Make posts seed idempotent against the shared Vercel Blob store

The Vercel Blob store is shared across environments and the
@payloadcms/storage-vercel-blob plugin uploads via put() without
allowOverwrite (and exposes no option to enable it). Cover images left
under the deterministic <slug>.<ext> key by an earlier run therefore made
the prod seed abort with "This blob already exists" on the first upload.

Delete any orphan blob at that key (via @vercel/blob del, idempotent) right
before creating a new media doc, so uploads are deterministic and the seed
stays re-runnable. Existing media rows are still reused, so no duplicate
media is created.

package.json

@@ -84,6 +84,7 @@
     "@types/node": "22.19.9",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
+    "@vercel/blob": "2.3.1",
     "@vitejs/plugin-react": "4.5.2",
     "eslint": "^9.39.2",
     "eslint-config-next": "15.4.11",

pnpm-lock.yaml

@@ -129,6 +129,9 @@ importers:
       '@types/react-dom':
         specifier: ^19.2.3
         version: 19.2.3(@types/react@19.2.14)
+      '@vercel/blob':
+        specifier: 2.3.1
+        version: 2.3.1
       '@vitejs/plugin-react':
         specifier: 4.5.2
         version: 4.5.2(vite@7.3.1(@types/node@22.19.9)(jiti@2.6.1)(lightningcss@1.30.2)(sass@1.77.4)(tsx@4.21.0)(yaml@2.8.2))

scripts/seed-posts.mjs

@@ -26,6 +26,7 @@
 import { config as loadEnv } from 'dotenv'
 import { JSDOM } from 'jsdom'
 import { convertHTMLToLexical, editorConfigFactory } from '@payloadcms/richtext-lexical'
+import { del as blobDel } from '@vercel/blob'
 import { getPayload } from 'payload'
 
 // Mirror Next.js precedence (.env.local wins over .env) without clobbering a
@@ -418,6 +419,24 @@ async function ensureCoverMedia(payload, { slug, coverUrl, alt }) {
   if (existing.docs.length > 0) return { id: existing.docs[0].id, created: false }
 
   const buffer = Buffer.from(await res.arrayBuffer())
+
+  // The Vercel Blob store is SHARED across environments, and the storage plugin
+  // (@payloadcms/storage-vercel-blob) calls `put()` without `allowOverwrite` and
+  // exposes no option to enable it. So a blob left behind under this deterministic
+  // key (`<slug>.<ext>`) by an earlier run in another environment would make the
+  // upload throw "This blob already exists". We have no DB media row for it here
+  // (checked above), so it's an orphan — delete it first so the upload is
+  // deterministic and this seed stays re-runnable. `del` is idempotent (no-op
+  // when the blob is absent).
+  const blobToken = process.env.BLOB_READ_WRITE_TOKEN
+  if (blobToken) {
+    try {
+      await blobDel(filename, { token: blobToken })
+    } catch (err) {
+      console.warn(`[seed:posts]   blob pre-delete skipped for ${filename}: ${err.message}`)
+    }
+  }
+
   const media = await payload.create({
     collection: 'media',
     data: { alt: alt || slug },