Sprint 1 : scaffolding complet de Glibredecision

Plateforme de decisions collectives pour Duniter/G1.
Backend FastAPI async + PostgreSQL (14 tables, 8 routers, 6 services,
moteur de vote avec formule d'inertie WoT/Smith/TechComm).
Frontend Nuxt 4 + Nuxt UI v3 + Pinia (9 pages, 5 stores).
Infrastructure Docker + Woodpecker CI + Traefik.
Documentation technique et utilisateur (15 fichiers).
Seed : Licence G1, Engagement Forgeron v2.0.0, 4 protocoles de vote.
30 tests unitaires (formules, mode params, vote nuance) -- tous verts.

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

backend/app/routers/websocket.py

@@ -0,0 +1,140 @@
+"""WebSocket router: live vote updates."""
+
+from __future__ import annotations
+
+import json
+import uuid
+from typing import Any
+
+from fastapi import APIRouter, WebSocket, WebSocketDisconnect
+
+router = APIRouter()
+
+
+# ── Connection manager ──────────────────────────────────────────────────────
+
+
+class ConnectionManager:
+    """Manages active WebSocket connections grouped by vote session ID."""
+
+    def __init__(self) -> None:
+        # session_id -> list of connected websockets
+        self._connections: dict[uuid.UUID, list[WebSocket]] = {}
+
+    async def connect(self, websocket: WebSocket, session_id: uuid.UUID) -> None:
+        """Accept a WebSocket connection and register it for a vote session."""
+        await websocket.accept()
+        if session_id not in self._connections:
+            self._connections[session_id] = []
+        self._connections[session_id].append(websocket)
+
+    def disconnect(self, websocket: WebSocket, session_id: uuid.UUID) -> None:
+        """Remove a WebSocket connection from the session group."""
+        if session_id in self._connections:
+            self._connections[session_id] = [
+                ws for ws in self._connections[session_id] if ws is not websocket
+            ]
+            if not self._connections[session_id]:
+                del self._connections[session_id]
+
+    async def broadcast(self, session_id: uuid.UUID, data: dict[str, Any]) -> None:
+        """Broadcast a message to all connections watching a given vote session."""
+        if session_id not in self._connections:
+            return
+
+        message = json.dumps(data, default=str)
+        dead: list[WebSocket] = []
+
+        for ws in self._connections[session_id]:
+            try:
+                await ws.send_text(message)
+            except Exception:
+                dead.append(ws)
+
+        # Clean up dead connections
+        for ws in dead:
+            self.disconnect(ws, session_id)
+
+
+manager = ConnectionManager()
+
+
+# ── WebSocket endpoint ──────────────────────────────────────────────────────
+
+
+@router.websocket("/live")
+async def live_updates(websocket: WebSocket) -> None:
+    """WebSocket endpoint for live vote session updates.
+
+    The client connects and sends a JSON message with the session_id
+    they want to subscribe to:
+
+        { "action": "subscribe", "session_id": "<uuid>" }
+
+    The server will then push vote update events to the client:
+
+        { "event": "vote_update", "session_id": "...", "votes_for": N, "votes_against": N, "votes_total": N }
+        { "event": "session_closed", "session_id": "...", "result": "adopted|rejected" }
+
+    The client can also unsubscribe:
+
+        { "action": "unsubscribe", "session_id": "<uuid>" }
+    """
+    await websocket.accept()
+    subscribed_sessions: set[uuid.UUID] = set()
+
+    try:
+        while True:
+            raw = await websocket.receive_text()
+
+            try:
+                data = json.loads(raw)
+            except json.JSONDecodeError:
+                await websocket.send_text(json.dumps({"error": "JSON invalide"}))
+                continue
+
+            action = data.get("action")
+            session_id_str = data.get("session_id")
+
+            if not action or not session_id_str:
+                await websocket.send_text(
+                    json.dumps({"error": "Champs 'action' et 'session_id' requis"})
+                )
+                continue
+
+            try:
+                session_id = uuid.UUID(session_id_str)
+            except ValueError:
+                await websocket.send_text(json.dumps({"error": "session_id invalide"}))
+                continue
+
+            if action == "subscribe":
+                if session_id not in subscribed_sessions:
+                    # Register this websocket in the manager for this session
+                    if session_id not in manager._connections:
+                        manager._connections[session_id] = []
+                    manager._connections[session_id].append(websocket)
+                    subscribed_sessions.add(session_id)
+
+                await websocket.send_text(
+                    json.dumps({"event": "subscribed", "session_id": str(session_id)})
+                )
+
+            elif action == "unsubscribe":
+                if session_id in subscribed_sessions:
+                    manager.disconnect(websocket, session_id)
+                    subscribed_sessions.discard(session_id)
+
+                await websocket.send_text(
+                    json.dumps({"event": "unsubscribed", "session_id": str(session_id)})
+                )
+
+            else:
+                await websocket.send_text(
+                    json.dumps({"error": f"Action inconnue: {action}"})
+                )
+
+    except WebSocketDisconnect:
+        # Clean up all subscriptions for this client
+        for session_id in subscribed_sessions:
+            manager.disconnect(websocket, session_id)