Slack Developer Updates & Release Notes

We're rolling out a wave of updates to agents on Slack, along with an important heads-up about the road ahead for the Assistant messaging experience.

Agent updates and the deprecation of assistant_view​

The Assistant messaging experience (assistant_view) will be deprecated in February 2027. The assistant-related methods that power it are being replaced by a new set of API methods: the Agent Sessions API. Agent sessions let users manage their conversations with your agent in one place, with a status, a title, and a stop button. The agents.sessions.setStatus and agents.sessions.rename API methods replace the assistant.threads.setStatus and assistant.threads.setTitle API methods, respectively. For now, your existing calls keep working through a compatibility bridge. See the Agent sessions guide to get started.

The Agent messaging experience (agent_view) is already available, and we recommend moving to it now. If your app still uses assistant_view, follow the migration guide to move to the new experience. Read more in the guide to developing agents.

What's new for agents​

Alongside this announcement, we're releasing a set of improvements to the agent experience:

• Upgraded Tools tab: a newly renamed and revamped Agents & Tools tab helps users find popular agents with a new landing page.
• Improved thread experience: including multi-agent stacking, thread naming, a revamped thinking UI, and a native stop button for agent streams. When a user stops your agent, your app receives an agent_session_stopped event.
• Plan and Task card block updates: UI refinements to the plan and task card blocks agents use to show their work.
• Marketplace data in the About tab: an agent's Marketplace data now appears in its About tab.
• Agent sessions in the sidebar: A new sidebar with pin / archive / unread and live updates.

An agent can answer a question in a thread, but some tasks become bigger than a single question. A coding agent may need to implement a change, share a prototype, and iterate on it. A research agent may need to gather information and work through decisions with the people involved. This kind of work needs more than a single response.

Slack Code is how agents and people work together to build with AI in Slack, creating dedicated channels for more involved work.

A channel is created from an existing conversation, context is carried forward, and agents and collaborators have a shared, visible place to work.

Within a session, agents can publish artifacts for people to oversee and iterate on:

• Code diffs, so people can review what changed
• Block Kit views, for structured interactive experiences
• HTML previews, for prototypes and generated interfaces
• Canvases, for longer-form content and collaboration

The work becomes multiplayer: teammates can join channels, review work, add context, and help make decisions, all while collaborating in the same session and with the same artifacts. Your agent manages the lifecycle, creating a channel when a task warrants one, sharing updates as the work progresses, and closing the session once the work is complete.

Read on to learn more:

• Slack Code: where your team and agents build together
• Build with AI as a team using Slack Code

We're excited to introduce the Slack MCP and Skills Plugin for AI tools, which bundles a set of skills that help you develop on the Slack platform alongside the Slack MCP Server. The plugin is currently available for Claude Code and Cursor.

Installing the plugin sets up two things:

Skills

Focused sets of instructions and references that your assistant loads automatically when a task calls for them. The plugin includes skills for Block Kit, scaffolding new apps, calling Web API methods, using the Slack CLI, composing messages, and searching Slack.

Slack MCP Server connection

The Slack MCP server lets you and your agent interact directly with your Slack workspace, such as searching channels, sending messages, and managing canvases.

Install the plugin in Claude Code with /plugin install slack@claude-plugins-official, or from the Cursor Marketplace.

Read the Slack MCP and Skills Plugin docs to get started.

Version 4.5.0 of the developer tools for the Slack platform has landed!

The Slack CLI now recommends the official Slack plugin to Claude Code users.

We've reduced the verbose output when using create --app to link an existing app during project creation.

We've added a --category flag to slack docs search command.

When the CLI errors because a prompt must be shown while in a non-TTY environment (AI agents, devops scripts, etc.), the error message now displays the prompt and, for app and team selection, the matching flags to select an option.

We've fixed a recurring unable_to_parse_json error caused by empty JSON files (credentials, config, or app state) left behind by an interrupted write; the CLI now treats them as empty state and recovers automatically.

Version 5.0.0 of Bolt for JS is here! This release follows the Node Slack SDK's shift from axios to the native Fetch API, removes the deprecated Workflow Steps from Apps feature, and raises the minimum Node.js version to 20.

If your app doesn't use proxy/TLS configuration or inspect respond() return values, this upgrade is possibly only a version bump.

New features

We've added a dispatcher option to the SocketModeReceiver class.

We've added instanceof operator support to error classes.

Breaking changes

We've raised the minimum Node.js version to 20.

We've removed the agent and clientTls options from the AppOptions interface.

We've updated the SocketModeReceiver class to accept a dispatcher option instead of proxy agents.

We've removed Workflow Steps from Apps.

We've updated the respond() utility function to return a native Response object.

We've upgraded the Node Slack SDK dependencies.

We've improved error handling throughout.

For full migration details, see the Bolt for JS v4 to v5 migration guide.

Our collection of Node Slack SDK packages have received new major versions.

All packages now require Node.js 20 or later. This is the only breaking change for the following packages:

• The cli-hooks package has been updated to v2.
• The cli-test package has been updated to v4.
• The logger package has been updated to v5.
• The oauth package has been updated to v4.
• The types package has been updated to v3.

Three packages have more substantial breaking changes:

• The socket-mode package has been updated to v3. See the guide on migrating @slack/socket-mode from v2 to v3 for handling breaking changes.
• The web-api package has been updated to v8. See the guide on migrating @slack/web-api from v7 to v8 for handling breaking changes.
• The webhook package has been updated to v8. See the guide on migrating @slack/webhook from v7 to v8 for handling breaking changes.

Most of the changes in those batch of updates fall under the theme of HTTP transport improvements, such as migrating from axios to the native Fetch API.

Agent apps can now receive context about what a user is currently viewing when they send a message. When a user has a channel, DM, thread, canvas, or list open and messages your app, Slack will pass that context automatically.

Here's what developers need to know:

New event: app_context_changed

Slack will send an app_context_changed event to your app whenever the user's active context changes. The event payload includes an ordered list of entities the user is currently viewing.

The app_context is now sent to message.im and app_home_opened events

Slack will also send the app_context to these events if the app is subscribed to the app_context_changed event.

Learn more in the guide to Developing agents.

Agents now support a new messaging experience, set by your app manifest:

Agent messaging experience (agent_view)

agent conversations now look & feel the same as a regular direct message. Gone is the history tab and new chat button. Instead, all of your conversations appear in the standard message tab and your agent can respond in-thread.

Assistant messaging experience (assistant_view)

agent conversations happen in separate Chat and History tabs.

New apps can only use the Agent messaging experience. Apps that already use the Assistant messaging experience can continue to use it for now, but assistant_view will eventually be deprecated, and we'll ask existing apps to migrate to agent_view.

The Agent messaging experience changes the following:

• Knowing when a user opens a DM: rely on the app_home_opened event to know when a user has actively opened a DM with your app. The assistant_thread_started event no longer indicates this. See Developing an agent for details.
• Suggested prompts: suggested prompts now live at the top of the Messages tab instead of within threads, and the thread_ts argument is no longer required when agent_view is enabled.
• Continuing a conversation: after a user sends a new message, calling the assistant.threads.setStatus API method on that thread automatically opens the thread to keep the conversation going.

The Slack CLI v4.4.0, Python SDK v3.43.0 with Bolt Python v1.29.0, and @slack/[email protected] (for the Node Slack SDK) are required to access the Agent View feature.

Already have an app using the Assistant messaging experience? Follow the migration checklist to move to the Agent messaging experience. Read more in the guide to developing agents.