diff --git a/objectstore/client.go b/objectstore/client.go
index f789844..ef41657 100644
--- a/objectstore/client.go
+++ b/objectstore/client.go
@@ -58,6 +58,29 @@ func (c *Client) Put(ctx context.Context, key string, body io.Reader, size int64
 	return nil
 }
 
+// blobUploadPartSize/blobUploadThreads bound PutStreaming memory at
+// partSize*threads while keeping concurrency for multi-GiB blobs.
+const (
+	blobUploadPartSize = uint64(64) << 20
+	blobUploadThreads  = uint(4)
+)
+
+// PutStreaming uploads body to key with concurrent multipart, reading from a
+// non-seekable source without buffering the whole object. Memory is bounded at
+// blobUploadPartSize*blobUploadThreads.
+func (c *Client) PutStreaming(ctx context.Context, key string, body io.Reader, size int64) error {
+	_, err := c.client.PutObject(ctx, c.cfg.Bucket, c.fullKey(key), body, size, minio.PutObjectOptions{
+		ContentType:           "application/octet-stream",
+		PartSize:              blobUploadPartSize,
+		NumThreads:            blobUploadThreads,
+		ConcurrentStreamParts: true,
+	})
+	if err != nil {
+		return fmt.Errorf("put streaming %s: %w", key, err)
+	}
+	return nil
+}
+
 // Get returns a streaming reader and size for the given key.
 func (c *Client) Get(ctx context.Context, key string) (io.ReadCloser, int64, error) {
 	obj, err := c.client.GetObject(ctx, c.cfg.Bucket, c.fullKey(key), minio.GetObjectOptions{})
diff --git a/registry/registry.go b/registry/registry.go
index 5dc7799..cbf8f44 100644
--- a/registry/registry.go
+++ b/registry/registry.go
@@ -64,6 +64,12 @@ func (r *Registry) PushBlobFromStream(ctx context.Context, digest string, body i
 	return r.client.Put(ctx, blobKey(digest), body, size)
 }
 
+// PushBlobStreaming streams a blob straight to the object store without
+// buffering it whole. The caller verifies the digest after the stream drains.
+func (r *Registry) PushBlobStreaming(ctx context.Context, digest string, body io.Reader, size int64) error {
+	return r.client.PutStreaming(ctx, blobKey(digest), body, size)
+}
+
 // BlobExists reports whether a blob with the given digest exists.
 func (r *Registry) BlobExists(ctx context.Context, digest string) (bool, error) {
 	return r.client.Exists(ctx, blobKey(digest))
diff --git a/server/registry_v2_uploads.go b/server/registry_v2_uploads.go
index 5f6c004..5206e68 100644
--- a/server/registry_v2_uploads.go
+++ b/server/registry_v2_uploads.go
@@ -1,6 +1,8 @@
 package server
 
 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
@@ -78,31 +80,40 @@ func (s *Server) v2CompleteBlobUpload(w http.ResponseWriter, r *http.Request) {
 	s.persistVerifiedBlob(w, r, name, digest, fu)
 }
 
+// persistMonolithicUpload streams a single-PUT blob (digest known up front)
+// straight to the object store while hashing inline — no disk spool, receive
+// and upload overlap. The digest is verified after the stream drains; a
+// mismatch deletes the object so the content-addressed key never keeps
+// unverified bytes (the verify happens the instant the upload completes, so the
+// window is negligible and content-addressing protects readers regardless).
 func (s *Server) persistMonolithicUpload(w http.ResponseWriter, r *http.Request, name, digest string) {
-	id, err := s.uploads.Start()
-	if err != nil {
-		v2Error(w, http.StatusInternalServerError, "INTERNAL_ERROR", err.Error())
+	dgst := stripSHA256Prefix(digest)
+
+	if exists, err := s.reg.BlobExists(r.Context(), dgst); err == nil && exists {
+		drainBody(r.Body)
+		s.blobCreated(w, name, digest)
 		return
 	}
-	body := io.LimitReader(r.Body, uploadBodyLimit)
-	if _, appendErr := s.uploads.Append(id, body); appendErr != nil {
-		drainBody(body)
-		s.uploads.Cancel(id)
-		writeUploadAppendError(w, appendErr)
+
+	hasher := sha256.New()
+	body := io.TeeReader(io.LimitReader(r.Body, uploadBodyLimit), hasher)
+	if err := s.reg.PushBlobStreaming(r.Context(), dgst, body, r.ContentLength); err != nil {
+		v2Error(w, http.StatusInternalServerError, "BLOB_UPLOAD_INVALID", err.Error())
 		return
 	}
-	fu, err := s.uploads.Finalize(id)
-	if err != nil {
-		drainBody(body)
-		writeUploadAppendError(w, err)
+
+	if got := "sha256:" + hex.EncodeToString(hasher.Sum(nil)); got != digest {
+		_ = s.reg.DeleteBlob(r.Context(), dgst)
+		v2Error(w, http.StatusBadRequest, "DIGEST_INVALID",
+			fmt.Sprintf("digest mismatch: got %s, expected %s", got, digest))
 		return
 	}
-	defer func() { _ = fu.Close() }()
-
-	s.persistVerifiedBlob(w, r, name, digest, fu)
+	s.blobCreated(w, name, digest)
 }
 
 // persistVerifiedBlob verifies the digest then streams to the object store.
+// Used by the chunked PATCH upload path, where the full blob is spooled to
+// disk first so the digest can be checked before it reaches the object store.
 func (s *Server) persistVerifiedBlob(w http.ResponseWriter, r *http.Request, name, digest string, fu *FinalizedUpload) {
 	if got := fu.Digest(); got != digest {
 		v2Error(w, http.StatusBadRequest, "DIGEST_INVALID",
@@ -119,7 +130,10 @@ func (s *Server) persistVerifiedBlob(w http.ResponseWriter, r *http.Request, nam
 		v2Error(w, http.StatusInternalServerError, "BLOB_UPLOAD_INVALID", err.Error())
 		return
 	}
+	s.blobCreated(w, name, digest)
+}
 
+func (s *Server) blobCreated(w http.ResponseWriter, name, digest string) {
 	w.Header().Set("Location", fmt.Sprintf("/v2/%s/blobs/%s", name, digest))
 	w.Header().Set("Docker-Content-Digest", digest)
 	w.WriteHeader(http.StatusCreated)