fix(slack): channel user identity, observation mode, and proactive messaging

[vybe]

Problem

Slack channel behavior has three related issues (parallel to #349 for Telegram):

1. User Identity Bug

Agent cannot see who sent a message in channels. The adapter passes sender_id (Slack user ID like U123ABC) but not the user's display name or real name. The agent sees:

What do you think about this approach?

Instead of:

[Channel: #engineering]
[From: John Smith (@johndoe)]

What do you think about this approach?

Root cause: slack_adapter._parse_mention() and _parse_thread_reply() don't fetch user info or include channel name in the context.

2. No Observation Mode

Slack adapter only handles:

• app_mention — @mentions in channels
• message.im — DMs
• Thread replies where bot already responded

There's no way for an agent to observe channel conversations without being explicitly @mentioned. This limits agents that should monitor discussions and contribute when relevant.

Slack API constraint: Observing all channel messages requires the channels:history and/or groups:history OAuth scopes, plus subscribing to message events (not just app_mention).

3. No Proactive Channel Messaging

Agent can wake up on schedule but cannot send messages to Slack channels. Issue #321 covers proactive DMs to users; this is about channel broadcasts.

Current state:

• Channel bindings are stored in slack_channel_agents
• Agent can send responses within the request/response flow
• No MCP tool for outbound channel messages outside that flow

---

Proposed Solution

Phase 1: Fix User Identity

Fetch user info via Slack API and include in context:

async def _enrich_user_context(self, event: dict, team_id: str) -> dict:
    """Fetch user display name and channel name for context."""
    bot_token = db.get_slack_workspace_bot_token(team_id)
    user_id = event.get("user")
    channel_id = event.get("channel")
    
    context = {}
    if bot_token and user_id:
        user_info = await slack_service.get_user_info(bot_token, user_id)
        if user_info:
            context["display_name"] = user_info.get("real_name") or user_info.get("name")
            context["username"] = user_info.get("name")
    
    if bot_token and channel_id:
        channel_info = await slack_service.get_channel_info(bot_token, channel_id)
        if channel_info:
            context["channel_name"] = channel_info.get("name")
    
    return context

Update message_router.py to format this context (shared with Telegram, see #349).

Phase 2: Observation Mode

Add ability for agents to observe channel conversations:

Option A: Event subscription approach

1. Add channels:history / groups:history scopes to OAuth
2. Subscribe to message events for bound channels
3. New observation_mode flag on slack_channel_agents
4. When enabled, all messages (not just @mentions) route to agent
5. Agent can respond with [NO_REPLY] to stay silent

Option B: Periodic polling (simpler)

1. Scheduled job fetches recent messages from bound channels
2. Agent receives batch context periodically
3. Can choose to respond or not

Recommendation: Option A aligns with Telegram #349 and provides real-time awareness.

Database changes:

• Add observation_mode boolean to slack_channel_agents
• Add channel_messages table for history persistence (or reuse session pattern)

Phase 3: Proactive Channel Messaging

Share MCP tools with Telegram (#349):

// Discover channels agent is bound to
list_channel_groups(channel_type?: "telegram" | "slack") 
  → Array<{channel_type, channel_id, channel_name, ...}>

// Send to a channel
send_group_message(
  channel_type: "telegram" | "slack",
  channel_id: string,
  message: string,
  thread_ts?: string  // Slack: optionally post in existing thread
) → {sent: boolean, message_id?: string}

Slack-specific considerations:

• Use chat.postMessage with the workspace's bot token
• Respect channel-level rate limits
• Consider unfurl_links: false for cleaner automated posts

---

Files to Modify

File	Changes
src/backend/adapters/slack_adapter.py	Add _enrich_user_context(), include in parsed messages
src/backend/adapters/message_router.py	Shared group context formatting (with #349)
src/backend/services/slack_service.py	Add get_user_info(), get_channel_info() if missing
src/backend/db/slack_channels.py	Add observation_mode column, message history
src/backend/adapters/transports/slack_socket.py	Subscribe to message events when observation enabled
src/mcp-server/src/tools/channels.ts	Shared tools (with #349)

---

OAuth Scope Changes

Current scopes (likely):

• chat:write, chat:write.customize
• users:read, users:read.email
• app_mentions:read

Additional scopes for observation mode:

• channels:history — read public channel messages
• groups:history — read private channel messages
• channels:read — get channel info

---

Acceptance Criteria

• Agent sees [Channel: #name] [From: Display Name (@username)] prefix
• observation_mode flag enables seeing all channel messages
• Agent can return [NO_REPLY] to skip responding
• Observation mode includes recent message history
• MCP tool list_channel_groups returns agent's Slack channels
• MCP tool send_group_message delivers to Slack channels
• Rate limiting prevents channel spam

Related

• fix(telegram): group chat user identity, observation mode, and proactive messaging #349 — Telegram group behavior (parallel implementation)
• feat: proactive agent messaging to channel users (Telegram / Slack / web) #321 — proactive DM messaging
• feat: Unified channel access control — verified-email identity, per-agent allow-list, access requests (web / Telegram / Slack) #311 — unified channel access control