fix(mcp): 修复配置导入、凭据管理与协议边界

修复生命周期锁阻塞事件循环、旧连接回调误停新连接及超时契约不一致。

补齐 MCP JSON 兼容导入、密钥拆分与失败重试，修复 Header 大小写草稿丢失，迁移大小写敏感的环境变量凭据。

在 SSE 行拼接前限制缓冲大小，增加并发、迁移和流式输入回归测试；忽略本机 MCP 数据及 server.json/servers.json。

验证：后端 185 项、前端 54 项测试通过，前端生产构建、相关文件 Ruff 与暂存差异检查通过。

backend/tests/test_api.py

@@ -2,6 +2,8 @@ import asyncio
 import threading
 from types import SimpleNamespace
 
+import pytest
+
 from app.contracts import (
     McpServerSecretStatus,
     McpServerSecretWriteRequest,
@@ -61,9 +63,7 @@ def test_mcp_secret_routes_offload_blocking_lifecycle_work(monkeypatch) -> None:
         )
     )
     deleted = asyncio.run(
-        routes.delete_mcp_server_secret(
-            "server-1", "TOKEN", kind="environment"
-        )
+        routes.delete_mcp_server_secret("server-1", "TOKEN", kind="environment")
     )
 
     assert written.configured is True
@@ -77,6 +77,172 @@ def test_health() -> None:
     assert response.model_dump() == {"status": "ok"}
 
 
+def test_mcp_create_and_trust_are_not_executed_on_event_loop(monkeypatch) -> None:
+    from app import routes
+    from app.contracts import McpServerCreateRequest, McpServerTrustRequest
+
+    caller = threading.get_ident()
+    workers = []
+
+    class Registry:
+        def create(self, request):
+            workers.append(threading.get_ident())
+            return "created"
+
+        def trust(self, server_id, digest):
+            workers.append(threading.get_ident())
+            return "trusted"
+
+    monkeypatch.setattr(routes, "container", SimpleNamespace(mcp_servers=Registry()))
+    assert (
+        asyncio.run(
+            routes.create_mcp_server(McpServerCreateRequest(name="test", command="uvx"))
+        )
+        == "created"
+    )
+    assert (
+        asyncio.run(
+            routes.trust_mcp_server(
+                "test", McpServerTrustRequest(command_digest="a" * 64)
+            )
+        )
+        == "trusted"
+    )
+    assert len(workers) == 2
+    assert all(worker != caller for worker in workers)
+
+
+def test_mcp_split_config_and_secret_requests_persist_without_plaintext(
+    monkeypatch,
+) -> None:
+    from fastapi.testclient import TestClient
+
+    from app import routes
+    from app.agent.tools import ToolRegistry
+    from app.config import get_settings
+    from app.extensions.mcp_registry import McpServerRegistry
+    from app.main import app
+    from app.providers.credentials import EncryptedCredentialStore
+
+    service = McpServerRegistry(
+        ToolRegistry(),
+        EncryptedCredentialStore(),
+        get_settings().data_dir,
+        allow_process_launch=True,
+    )
+    monkeypatch.setattr(routes, "container", SimpleNamespace(mcp_servers=service))
+    client = TestClient(app)
+    config = {
+        "name": "MiniMax configuration test",
+        "command": "uvx",
+        "environment": {"MINIMAX_API_HOST": "https://api.minimaxi.com"},
+        "secret_environment_keys": ["MINIMAX_API_KEY"],
+        "startup_timeout_seconds": 120,
+        "tool_timeout_seconds": 300,
+    }
+    # Reproduce the old frontend payload. The backend still enforces separation.
+    invalid = client.post(
+        "/api/mcp/servers",
+        json={
+            **config,
+            "environment": {
+                **config["environment"],
+                "MINIMAX_API_KEY": "synthetic-only",
+            },
+        },
+    )
+    assert invalid.status_code == 422
+    assert invalid.json()["error"]["code"] == "MCP_ENVIRONMENT_INVALID"
+    created = client.post("/api/mcp/servers", json=config)
+    assert created.status_code == 201
+    server_id = created.json()["server_id"]
+    saved = client.put(
+        f"/api/mcp/servers/{server_id}/secrets/MINIMAX_API_KEY",
+        json={"secret": "synthetic-only"},
+    )
+    assert saved.status_code == 200
+    current = client.get(f"/api/mcp/servers/{server_id}")
+    assert current.json()["secret_environment"] == {"MINIMAX_API_KEY": True}
+    assert "synthetic-only" not in current.text
+    assert "synthetic-only" not in service._path.read_text(encoding="utf-8")
+    _, credentials_path = service.credentials._paths()
+    assert "synthetic-only" not in credentials_path.read_text(encoding="utf-8")
+    assert not current.json()["enabled"]  # Saving never starts a third-party process.
+    client.close()
+
+
+@pytest.mark.parametrize("operation", ["create", "trust"])
+def test_mcp_lifecycle_lock_contention_keeps_event_loop_responsive(
+    monkeypatch,
+    operation,
+) -> None:
+    from app import routes
+    from app.agent.tools import ToolRegistry
+    from app.config import get_settings
+    from app.contracts import McpServerCreateRequest, McpServerTrustRequest
+    from app.extensions.mcp_registry import McpServerRegistry
+    from app.providers.credentials import EncryptedCredentialStore
+
+    service = McpServerRegistry(
+        ToolRegistry(),
+        EncryptedCredentialStore(),
+        get_settings().data_dir,
+        allow_process_launch=True,
+    )
+    request = McpServerCreateRequest(
+        name="Lock contention fixture", command="not-executed"
+    )
+    server = service.create(request)
+    monkeypatch.setattr(routes, "container", SimpleNamespace(mcp_servers=service))
+    entered = threading.Event()
+    locked = threading.Event()
+    release = threading.Event()
+    original = getattr(service, operation)
+
+    def observed(*args):
+        entered.set()
+        return original(*args)
+
+    def hold_lifecycle_lock():
+        with service._lifecycle_lock:
+            locked.set()
+            release.wait(timeout=5)
+
+    monkeypatch.setattr(service, operation, observed)
+    holder = threading.Thread(target=hold_lifecycle_lock, daemon=True)
+    holder.start()
+    # An independent watchdog lets the test fail rather than hang if a regression
+    # blocks the event loop itself (an asyncio timeout alone cannot catch that).
+    watchdog = threading.Timer(5, release.set)
+    watchdog.start()
+
+    async def exercise():
+        pending = asyncio.create_task(
+            routes.create_mcp_server(request)
+            if operation == "create"
+            else routes.trust_mcp_server(
+                server.server_id,
+                McpServerTrustRequest(command_digest=server.command_digest),
+            )
+        )
+        try:
+            assert await asyncio.to_thread(entered.wait, 2)
+            assert not pending.done()
+            assert not release.is_set()
+            assert (await health()).status == "ok"
+        finally:
+            release.set()
+            await pending
+
+    try:
+        assert locked.wait(timeout=2)
+        asyncio.run(exercise())
+    finally:
+        release.set()
+        watchdog.cancel()
+        holder.join(timeout=2)
+
+
 def test_service_status() -> None:
     response = asyncio.run(service_status())
 
@@ -93,7 +259,9 @@ def test_core_collections_are_typed() -> None:
 
     assert notes.items == []
     assert notes.page.limit == 20
-    assert [skill.manifest.skill_id for skill in skills.items] == ["knowledge-assistant"]
+    assert [skill.manifest.skill_id for skill in skills.items] == [
+        "knowledge-assistant"
+    ]
     assert skills.items[0].status == "ready"
     assert [plugin.manifest.plugin_id for plugin in plugins.items] == ["text-tools"]
     assert plugins.items[0].status == "ready"
@@ -114,9 +282,15 @@ def test_provider_presets_include_openai_and_deepseek() -> None:
 def test_provider_presets_static_route_precedes_provider_id_route() -> None:
     from app.routes import router
 
-    get_paths = [route.path for route in router.routes if "GET" in getattr(route, "methods", set())]
+    get_paths = [
+        route.path
+        for route in router.routes
+        if "GET" in getattr(route, "methods", set())
+    ]
 
-    assert get_paths.index("/api/providers/presets") < get_paths.index("/api/providers/{provider_id}")
+    assert get_paths.index("/api/providers/presets") < get_paths.index(
+        "/api/providers/{provider_id}"
+    )
 
 
 def test_openapi_contains_documented_frontend_interfaces() -> None: