Slack bolt python use metadata when using blocks in say() function

Question

I have this block of code which is responsible for selecting the namespace:

@app.command("/enable_worker")
def enable_worker(ack, body, say):
 ack()
 blocks = [
 {
 "type": "section",
 "block_id": "section678",
 "text": {
 "type": "mrkdwn",
 "text": ":one: Select the environment you want to setup:"
 },
 "accessory": {
 "action_id": "environment_selector",
 "type": "static_select",
 "placeholder": {
 "type": "plain_text",
 "text": "Select an environment"
 },
 "options": []
 }
 }
 ]
 services = get_services()
 for namespace, service in services.items():
 ns_data = {
 "text": {
 "type": "plain_text",
 "text": f"{namespace}"
 },
 "value": f"{namespace}"
 }
 blocks[0]["accessory"]["options"].append(ns_data)
 say(blocks=blocks)

And this handler for environment_selector:

@app.action("environment_selector")
def environment_selector(ack, body, say):
 ack()
 workers_in_ns = get_services(body["actions"][0]["selected_option"]["value"])
 workers = workers_in_ns[body["actions"][0]["selected_option"]["value"]]
 blocks = [
 {
 "type": "section",
 "block_id": "section678",
 "text": {
 "type": "mrkdwn",
 "text": ":two: Select the worker in this environment you want to update:"
 },
 "accessory": {
 "action_id": "worker_selector",
 "type": "static_select",
 "placeholder": {
 "type": "plain_text",
 "text": "Select a worker"
 },
 "options": []
 }
 }
 ]
 for worker in workers:
 w_data = {
 "text": {
 "type": "plain_text",
 "text": f"{worker[0]}"
 },
 "value": f"{worker[0]}"
 }
 blocks[0]["accessory"]["options"].append(w_data)
 say(blocks=blocks, metadata={"namespace": body["actions"][0]["selected_option"]["value"]})

And I want to pass the namespace to the handler of worker_selector:

@app.action("worker_selector")
def worker_selector(ack, body, say):
 ack()
 print(body)

But the output of body here has no element metadata, how can I pass this variable to the handler?