Add db uuid4 func and uuid insert message param

internal/db/queries.go

@@ -313,6 +313,8 @@ type InsertMessageParams struct {
 	Content string
 	// ConversationId identifies the conversation that owns the new row.
 	ConversationId string
+	// Id is the new row's UUID. Nil generates a version 4 UUID.
+	Id *uuid.UUID
 	// Metadata is inference JSON converted to JSONB for storage.
 	// Nil stores SQL NULL; malformed JSON causes insertion to fail.
 	Metadata jsontext.Value
@@ -324,6 +326,12 @@ type InsertMessageParams struct {
 
 // InsertMessage creates a new message.
 func (q *Queries) InsertMessage(ctx context.Context, arg InsertMessageParams) (*Message, error) {
+	var id uuid.UUID
+	if arg.Id == nil {
+		id = uuid.NewV4()
+	} else {
+		id = *arg.Id
+	}
 	var metadataArg any
 	if arg.Metadata != nil {
 		metadataArg = string(arg.Metadata)
@@ -331,7 +339,7 @@ func (q *Queries) InsertMessage(ctx context.Context, arg InsertMessageParams) (*
 	row := q.db.QueryRowContext(
 		ctx,
 		insertMessage,
-		uuid.New().String(),
+		id.String(),
 		arg.Content,
 		arg.ConversationId,
 		metadataArg,