Merge 2f1a8b6e28 into 3e1479c052

litellm/proxy/proxy_server.py

@@ -2290,11 +2290,9 @@ def run_ollama_serve():
         with open(os.devnull, "w") as devnull:
             subprocess.Popen(command, stdout=devnull, stderr=devnull)
     except Exception as e:
-        verbose_proxy_logger.debug(
-            f"""
+        verbose_proxy_logger.debug(f"""
             LiteLLM Warning: proxy started with `ollama` model\n`ollama serve` failed with Exception{e}. \nEnsure you run `ollama serve`
-        """
-        )
+        """)
 
 
 def _get_process_rss_mb() -> Optional[float]:
@@ -14526,3 +14524,27 @@ async def dynamic_mcp_route(mcp_server_name: str, request: Request):
 app.mount(path=BASE_MCP_ROUTE, app=mcp_app)
 app.include_router(mcp_rest_endpoints_router)
 app.include_router(mcp_discoverable_endpoints_router)
+
+
+# Rewrite /mcp -> /mcp/ internally to avoid 307 redirect from Starlette's
+# mounted sub-application routing.  Many MCP clients (e.g. Claude Code) send
+# POST /mcp and do not follow redirects for POST, which drops the request body.
+# Using a pure ASGI middleware (not BaseHTTPMiddleware) keeps SSE streaming intact.
+class _MCPTrailingSlashMiddleware:
+    """Transparently append '/' to the MCP mount path so Starlette serves it
+    directly instead of responding with 307 Temporary Redirect."""
+
+    def __init__(self, app: Any) -> None:
+        self.app = app
+
+    async def __call__(self, scope: Any, receive: Any, send: Any) -> None:
+        if scope["type"] == "http" and scope.get("path") == BASE_MCP_ROUTE:
+            scope = dict(
+                scope,
+                path=BASE_MCP_ROUTE + "/",
+                raw_path=(scope.get("raw_path") or BASE_MCP_ROUTE.encode()) + b"/",
+            )
+        await self.app(scope, receive, send)
+
+
+app.add_middleware(_MCPTrailingSlashMiddleware)

tests/mcp_tests/test_mcp_trailing_slash_middleware.py

@@ -0,0 +1,126 @@
+"""
+Unit tests for _MCPTrailingSlashMiddleware.
+
+Validates that the middleware rewrites scope["path"] (and scope["raw_path"])
+from BASE_MCP_ROUTE to BASE_MCP_ROUTE + "/" for HTTP scopes, and passes
+everything else through unchanged.
+"""
+
+import asyncio
+from typing import Optional
+
+# The middleware is defined at module scope in proxy_server.py alongside heavy
+# imports we don't want here.  Re-implement the same class locally to test the
+# logic in isolation (it's only ~10 lines) while keeping the test dependency-free.
+
+BASE_MCP_ROUTE = "/mcp"
+
+
+class _MCPTrailingSlashMiddleware:
+    """Mirror of the production middleware for isolated testing."""
+
+    def __init__(self, app):
+        self.app = app
+
+    async def __call__(self, scope, receive, send):
+        if scope["type"] == "http" and scope.get("path") == BASE_MCP_ROUTE:
+            scope = dict(
+                scope,
+                path=BASE_MCP_ROUTE + "/",
+                raw_path=(scope.get("raw_path") or BASE_MCP_ROUTE.encode()) + b"/",
+            )
+        await self.app(scope, receive, send)
+
+
+# ── helpers ──────────────────────────────────────────────────────────────
+
+
+class _Recorder:
+    """Dummy ASGI app that records the scope it was called with."""
+
+    def __init__(self):
+        self.scopes: list = []
+
+    async def __call__(self, scope, receive, send):
+        self.scopes.append(scope)
+
+
+def _make_http_scope(path: str, raw_path: Optional[bytes] = None) -> dict:
+    scope: dict = {"type": "http", "path": path}
+    if raw_path is not None:
+        scope["raw_path"] = raw_path
+    return scope
+
+
+# ── tests ────────────────────────────────────────────────────────────────
+
+
+def test_rewrites_exact_mcp_path():
+    """POST /mcp should be rewritten to /mcp/."""
+    recorder = _Recorder()
+    mw = _MCPTrailingSlashMiddleware(recorder)
+
+    scope = _make_http_scope("/mcp", b"/mcp")
+    asyncio.run(mw(scope, None, None))
+
+    assert len(recorder.scopes) == 1
+    assert recorder.scopes[0]["path"] == "/mcp/"
+    assert recorder.scopes[0]["raw_path"] == b"/mcp/"
+
+
+def test_no_rewrite_for_mcp_subpath():
+    """/mcp/foo should NOT be rewritten."""
+    recorder = _Recorder()
+    mw = _MCPTrailingSlashMiddleware(recorder)
+
+    scope = _make_http_scope("/mcp/foo", b"/mcp/foo")
+    asyncio.run(mw(scope, None, None))
+
+    assert recorder.scopes[0]["path"] == "/mcp/foo"
+    assert recorder.scopes[0]["raw_path"] == b"/mcp/foo"
+
+
+def test_no_rewrite_for_other_paths():
+    """/health should pass through unchanged."""
+    recorder = _Recorder()
+    mw = _MCPTrailingSlashMiddleware(recorder)
+
+    scope = _make_http_scope("/health", b"/health")
+    asyncio.run(mw(scope, None, None))
+
+    assert recorder.scopes[0]["path"] == "/health"
+
+
+def test_no_rewrite_for_non_http_scope():
+    """WebSocket or lifespan scopes should pass through unchanged."""
+    recorder = _Recorder()
+    mw = _MCPTrailingSlashMiddleware(recorder)
+
+    scope = {"type": "websocket", "path": "/mcp"}
+    asyncio.run(mw(scope, None, None))
+
+    assert recorder.scopes[0]["path"] == "/mcp"
+
+
+def test_raw_path_fallback_when_absent():
+    """If raw_path is missing from scope, middleware should still work."""
+    recorder = _Recorder()
+    mw = _MCPTrailingSlashMiddleware(recorder)
+
+    scope = _make_http_scope("/mcp")  # no raw_path
+    asyncio.run(mw(scope, None, None))
+
+    assert recorder.scopes[0]["path"] == "/mcp/"
+    assert recorder.scopes[0]["raw_path"] == b"/mcp/"
+
+
+def test_already_trailing_slash_no_double():
+    """/mcp/ should NOT be rewritten (exact match only)."""
+    recorder = _Recorder()
+    mw = _MCPTrailingSlashMiddleware(recorder)
+
+    scope = _make_http_scope("/mcp/", b"/mcp/")
+    asyncio.run(mw(scope, None, None))
+
+    assert recorder.scopes[0]["path"] == "/mcp/"
+    assert recorder.scopes[0]["raw_path"] == b"/mcp/"