diff --git a/docs/doctoring/strix-openai-fallback-api-base-routing.md b/docs/doctoring/strix-openai-fallback-api-base-routing.md
index d38d222d4..5e65387c4 100644
--- a/docs/doctoring/strix-openai-fallback-api-base-routing.md
+++ b/docs/doctoring/strix-openai-fallback-api-base-routing.md
@@ -71,7 +71,11 @@ Regression evidence proves that:
 8. the workflow provisions the override file and passes it into the gate env;
 9. the required-workflow smoke contract pins both sides of the wiring; and
 10. the stale `gpt-5.6-luna` expectations left behind by the model rename are
-   aligned with the valid `gpt-5.4` contract in queue-contract tests.
+   aligned with the valid `gpt-5.4` contract in queue-contract tests; and
+11. the direct GPT-5.4 fallback clears reasoning effort to `none` because the
+    pinned Strix scanner uses Chat Completions function tools, a combination
+    the provider rejects when `reasoning_effort` is present. Other models keep
+    the workflow's configured `high` effort.
 
 ## Limitations
 
diff --git a/scripts/ci/strix_quick_gate.sh b/scripts/ci/strix_quick_gate.sh
index c9aa41545..483149bed 100755
--- a/scripts/ci/strix_quick_gate.sh
+++ b/scripts/ci/strix_quick_gate.sh
@@ -2580,6 +2580,14 @@ run_strix_once() {
 	local start_epoch
 	start_epoch="$(date +%s)"
 	local child_llm_api_key=""
+	local child_reasoning_effort="${STRIX_REASONING_EFFORT:-}"
+	case "$(normalize_model "$model")" in
+	openai-direct/gpt-5.4 | openai_direct/gpt-5.4)
+		# OpenAI rejects function tools plus reasoning_effort for GPT-5.4 on
+		# Chat Completions, the transport used by the pinned Strix scanner.
+		child_reasoning_effort="none"
+		;;
+	esac
 	if ! is_vertex_model "$(normalize_model "$model")"; then
 		child_llm_api_key="$LLM_API_KEY"
 		if is_github_models_model "$(normalize_model "$model")" && [ -n "$STRIX_GITHUB_MODELS_KEY" ]; then
@@ -2597,6 +2605,7 @@ run_strix_once() {
 	set -o pipefail
 	set +e
 	STRIX_CHILD_MODEL="$child_model" \
+	STRIX_CHILD_REASONING_EFFORT="$child_reasoning_effort" \
 	STRIX_CHILD_LLM_API_KEY="$child_llm_api_key" \
 	STRIX_CHILD_LLM_API_BASE="$llm_api_base_value" \
 	STRIX_CHILD_REPORTS_DIR="$ACTIVE_REPORTS_DIR" \
@@ -2682,6 +2691,8 @@ for key in (
     value = os.environ.get(key)
     if value:
         child_env[key] = value
+if os.environ.get("STRIX_CHILD_REASONING_EFFORT"):
+    child_env["STRIX_REASONING_EFFORT"] = os.environ["STRIX_CHILD_REASONING_EFFORT"]
 llm_api_base = os.environ.get("STRIX_CHILD_LLM_API_BASE", "")
 if llm_api_base:
     child_env["LLM_API_BASE"] = llm_api_base
diff --git a/scripts/ci/test_strix_quick_gate.sh b/scripts/ci/test_strix_quick_gate.sh
index 3d3449dae..1fc84469e 100755
--- a/scripts/ci/test_strix_quick_gate.sh
+++ b/scripts/ci/test_strix_quick_gate.sh
@@ -3415,6 +3415,10 @@ REPORT
 			exit 1
 			;;
 		openai/gpt-5.4)
+			if [ "${STRIX_REASONING_EFFORT:-}" != "none" ]; then
+				echo "direct OpenAI GPT-5.4 fallback retained unsupported reasoning effort (${STRIX_REASONING_EFFORT:-<unset>})" >&2
+				exit 29
+			fi
 			if [ "${LLM_API_KEY:-}" != "openai-fallback-token" ]; then
 				echo "unexpected direct-OpenAI fallback key (${LLM_API_KEY:-<unset>})" >&2
 				exit 26
@@ -5701,6 +5705,7 @@ PY
 	if [ "$scenario" = "nvidia-rate-limit-openai-direct-fallback-clears-api-base" ]; then
 		printf '%s' 'openai-fallback-token' >"$tmp_dir/openai_fallback_key.txt"
 		env_cmd+=(STRIX_OPENAI_FALLBACK_KEY_FILE="$tmp_dir/openai_fallback_key.txt")
+		env_cmd+=(STRIX_REASONING_EFFORT="high")
 	fi
 	if [ "$scenario" = "openai-direct-quota-github-models-fallback-success" ]; then
 		printf '%s' 'https://models.github.ai/inference' >"$tmp_dir/github_models_api_base.txt"