'
@@ -18,6 +18,16 @@ function rkeyFromUri (uri: string): string {
   return uri.split('/').pop() ?? ''
 }
 
+/**
+ * Record values hold lex representations (a blob ref's `ref` is a `Cid`
+ * instance), which `JSON.stringify` would emit as DAG-JSON (`{ '/': cid }`).
+ * The admin UI posts values straight back to us, and `writeRecord` decodes
+ * them with `jsonToLex`, which only accepts the `{ $link: cid }` form.
+ */
+function toJsonValue<T extends RecordSchema> (value: Infer<T>): Infer<T> {
+  return lexToJson(value) as Infer<T>
+}
+
 function assertRkey (rkey: string | undefined): asserts rkey is string {
   if (!rkey || rkey === 'undefined' || rkey === 'null') {
     throw createError({ statusCode: 400, statusMessage: 'Missing or invalid rkey.' })
@@ -36,7 +46,7 @@ export async function listAdminRecords<T extends RecordSchema> (
       rkey: rkeyFromUri(r.uri),
       uri: r.uri,
       cid: r.cid,
-      value: r.value as Infer<T>,
+      value: toJsonValue<T>(r.value as Infer<T>),
     })
   }
   if (options.sortBy) {
@@ -67,7 +77,7 @@ export async function getAdminRecord<T extends RecordSchema> (
   const { client, did } = await requireAdminClient(event)
   try {
     const res = await client.get(schema, { repo: did, rkey } as unknown as GetOptions<T>)
-    return { rkey, uri: res.uri, cid: res.cid ?? '', value: res.value }
+    return { rkey, uri: res.uri, cid: res.cid ?? '', value: toJsonValue<T>(res.value) }
   }
   catch (err) {
     if (err instanceof XrpcResponseError && err.status === 404) {
diff --git a/shared/cms/blob.ts b/shared/cms/blob.ts
index 4733b4c5..8aa6559c 100644
--- a/shared/cms/blob.ts
+++ b/shared/cms/blob.ts
@@ -1,18 +1,20 @@
 /**
- * Extract the base32 CID string from a blob ref. Accepts the IPLD-JSON
- * form (`{ ref: { $link: cid } }`) and a `BlobRef` instance with a `CID`
- * `ref`.
+ * Extract the base32 CID string from a blob ref. Accepts the IPLD-JSON form
+ * (`{ ref: { $link: cid } }`), the DAG-JSON form (`{ ref: { '/': cid } }`)
+ * produced when a `CID` instance is serialised with `JSON.stringify`, the
+ * legacy untyped form (`{ cid }`), and a `BlobRef` instance with a `CID` `ref`.
  */
 export function cidFromBlob (blob: unknown): string | null {
   if (!blob || typeof blob !== 'object') return null
   const b = blob as Record<string, unknown>
 
-  const ref = b.ref
+  const ref = b.ref ?? b.cid
   if (!ref) return null
   if (typeof ref === 'string') return ref
   if (typeof ref === 'object') {
     const r = ref as Record<string, unknown>
     if (typeof r.$link === 'string') return r.$link
+    if (typeof r['/'] === 'string') return r['/']
     const s = String(ref)
     if (s && s !== '[object Object]') return s
   }
diff --git a/test/unit/blob.spec.ts b/test/unit/blob.spec.ts
index 422ef0fa..705c9d6e 100644
--- a/test/unit/blob.spec.ts
+++ b/test/unit/blob.spec.ts
@@ -6,6 +6,14 @@ describe('cidFromBlob', () => {
     expect(cidFromBlob({ $type: 'blob', ref: { $link: 'bafyabc' }, mimeType: 'image/png', size: 10 })).toBe('bafyabc')
   })
 
+  it('reads the DAG-JSON blob shape', () => {
+    expect(cidFromBlob({ $type: 'blob', ref: { '/': 'bafyabc' }, mimeType: 'image/png', size: 10 })).toBe('bafyabc')
+  })
+
+  it('reads the legacy untyped blob shape', () => {
+    expect(cidFromBlob({ cid: 'bafyabc', mimeType: 'image/png' })).toBe('bafyabc')
+  })
+
   it('returns null for non-blob input', () => {
     expect(cidFromBlob(null)).toBeNull()
     expect(cidFromBlob('nope')).toBeNull()
-- 
2.51.2