diff --git a/headroom/cli/wrap.py b/headroom/cli/wrap.py
index 3db3151e3..822414c6a 100644
--- a/headroom/cli/wrap.py
+++ b/headroom/cli/wrap.py
@@ -5090,8 +5090,11 @@ def copilot(
                 "automatic model selection."
             )
 
+        env_wire_api = env.get("COPILOT_PROVIDER_WIRE_API")
         effective_wire_api = wire_api or (
-            _copilot_default_wire_api_for_model(selected_model) if subscription else "completions"
+            env_wire_api
+            if env_wire_api in {"completions", "responses"}
+            else _copilot_default_wire_api_for_model(selected_model)
         )
         env["COPILOT_PROVIDER_TYPE"] = "openai"
         # Per-project savings: the Copilot CLI cannot send custom headers, so
diff --git a/tests/test_cli/test_wrap_copilot.py b/tests/test_cli/test_wrap_copilot.py
index cc4fe724c..98f261f09 100644
--- a/tests/test_cli/test_wrap_copilot.py
+++ b/tests/test_cli/test_wrap_copilot.py
@@ -279,6 +279,78 @@ def test_wrap_copilot_prefers_existing_oauth_session(
     assert f"COPILOT_PROVIDER_API_URL={DEFAULT_API_URL}" in captured["env_vars_display"]
 
 
+@pytest.mark.parametrize(
+    ("model", "expected_wire_api"),
+    [
+        ("gpt-5.4", "responses"),
+        ("gpt-4.1", "completions"),
+    ],
+)
+def test_wrap_copilot_oauth_defaults_wire_api_for_selected_model(
+    runner: CliRunner,
+    wrap_modules: tuple[types.ModuleType, click.Group],
+    monkeypatch: pytest.MonkeyPatch,
+    model: str,
+    expected_wire_api: str,
+) -> None:
+    """OAuth sessions use the same model-aware wire API default as subscriptions."""
+    _wrap_cli, main = wrap_modules
+    _clear_copilot_env(monkeypatch)
+    captured: dict[str, object] = {}
+
+    def fake_launch_tool(**kwargs):  # noqa: ANN003
+        captured.update(kwargs)
+
+    with (
+        patch("headroom.cli.wrap.shutil.which", return_value="copilot"),
+        patch("headroom.cli.wrap.resolve_client_bearer_token", return_value="gho-existing"),
+        patch("headroom.cli.wrap.has_oauth_auth", return_value=True),
+        patch("headroom.cli.wrap._launch_tool", side_effect=fake_launch_tool),
+    ):
+        result = runner.invoke(
+            main,
+            ["wrap", "copilot", "--no-rtk", "--", "--model", model],
+        )
+
+    assert result.exit_code == 0, result.output
+    env = captured["env"]
+    assert isinstance(env, dict)
+    assert env["COPILOT_PROVIDER_WIRE_API"] == expected_wire_api
+    assert f"COPILOT_PROVIDER_WIRE_API={expected_wire_api}" in captured["env_vars_display"]
+
+
+@pytest.mark.parametrize("wire_api", ["completions", "responses"])
+def test_wrap_copilot_oauth_honors_existing_wire_api(
+    runner: CliRunner,
+    wrap_modules: tuple[types.ModuleType, click.Group],
+    monkeypatch: pytest.MonkeyPatch,
+    wire_api: str,
+) -> None:
+    _wrap_cli, main = wrap_modules
+    _clear_copilot_env(monkeypatch)
+    monkeypatch.setenv("COPILOT_PROVIDER_WIRE_API", wire_api)
+    captured: dict[str, object] = {}
+
+    def fake_launch_tool(**kwargs):  # noqa: ANN003
+        captured.update(kwargs)
+
+    with (
+        patch("headroom.cli.wrap.shutil.which", return_value="copilot"),
+        patch("headroom.cli.wrap.resolve_client_bearer_token", return_value="gho-existing"),
+        patch("headroom.cli.wrap.has_oauth_auth", return_value=True),
+        patch("headroom.cli.wrap._launch_tool", side_effect=fake_launch_tool),
+    ):
+        result = runner.invoke(
+            main,
+            ["wrap", "copilot", "--no-rtk", "--", "--model", "gpt-5.4"],
+        )
+
+    assert result.exit_code == 0, result.output
+    env = captured["env"]
+    assert isinstance(env, dict)
+    assert env["COPILOT_PROVIDER_WIRE_API"] == wire_api
+
+
 def test_wrap_copilot_subscription_uses_github_auth_without_provider_key(
     runner: CliRunner,
     wrap_modules: tuple[types.ModuleType, click.Group],
diff --git a/tests/test_provider_copilot_wrap.py b/tests/test_provider_copilot_wrap.py
index 849da6b98..45beceb12 100644
--- a/tests/test_provider_copilot_wrap.py
+++ b/tests/test_provider_copilot_wrap.py
@@ -93,6 +93,7 @@ def test_validate_configuration_rejects_invalid_combinations() -> None:
     [
         ("gpt-5.5", True),
         ("gpt-5-codex", True),
+        ("gpt-5.4", True),
         ("openai/gpt-5.4", True),
         ("o1", True),
         ("o3-mini", True),