Coding Agent Slack Notifications

Slack notifications for AI coding agents. Get notified in Slack when your agent finishes a task, encounters an error, or needs your input.

Works with Claude Code and OpenCode.

Prerequisites

A Slack incoming webhook URL. See Adding a Slack App With Inbound Webhooks below if you don't have one yet.

Installation

git clone https://github.com/james-hill/coding-agent-slack-notifications.git
cd coding-agent-slack-notifications

Claude Code

./install-claudecode.sh

This registers hooks in ~/.claude/settings.json that fire on Stop and Notification events.

OpenCode

./install-opencode.sh

This copies the TypeScript plugin to ~/.config/opencode/plugins/. The plugin listens for session.idle, session.error, and permission.asked events.

Both installers copy notify.yaml.template to ~/.config/slack-notifications/notify.yaml if it doesn't already exist. They also install slash commands so you can manage notifications from within your agent.

Configuration

The easiest way to configure is with the /notify-config slash command from within your agent session:

/notify-config webhook_url https://hooks.slack.com/services/<YOUR-WEBHOOK-URL>
/notify-config debounce_seconds 5
/notify-config                   # show current values

You can also edit ~/.config/slack-notifications/notify.yaml directly:

enabled: true
webhook_url: https://hooks.slack.com/services/<YOUR-WEBHOOK-URL>
debounce_seconds: 10

Key	Default	Description
enabled	false	Enable or disable notifications entirely
webhook_url	(none)	Slack incoming webhook URL
debounce_seconds	10	Debounce window — waits this many seconds and only sends if no newer event occurs

Environment variables override config file values. Set them in your shell profile (e.g. ~/.zshrc) or in a .env file if you're using Docker Compose.

Variable	Overrides
SLACK_NOTIFICATIONS_WEBHOOK	webhook_url
SLACK_NOTIFICATIONS_DEBOUNCE_SECONDS	debounce_seconds

Slash Commands

These are installed automatically and available inside your agent session:

Command	Description
/notify-on	Enable notifications
/notify-off	Disable notifications
/notify-config <key> <value>	Update webhook_url or debounce_seconds
/notify-config	Show current config values

Files

File	Description
notify.py	Shared notification script that posts to Slack
notify.yaml.template	Config template (copied to ~/.config/slack-notifications/notify.yaml on install)
install-claudecode.sh	Installer for Claude Code hooks
opencode-plugin.ts	OpenCode plugin (TypeScript)
install-opencode.sh	Installer for OpenCode plugin
commands/	Slash command definitions installed for agent use

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Appendix: Adding a Slack App With Inbound Webhooks

Step 1: Create a private Slack channel

• Open Slack and click the + icon next to Channels in the left sidebar
• Select Create a new channel
• Name it agent-notifications (or similar — any name you like)
• Set the channel to Private
• Click Create

Step 2: Create a Slack app and configure incoming webhooks

• Go to https://api.slack.com/apps
• Click Create New App
• Select From scratch
• Give your app a name (e.g., "OpenCode Notifications")
• Select your workspace from the dropdown
• Click Create App
• In the left sidebar, click Incoming Webhooks
• Toggle Activate Incoming Webhooks to On
• Click Add New Webhook to Workspace
• Select the channel you created earlier
• Click Allow

Step 3: Get the webhook URL

After allowing, you'll see a webhook URL that looks like:

https://hooks.slack.com/services/<YOUR-WEBHOOK-URL>

Copy this URL — you'll use it during configuration.

Step 4: Configure and test

After installing, set your webhook URL and enable notifications from within your coding agent:

/notify-config webhook_url https://hooks.slack.com/services/<YOUR-WEBHOOK-URL>
/notify-on

Run a simple command and wait for it to complete. You should receive a message in your Slack channel when the agent finishes.

Use /notify-on and /notify-off inside your coding agent session to control notifications at any time.