Initial project structure

Scaffold all modules, route stubs, data models, and config.
No logic implemented yet — all core methods raise NotImplementedError.
Establishes the full directory layout matching the architecture in CLAUDE.md.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

fellowship/hub/connection_hub.py

@@ -0,0 +1,71 @@
+"""
+Connection hub — manages all WebSocket and SSE connections for a session.
+Broadcasts events to every connected member.
+Multiple talkers and unlimited observers can be connected simultaneously.
+"""
+
+import logging
+from dataclasses import dataclass, field
+from typing import Literal
+
+from fastapi import WebSocket
+from pydantic import BaseModel
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class ConnectedMember:
+    websocket: WebSocket
+    role: Literal["talker", "observer"]
+    talker_id: str | None = None      # Only set for talkers
+    talker_name: str | None = None    # Only set for talkers
+
+
+class ConnectionHub:
+    def __init__(self, session_token: str) -> None:
+        self.session_token = session_token
+        self._members: list[ConnectedMember] = []
+
+    async def connect(self, member: ConnectedMember) -> None:
+        """Accept and register a new WebSocket connection."""
+        await member.websocket.accept()
+        self._members.append(member)
+        logger.info("[%s] member connected role=%s", self.session_token[:8], member.role)
+
+    def disconnect(self, websocket: WebSocket) -> None:
+        """Remove a disconnected WebSocket from the member list."""
+        self._members = [m for m in self._members if m.websocket is not websocket]
+
+    async def broadcast(self, event: BaseModel) -> None:
+        """Send an event to all connected members."""
+        raise NotImplementedError
+
+    async def send_to(self, websocket: WebSocket, event: BaseModel) -> None:
+        """Send an event to a single connection."""
+        raise NotImplementedError
+
+    def talker_count(self) -> int:
+        return sum(1 for m in self._members if m.role == "talker")
+
+    def observer_count(self) -> int:
+        return sum(1 for m in self._members if m.role == "observer")
+
+    def member_count(self) -> int:
+        return len(self._members)
+
+
+# Global registry of hubs — one per active session, keyed by session token
+_hubs: dict[str, ConnectionHub] = {}
+
+
+def get_hub(session_token: str) -> ConnectionHub:
+    """Get or create the ConnectionHub for a session."""
+    if session_token not in _hubs:
+        _hubs[session_token] = ConnectionHub(session_token)
+    return _hubs[session_token]
+
+
+def remove_hub(session_token: str) -> None:
+    """Remove the hub when a session ends."""
+    _hubs.pop(session_token, None)