Approve Slack Messages From an AI Agent

Put a human approval step in front of every Slack message your AI agent sends — review, edit, or reject the exact wording before chat.postMessage fires.

Two different "Slack" problems

There are two unrelated things people mean by "Slack" and Impri approvals, and it's worth being explicit about which one this page covers. Approve AI agent actions from Slack is about using Slack as your notification channel — approval cards for any kind of action (emails, GitHub issues, refunds) show up in a Slack DM with buttons. This page is the other direction: your agent's job is to post messages into Slack, and you want a human to read the exact text before it goes out. The action being gated has kind: "slack.message.send", not the notification transport.

You can combine both — get the review card in Slack for an action that itself posts to Slack — but for a customer-facing channel, most teams don't want approve/reject noise landing in the same workspace the customer can see, so the example below routes notifications elsewhere.

Scenario: a bot in a shared support channel

A company runs a support bot in a Slack Connect channel shared with a customer. The bot reads incoming messages, drafts a reply, and — before this gate existed — posted it immediately. One bad reply in a channel the customer can see is worse than a slow reply, so every draft now waits for a teammate to approve it from their phone.

python
import os
import time
import httpx
from slack_sdk import WebClient

IMPRI_API_KEY = os.environ["IMPRI_API_KEY"]
IMPRI_BASE = "https://api.impri.dev"
slack = WebClient(token=os.environ["SLACK_BOT_TOKEN"])


def propose_and_wait(channel: str, draft: str) -> tuple[str, str] | None:
    """Push a Slack reply draft for approval. Returns (action_id, approved_text), or None."""
    resp = httpx.post(
        f"{IMPRI_BASE}/v1/actions",
        headers={"Authorization": f"Bearer {IMPRI_API_KEY}"},
        json={
            "kind": "slack.message.send",
            "title": f"Reply in #{channel}",
            "preview": {"format": "plain", "body": draft},
            "expires_in": 900,              # 15 minutes — a stale support reply isn't worth sending
            "editable": ["preview.body"],
        },
        timeout=10,
    )
    resp.raise_for_status()
    action_id = resp.json()["id"]

    while True:
        poll = httpx.get(
            f"{IMPRI_BASE}/v1/actions/{action_id}",
            headers={"Authorization": f"Bearer {IMPRI_API_KEY}"},
            timeout=10,
        ).json()
        if poll["status"] != "pending":
            break
        time.sleep(5)

    if poll["status"] != "approved":
        return None

    return action_id, poll["decision"]["final_preview"]["body"]


def handle_customer_message(channel_id: str, draft_reply: str) -> None:
    decision = propose_and_wait(channel_id, draft_reply)
    if decision is None:
        return  # rejected or expired — the bot stays quiet

    action_id, approved_text = decision
    slack.chat_postMessage(channel=channel_id, text=approved_text)

    httpx.post(
        f"{IMPRI_BASE}/v1/actions/{action_id}/result",
        headers={"Authorization": f"Bearer {IMPRI_API_KEY}"},
        json={"status": "executed"},
        timeout=10,
    )

handle_customer_message never calls slack.chat_postMessage on a rejected or expired draft — propose_and_wait returns None and the function exits before reaching the Slack client at all.

What the reviewer sees and can change

Because editable includes preview.body, the approver can fix a tone problem or a factual slip directly in the Impri card before tapping approve. poll["decision"]["final_preview"]["body"] always carries whatever the reviewer left — the edited version if they changed it, the original otherwise — so handle_customer_message never needs to check whether an edit happened; it just uses the field.

Field What it controls
preview.body The draft text shown to the reviewer, and posted to Slack if approved unedited
editable: ["preview.body"] Lets the reviewer rewrite the reply before approving
expires_in: 900 How long an unanswered draft stays postable — short here because support replies age fast
decision.final_preview.body What actually gets sent — always read from here, never from the original draft

Picking where the approval notification lands

Nothing about this pattern requires the approval card itself to avoid Slack — you can route it to a Slack channel via Slack approval exactly as described there, as long as it's a different, internal channel from the one the bot posts into. If you'd rather not stand up Slack OAuth just for reviewing outbound bot messages, a push notification through ntfy or web push gets a reviewer the same one-tap approve/reject without opening Slack at all.

Where this breaks down

This gate only holds if slack.chat_postMessage(or your equivalent Slack call) is unreachable except through handle_customer_message. If the bot process also has a cron job, a webhook handler, or another code path that holds the same SLACK_BOT_TOKEN and can post independently, that path bypasses the gate — Impri has no way to intercept a Slack API call it never sees. Keep the bot token scoped to the one function that calls propose_and_wait first.

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