fix(proxy): handle 404 with model-not-found guidance (#1748)

* fix(proxy): handle BYOK 404 with model-not-found guidance

After user BYOK error handling, return a helpful message when the
upstream provider responds with 404, indicating the model does not
exist or is no longer available. Recommends switching to
kilo-auto/balanced, with explicit /model instructions for
kiloclaw/openclaw users.

* fix: move 404 model-not-found handler outside BYOK block

The 404 handler should apply to all users, not just BYOK users.

* fix: recommend kilo-auto/free when user balance is zero

When the user has no credits, recommend kilo-auto/free instead of
kilo-auto/balanced in the 404 model-not-found message.

* fix: add BYOK-specific 404 message without auto model recommendation

BYOK users get a plain message pointing them to check the model name
and their API provider, while non-BYOK users still get the auto model
recommendation.

* fix: drop kilocode/ prefix from non-claw 404 recommendation

* fix: remove BYOK 404 entry from byokErrorMessages

* Format

---------

Co-authored-by: kiloconnect[bot] <240665456+kiloconnect[bot]@users.noreply.github.com>
Co-authored-by: Christiaan Arnoldus <christiaan.arnoldus@outlook.com>

Author: kilo-code-bot[bot]

src/app/api/openrouter/[...path]/route.ts

@@ -591,6 +591,8 @@ export async function POST(request: NextRequest): Promise<NextResponseType<unkno
       request: requestBodyParsed,
       response,
       isUserByok: !!userByok,
+      feature,
+      balance: (await balanceAndSettingsPromise).balance,
     });
     if (errorResponse) {
       return errorResponse;

src/lib/llm-proxy-helpers.ts

@@ -142,11 +142,15 @@ export async function makeErrorReadable({
   request,
   response,
   isUserByok,
+  feature,
+  balance,
 }: {
   requestedModel: string;
   request: GatewayRequest;
   response: Response;
   isUserByok: boolean;
+  feature: FeatureValue | null;
+  balance: number;
 }) {
   if (response.status < 400) {
     return undefined;
@@ -163,6 +167,16 @@ export async function makeErrorReadable({
     }
   }
 
+  if (response.status === 404) {
+    const recommendedModel = balance <= 0 ? KILO_AUTO_FREE_MODEL : KILO_AUTO_BALANCED_MODEL;
+    const recommendation =
+      feature === 'kiloclaw' || feature === 'openclaw'
+        ? `The model "${requestedModel}" does not exist or is no longer available. We recommend switching to ${recommendedModel.name}: /model kilocode/${recommendedModel.id}`
+        : `The model "${requestedModel}" does not exist or is no longer available. We recommend switching to ${recommendedModel.id}.`;
+    warnExceptInTest(`Responding with 404 ${recommendation}`);
+    return NextResponse.json({ error: recommendation, message: recommendation }, { status: 404 });
+  }
+
   // Sometimes we get generic or nonsensical errors when the context length is exceeded
   // (such as "Internal Server Error" or "No allowed providers are available for the selected model")
   const model = kiloFreeModels.find(m => m.public_id === requestedModel);