hermes - 💡(How to fix) Fix feat: Slack adapter — add channel/DM history read scopes and message.channels event subscription

Problem

The Slack gateway adapter currently only supports receiving messages directed at the bot (DMs + explicit @mentions). It cannot read channel history or fetch messages by link/timestamp. This makes it impossible for Hermes to:

• Read a Slack thread when a user drops a slack:// link in chat
• Retrieve historical context from a channel on demand
• Process messages in public/private channels the bot is a member of

The troubleshooting note in the skill already documents the symptom:

Slack bot only works in DMs: Must subscribe to message.channels event. Without it, the bot ignores public channels.

But even subscribing to the event doesn't grant the bot permission to fetch history via the API — that requires additional OAuth scopes.

Required OAuth Bot Token Scopes

For fetching a specific message by link (e.g. https://workspace.slack.com/archives/C0AFX21T06R/p1234567890), the adapter needs to call conversations.history with channel + latest/oldest clamped to that timestamp, which requires channels:history or groups:history depending on channel type.

Required Event Subscriptions (Bot Events)

Proposed Changes

1. OAuth scope manifest — add the six scopes above to the Slack app manifest / setup wizard so users get prompted to re-authorize when upgrading.

2. gateway/platforms/slack.py — expose a fetch_message(channel_id, ts) helper that calls conversations.history and a fetch_thread(channel_id, thread_ts) helper that calls conversations.replies. Wire these up so the gateway can resolve Slack permalink URLs dropped into chat.

3. hermes gateway setup — update the Slack setup wizard to display the required scopes checklist and warn if the token's granted scopes are missing any of the above (using auth.test + apps.permissions.info or parsing the x-oauth-scopes header).

4. Docs — update the Slack platform page to list the required scopes and note that the bot must be invited to any channel it should read (Slack requires this even with channels:history).

Workaround (Today)

Users can manually call the Slack Web API from Hermes via terminal + curl:

curl -s "https://slack.com/api/conversations.history?channel=C0AFX21T06R&limit=10"   -H "Authorization: Bearer $SLACK_BOT_TOKEN" | jq .messages

But this requires the token to already have channels:history and is not surfaced as a native Hermes capability.

References

• Slack API — conversations.history
• Slack API — conversations.replies
• Hermes skill troubleshooting note: "Slack bot only works in DMs: Must subscribe to message.channels event"
• Reported in: internal LaVie session (channels #C0AFX21T06R, #C0AK2H2B1FV unreadable)