diff --git a/headroom/providers/proxy_routes.py b/headroom/providers/proxy_routes.py
index d215edf8c..ce6b5fe08 100644
--- a/headroom/providers/proxy_routes.py
+++ b/headroom/providers/proxy_routes.py
@@ -474,6 +474,13 @@ async def _handle_chatgpt_codex_images(
 def register_provider_routes(app: FastAPI, proxy: Any) -> None:
     """Register provider-specific proxy endpoints."""
 
+    def normalize_request_path(request: Request, path: str) -> None:
+        request.scope["path"] = path
+        if "raw_path" in request.scope:
+            request.scope["raw_path"] = quote(path).encode("ascii")
+        if hasattr(request, "_url"):
+            delattr(request, "_url")
+
     async def vertex_publisher_passthrough(request: Request, publisher: str, action: str):
         return await proxy.handle_passthrough(
             request,
@@ -486,6 +493,11 @@ def register_provider_routes(app: FastAPI, proxy: Any) -> None:
     async def anthropic_messages(request: Request):
         return await proxy.handle_anthropic_messages(request)
 
+    @app.post("/anthropic/v1/messages")
+    async def foundry_anthropic_messages(request: Request):
+        normalize_request_path(request, "/v1/messages")
+        return await proxy.handle_anthropic_messages(request, _api_target(proxy, "anthropic"))
+
     # AWS Bedrock InvokeModel passthrough. Registered ONLY when an upstream is
     # configured (`--bedrock-api-url` / BEDROCK_TARGET_API_URL): without it,
     # `/model/{id}/invoke` keeps falling through to the catch-all (verbatim,
diff --git a/tests/test_provider_proxy_routes.py b/tests/test_provider_proxy_routes.py
index c80c03701..be588a3c1 100644
--- a/tests/test_provider_proxy_routes.py
+++ b/tests/test_provider_proxy_routes.py
@@ -173,6 +173,14 @@ def test_provider_passthrough_routes_forward_expected_targets(monkeypatch) -> No
             "model": "claude-3-5-sonnet@20240620",
             "force_stream": False,
         }
+        assert client.post("/anthropic/v1/messages?beta=true").json() == {
+            "handler": "handle_anthropic_messages",
+            "path": "/v1/messages",
+            "upstream_base_url": "https://api.anthropic.test",
+            "provider": "anthropic",
+            "model": None,
+            "force_stream": False,
+        }
         non_anthropic_raw = client.post(
             "/projects/p/locations/us-central1/publishers/google/models/gemini-2.0-flash:rawPredict"
         ).json()
@@ -336,6 +344,11 @@ def test_provider_specific_routes_delegate_to_expected_proxy_handlers(monkeypatc
 
     with TestClient(_app()) as client:
         assert client.post("/v1/messages").json()["handler"] == "handle_anthropic_messages"
+        assert client.post("/anthropic/v1/messages").json() == {
+            "handler": "handle_anthropic_messages",
+            "path": "/v1/messages",
+            "args": ["https://api.anthropic.test"],
+        }
         assert (
             client.post("/v1/messages/batches").json()["handler"] == "handle_anthropic_batch_create"
         )