fix(translator): map Claude stop_sequences and stop to Gemini stopSequences (#12785)

open-sse/translator/request/claude-to-gemini.ts

@@ -1,9 +1,6 @@
 import { register } from "../registry.ts";
 import { FORMATS } from "../formats.ts";
-import {
-  DEFAULT_SAFETY_SETTINGS,
-  cleanJSONSchemaForAntigravity,
-} from "../helpers/geminiHelper.ts";
+import { DEFAULT_SAFETY_SETTINGS, cleanJSONSchemaForAntigravity } from "../helpers/geminiHelper.ts";
 import { buildGeminiTools, sanitizeGeminiToolName } from "../helpers/geminiToolsSanitizer.ts";
 import {
   buildGeminiThoughtSignatureKey,
@@ -83,6 +80,10 @@ export function claudeToGeminiRequest(model, body, stream, credentials = null) {
       result.generationConfig.maxOutputTokens = maxOutputTokens;
     }
   }
+  if (body.stop_sequences !== undefined || body.stop !== undefined) {
+    const rawStop = body.stop_sequences ?? body.stop;
+    result.generationConfig.stopSequences = Array.isArray(rawStop) ? rawStop : [rawStop];
+  }
 
   // ── System instruction ─────────────────────────────────────────
   if (body.system) {

tests/unit/translator-claude-to-gemini.test.ts

@@ -486,3 +486,34 @@ test("Claude -> Gemini non-numeric budget_tokens falls through to effort path",
     includeThoughts: true,
   });
 });
+
+test("Claude -> Gemini maps stop_sequences and stop to generationConfig.stopSequences", () => {
+  const result1 = claudeToGeminiRequest(
+    "gemini-2.5-pro",
+    {
+      messages: [{ role: "user", content: [{ type: "text", text: "hi" }] }],
+      stop_sequences: ["STOP", "\nHuman:"],
+    },
+    false
+  );
+  assert.deepEqual(result1.generationConfig.stopSequences, ["STOP", "\nHuman:"]);
+
+  const result2 = claudeToGeminiRequest(
+    "gemini-2.5-pro",
+    {
+      messages: [{ role: "user", content: [{ type: "text", text: "hi" }] }],
+      stop: "SINGLE_STOP",
+    },
+    false
+  );
+  assert.deepEqual(result2.generationConfig.stopSequences, ["SINGLE_STOP"]);
+
+  const result3 = claudeToGeminiRequest(
+    "gemini-2.5-pro",
+    {
+      messages: [{ role: "user", content: [{ type: "text", text: "hi" }] }],
+    },
+    false
+  );
+  assert.strictEqual(result3.generationConfig.stopSequences, undefined);
+});