diff --git a/libs/types/src/provider-utils.ts b/libs/types/src/provider-utils.ts
index eadc41bb..772d4d7c 100644
--- a/libs/types/src/provider-utils.ts
+++ b/libs/types/src/provider-utils.ts
@@ -7,7 +7,7 @@
  */
 
 import type { ModelProvider } from './settings.js';
-import { CURSOR_MODEL_MAP, LEGACY_CURSOR_MODEL_MAP } from './cursor-models.js';
+import { LEGACY_CURSOR_MODEL_MAP } from './cursor-models.js';
 import { CLAUDE_MODEL_MAP, CODEX_MODEL_MAP } from './model.js';
 import { OPENCODE_MODEL_CONFIG_MAP, LEGACY_OPENCODE_MODEL_MAP } from './opencode-models.js';
 import { GEMINI_MODEL_MAP } from './gemini-models.js';
@@ -370,6 +370,16 @@ export function normalizeModelString(model: string | undefined | null): string {
  * supportsStructuredOutput('gemini-2.5-pro') // false
  */
 export function supportsStructuredOutput(model: string | undefined | null): boolean {
+  // Exclude proxy providers first - they may have Claude/Codex in the model name
+  // but route through different APIs that don't support structured output
+  if (
+    isCursorModel(model) ||
+    isGeminiModel(model) ||
+    isOpencodeModel(model) ||
+    isCopilotModel(model)
+  ) {
+    return false;
+  }
   return isClaudeModel(model) || isCodexModel(model);
 }