fix(executor): normalize max effort for openai shape providers

open-sse/executors/base.ts

@@ -221,7 +221,8 @@ function hasActiveClaudeThinking(body: Record<string, unknown>): boolean {
  * through unchanged, and Claude models default to xhigh support unless marked
  * as legacy unsupported entries. max support is Claude/CC-compatible only and
  * intentionally separate: older Opus/Sonnet models may support max even when
- * they do not support xhigh.
+ * they do not support xhigh. For OpenAI-shape providers, normalize max to
+ * xhigh when that top tier is allowed; otherwise downgrade to high.
  */
 const MISTRAL_NO_REASONING_EFFORT_PATTERN = /devstral/i;
 const GITHUB_NO_REASONING_EFFORT_PATTERN = /(claude|haiku|oswe)/i;
@@ -251,9 +252,27 @@ export function sanitizeReasoningEffortForProvider(
   const effortStr = typeof effort === "string" ? effort.toLowerCase() : "";
   const modelStr = model || "";
 
-  const shouldDowngradeXHigh = effortStr === "xhigh" && !supportsXHighEffort(provider, modelStr);
+  const supportsXHigh = supportsXHighEffort(provider, modelStr);
+  const shouldDowngradeXHigh = effortStr === "xhigh" && !supportsXHigh;
+  const shouldNormalizeMaxToXHigh =
+    effortStr === "max" && !supportsMaxEffortForProvider(provider, modelStr) && supportsXHigh;
   const shouldDowngradeMax =
-    effortStr === "max" && !supportsMaxEffortForProvider(provider, modelStr);
+    effortStr === "max" && !supportsMaxEffortForProvider(provider, modelStr) && !supportsXHigh;
+
+  if (shouldNormalizeMaxToXHigh) {
+    log?.info?.(
+      "REASONING_SANITIZE",
+      `${provider}/${modelStr}: normalized reasoning_effort max → xhigh`
+    );
+    const next: Record<string, unknown> = { ...b };
+    if (hasTopLevelReasoningEffort) {
+      next.reasoning_effort = "xhigh";
+    }
+    if (reasoning) {
+      next.reasoning = { ...reasoning, effort: "xhigh" };
+    }
+    return next;
+  }
 
   if (shouldDowngradeXHigh || shouldDowngradeMax) {
     log?.info?.(
@@ -797,7 +816,10 @@ export class BaseExecutor {
               delete (tb.output_config as Record<string, unknown>).effort;
             }
             appliedEffort = "off";
-          } else if (headerEffort && ["low", "medium", "high", "xhigh", "max"].includes(headerEffort)) {
+          } else if (
+            headerEffort &&
+            ["low", "medium", "high", "xhigh", "max"].includes(headerEffort)
+          ) {
             const oc =
               tb.output_config && typeof tb.output_config === "object"
                 ? (tb.output_config as Record<string, unknown>)

tests/unit/base-executor-sanitize-effort.test.ts

@@ -43,6 +43,44 @@ test("sanitizeReasoningEffortForProvider: xiaomi-mimo downgrades max → high",
   );
 });
 
+test("sanitizeReasoningEffortForProvider: OpenAI-compatible Gemini normalizes max → xhigh", () => {
+  const log = makeLog();
+  const body = {
+    model: "gemini-3.1-pro-preview",
+    reasoning_effort: "max",
+    messages: [{ role: "user", content: "hi" }],
+  };
+  const result = sanitizeReasoningEffortForProvider(
+    body,
+    "openai-compatible-free1",
+    "gemini-3.1-pro-preview",
+    log
+  );
+  assert.notEqual(result, body, "must return a new object when mutating");
+  assert.equal((result as any).reasoning_effort, "xhigh");
+  assert.ok(
+    log.messages.some(([tag, m]) => tag === "REASONING_SANITIZE" && /max → xhigh/.test(m)),
+    "logs the normalization"
+  );
+});
+
+test("sanitizeReasoningEffortForProvider: nested OpenAI reasoning max normalizes to xhigh", () => {
+  const body = {
+    model: "gemini-3.1-pro-preview",
+    reasoning: { effort: "max", summary: "auto" },
+    input: [],
+  };
+  const result = sanitizeReasoningEffortForProvider(
+    body,
+    "openai-compatible-free1",
+    "gemini-3.1-pro-preview",
+    null
+  );
+  assert.equal((result as any).reasoning.effort, "xhigh");
+  assert.equal((result as any).reasoning.summary, "auto", "other reasoning fields preserved");
+  assert.equal((result as any).reasoning_effort, undefined);
+});
+
 test("sanitizeReasoningEffortForProvider: claude preserves max for Opus/Sonnet and downgrades Haiku", () => {
   const sonnetBody = {
     model: "claude-sonnet-4-6",