Slackline

slackline gives the agent a Slack account it owns. Messages arrive from the agent under its own name, and the agent acts on its own:

• It posts to any channel or thread under its own name, and it can attach files. (slackline send)
• It reads recent channel and thread history when it needs context. (slackline read)
• It asks a question and waits for a person to reply, then returns the answer or reports a timeout. (slackline ask)
• It streams mentions, direct messages, reactions, and thread replies as they happen, one compact event line at a time. (slackline listen)
• It adds and removes emoji reactions. (slackline react)
• It downloads files people share with it. (slackline download)

Runtime output is short and agent-readable. read and listen default to compact text, while JSON remains available with --format json where a script needs exact fields.

Once an administrator has provisioned a bot (see Running it), a developer points slackline at that bot's tokens and the agent is live. The whole catalog is one binary:

Available Commands:
  ask         Send a message and wait for a reply
  auth        Authentication commands
  channels    List Slack channels visible to the bot
  download    Download a file from Slack by file ID
  init        Configure slackline with existing tokens
  listen      Listen for real-time Slack events
  provision   Create a Slack app via the manifest API (machine-readable JSON output)
  react       Add or remove emoji reactions on a message
  read        Read messages from a Slack channel
  send        Send a message (and optionally one or more files) to a Slack channel

A first session takes three commands:

slackline init                                              # store the bot's tokens
slackline auth status                                       # confirm the identity
slackline send --channel '#ops' --message 'Deploy finished'

send returns the channel and timestamp of the posted message as JSON, so the agent can thread its next reply. To watch for work, the agent streams events and filters to the types it cares about:

slackline listen --type mention

Each event is one line on stdout. listen describes its own output:

Default text examples:
  mention C123 U123 100.001 <@UBOT> hello
  dm D123 U123 100.002 hello
  thread_reply C123 U123 100.003 thread=100.001 parent=UBOT reply
  reaction added C123 U123 item=100.001 thumbsup
  file F123 report.pdf 12345 application/pdf Q4 Report

The exact output each command returns is documented in the README. The command examples above are real; a live message response carries values from your own workspace, so producing one needs a configured bot.

slackline fits teams that run AI agents and want those agents working inside Slack: posting build and incident updates, watching channels for mentions, answering in threads, and reacting to events. It fits developers who want a scriptable Slack identity they can drive from a shell or a cron job.

It is built for agents and automation. People who want a chat client for themselves are served better by Slack's own apps. It is messaging and events, so a project that needs a full Slack app experience, with Block Kit interfaces and slash-command backends, needs an app framework instead. It runs on darwin/arm64 and linux/amd64; other platforms are out of scope today.

• The agent reads, asks, and listens only in channels it has joined. A person adds it with /invite @bot-name. (user)
• Live event streaming holds a Socket Mode connection open and runs for as long as the process runs. (user)
• Provisioning a brand-new bot drives Slack's admin web pages through browser automation for the install and token steps. (operator)
• An app token's validity cannot be checked through Slack's REST API, so auth status reports it as configured rather than valid. (operator)
• Supported platforms today are darwin/arm64 and linux/amd64. (operator)