Allows to translate model names like claude-sonnet-4-5-20250929 properly

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

@@ -48,7 +48,13 @@ 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-")) {
+  if (/^claude-opus-4-5-\d{8}$/.test(model)) {
+    return "claude-opus-4.5"
+  } else if (/^claude-sonnet-4-5-\d{8}$/.test(model)) {
+    return "claude-sonnet-4.5"
+  } else if (/^claude-haiku-4-5-\d{8}$/.test(model)) {
+    return "claude-haiku-4.5"
+  } else 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")

tests/anthropic-request.test.ts

@@ -197,6 +197,36 @@ describe("Anthropic to OpenAI translation logic", () => {
     expect(assistantMessage?.tool_calls).toHaveLength(1)
     expect(assistantMessage?.tool_calls?.[0].function.name).toBe("get_weather")
   })
+
+  test("should translate claude-opus-4-5-20251101 to claude-opus-4.5", () => {
+    const anthropicPayload: AnthropicMessagesPayload = {
+      model: "claude-opus-4-5-20251101",
+      messages: [{ role: "user", content: "Hello!" }],
+      max_tokens: 100,
+    }
+    const openAIPayload = translateToOpenAI(anthropicPayload)
+    expect(openAIPayload.model).toBe("claude-opus-4.5")
+  })
+
+  test("should translate claude-sonnet-4-5-20250929 to claude-sonnet-4.5", () => {
+    const anthropicPayload: AnthropicMessagesPayload = {
+      model: "claude-sonnet-4-5-20250929",
+      messages: [{ role: "user", content: "Hello!" }],
+      max_tokens: 100,
+    }
+    const openAIPayload = translateToOpenAI(anthropicPayload)
+    expect(openAIPayload.model).toBe("claude-sonnet-4.5")
+  })
+
+  test("should translate claude-haiku-4-5-20250929 to claude-haiku-4.5", () => {
+    const anthropicPayload: AnthropicMessagesPayload = {
+      model: "claude-haiku-4-5-20250929",
+      messages: [{ role: "user", content: "Hello!" }],
+      max_tokens: 100,
+    }
+    const openAIPayload = translateToOpenAI(anthropicPayload)
+    expect(openAIPayload.model).toBe("claude-haiku-4.5")
+  })
 })
 
 describe("OpenAI Chat Completion v1 Request Payload Validation with Zod", () => {