diff --git a/agent/auxiliary_client.py b/agent/auxiliary_client.py
index b4edb01458..d074dac14d 100644
--- a/agent/auxiliary_client.py
+++ b/agent/auxiliary_client.py
@@ -112,6 +112,7 @@ from agent.model_metadata import (
     strip_codex_context_variant_suffix as _strip_codex_ctx_variant,
 )
 from hermes_cli.config import get_hermes_home
+from hermes_cli.route_identity import normalize_route_base_url
 from hermes_constants import OPENROUTER_BASE_URL
 from utils import base_url_host_matches, base_url_hostname, env_float, is_truthy_value, model_forces_max_completion_tokens, normalize_proxy_env_vars
 
@@ -2903,7 +2904,7 @@ def _normalize_chain_label(provider: str) -> str:
 def _unhealthy_cache_key(provider: str, base_url: Optional[str] = None) -> Any:
     """Provider-wide key, or endpoint-specific key for an explicit custom endpoint."""
     label = _normalize_chain_label(provider)
-    endpoint = _custom_health_base_url(provider, base_url).lower().rstrip("/")
+    endpoint = normalize_route_base_url(_custom_health_base_url(provider, base_url))
     if endpoint:
         return "custom-endpoint", endpoint
     return label
diff --git a/agent/backend_identity.py b/agent/backend_identity.py
index ecf9f2f66b..434a8a57e4 100644
--- a/agent/backend_identity.py
+++ b/agent/backend_identity.py
@@ -15,6 +15,8 @@ from dataclasses import dataclass
 from enum import Enum
 from typing import Optional
 
+from hermes_cli.route_identity import normalize_route_base_url
+
 logger = logging.getLogger(__name__)
 
 
@@ -51,7 +53,8 @@ class BackendIdentity:
         base_url: Optional[str] = None,
     ) -> "BackendIdentity":
         return cls(
-            provider=_norm(provider), model=_norm(model), base_url=_norm(base_url).rstrip("/"),
+            provider=_norm(provider), model=_norm(model),
+            base_url=normalize_route_base_url(base_url),
         )
 
 
diff --git a/tests/agent/test_auxiliary_client.py b/tests/agent/test_auxiliary_client.py
index a5875c7504..4054fc7466 100644
--- a/tests/agent/test_auxiliary_client.py
+++ b/tests/agent/test_auxiliary_client.py
@@ -4156,6 +4156,19 @@ class TestAuxUnhealthyCache:
         or_try.assert_not_called()
         custom_try.assert_not_called()
 
+    def test_custom_health_url_identity_preserves_path_and_query_case(self):
+        from agent.auxiliary_client import _is_provider_unhealthy, _mark_provider_unhealthy
+
+        _mark_provider_unhealthy("custom", base_url="https://Example.test/API/v1/")
+
+        assert _is_provider_unhealthy("custom", "https://example.TEST/API/v1") is True
+        assert _is_provider_unhealthy("custom", "https://example.test/api/v1") is False
+
+        _mark_provider_unhealthy("custom", base_url="https://example.test/API/v1?token=AbC")
+        assert _is_provider_unhealthy(
+            "custom", "https://example.test/API/v1?token=abc",
+        ) is False
+
     def test_call_llm_marks_provider_unhealthy_on_402(self, monkeypatch):
         """A 402 from call_llm causes the provider to be marked unhealthy
         so the next call skips it instead of re-trying the same depleted
diff --git a/tests/agent/test_backend_identity.py b/tests/agent/test_backend_identity.py
index 4cb6360975..1cc9db84b8 100644
--- a/tests/agent/test_backend_identity.py
+++ b/tests/agent/test_backend_identity.py
@@ -85,10 +85,24 @@ class TestSameCredentialSurface:
 class TestSameEndpoint:
     def test_same_explicit_url_is_same_endpoint(self):
         a = _id("a", "m1", "http://host:8000/v1/")
-        b = _id("b", "m2", "http://HOST:8000/v1")  # trailing slash + case
+        b = _id("b", "m2", "http://HOST:8000/v1")  # trailing slash + host case
         assert same_endpoint(a, b)
         assert should_skip_candidate(a, b, FailureScope.ENDPOINT)
 
+    def test_path_and_query_case_distinguish_endpoints(self):
+        failed = _id("custom", "m", "https://Example.test/API/v1?token=AbC")
+
+        assert not should_skip_candidate(
+            _id("custom", "m", "https://example.test/api/v1?token=AbC"),
+            failed,
+            FailureScope.ENDPOINT,
+        )
+        assert not should_skip_candidate(
+            _id("custom", "m", "https://example.test/API/v1?token=abc"),
+            failed,
+            FailureScope.ENDPOINT,
+        )
+
     def test_different_urls_are_different_endpoints(self):
         assert not same_endpoint(
             _id("a", "m", "http://h1/v1"), _id("a2", "m", "http://h2/v1")