surfaces/docs/superpowers/specs/2026-04-24-matrix-multi-agent-routing-design.md

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# Matrix Multi-Agent Routing Design
## Goal
Move the Matrix surface from a single hardcoded upstream agent to a user-selectable multi-agent model, while preserving the existing room-based UX and the current `PlatformClient` boundary.
The result should be:
- one Matrix bot can work with multiple upstream agents
- users can choose an agent from the full configured list
- each chat is bound to exactly one agent
- switching the selected agent does not silently retarget an existing chat
## Core Decision
The selected routing model is:
`user.selected_agent_id + room.agent_id + room.platform_chat_id`
This means:
- the user has one current selected agent
- each Matrix working room stores the agent it is bound to
- each Matrix working room stores its own `platform_chat_id`
- a room never changes agent implicitly
- the shared `PlatformClient` protocol remains unchanged
- Matrix multi-agent routing is implemented by a single routing facade that delegates to per-agent real clients
## Why This Decision
The current Matrix adapter already separates:
- user-facing room organization
- local chat labels such as `C1`, `C2`, `C3`
- platform-facing conversation identity via `platform_chat_id`
Adding multi-agent support should preserve that shape instead of replacing it.
If routing depended only on the current user selection, then an old room could start talking to a different agent after a switch. That would make room history and backend context hard to reason about. Binding an agent to the room keeps the conversation model explicit.
## Scope
This design covers:
- agent selection by the user inside the Matrix surface
- durable storage of the selected agent
- durable storage of the room-bound agent
- routing normal messages and context commands to the correct upstream agent
- behavior when a room becomes stale after an agent switch
This design does not cover:
- per-agent workspace isolation
- platform-side agent lifecycle or memory persistence
- per-user allowlists for available agents
- Telegram or other surfaces
## Configuration Model
### Agent registry
Available agents are defined in a local config file loaded once at bot startup.
Example:
```yaml
agents:
- id: agent-1
label: Analyst
- id: agent-2
label: Research
- id: agent-3
label: Ops
```
Rules:
- every entry must have a stable `id`
- every entry must have a user-visible `label`
- all configured agents are selectable by all users
- config changes apply only after bot restart
### Startup validation
If the agent config is missing, empty, or invalid, the Matrix bot must fail fast on startup with a clear operator error.
## Durable State Model
### User-level state
User metadata keeps the current selected agent.
Example `matrix_user:*` shape:
```json
{
"space_id": "!space:example.org",
"next_chat_index": 4,
"selected_agent_id": "agent-2"
}
```
Meaning:
- `selected_agent_id` controls future chat creation and activation of an unbound room
- `selected_agent_id` does not rewrite already bound rooms
### Room-level state
Room metadata stores the agent bound to that chat.
Example `matrix_room:*` shape:
```json
{
"room_type": "chat",
"chat_id": "C3",
"display_name": "Чат 3",
"matrix_user_id": "@alice:example.org",
"space_id": "!space:example.org",
"platform_chat_id": "42",
"agent_id": "agent-2"
}
```
Rules:
- one room binds to exactly one `agent_id`
- one room binds to exactly one current `platform_chat_id`
- once a room becomes stale after an agent switch, it never becomes active again
## Runtime Semantics
### `!start`
`!start` remains lightweight:
- if no agent is selected, the bot explains that an agent must be selected before normal messaging
- if an agent is already selected, the bot reports the current selection and reminds the user that `!new` creates a new room under that agent
### `!agent`
Introduce an agent-selection command.
Behavior:
- `!agent` shows the available agent list
- agent selection stores `selected_agent_id` in user metadata
- after a successful switch, the bot tells the user that existing chats bound to another agent are stale and that `!new` is required for continued work
The exact UI can be text-first for MVP. A richer UI can be added later without changing the state model.
### Normal message without selected agent
If the user has not selected an agent yet:
- do not call the platform
- return the available agent list
- ask the user to choose one first
This is an intentional one-time routing handshake, not an accidental fallback.
In a multi-agent deployment, the surface must not silently guess which agent an unbound user should talk to.
### Selecting an agent inside an unbound chat
If the current room has never been bound to any agent:
- store the new `selected_agent_id` for the user
- bind the current room to that same `agent_id`
- allow the room to become the active working chat immediately
This avoids forcing `!new` for the user's first usable chat.
### `!new`
`!new` creates a new working room under the current selected agent.
Behavior:
1. require `selected_agent_id`
2. create the new Matrix room
3. allocate a new `platform_chat_id`
4. store `agent_id = selected_agent_id` in the new room metadata
### Normal message in an unbound room with selected agent
If a room exists but has no `agent_id` yet and the user already has `selected_agent_id`:
- bind the room to `selected_agent_id`
- ensure it has `platform_chat_id`
- continue normal message dispatch
### Normal message in a bound room
If the room already has `agent_id` and it matches the current selected agent:
- route the message to that `agent_id`
- use the room's `platform_chat_id`
### Stale room after agent switch
If the room's bound `agent_id` differs from the user's current `selected_agent_id`:
- do not call the platform
- treat the room as stale
- return a short message telling the user that this chat belongs to the old agent and that they must use `!new`
### Returning to a previously selected agent
If the user later selects an old agent again:
- previously stale rooms do not become valid again
- the user must still create a fresh room via `!new`
## Routing and Component Changes
### Agent registry loader
Add a small loader responsible for:
- reading `agents.yaml`
- validating ids and labels
- exposing a read-only registry to runtime code
The runtime should not parse YAML ad hoc during message handling.
### Matrix runtime pre-check
Before dispatching a normal message, the Matrix runtime must resolve:
- whether the user has `selected_agent_id`
- whether the current room already has `agent_id`
- whether the room can be bound now
- whether the room is stale
This pre-check happens before handing the message to the existing dispatcher path.
### Routed platform client
The selected implementation keeps the shared `PlatformClient` protocol unchanged.
The Matrix runtime owns one routing-aware facade, for example `RoutedPlatformClient`, that implements `PlatformClient` and delegates to agent-specific real clients.
Responsibilities:
- resolve the current room binding from local Matrix metadata
- translate a local Matrix logical chat id into the room's `platform_chat_id`
- choose the correct per-agent delegate for the room's bound `agent_id`
- keep `get_or_create_user`, `get_settings`, and `update_settings` behavior stable for the rest of the runtime
This keeps the multi-agent logic inside the Matrix integration boundary instead of pushing agent selection into the shared protocol.
### Real platform bridge delegates
The current real backend path hardcodes a single runtime-level `agent_id`.
That must be replaced with per-agent delegates hidden behind the routing facade.
The selected design is:
- `RealPlatformClient` remains the low-level direct-agent delegate for one configured `agent_id`
- the routing facade holds or creates one `RealPlatformClient` delegate per configured agent
- `send_message(...)` and `stream_message(...)` on the facade resolve the room target and forward the call to the matching delegate
- the delegate creates a fresh upstream `AgentApi` for its configured `agent_id`
- no long-lived `AgentApi` instances are cached by user
This preserves the current fresh-connection-per-request behavior while avoiding a protocol break for Telegram or other surfaces.
## Error Handling
### Missing or invalid selected agent
If `selected_agent_id` is absent:
- ask the user to select an agent
If `selected_agent_id` points to an agent that no longer exists in config:
- treat the selection as invalid
- ask the user to select again
### Missing room binding
If the room has no `agent_id`:
- bind it only when the user has a valid current selection
- otherwise return the selection prompt
### Stale room
If the room is stale:
- do not attempt fallback routing
- do not silently rewrite room metadata
- instruct the user to run `!new`
### Invalid config
If the bot cannot load a valid agent registry:
- fail at startup
- do not start in degraded single-agent mode
## Testing Expectations
Tests for this design should prove:
- config parsing and startup validation
- selecting an agent persists `selected_agent_id`
- selecting an agent inside an unbound room activates that room
- `!new` binds the new room to the selected agent
- messages in a bound room use that room's `agent_id`
- stale rooms reject normal messaging with a clear `!new` instruction
- returning to the same agent later does not revive stale rooms
## Migration Notes
Existing rooms may have `platform_chat_id` but no `agent_id`.
For this MVP, treat those rooms as legacy-unbound rooms:
- if the user has a valid selected agent, the room may be bound on first use
- if no agent is selected, the room prompts for selection first
No automatic migration across agents is introduced.
### Existing users without `selected_agent_id`
Existing users upgraded from the single-agent model may have working rooms but no stored `selected_agent_id`.
For this MVP, that is handled explicitly:
- normal messaging is paused until the user selects an agent
- the first valid selection can bind an unbound room immediately
- the surface does not auto-assign a default agent in a multi-agent config
This is intentional. Once more than one agent exists, silent migration would be ambiguous and could route a user to the wrong backend target.