fix: claude code sub-agent models

- add translation for exact model numbers

Author: garethknowles

src/routes/messages/non-stream-translation.ts

@@ -26,11 +26,13 @@ import { mapOpenAIStopReasonToAnthropic } from "./utils"
 
 // Payload translation
 
+
+
 export function translateToOpenAI(
   payload: AnthropicMessagesPayload,
 ): ChatCompletionsPayload {
   return {
-    model: payload.model,
+    model: translateModelName(payload.model),
     messages: translateAnthropicMessagesToOpenAI(
       payload.messages,
       payload.system,
@@ -46,6 +48,16 @@ export function translateToOpenAI(
   }
 }
 
+function translateModelName(model: string): string {
+  // Subagent requests use a specific model number which Copilot doesn't support
+  if (model.startsWith("claude-sonnet-4-")) {
+    return model.replace(/^claude-sonnet-4-.*/, "claude-sonnet-4")
+  } else if (model.startsWith("claude-opus-")) {
+    return model.replace(/^claude-opus-4-.*/, "claude-opus-4")
+  }
+  return model
+}
+
 function translateAnthropicMessagesToOpenAI(
   anthropicMessages: Array<AnthropicMessage>,
   system: string | Array<AnthropicTextBlock> | undefined,