fix(gemini): guard terminal model turns and unresponded functionCalls in normalizeGeminiContents

open-sse/translator/formats/gemini.js

@@ -432,7 +432,7 @@ export function cleanJSONSchemaForAntigravity(schema) {
   return cleaned;
 }
 
-// Merge adjacent same-role messages, strip empty parts, ensure initial user turn
+// Merge adjacent same-role messages, strip empty parts, ensure initial and terminal user turns
 export function normalizeGeminiContents(contents) {
   const out = [];
   for (const c of contents || []) {
@@ -446,6 +446,23 @@ export function normalizeGeminiContents(contents) {
   if (out.length > 0 && out[0].role !== "user") {
     out.unshift({ role: "user", parts: [{ text: "..." }] });
   }
+  if (out.length > 0 && out.at(-1).role === "model") {
+    const fnCalls = (out.at(-1).parts || []).filter(p => p && p.functionCall);
+    if (fnCalls.length > 0) {
+      const responses = fnCalls.map(p => {
+        const call = p.functionCall || {};
+        const fr = {
+          name: call.name || "tool",
+          response: { result: "Continue." }
+        };
+        if (call.id) fr.id = call.id;
+        return { functionResponse: fr };
+      });
+      out.push({ role: "user", parts: responses });
+    } else {
+      out.push({ role: "user", parts: [{ text: "Continue." }] });
+    }
+  }
   return out;
 }