Custom Slack apps

A custom Slack app answers as one specific Erstan Agent, using its own name, bot account, and Slack installation. Configure it in the Agent’s Triggers section. An Agent can have several custom apps; an app has one Agent assignment at a time.

Before you start

Save the Agent with a single Chat trigger and confirm it is ready to run.
You need edit access to the Agent and permission to create and install apps in your Slack workspace.
People using the app need an Erstan account whose email matches their Slack profile, access to the Agent, and membership in the connection’s workspace or team as selected during setup.

Create an app

Choose the custom app option

Open Agents → your Agent → Triggers → Add trigger. Choose Slack Trigger, click Add trigger, then choose New custom app. Choose Use @erstan in a channel to assign the shared bot to this Agent in a selected channel.

Set the app details

Enter the app name, the tag people mention, and an optional description. Choose Workspace members, Only me, or This Agent’s team when a team is available. Click Continue.

Create and install in Slack

Copy the generated manifest and open Slack’s app dashboard. Choose Create New App → From an app manifest, select the workspace, and paste the JSON. Save and install the app. The manifest enables event subscriptions, interactive approvals, and a writable Messages tab. Set the icon in Slack’s Basic Information → Display Information.

Connect the credentials

In Slack, open Basic Information → App Credentials. In Erstan’s next step, enter Client ID, Client Secret, and Signing Secret, then click Connect to Slack. Complete authorization in the popup. Erstan encrypts these secrets on the server.

Start a conversation

Use the displayed invite command in a channel, then mention the app. You can also open a DM using Open in Slack. A new top-level message starts a conversation; reply in its thread to continue.

Setup stays in the trigger’s settings pane through App details, Slack setup, and Connect. Only Slack authorization opens a popup. Use Save and close to return later: the saved trigger has one Continue setup action, and adding Slack again resumes that unfinished setup. Connected Slack apps and channel bindings appear beside Chat and your other triggers in Inputs.

Use the shared Erstan app

Choose Use @erstan in a channel to make this Agent the default responder in a channel. If the shared app is not connected, select Connect Erstan to Slack and complete authorization in the popup. The channel picker appears here automatically afterward. Active channels the app has joined load from Slack automatically. Search by channel name, select a channel, and click Assign channel. For a missing channel, invite @erstan in Slack and use Refresh channels. Private channels appear only when the app has access. A workspace owner or admin manages the shared installation and channel assignments. New conversations with @erstan in that channel start this Agent directly. Asking the general Erstan assistant to delegate is useful for individual requests; assigning a channel saves that starting choice. The Agent’s delegation, access, and approval rules still apply. Manage Slack connection opens workspace administration separately and preserves your trigger setup.

Connect an existing app

Choose Existing Slack app. In the setup instructions, expand Manifest and manual configuration for the exact OAuth redirect, event subscription, interactivity URL, bot scopes, and bot events. Merge these into the existing Slack app’s configuration, enable a writable Messages tab, reinstall, and connect its credentials. Changing an existing app’s event URL redirects its events to Erstan. Use an app intended for this Agent. Each installation connects to one Slack workspace; token rotation must be disabled.

Conversation settings

Setting	Behavior
Thread replies	Answer every message in an established channel thread, or require an explicit mention. DMs do not require a mention.
Show delegation updates	Show short progress updates about delegated work.
Receive messages	Pause or enable the app connection.
Use for Slack message steps	Choose which bot sends configured Slack message steps during Erstan chats and scheduled runs. An inbound Slack conversation keeps its originating bot, including delegated work. Personal Slack connector tools retain their own connected account.

In a thread, send !link to open your run in Erstan or !stop to request cancellation. These controls only access your own run. Approval buttons use the same permissions and durable decisions as the Erstan app. Requests for more information use the existing conversation reply flow.

Reconnect, reassign, or remove

Reconnect uses the saved credentials. Select Update credentials to replace them. If the trigger needs permissions, use Update permissions, apply the displayed configuration in Slack, and reconnect.
Test connection checks the current bot token and installation identity.
To move a connected app, add a Slack Trigger in another Agent, choose Use a connected app, review the assignment, and confirm Assign app. You need edit access to both Agents. Start a new Slack thread afterward; existing runs stay with their original Agent.
Remove trigger deletes the Erstan connection after confirmation. Uninstall the app separately in Slack if you also want to revoke its installation there.

Troubleshooting

Problem	What to check
Needs a Chat trigger	Save one unambiguous Chat trigger on the Agent, then continue setup.
Slack cannot verify the event URL	Use the exact generated URL. The API must be publicly reachable over HTTPS. After saving credentials, save Event Subscriptions again if Slack requests verification. An untouched draft handshake expires after 24 hours; create a new draft if needed.
Cannot send DMs	Enable the Messages tab and allow messages to the app; verify the manifest’s DM scopes and events, then reinstall.
App does not respond in a channel	Invite the app, mention its bot, and check Receive messages, thread settings, and the sender’s Erstan access.
OAuth popup was closed	Reopen Connect to Slack. A completed installation is recovered when the popup closes.
Reconnect reports a different app or workspace	Use the original installation, or create a separate Erstan connection for the new app.
Credential encryption key is missing	Ask the server operator to configure `SLACK_CUSTOM_APP_CREDENTIAL_SECRET` on API and worker instances.

Custom app setup does not add new Slack tool types. Approvals and conversation replies use Erstan’s existing Slack capabilities; arbitrary Slack forms, modal authoring, and personal connector authentication remain separate features.

​Before you start

​Create an app

​Use the shared Erstan app

​Connect an existing app

​Conversation settings

​Reconnect, reassign, or remove

​Troubleshooting