Version Packages (#963)

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Author: github-actions[bot]

.changeset/etag-support.md

@@ -1,5 +1,71 @@
 # @vercel/blob
 
+## 2.1.0
+
+### Minor Changes
+
+- 6c68442: Add ETag support for conditional writes (optimistic concurrency control)
+
+  - Return `etag` in all blob responses (put, copy, head, list, multipart)
+  - Accept `ifMatch` option in put/copy/createMultipartUpload for conditional writes
+  - Add `BlobPreconditionFailedError` for ETag mismatch (HTTP 412)
+
+  ## Usage Example: Preventing Lost Updates
+
+  When multiple users or processes might update the same blob concurrently, use `ifMatch` to ensure you don't overwrite someone else's changes:
+
+  ```typescript
+  import { put, head, BlobPreconditionFailedError } from "@vercel/blob";
+
+  // User 1: Read the current blob and get its ETag
+  const metadata = await head("config.json");
+  console.log(metadata.etag); // e.g., '"abc123"'
+
+  // User 2: Also reads the same blob (same ETag)
+  const metadata2 = await head("config.json");
+
+  // User 1: Updates the blob with ifMatch
+  // This succeeds because the ETag matches
+  const result1 = await put(
+    "config.json",
+    JSON.stringify({ setting: "user1" }),
+    {
+      access: "public",
+      allowOverwrite: true, // Required when updating existing blobs
+      ifMatch: metadata.etag, // Only write if ETag still matches
+    }
+  );
+  console.log(result1.etag); // New ETag: '"def456"'
+
+  // User 2: Tries to update with their (now stale) ETag
+  // This fails because User 1 already changed the blob
+  try {
+    await put("config.json", JSON.stringify({ setting: "user2" }), {
+      access: "public",
+      allowOverwrite: true,
+      ifMatch: metadata2.etag, // Stale ETag - blob was modified!
+    });
+  } catch (error) {
+    if (error instanceof BlobPreconditionFailedError) {
+      // The blob was modified since we last read it
+      // Re-fetch, merge changes, and retry
+      const freshMetadata = await head("config.json");
+      await put("config.json", JSON.stringify({ setting: "user2" }), {
+        access: "public",
+        allowOverwrite: true,
+        ifMatch: freshMetadata.etag, // Use fresh ETag
+      });
+    }
+  }
+  ```
+
+  ### Key Points
+
+  - **`allowOverwrite: true`**: Required when updating an existing blob at the same path
+  - **`ifMatch`**: Only performs the write if the blob's current ETag matches this value
+  - **Combined**: "Overwrite, but only if the blob hasn't changed since I last read it"
+  - ETags follow RFC 7232 format with surrounding quotes (e.g., `"abc123"`)
+
 ## 2.0.1
 
 ### Patch Changes

packages/blob/CHANGELOG.md

@@ -1,6 +1,6 @@
 {
   "name": "@vercel/blob",
-  "version": "2.0.1",
+  "version": "2.1.0",
   "description": "The Vercel Blob JavaScript API client",
   "homepage": "https://vercel.com/storage/blob",
   "repository": {

packages/blob/package.json

@@ -1,5 +1,12 @@
 # vercel-storage-integration-test-suite
 
+## 0.3.15
+
+### Patch Changes
+
+- Updated dependencies [6c68442]
+  - @vercel/blob@2.1.0
+
 ## 0.3.14
 
 ### Patch Changes

test/next/CHANGELOG.md

@@ -1,6 +1,6 @@
 {
   "name": "vercel-storage-integration-test-suite",
-  "version": "0.3.14",
+  "version": "0.3.15",
   "private": true,
   "scripts": {
     "build": "next build",