Summary

• Add Slack as the 8th messaging channel using Socket Mode (WebSocket-based, no public HTTP endpoint needed)
• Support bidirectional messaging in channels, DMs, and threads with per-thread session context
• Handle @mentions, ack reactions (:eyes: on receipt, :white_check_mark: after reply), and /picoclaw slash commands
• Support file/attachment downloads with Groq Whisper audio transcription
• Allowlist filtering by Slack user ID

Files Changed

• pkg/channels/slack.go — Full Slack channel implementation (Socket Mode, events, threads, reactions, files)
• pkg/channels/slack_test.go — Unit tests for ChatID parsing, bot mention stripping, constructor validation, allowlist
• pkg/config/config.go — Add SlackConfig struct with bot_token, app_token, allow_from
• pkg/channels/manager.go — Register Slack channel in initChannels()
• cmd/picoclaw/main.go — Wire Groq transcriber to Slack channel
• config.example.json — Add Slack config section
• go.mod / go.sum — Add github.com/slack-go/slack v0.17.3 dependency

Configuration

{
  "channels": {
    "slack": {
      "enabled": true,
      "bot_token": "xoxb-...",
      "app_token": "xapp-...",
      "allow_from": []
    }
  }
}

Slack App Setup

1. Create Slack App at api.slack.com/apps
2. Enable Socket Mode → generate App-Level Token (xapp-...)
3. Bot Token Scopes: chat:write, channels:history, groups:history, im:history, mpim:history, reactions:read, reactions:write, files:read, commands, app_mentions:read
4. Event Subscriptions: message.channels, message.groups, message.im, message.mpim, app_mention, reaction_added, reaction_removed
5. Optional: Create slash command /picoclaw
6. Install to workspace → copy Bot Token (xoxb-...)

Test plan

• go build ./... compiles cleanly
• go test ./... all tests pass
• go vet ./... no issues
• Manual test with a Slack workspace (requires Slack App setup)

Closes #31

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