diff --git a/headroom/providers/copilot/wrap.py b/headroom/providers/copilot/wrap.py
index 518b302ed..db1610a3b 100644
--- a/headroom/providers/copilot/wrap.py
+++ b/headroom/providers/copilot/wrap.py
@@ -22,6 +22,10 @@ def resolve_provider_type(
         return provider_type
 
     env = environ or os.environ
+    # Check COPILOT_PROVIDER_TYPE env var before falling back to backend default.
+    env_type = env.get("COPILOT_PROVIDER_TYPE")
+    if env_type in {"anthropic", "openai"}:
+        return env_type
     effective_backend = backend or env.get("HEADROOM_BACKEND") or "anthropic"
     return "anthropic" if effective_backend == "anthropic" else "openai"
 
diff --git a/tests/test_provider_copilot_wrap.py b/tests/test_provider_copilot_wrap.py
index c3d082915..849da6b98 100644
--- a/tests/test_provider_copilot_wrap.py
+++ b/tests/test_provider_copilot_wrap.py
@@ -47,7 +47,30 @@ def test_detect_running_proxy_backend_requires_string_backend(monkeypatch) -> No
 
 
 def test_resolve_provider_type_prefers_explicit_and_env() -> None:
-    assert resolve_provider_type("anthropic", "openai") == "openai"
+    assert (
+        resolve_provider_type(
+            "anthropic",
+            "openai",
+            {"COPILOT_PROVIDER_TYPE": "anthropic", "HEADROOM_BACKEND": "anthropic"},
+        )
+        == "openai"
+    )
+    assert (
+        resolve_provider_type(
+            "anthropic",
+            "auto",
+            {"COPILOT_PROVIDER_TYPE": "openai", "HEADROOM_BACKEND": "anthropic"},
+        )
+        == "openai"
+    )
+    assert (
+        resolve_provider_type(
+            None,
+            "auto",
+            {"COPILOT_PROVIDER_TYPE": "not-a-provider", "HEADROOM_BACKEND": "anthropic"},
+        )
+        == "anthropic"
+    )
     assert resolve_provider_type(None, "auto", {"HEADROOM_BACKEND": "anthropic"}) == "anthropic"
     assert resolve_provider_type(None, "auto", {"HEADROOM_BACKEND": "anyllm"}) == "openai"