diff --git a/agent/image_routing.py b/agent/image_routing.py
index 5eb962bfdf..099c6d9014 100644
--- a/agent/image_routing.py
+++ b/agent/image_routing.py
@@ -99,14 +99,13 @@ def _clean_str(raw: Any) -> str:
     return str(raw or "").strip()
 
 
-def _runtime_main(key: str) -> str:
-    """Stripped context-local main-runtime value, or "" when unavailable."""
+def _runtime_main(key: str) -> Any:
+    """Context-local credential source or stripped runtime text; "" when unavailable."""
     try:
         from agent.auxiliary_client import _runtime_main_value
 
-        from agent.command_token_source import materialize_probe_api_key
         value = _runtime_main_value(key)
-        return materialize_probe_api_key(value) if key == "api_key" else _clean_str(value)
+        return value if key == "api_key" else _clean_str(value)
     except Exception:
         return ""
 
@@ -178,6 +177,12 @@ def _resolve_inference_value(
     → ``custom_providers[].<key>``, ``<name>`` covering the provider and
     ``model.provider`` in both bare and ``custom:``-prefixed forms."""
     runtime = _runtime_main(key)
+    # A declared source owns authentication even when its mint fails.
+    if key == "api_key":
+        from agent.command_token_source import materialize_probe_api_key
+        if callable(runtime):
+            return materialize_probe_api_key(runtime)
+        runtime = materialize_probe_api_key(runtime)
     if runtime and runtime_ok(runtime):
         return runtime
     if not isinstance(cfg, dict):
diff --git a/hermes_cli/models_local.py b/hermes_cli/models_local.py
index 3944e85f20..16e7457cef 100644
--- a/hermes_cli/models_local.py
+++ b/hermes_cli/models_local.py
@@ -158,8 +158,9 @@ def _get_ollama_native_headers(base_url: Optional[str], *, api_key: Optional[str
     if not configured_matches and not explicit_key:
         return {}
     headers = _get_ollama_request_headers() if configured_matches else {}
-    if explicit_key:
+    if explicit_key or callable(api_key):
         _drop_authorization(headers)
+    if explicit_key:
         headers["Authorization"] = f"Bearer {explicit_key}"
     return headers
 
diff --git a/tests/agent/test_capability_probe_credentials.py b/tests/agent/test_capability_probe_credentials.py
index cac7ad56e7..ef27e6988c 100644
--- a/tests/agent/test_capability_probe_credentials.py
+++ b/tests/agent/test_capability_probe_credentials.py
@@ -30,9 +30,31 @@ def test_capability_paths_share_concrete_bearer(credential, expected):
         auxiliary_client.clear_runtime_main()
 
 
-def test_failed_callable_never_becomes_a_bearer():
+def test_failed_callable_never_becomes_a_bearer(monkeypatch):
     def failed():
         raise RuntimeError("secret-bearing command failure")
     for value in (failed, lambda: object(), object(), None):
         assert model_metadata._auth_headers(value) == {}
         assert "Authorization" not in models_local._lmstudio_request_headers(value)
+
+    from hermes_cli import models
+    url = "http://localhost:11434/v1"
+    configured = {"base_url": url, "api_key": "provider-fallback", "extra_headers": {
+        "aUtHoRiZaTiOn": "Bearer configured-fallback", "X-Probe-Fixture": "preserved",
+    }}
+    monkeypatch.setattr(models, "_get_provider_config_dict", lambda _: configured)
+    for value in (failed, lambda: object(), lambda: ""):
+        auxiliary_client.set_runtime_main("custom", "fixture", api_key=value)
+        try:
+            for cfg in ({"model": {"api_key": "model-fallback"}},
+                        {"providers": {"custom": {"api_key": "provider-fallback"}}}):
+                assert image_routing._resolve_inference_api_key(cfg, "custom") == ""
+            assert models_local._get_ollama_native_headers(url, api_key=value) == {
+                "X-Probe-Fixture": "preserved",
+            }
+            assert auxiliary_client._runtime_main_value("api_key") is value
+        finally:
+            auxiliary_client.clear_runtime_main()
+    # An absent explicit credential still permits configured authentication.
+    assert models_local._get_ollama_native_headers(url)["aUtHoRiZaTiOn"] == "Bearer configured-fallback"
+    assert image_routing._resolve_inference_api_key({"model": {"api_key": "model-fallback"}}, "custom") == "model-fallback"
diff --git a/website/docs/integrations/providers.md b/website/docs/integrations/providers.md
index 1007319612..dfeeda226f 100644
--- a/website/docs/integrations/providers.md
+++ b/website/docs/integrations/providers.md
@@ -1327,7 +1327,10 @@ Vision, thinking, and native local-model capability probes materialize the same
 callable credential used by chat before building authentication headers. They
 reuse the command token cache without replacing the chat client's callable.
 If a command cannot mint a string token, these best-effort probes send no bearer
-rather than an object representation; chat retains its normal error handling.
+rather than an object representation or a lower-priority configured credential.
+Native local-model probes remove inherited Authorization on a failed explicit
+callable while retaining unrelated configured headers. Chat retains its normal
+error handling.
 
 Enterprise gateways often issue short-lived bearer tokens (SSO/OIDC brokers, cloud IAM, internal auth proxies) rather than static API keys, so a token copied into `.env` goes stale mid-session and requests start returning 401. `key_cmd` names a command that *prints* a token; Hermes runs it and caches the result until shortly before expiry, so long sessions keep working with no restart: