Fix temperature=400 retry for OpenAI-compatible endpoints

backend/src/utils/llm/providers.ts

@@ -364,6 +364,31 @@ function clampTemperature(model: string, requested: number): number {
   return requested;
 }
 
+/**
+ * Detects the "this model only supports the default temperature" error.
+ *
+ * Real OpenAI populates `err.code === "unsupported_value"` and
+ * `err.param === "temperature"`, but many OpenAI-*compatible* endpoints only
+ * return the message string (e.g. "Unsupported value: 'temperature' does not
+ * support 0.7 with this model. Only the default (1) value is supported.")
+ * without those structured fields, so we fall back to matching the text.
+ */
+export function isTemperatureUnsupportedError(err: any): boolean {
+  const param = err?.param ?? err?.error?.param;
+  const code = err?.code ?? err?.error?.code;
+  if (code === "unsupported_value" && param === "temperature") return true;
+
+  const message = String(
+    err?.message ?? err?.error?.message ?? "",
+  ).toLowerCase();
+  return (
+    message.includes("temperature") &&
+    (message.includes("does not support") ||
+      message.includes("only the default") ||
+      message.includes("unsupported value"))
+  );
+}
+
 function normalizeFinishReason(raw: string | null | undefined): FinishReason {
   if (raw === "stop" || raw === "end_turn") return "stop";
   if (raw === "tool_calls" || raw === "tool_use") return "tool_calls";
@@ -623,9 +648,7 @@ export async function invoke_llm(opts: InvokeOptions): Promise<InvokeResult> {
     return await tryCompletion(requestedTemp);
   } catch (err: any) {
     const isTempUnsupported =
-      err?.code === "unsupported_value" &&
-      err?.param === "temperature" &&
-      requestedTemp !== 1;
+      requestedTemp !== 1 && isTemperatureUnsupportedError(err);
 
     if (isTempUnsupported) {
       console.warn(
@@ -1259,9 +1282,7 @@ export async function invoke_llm_streaming(
     return await runStream(requestedTemp);
   } catch (err: any) {
     const isTempUnsupported =
-      err?.code === "unsupported_value" &&
-      err?.param === "temperature" &&
-      requestedTemp !== 1;
+      requestedTemp !== 1 && isTemperatureUnsupportedError(err);
 
     if (isTempUnsupported) {
       console.warn(`[inference] Retrying stream with temperature=1`);

backend/tests/temperatureRetry.test.ts

@@ -0,0 +1,51 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { isTemperatureUnsupportedError } from "../src/utils/llm/providers";
+
+test("detects structured OpenAI unsupported_value/temperature error", () => {
+  const err = {
+    status: 400,
+    code: "unsupported_value",
+    param: "temperature",
+    message: "Unsupported value: 'temperature' does not support 0.7 with this model.",
+  };
+  assert.equal(isTemperatureUnsupportedError(err), true);
+});
+
+test("detects OpenAI-compatible endpoints that only return a message string", () => {
+  // Many OpenAI-compatible servers omit err.code/err.param and only set the
+  // message — this is the exact error users hit against such endpoints.
+  const err = {
+    status: 400,
+    message:
+      "400 Unsupported value: 'temperature' does not support 0.7 with this model. Only the default (1) value is supported.",
+  };
+  assert.equal(isTemperatureUnsupportedError(err), true);
+});
+
+test("detects nested error object shape", () => {
+  const err = {
+    error: {
+      code: "unsupported_value",
+      param: "temperature",
+      message: "temperature does not support 0.7",
+    },
+  };
+  assert.equal(isTemperatureUnsupportedError(err), true);
+});
+
+test("ignores unrelated errors", () => {
+  assert.equal(
+    isTemperatureUnsupportedError({ status: 500, message: "internal server error" }),
+    false,
+  );
+  assert.equal(
+    isTemperatureUnsupportedError({
+      code: "unsupported_value",
+      param: "top_p",
+      message: "Unsupported value: 'top_p'",
+    }),
+    false,
+  );
+  assert.equal(isTemperatureUnsupportedError(undefined), false);
+});