feat(mcp): catalogue préconfiguré + état persisté + infra pytest

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/mcp_client.py

@@ -0,0 +1,89 @@
+"""Client MCP : catalogue préconfiguré + sessions vers les serveurs activés.
+
+Un serveur désactivé n'est jamais démarré et n'expose aucun outil au modèle
+(chaque outil injecté coûte du contexte). Connexion lazy au premier message,
+session réutilisée ensuite. Toute panne est non bloquante pour le chat.
+"""
+from __future__ import annotations
+
+import logging
+
+from . import db
+
+logger = logging.getLogger(__name__)
+
+MCP_KEY = "mcp"
+
+# Catalogue embarqué. command=None => serveur "custom" (commande utilisateur).
+CATALOG: dict[str, dict] = {
+    "playwright": {
+        "label": "Playwright (navigateur)",
+        "description": "Pilote un vrai navigateur : naviguer, cliquer, lire "
+                       "la console, captures. L'agent teste réellement ses pages.",
+        "command": ["npx", "@playwright/mcp@latest", "--headless"],
+        "url_param": False,
+        "env_params": [],
+        # Limite le nombre d'outils injectés dans le prompt.
+        "expose": [
+            "browser_navigate", "browser_click", "browser_type",
+            "browser_snapshot", "browser_console_messages",
+            "browser_take_screenshot",
+        ],
+    },
+    "context7": {
+        "label": "Context7 (documentation)",
+        "description": "Documentation à jour de n'importe quelle librairie ou "
+                       "framework (React, FastAPI, Tailwind…).",
+        "command": ["npx", "-y", "@upstash/context7-mcp"],
+        "url_param": False,
+        "env_params": [],
+        "expose": None,
+    },
+    "fetch": {
+        "label": "Fetch (lecture web)",
+        "description": "Lit proprement n'importe quelle URL (markdown épuré).",
+        "command": ["python", "-m", "mcp_server_fetch"],
+        "url_param": False,
+        "env_params": [],
+        "expose": None,
+    },
+    "searxng": {
+        "label": "SearxNG (recherche web)",
+        "description": "Vraie recherche web via une instance SearxNG "
+                       "(renseigner SEARXNG_URL).",
+        "command": ["npx", "-y", "mcp-searxng"],
+        "url_param": False,
+        "env_params": ["SEARXNG_URL"],
+        "expose": None,
+    },
+    "custom": {
+        "label": "Personnalisé",
+        "description": "N'importe quel serveur MCP : colle une commande "
+                       "(stdio) ou une URL (streamable HTTP).",
+        "command": None,
+        "url_param": True,
+        "env_params": [],
+        "expose": None,
+    },
+}
+
+
+def get_mcp_state() -> dict:
+    """État activé/params de chaque serveur du catalogue (défaut : désactivé)."""
+    stored = db.get_config_value(MCP_KEY) or {}
+    return {
+        sid: {
+            "enabled": bool(stored.get(sid, {}).get("enabled", False)),
+            "params": dict(stored.get(sid, {}).get("params", {})),
+        }
+        for sid in CATALOG
+    }
+
+
+def set_mcp_state(sid: str, *, enabled: bool, params: dict) -> dict:
+    if sid not in CATALOG:
+        raise KeyError(sid)
+    state = get_mcp_state()
+    state[sid] = {"enabled": enabled, "params": dict(params)}
+    db.set_config_value(MCP_KEY, state)
+    return state

backend/requirements.txt

@@ -8,3 +8,6 @@ httpx==0.28.1
 pydantic==2.12.5
 pydantic-settings==2.7.1
 psutil==7.2.2
+mcp>=1.9
+pytest>=8.3
+pytest-asyncio>=0.25

backend/tests/test_mcp_config.py

@@ -0,0 +1,39 @@
+import os
+import tempfile
+
+os.environ.setdefault("DATA_DIR", tempfile.mkdtemp())
+os.environ.setdefault("WORKSPACE_DIR", tempfile.mkdtemp())
+
+from app import db  # noqa: E402
+from app import mcp_client  # noqa: E402
+
+db.init_db()
+
+
+def test_catalog_has_preconfigured_servers():
+    for sid in ("playwright", "context7", "fetch", "searxng", "custom"):
+        assert sid in mcp_client.CATALOG
+        assert mcp_client.CATALOG[sid]["label"]
+
+
+def test_state_defaults_disabled():
+    state = mcp_client.get_mcp_state()
+    assert set(state) == set(mcp_client.CATALOG)
+    assert all(not s["enabled"] for s in state.values())
+
+
+def test_toggle_persists():
+    mcp_client.set_mcp_state("fetch", enabled=True, params={})
+    assert mcp_client.get_mcp_state()["fetch"]["enabled"] is True
+    mcp_client.set_mcp_state("fetch", enabled=False, params={})
+    assert mcp_client.get_mcp_state()["fetch"]["enabled"] is False
+
+
+def test_custom_params_persist():
+    mcp_client.set_mcp_state(
+        "custom", enabled=False, params={"command": "npx -y some-mcp"}
+    )
+    assert (
+        mcp_client.get_mcp_state()["custom"]["params"]["command"]
+        == "npx -y some-mcp"
+    )