Summary

Two one-line fixes in gateway/platforms/matrix.py to ensure Matrix rooms are identifiable in session context:

Fix 1 (first commit): _resolve_message_context() now calls get_chat_info() to resolve the Matrix room name from m.room.name state and passes chat_name + chat_type to build_source(). Previously these were omitted — every room showed as the sender display name.

Fix 2 (second commit): get_chat_info() now overrides chat_type to "group" when a room has m.room.name. A named Matrix room is semantically a workspace, not a personal DM, regardless of member count.

Together these ensure named rooms appear as "group: RoomName" in session source descriptions instead of the generic "DM with AVP".

Problem

The Matrix adapter was omitting chat_name when building session sources. Even after fix 1 propagated the room name, session.py ignored chat_name for chat_type="dm" rooms. Since all self-hosted Matrix rooms are 2-person (user + bot), _is_dm_room() returned True for every room — making all rooms appear identical in the system prompt.

Data flow (after both fixes)

Matrix message arrives in "Development" room
  → _resolve_message_context()
    → get_chat_info(room_id)
      → _is_dm_room() → True → chat_type = "dm"
      → get_state_event(m.room.name) → "Development"
      → name = "Development"
      → chat_type = "group"  ← FIX 2: named room = workspace
    → build_source(chat_name="Development", chat_type="group")
  → SessionSource.description → "group: Development"
  → Agent prompt: "Source: Matrix (group: Development)"

Design consistency

Session migration

• New sessions: Immediately correct — chat_type is "group" for named rooms.
• Existing sessions: Have chat_type="dm" baked into the session key and data. They must be deleted for the fix to take effect. sessions.json and channel_directory.json will auto-rebuild on next messages.
• No data loss: Honcho memory, local memory, skills, config, and cron jobs are untouched.

To apply on an existing deployment:

systemctl --user stop hermes-gateway
rm ~/.hermes/sessions/sessions.json
rm ~/.hermes/sessions/session_*.json    # optional: individual session traces
rm ~/.hermes/channel_directory.json
systemctl --user start hermes-gateway

Verification

1. Send a message from a named Matrix room (Development, Homeassistant, etc.)
2. Check ~/.hermes/sessions/sessions.json — origin should show chat_type: "group" and correct display_name
3. Agent system prompt should show "Source: Matrix (group: Development)" instead of "Source: Matrix (DM with AVP)"

Closes #38805