diff --git a/frontend/scene-generator/llm-client.js b/frontend/scene-generator/llm-client.js
index 9018001..54fda63 100644
--- a/frontend/scene-generator/llm-client.js
+++ b/frontend/scene-generator/llm-client.js
@@ -747,6 +747,52 @@ async function analyzeScene(sourceDir, dirContents, config) {
   };
 }
 
+function validateExtractedSceneInfo(sceneIr) {
+  const issues = [];
+
+  // Check: at least one apiEndpoint has contentType
+  const endpointsWithCt = (sceneIr.apiEndpoints || []).filter(
+    ep => ep && ep.contentType
+  );
+  if ((sceneIr.apiEndpoints || []).length > 0 && endpointsWithCt.length === 0) {
+    issues.push("missing_contentType_on_endpoints");
+  }
+
+  // Check: at least one mode has responsePath (if modes exist)
+  if ((sceneIr.modes || []).length > 0) {
+    const modesWithPath = sceneIr.modes.filter(m => m.responsePath !== undefined && m.responsePath !== null);
+    if (modesWithPath.length === 0) {
+      issues.push("missing_responsePath_on_modes");
+    }
+  }
+
+  // Check: workflowArchetype is set
+  if (!sceneIr.workflowArchetype) {
+    issues.push("missing_workflowArchetype");
+  }
+
+  return issues;
+}
+
+function mergeSceneIrFields(repaired, original) {
+  const merged = {};
+  // Only fill fields that were empty/missing in original
+  const criticalFields = ['workflowArchetype', 'defaultMode', 'modeSwitchField'];
+  for (const field of criticalFields) {
+    if (!original[field] && repaired[field]) {
+      merged[field] = repaired[field];
+    }
+  }
+  // For arrays, merge if original is empty
+  if ((!original.apiEndpoints || original.apiEndpoints.length === 0) && repaired.apiEndpoints) {
+    merged.apiEndpoints = repaired.apiEndpoints;
+  }
+  if ((!original.modes || original.modes.length === 0) && repaired.modes) {
+    merged.modes = repaired.modes;
+  }
+  return merged;
+}
+
 async function analyzeSceneDeep(sourceDir, dirContents, config) {
   const content = await requestChatCompletionWithRetry(
     [
@@ -807,6 +853,30 @@ async function analyzeSceneDeep(sourceDir, dirContents, config) {
     }
   }
 
+  // POST-EXTRACTION VALIDATION: one-shot retry for missing fields
+  const issues = validateExtractedSceneInfo(normalized);
+  if (issues.length > 0) {
+    const followUpPrompt = `The previous extraction has these issues:\n${issues.join('\n')}\nPlease re-analyze the source snippets and fill in the missing fields. Use defaults if truly unavailable.`;
+
+    try {
+      const followUpContent = await requestChatCompletionWithRetry(
+        [
+          { role: "system", content: DEEP_SYSTEM_PROMPT },
+          { role: "user", content: followUpPrompt },
+        ],
+        { ...config, maxTokens: 2400, timeoutMs: DEEP_REQUEST_TIMEOUT_MS, retryAttempts: 1 }
+      );
+
+      const repaired = normalizeSceneIr(await extractJsonFromResponseWithRepair(followUpContent, config));
+      // Merge repaired fields into normalized (only fill empty fields)
+      const mergeResult = mergeSceneIrFields(repaired, normalized);
+      Object.assign(normalized, mergeResult);
+    } catch (error) {
+      // Silently continue with original extraction if retry fails
+      // The auto-wrap logic (above) will handle empty modes
+    }
+  }
+
   return normalized;
 }