diff --git a/builtin/rebase--interactive.c b/builtin/rebase--interactive.c
index b4190e58e1..ffbe14cef5 100644
--- a/builtin/rebase--interactive.c
+++ b/builtin/rebase--interactive.c
@@ -71,7 +71,6 @@ static int do_interactive_rebase(struct replay_opts *opts, unsigned flags,
 	const char *head_hash = NULL;
 	char *revisions = NULL, *shortrevisions = NULL;
 	struct argv_array make_script_args = ARGV_ARRAY_INIT;
-	FILE *todo_list_file;
 	struct todo_list todo_list = TODO_LIST_INIT;
 
 	if (prepare_branch_to_be_rebased(opts, switch_to))
@@ -94,14 +93,6 @@ static int do_interactive_rebase(struct replay_opts *opts, unsigned flags,
 	if (!upstream && squash_onto)
 		write_file(path_squash_onto(), "%s\n", squash_onto);
 
-	todo_list_file = fopen(rebase_path_todo(), "w");
-	if (!todo_list_file) {
-		free(revisions);
-		free(shortrevisions);
-
-		return error_errno(_("could not open %s"), rebase_path_todo());
-	}
-
 	argv_array_pushl(&make_script_args, "", revisions, NULL);
 	if (restrict_revision)
 		argv_array_push(&make_script_args, restrict_revision);
@@ -109,16 +100,17 @@ static int do_interactive_rebase(struct replay_opts *opts, unsigned flags,
 	ret = sequencer_make_script(the_repository, &todo_list.buf,
 				    make_script_args.argc, make_script_args.argv,
 				    flags);
-	fputs(todo_list.buf.buf, todo_list_file);
-	fclose(todo_list_file);
 
 	if (ret)
 		error(_("could not generate todo list"));
 	else {
 		discard_cache();
-		ret = complete_action(the_repository, opts, flags,
-				      shortrevisions, onto_name, onto,
-				      head_hash, commands, autosquash);
+		if (todo_list_parse_insn_buffer(the_repository, todo_list.buf.buf,
+						&todo_list))
+			BUG("unusable todo list");
+
+		ret = complete_action(the_repository, opts, flags, shortrevisions, onto_name,
+				      onto, head_hash, commands, autosquash, &todo_list);
 	}
 
 	free(revisions);
diff --git a/sequencer.c b/sequencer.c
index cf716fa5b8..1d5cd2fc27 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4817,93 +4817,82 @@ static int skip_unnecessary_picks(struct repository *r, struct object_id *output
 	return 0;
 }
 
+static int todo_list_rearrange_squash(struct todo_list *todo_list);
+
 int complete_action(struct repository *r, struct replay_opts *opts, unsigned flags,
 		    const char *shortrevisions, const char *onto_name,
 		    const char *onto, const char *orig_head, struct string_list *commands,
-		    unsigned autosquash)
+		    unsigned autosquash, struct todo_list *todo_list)
 {
 	const char *shortonto, *todo_file = rebase_path_todo();
-	struct todo_list todo_list = TODO_LIST_INIT;
-	struct strbuf *buf = &(todo_list.buf);
+	struct todo_list new_todo = TODO_LIST_INIT;
+	struct strbuf *buf = &todo_list->buf;
 	struct object_id oid;
-	struct stat st;
 
 	get_oid(onto, &oid);
 	shortonto = find_unique_abbrev(&oid, DEFAULT_ABBREV);
 
-	if (!lstat(todo_file, &st) && st.st_size == 0 &&
-	    write_message("noop\n", 5, todo_file, 0))
-		return -1;
+	if (buf->len == 0) {
+		struct todo_item *item = append_new_todo(todo_list);
+		item->command = TODO_NOOP;
+		item->commit = NULL;
+		item->arg_len = item->arg_offset = item->flags = item->offset_in_buf = 0;
+	}
 
-	if (autosquash && rearrange_squash_in_todo_file(r))
+	if (autosquash && todo_list_rearrange_squash(todo_list))
 		return -1;
 
 	if (commands->nr)
-		sequencer_add_exec_commands(r, commands);
+		todo_list_add_exec_commands(todo_list, commands);
 
-	if (strbuf_read_file(buf, todo_file, 0) < 0)
-		return error_errno(_("could not read '%s'."), todo_file);
-
-	if (todo_list_parse_insn_buffer(r, buf->buf, &todo_list)) {
-		todo_list_release(&todo_list);
-		return error(_("unusable todo list: '%s'"), todo_file);
-	}
-
-	if (count_commands(&todo_list) == 0) {
+	if (count_commands(todo_list) == 0) {
 		apply_autostash(opts);
 		sequencer_remove_state(opts);
-		todo_list_release(&todo_list);
 
 		return error(_("nothing to do"));
 	}
 
-	strbuf_addch(buf, '\n');
-	strbuf_commented_addf(buf, Q_("Rebase %s onto %s (%d command)",
-				      "Rebase %s onto %s (%d commands)",
-				      count_commands(&todo_list)),
-			      shortrevisions, shortonto, count_commands(&todo_list));
-	append_todo_help(0, flags & TODO_LIST_KEEP_EMPTY, buf);
-
-	if (write_message(buf->buf, buf->len, todo_file, 0)) {
-		todo_list_release(&todo_list);
-		return -1;
-	}
+	if (todo_list_write_to_file(r, todo_list, todo_file,
+				    shortrevisions, shortonto, -1,
+				    flags | TODO_LIST_SHORTEN_IDS | TODO_LIST_APPEND_TODO_HELP))
+		return error_errno(_("could not write '%s'"), todo_file);
 
 	if (copy_file(rebase_path_todo_backup(), todo_file, 0666))
 		return error(_("could not copy '%s' to '%s'."), todo_file,
 			     rebase_path_todo_backup());
 
-	if (transform_todo_file(r, flags | TODO_LIST_SHORTEN_IDS))
-		return error(_("could not transform the todo list"));
-
-	strbuf_reset(buf);
-
-	if (launch_sequence_editor(todo_file, buf, NULL)) {
+	if (launch_sequence_editor(todo_file, &new_todo.buf, NULL)) {
 		apply_autostash(opts);
 		sequencer_remove_state(opts);
-		todo_list_release(&todo_list);
 
 		return -1;
 	}
 
-	strbuf_stripspace(buf, 1);
-	if (buf->len == 0) {
+	strbuf_stripspace(&new_todo.buf, 1);
+	if (new_todo.buf.len == 0) {
 		apply_autostash(opts);
 		sequencer_remove_state(opts);
-		todo_list_release(&todo_list);
+		todo_list_release(&new_todo);
 
 		return error(_("nothing to do"));
 	}
 
-	todo_list_release(&todo_list);
-
-	if (check_todo_list_from_file(r)) {
+	if (todo_list_parse_insn_buffer(r, new_todo.buf.buf, &new_todo) ||
+	    todo_list_check(todo_list, &new_todo)) {
+		fprintf(stderr, _(edit_todo_list_advice));
 		checkout_onto(opts, onto_name, onto, orig_head);
+		todo_list_release(&new_todo);
+
 		return -1;
 	}
 
-	if (transform_todo_file(r, flags & ~(TODO_LIST_SHORTEN_IDS)))
-		return error(_("could not transform the todo list"));
+	if (todo_list_write_to_file(r, &new_todo, todo_file, NULL, NULL, -1,
+				    flags & ~(TODO_LIST_SHORTEN_IDS))) {
+		todo_list_release(&new_todo);
+		return error_errno(_("could not write '%s'"), todo_file);
+	}
+
+	todo_list_release(&new_todo);
 
 	if (opts->allow_ff && skip_unnecessary_picks(r, &oid))
 		return error(_("could not skip unnecessary pick commands"));
diff --git a/sequencer.h b/sequencer.h
index e25f5151d3..7029b39cd6 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -152,7 +152,7 @@ int check_todo_list_from_file(struct repository *r);
 int complete_action(struct repository *r, struct replay_opts *opts, unsigned flags,
 		    const char *shortrevisions, const char *onto_name,
 		    const char *onto, const char *orig_head, struct string_list *commands,
-		    unsigned autosquash);
+		    unsigned autosquash, struct todo_list *todo_list);
 int rearrange_squash_in_todo_file(struct repository *r);
 
 extern const char sign_off_header[];