From a26ec5e26808432357cf23505291ade34b396d74 Mon Sep 17 00:00:00 2001
From: Returner_org <apavel72hd.kuba@outlook.com>
Date: Sun, 28 Jun 2026 15:13:33 +0300
Subject: [PATCH] =?UTF-8?q?feat(core):=20TraceMiddleware=20=D0=B4=D0=BB?=
 =?UTF-8?q?=D1=8F=20=D0=BF=D1=80=D0=BE=D0=B1=D1=80=D0=BE=D1=81=D0=B0=20X-T?=
 =?UTF-8?q?race-Id?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- читает X-Trace-Id из запроса или генерит новый ULID
- кладёт trace_id в ContextVar на время запроса
- возвращает X-Trace-Id в заголовке ответа
---
 src/elexam_core/middleware.py | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 src/elexam_core/middleware.py

diff --git a/src/elexam_core/middleware.py b/src/elexam_core/middleware.py
new file mode 100644
index 0000000..b004a18
--- /dev/null
+++ b/src/elexam_core/middleware.py
@@ -0,0 +1,24 @@
+from starlette.middleware.base import BaseHTTPMiddleware, RequestResponseEndpoint
+from starlette.requests import Request
+from starlette.responses import Response
+from ulid import ULID
+
+from elexam_core.context import trace_id_context
+
+
+TRACE_HEADER: str = "X-Trace-Id"
+
+
+class TraceMiddleware(BaseHTTPMiddleware):
+    async def dispatch(self, request: Request, call_next: RequestResponseEndpoint) -> Response:
+        header_trace_id = request.headers.get(TRACE_HEADER, default=None)
+        trace_id = header_trace_id or str(ULID())
+        token = trace_id_context.set(trace_id)
+
+        try:
+            response = await call_next(request)
+        finally:
+            trace_id_context.reset(token)
+
+        response.headers[TRACE_HEADER] = trace_id
+        return response
\ No newline at end of file