fix(gemini-cli): raise output floor for thinking and add validated toolConfig (#2486)

Gemini CLI requests with small max_tokens spend the whole output budget on
thoughts after reasoning_effort maps to thinkingConfig, returning blank
content or finish=length. Raise maxOutputTokens floors per thinking level/
budget (clamped to caps.maxOutput). Also emit toolConfig
functionCallingConfig.mode=VALIDATED for Gemini CLI tool requests to avoid
MALFORMED_FUNCTION_CALL.

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/translator/concerns/thinkingUnified.js

@@ -148,18 +148,57 @@ function toKimiReasoningEffort(cfg) {
   return null;
 }
 
+const GEMINI_LEVEL_OUTPUT_FLOOR = {
+  minimal: 4096,
+  low: 8192,
+  medium: 16384,
+  high: 65535,
+};
+
+function geminiBudgetOutputFloor(budget) {
+  if (budget === -1) return 32768;
+  if (!Number.isFinite(budget)) return 32768;
+  if (budget <= 1024) return 8192;
+  if (budget <= 8192) return 16384;
+  if (budget <= 24576) return 32768;
+  return 65535;
+}
+
+function geminiLevelOutputFloor(level) {
+  return GEMINI_LEVEL_OUTPUT_FLOOR[level] || GEMINI_LEVEL_OUTPUT_FLOOR.high;
+}
+
 // Gemini nests thinkingConfig under generationConfig. gemini-cli / antigravity wrap
 // the whole request in a { request: { generationConfig } } envelope — target the
 // envelope's generationConfig when present, else the top-level one.
+function getGeminiGenerationConfig(body) {
+  if (body.request && typeof body.request === "object") {
+    if (!body.request.generationConfig || typeof body.request.generationConfig !== "object") {
+      body.request.generationConfig = {};
+    }
+    return body.request.generationConfig;
+  }
+  if (!body.generationConfig || typeof body.generationConfig !== "object") {
+    body.generationConfig = {};
+  }
+  return body.generationConfig;
+}
+
 function setGeminiThinking(body, tc) {
-  const gc = body.request?.generationConfig
-    ? body.request.generationConfig
-    : (body.generationConfig && typeof body.generationConfig === "object"
-        ? body.generationConfig
-        : (body.generationConfig = {}));
+  const gc = getGeminiGenerationConfig(body);
   gc.thinkingConfig = tc;
 }
 
+function ensureGeminiOutputFloor(body, floor, caps) {
+  const cap = Number.isFinite(caps?.maxOutput) ? caps.maxOutput : floor;
+  const target = Math.min(floor, cap);
+  const gc = getGeminiGenerationConfig(body);
+  const current = Number(gc.maxOutputTokens);
+  if (!Number.isFinite(current) || current < target) {
+    gc.maxOutputTokens = target;
+  }
+}
+
 // Strip every known thinking field from a body (used before re-applying / when unsupported).
 function stripAll(body) {
   delete body.thinking;
@@ -203,12 +242,14 @@ function applyFormat(fmt, body, cfg, caps) {
     case "gemini-level": {
       const level = none ? "minimal" : toGeminiThinkingLevel(eff);
       setGeminiThinking(body, { thinkingLevel: level, includeThoughts: level !== "minimal" });
+      ensureGeminiOutputFloor(body, geminiLevelOutputFloor(level), caps);
       break;
     }
     case "gemini-budget": {
       if (none && canDisable) { setGeminiThinking(body, { thinkingBudget: 0, includeThoughts: false }); break; }
       const budget = toBudget(eff, caps.thinkingRange);
       setGeminiThinking(body, { thinkingBudget: budget ?? -1, includeThoughts: true });
+      ensureGeminiOutputFloor(body, geminiBudgetOutputFloor(budget ?? -1), caps);
       break;
     }
     case "zai": {

open-sse/translator/request/openai-to-gemini.js

@@ -281,18 +281,17 @@ function wrapInCloudCodeEnvelope(model, geminiCLI, credentials = null, isAntigra
   // Antigravity specific fields
   if (isAntigravity) {
     envelope.requestType = "agent";
-
-    // Add toolConfig for Antigravity
-    if (geminiCLI.tools?.length > 0) {
-      envelope.request.toolConfig = {
-        functionCallingConfig: { mode: "VALIDATED" }
-      };
-    }
   } else {
     // Keep safetySettings for Gemini CLI
     envelope.request.safetySettings = geminiCLI.safetySettings;
   }
 
+  if (geminiCLI.tools?.length > 0) {
+    envelope.request.toolConfig = {
+      functionCallingConfig: { mode: "VALIDATED" }
+    };
+  }
+
   return envelope;
 }