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+# Side Chat Spec (muse.ai)
+
+## Overview
+Side chats are isolated conversation contexts within a muse.ai agent.
+Each side chat maps to an organizational unit (channel, thread, task)
+with rich metadata for orchestration.
+
+## Data Model
+
+```json
+{
+  "side_chat_id": "string (unique, from muse.ai)",
+  "channel_id": "string (required) - the front-door channel this belongs to (e.g., '#lobby', '#ops')",
+  "thread_id": "string (optional) - specific thread within the channel, if applicable",
+  "agent": "string (required) - which muse agent owns this side chat (e.g., 'muse', 'pip', '646')",
+  "prompted_by": "string (optional) - what triggered creation: 'operator', 'agent', 'timer', 'user'",
+  "mentioned_by": "string (optional) - if created from an @mention, who mentioned",
+  "timespan": {
+    "start": "ISO8601 (required) - when this side chat context begins",
+    "end": "ISO8601 (optional) - when it ends, if bounded"
+  },
+  "purpose": "string (required) - why this side chat exists (e.g., 'onboarding', 'incident-123', 'sprint-planning')",
+  "status": "active | archived | pending",
+  "metadata": {
+    "created_at": "ISO8601",
+    "last_activity": "ISO8601",
+    "message_count": "integer",
+    "participants": ["array of agent/user IDs"],
+    "tags": ["array of strings"]
+  }
+}
+```
+
+## Compact Notation
+`{channel_id:thread?:agent:prompted_by:timespan}`
+
+Examples:
+- `{#lobby::muse:operator:2026-10-03T14:00/2026-10-03T15:00}` 
+  → Lobby channel, no thread, muse agent, prompted by operator, 1-hour span
+- `{#ops:thread-123:pip:timer:2026-10-03T00:00/}` 
+  → Ops channel, thread-123, pip agent, prompted by timer, open-ended
+
+## Lifecycle
+
+1. **Create**: Operator or agent initiates via chat API
+   - `muse-chat-api.py --account <agent> sidechat create --channel <id> --purpose <str>`
+   - Returns `side_chat_id`
+
+2. **Activate**: Switch API context to the side chat
+   - `muse-chat-api.py --account <agent> sidechat use <id>`
+   - Subsequent `send`/`messages` operate in this context
+
+3. **Archive**: Mark as done, preserve history
+   - `muse-chat-api.py --account <agent> sidechat archive <id>`
+
+4. **List**: Show all side chats for an agent
+   - `muse-chat-api.py --account <agent> sidechat list`
+
+## Mapping to Front-Door
+
+| muse.ai side chat | front-door equivalent |
+|-------------------|----------------------|
+| channel_id | Chat channel (#lobby, #ops) |
+| thread_id | Board thread or chat thread |
+| agent | Agent identity (muse, pip, 646) |
+| timespan | Incident window, sprint, task duration |
+| purpose | Ticket ID, onboarding flow, etc. |
+
+## Why This Matters
+
+- **Isolation**: Each side chat is a separate context — no cross-contamination
+- **Orchestration**: Operators can manage dozens of agents by channel/purpose/timespan
+- **Audit**: Every side chat has provenance (who created, why, when)
+- **Agent-first**: Agents can create side chats for subtasks, operators oversee via metadata
+
+## Implementation Status
+
+- [ ] `sidechat create` command in muse-chat-api.py
+- [ ] `sidechat list` command
+- [ ] `sidechat use` (context switch)
+- [ ] `sidechat archive` command
+- [ ] Metadata persistence (local JSON or via API)
+- [ ] Integration with front-door channels
+
+## Notes
+
+- Side chats are a muse.ai UI feature (the "new chat" / sidebar).
+- The API manipulates them via CDP (clicking, navigating).
+- Metadata is maintained by the operator layer, not muse.ai itself.
+- This spec is version 0.1 — will evolve as we discover the API surface.