hermes - 💡(How to fix) Fix send_message: Discord DMs fail with 'Unknown Channel' when target is a user ID

Summary

send_message cannot deliver Discord DMs when given a user ID. It treats every numeric ID after discord: as a channel ID and calls POST /channels/{id}/messages directly, which returns 404 Unknown Channel (10003) because user IDs are not channel IDs.

Discord requires opening a DM channel first via POST /users/@me/channels with {"recipient_id": USER_ID}, then posting to the resulting channel ID.

Reproduction

1. Configure Discord bot token (DISCORD_BOT_TOKEN) and confirm gateway is running.
2. Get any Discord user ID that shares a guild with the bot.
3. Call:

   send_message(target="discord:1173534822736597085", message="hi")

Expected

DM is delivered to the target user.

Actual

{"error": "Discord API error (404): {\"message\": \"Unknown Channel\", \"code\": 10003}"}

Workaround

Currently the only path is calling Discord's REST API directly:

# 1) Open or fetch DM channel
curl -X POST https://discord.com/api/v10/users/@me/channels \
  -H "Authorization: Bot $DISCORD_BOT_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"recipient_id":"USER_ID"}'
# → returns {"id": "DM_CHANNEL_ID", ...}

# 2) Send message
curl -X POST https://discord.com/api/v10/channels/DM_CHANNEL_ID/messages \
  -H "Authorization: Bot $DISCORD_BOT_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"content":"hi"}'

This works but bypasses the tool entirely (no chunking, retries, or adapter features).

Suggested fix

In tools/send_message_tool.py Discord branch (around the Platform.DISCORD dispatch, ~L250):

1. Introduce an explicit discord:dm:USER_ID syntax (most explicit, no ambiguity), or
2. Auto-detect: when the supplied ID resolves to a user (via GET /users/{id} or by failing the channel send with 10003), open a DM channel via POST /users/@me/channels and retry.

Option 1 is preferable — it's unambiguous, avoids an extra round-trip, and is consistent with Telegram-style chat_id semantics. The existing target-parser (_parse_target / _NUMERIC_TOPIC_RE) already handles prefix-style routing (e.g. discord:CHANNEL_ID:THREAD_ID), so adding a dm: keyword is a small change.

Cache the resulting DM channel id per-recipient to avoid hitting /users/@me/channels on every send.

Doc update

The target parameter description in the tool schema (line ~130) lists Discord formats but not DMs. Should mention discord:dm:USER_ID (or whatever syntax is chosen) once implemented.

Environment

• Hermes v2026.3.28
• discord.py 2.7.1, aiohttp 3.13.5
• Python venv at ~/.hermes/hermes-agent/venv