G §57, §345: a replace leaves the object it replaced, and a value over a bundle's object limit is refused, never split

Builds: design 47 G §57, §345

Claude-Session: https://claude.ai/code/session_01JG73KEq4zoDfM9WtYpcQgZ

go/stateobjects/ref.go

@@ -27,9 +27,6 @@ type Ref struct {
 	Object string `json:"object"`
 	// Size is the object's size in bytes.
 	Size int64 `json:"size"`
-	// Parts is how many objects the bytes are split over, named `<Object>.<n>` from 0, when the store takes no object as
-	// large as the value (a bundle's runtime carries a message of 16 MiB); zero is one object named Object.
-	Parts int `json:"parts,omitempty"`
 	// Digest is the hex SHA-256 of the object's bytes; a reader checks it after the read.
 	Digest string `json:"sha256"`
 	// Form is FormVersion.
@@ -37,7 +34,7 @@ type Ref struct {
 }
 
 func (r Ref) valid() bool {
-	if r.Store == "" || r.Object == "" || r.Size < 0 || r.Parts < 0 || r.Form != FormVersion || len(r.Digest) != 64 {
+	if r.Store == "" || r.Object == "" || r.Size < 0 || r.Form != FormVersion || len(r.Digest) != 64 {
 		return false
 	}
 	_, err := hex.DecodeString(r.Digest)