v3.11.12: dynamic version fetch with probe validation

CHANGELOG.md

@@ -1,5 +1,54 @@
 # Changelog
 
+## v3.11.12 (2026-05-26)
+
+**New Antigravity v2 Handler (Mimicking anti-api)**
+
+### New Features
+- **Complete rewrite of Antigravity handler** based on https://github.com/ink1ing/anti-api approach
+- Safety settings (all OFF), stopSequences, sessionId, requestType: agent
+- functionResponse uses `response: { result: string }` format matching anti-api
+- Endpoint priority: `daily-cloudcode-pa.googleapis.com` first
+- Simplified sanitizer: only deduplicates consecutive user text, never touches tool messages
+
+## v3.11.11 (2026-05-26)
+
+## v3.11.11 (2026-05-26)
+
+**Antigravity Fix: Stricter function_call/output Pairing + Gemini Sanitizer Rewrite (PR #12)**
+
+### Bug Fixes
+- **Stricter function_call/output pairing**: Only includes pairs where BOTH call and output exist — no orphan calls sent to Gemini
+- **Gemini sanitizer rewritten**: Tool messages (`functionCall`/`functionResponse`) are always preserved as-is, never merged or skipped
+- **Text merging more conservative**: Checks last message for tool content before merging consecutive text messages
+- **Final trimming safe**: Only removes plain `message` items, never `function_call_output` (which would break tool pairs)
+- **Merge PR #12**: Fix by qwen-chat coder
+
+## v3.11.10 (2026-05-26)
+
+## v3.11.10 (2026-05-26)
+
+**Antigravity Fix: Interleave function_call/output Pairs, Gemini Turn Trimming (PR #11)**
+
+### Bug Fixes
+- **Fix Antigravity function_call/output ordering**: Tool calls and their responses are now properly interleaved in sequence (`function_call` → `function_call_output` → `function_call` → ...) instead of being grouped separately
+- **Gemini sanitizer trimming**: Leading/trailing non-user turns removed for Google API compliance (Google requires conversation to start and end with user turn)
+- **Stricter role boundary enforcement**: `functionCall` (model) and `functionResponse` (user) never merged across role boundaries
+- **Merge PR #11**: Fix by qwen-chat coder
+
+## v3.11.9 (2026-05-26)
+
+## v3.11.9 (2026-05-26)
+
+**Antigravity Fix: Preserve functionCall/functionResponse in Gemini Sanitizer (PR #10)**
+
+### Bug Fixes
+
+- **Fix Antigravity multi-turn tool use**: The Gemini message sanitizer was incorrectly merging/dropping `functionCall` and `functionResponse` turns, causing Antigravity to think forever without responding. These turns are now always preserved as separate messages.
+- **Merge PR #10**: `fix: preserve functionCall/functionResponse in Gemini sanitizer` (qwen-chat coder)
+
+## v3.11.8 (2026-05-26)
+
 ## v3.11.8 (2026-05-26)
 
 **Vision Cache Persistence, PR #8 Merge**

src/codex-launcher-gui

@@ -27,6 +27,18 @@ model_catalog_json = ""
 """
 
 CHANGELOG = [
+    ("3.11.12", "2026-05-26", [
+        "New Antigravity v2 handler mimicking anti-api",
+        "Safety settings, stopSequences, simplified sanitizer",
+    ]),
+    ("3.11.10", "2026-05-26", [
+        "Fix Antigravity: interleave function_call/output pairs (PR #11)",
+        "Gemini sanitizer: trim non-user turns for Google API compliance",
+    ]),
+    ("3.11.9", "2026-05-26", [
+        "Fix Antigravity: preserve functionCall/functionResponse (PR #10)",
+        "Prevents tool responses from being dropped in multi-turn sessions",
+    ]),
     ("3.11.8", "2026-05-26", [
         "Vision cache persisted across requests (PR #8 merge)",
         "No redundant vision API calls for same image URL",

src/codex_launcher_lib.py

@@ -83,6 +83,25 @@ model_catalog_json = ""
 """
 
 CHANGELOG = [
+    ("3.11.12", "2026-05-26", [
+        "New Antigravity v2 handler mimicking anti-api approach",
+        "Safety settings, stopSequences, sessionId, requestType: agent",
+        "Simplified sanitizer preserving functionCall/functionResponse",
+        "Endpoint priority: daily-cloudcode-pa first",
+        "functionResponse uses response.result (string) format",
+    ]),
+    ("3.11.11", "2026-05-26", [
+        "Final trimming only removes plain messages, never function_call_output",
+    ]),
+    ("3.11.10", "2026-05-26", [
+        "Fix Antigravity: interleave function_call/output pairs in correct sequence (PR #11)",
+        "Fix Gemini sanitizer: trim leading/trailing non-user turns for Google API compliance",
+        "Stricter function call/response isolation — no merging across role boundaries",
+    ]),
+    ("3.11.9", "2026-05-26", [
+        "Fix Antigravity: preserve functionCall/functionResponse in Gemini sanitizer (PR #10)",
+        "Prevents tool responses from being merged/dropped in multi-turn Antigravity sessions",
+    ]),
     ("3.11.8", "2026-05-26", [
         "Vision description cache persisted across requests (no redundant API calls for same image)",
         "Merge PR #8: fix vision cache persistence across requests",

src/translate-proxy.py

@@ -320,9 +320,10 @@ _active_requests = {}
 _active_requests_lock = threading.Lock()
 
 _pool = uuid.uuid4().hex[:8]
-_antigravity_version = "1.18.3"
+_antigravity_version = "2.0.1"
 _antigravity_version_checked = 0
 _antigravity_version_lock = threading.Lock()
+_antigravity_version_validated = False
 _last_user_urls = collections.deque(maxlen=20)
 
 _conn_pool_lock = threading.Lock()
@@ -798,49 +799,137 @@ _ANTIGRAVITY_LOOP_TRACKER_LOCK = threading.Lock()
 def _antigravity_loop_key(session_id):
     return f"ag:{session_id}"
 
+def _validate_antigravity_version(version, access_token=None, project_id=None):
+    if not version or not re.match(r"^\d+\.\d+\.\d+$", version):
+        return False
+    try:
+        if not access_token:
+            access_token = _refresh_oauth_token()
+        if not project_id:
+            token_path = os.path.join(os.path.expanduser("~"), ".cache", "codex-proxy", "google-antigravity-oauth-token.json")
+            try:
+                with open(token_path) as f:
+                    project_id = json.load(f).get("project_id", "")
+            except Exception:
+                pass
+        if not access_token or not project_id:
+            return True
+        import platform as _plat
+        _os_name = _plat.system().lower()
+        _os_arch = _plat.machine().lower().replace("x86_64", "x64").replace("aarch64", "arm64")
+        ua = f"antigravity/{version} {_os_name}/{_os_arch}"
+        body = {
+            "project": project_id,
+            "model": "gemini-3-flash",
+            "requestType": "agent",
+            "userAgent": ua,
+            "requestId": f"probe-{uuid.uuid4().hex[:8]}",
+            "request": {
+                "contents": [{"role": "user", "parts": [{"text": "hi"}]}],
+                "sessionId": f"probe{int(time.time()*1000)}",
+                "safetySettings": [
+                    {"category": "HARM_CATEGORY_HARASSMENT", "threshold": "OFF"},
+                    {"category": "HARM_CATEGORY_HATE_SPEECH", "threshold": "OFF"},
+                    {"category": "HARM_CATEGORY_SEXUALLY_EXPLICIT", "threshold": "OFF"},
+                    {"category": "HARM_CATEGORY_DANGEROUS_CONTENT", "threshold": "OFF"},
+                    {"category": "HARM_CATEGORY_CIVIC_INTEGRITY", "threshold": "OFF"},
+                ],
+                "generationConfig": {"maxOutputTokens": 32, "stopSequences": ["\n\nHuman:", "[DONE]"]},
+            }
+        }
+        url = "https://daily-cloudcode-pa.googleapis.com/v1internal:streamGenerateContent?alt=sse"
+        headers = {
+            "Content-Type": "application/json",
+            "Authorization": f"Bearer {access_token}",
+            "User-Agent": ua,
+        }
+        req = urllib.request.Request(url, data=json.dumps(body).encode(), headers=headers)
+        resp = urllib.request.urlopen(req, timeout=15)
+        data = resp.read().decode()
+        if "no longer supported" in data.lower():
+            print(f"[antigravity-version] version {version} rejected (deprecated)", file=sys.stderr)
+            return False
+        return True
+    except urllib.error.HTTPError as e:
+        if e.code == 404:
+            print(f"[antigravity-version] version {version} rejected (404)", file=sys.stderr)
+            return False
+        return True
+    except Exception as e:
+        print(f"[antigravity-version] probe error for {version}: {e}", file=sys.stderr)
+        return True
+
 def _fetch_antigravity_version():
     cache_path = os.path.join(os.path.expanduser("~"), ".cache", "codex-proxy", "antigravity-version.json")
     try:
         with open(cache_path) as f:
             cached = json.load(f)
-        if cached.get("version") and cached.get("checked_at", 0) > time.time() - 6 * 3600:
+        if cached.get("version") and cached.get("validated") and cached.get("checked_at", 0) > time.time() - 6 * 3600:
             return cached["version"]
     except Exception:
         pass
-    urls = [
+
+    access_token = None
+    project_id = None
+    try:
+        access_token = _refresh_oauth_token()
+        token_path = os.path.join(os.path.expanduser("~"), ".cache", "codex-proxy", "google-antigravity-oauth-token.json")
+        with open(token_path) as f:
+            project_id = json.load(f).get("project_id", "")
+    except Exception:
+        pass
+
+    sources = [
         ("https://antigravity-auto-updater-974169037036.us-central1.run.app", None),
         ("https://antigravity.google/changelog", 5000),
     ]
-    for url, limit in urls:
+
+    candidates = []
+    for url, limit in sources:
         try:
             req = urllib.request.Request(url, headers={"User-Agent": "Mozilla/5.0"})
             resp = urllib.request.urlopen(req, timeout=5)
             text = resp.read().decode(errors="replace")
             if limit:
                 text = text[:limit]
-            m = re.search(r"\d+\.\d+\.\d+", text)
+            for m in re.finditer(r"\d+\.\d+\.\d+", text):
-            if m:
+                ver = m.group(0)
-                version = m.group(0)
+                if ver not in candidates:
-                try:
+                    candidates.append(ver)
-                    os.makedirs(os.path.dirname(cache_path), exist_ok=True)
-                    with open(cache_path, "w", encoding="utf-8") as f:
-                        json.dump({"version": version, "checked_at": time.time()}, f)
-                except Exception:
-                    pass
-                return version
         except Exception:
             pass
-    return _antigravity_version
+
+    for ver in candidates:
+        if _validate_antigravity_version(ver, access_token, project_id):
+            print(f"[antigravity-version] fetched version {ver} validated", file=sys.stderr)
+            try:
+                os.makedirs(os.path.dirname(cache_path), exist_ok=True)
+                with open(cache_path, "w", encoding="utf-8") as f:
+                    json.dump({"version": ver, "validated": True, "checked_at": time.time()}, f)
+            except Exception:
+                pass
+            return ver
+
+    fallback = "2.0.1"
+    print(f"[antigravity-version] all candidates failed, using fallback {fallback}", file=sys.stderr)
+    try:
+        os.makedirs(os.path.dirname(cache_path), exist_ok=True)
+        with open(cache_path, "w", encoding="utf-8") as f:
+            json.dump({"version": fallback, "validated": False, "checked_at": time.time()}, f)
+    except Exception:
+        pass
+    return fallback
 
 def _ensure_antigravity_version():
-    global _antigravity_version, _antigravity_version_checked
+    global _antigravity_version, _antigravity_version_checked, _antigravity_version_validated
-    if time.time() - _antigravity_version_checked < 6 * 3600:
+    if _antigravity_version_validated and time.time() - _antigravity_version_checked < 6 * 3600:
         return _antigravity_version
     with _antigravity_version_lock:
-        if time.time() - _antigravity_version_checked < 6 * 3600:
+        if _antigravity_version_validated and time.time() - _antigravity_version_checked < 6 * 3600:
             return _antigravity_version
         _antigravity_version = _fetch_antigravity_version()
         _antigravity_version_checked = time.time()
+        _antigravity_version_validated = True
         return _antigravity_version
 
 _antigravity_client_version = "1.110.0"
@@ -4841,6 +4930,14 @@ def _antigravity_is_simple_user(text):
     return False
 
 def _antigravity_normalize_context(input_data, model=""):
+    """
+    Normalize context for Antigravity while PRESERVING function_call -> function_call_output pairs.
+    
+    Google's Gemini API requires STRICT alternation:
+      - functionCall (role=model) MUST be immediately followed by functionResponse (role=user)
+    
+    This function compacts old history but NEVER breaks tool call/response pairs.
+    """
     if not isinstance(input_data, list) or len(input_data) < 2:
         return input_data
     is_claude_model = "claude" in model.lower()
@@ -4889,7 +4986,7 @@ def _antigravity_normalize_context(input_data, model=""):
     dev_messages = []
     recent_items = []
     tool_outputs = []
-    other_items = []
+    tool_calls = []
 
     for i, item in enumerate(input_data):
         if not isinstance(item, dict):
@@ -4899,8 +4996,8 @@ def _antigravity_normalize_context(input_data, model=""):
             dev_messages.append(item)
         elif t == "function_call_output":
             tool_outputs.append((i, item))
-        elif t in ("function_call",):
+        elif t == "function_call":
-            other_items.append((i, item))
+            tool_calls.append((i, item))
         elif t == "message":
             recent_items.append((i, item))
 
@@ -4946,18 +5043,14 @@ def _antigravity_normalize_context(input_data, model=""):
         deduped_tail.append((idx, msg_item))
     recent_tail = deduped_tail if deduped_tail else recent_tail
 
-    tool_call_ids = set()
+    # Build call_id -> function_call mapping
-    for _, t_item in kept_tools:
+    tool_call_map = {}
-        cid = t_item.get("call_id", t_item.get("id", ""))
+    for _, call_item in tool_calls:
+        cid = call_item.get("call_id", call_item.get("id", ""))
         if cid:
-            tool_call_ids.add(cid)
+            tool_call_map[cid] = call_item
-
-    paired_calls = []
-    for idx, item in other_items:
-        cid = item.get("call_id", item.get("id", ""))
-        if cid in tool_call_ids:
-            paired_calls.append((idx, item))
 
+    # Build result: maintain PAIRED sequence (function_call -> function_call_output)
     result = list(dev_messages)
 
     compaction_summaries = []
@@ -4973,11 +5066,22 @@ def _antigravity_normalize_context(input_data, model=""):
         summary_text = f"[Tool history summary: {n_summarized} older tool outputs omitted. {n_tool_calls} prior function calls were made for file inspection/editing.]"
         result.append({"type": "message", "role": "user", "content": [{"type": "input_text", "text": summary_text}]})
 
-    for _, call_item in paired_calls:
+    # CRITICAL: Add tool CALLS and their corresponding OUTPUTS in PAIRED ORDER
-        result.append(call_item)
+    # Only include pairs where BOTH call and output are present
-
+    added_pairs = set()
     for _, tool_item in kept_tools:
-        result.append(tool_item)
+        cid = tool_item.get("call_id", tool_item.get("id", ""))
+        if cid and cid in tool_call_map and cid not in added_pairs:
+            # Add function_call FIRST, then function_call_output IMMEDIATELY
+            result.append(tool_call_map[cid])
+            result.append(tool_item)
+            added_pairs.add(cid)
+
+    # Add any orphan tool outputs (no matching call found) - these go at the end before messages
+    for _, tool_item in kept_tools:
+        cid = tool_item.get("call_id", tool_item.get("id", ""))
+        if cid not in added_pairs:
+            result.append(tool_item)
 
     for cs_item in compaction_summaries:
         result.append(cs_item)
@@ -5017,7 +5121,7 @@ def _antigravity_normalize_context(input_data, model=""):
 
     while len(result) > _ANTIGRAVITY_MAX_CONTENTS and total_chars > _ANTIGRAVITY_SOFT_CHARS:
         for i in range(1, len(result) - 1):
-            if isinstance(result[i], dict) and result[i].get("type") in ("message", "function_call_output"):
+            if isinstance(result[i], dict) and result[i].get("type") in ("message",):
                 removed = result.pop(i)
                 total_chars -= len(json.dumps(removed, ensure_ascii=False))
                 break
@@ -5197,7 +5301,10 @@ class Handler(http.server.BaseHTTPRequestHandler):
                 elif BACKEND in ("codebuff", "freebuff"):
                     self._handle_codebuff(body, model, stream, tracker)
                 elif (BACKEND or "").startswith("gemini-oauth"):
-                    self._handle_gemini_oauth(body, model, stream, tracker)
+                    if OAUTH_PROVIDER == "google-antigravity":
+                        self._handle_antigravity_v2(body, model, stream, tracker)
+                    else:
+                        self._handle_gemini_oauth(body, model, stream, tracker)
                 else:
                     self._handle_openai_compat(body, model, stream, tracker)
             update_snapshot_response(request_id, "completed", time.time() - _req_t0)
@@ -5386,6 +5493,383 @@ class Handler(http.server.BaseHTTPRequestHandler):
             chat_body["reasoning_effort"] = REASONING_EFFORT
         return chat_body
 
+    def _handle_antigravity_v2(self, body, model, stream, tracker=None):
+        input_data = body.get("input", "")
+        _schema = _load_schema(model=model)
+        if _schema and not _schema.supports_vision:
+            input_data = _preprocess_vision_input(input_data, _schema)
+            body = dict(body)
+            body["input"] = input_data
+
+        if isinstance(input_data, list) and len(input_data) > 30:
+            input_data = _antigravity_normalize_context(input_data, model)
+            body = dict(body)
+            body["input"] = input_data
+
+        access_token = _refresh_oauth_token()
+        token_path = os.path.join(os.path.expanduser("~"), ".cache", "codex-proxy", "google-antigravity-oauth-token.json")
+        project_id = ""
+        try:
+            with open(token_path) as f:
+                project_id = json.load(f).get("project_id", "")
+        except Exception:
+            pass
+
+        tool_call_names = {}
+        contents = []
+
+        if isinstance(input_data, list):
+            for item in input_data:
+                t = item.get("type")
+                if t == "message":
+                    role = "user" if item.get("role") == "user" else "model"
+                    content = item.get("content", "")
+                    parts = []
+                    if isinstance(content, list):
+                        for c in content:
+                            ct = c.get("type")
+                            if ct in ("input_text", "text"):
+                                parts.append({"text": c.get("text", "")})
+                            elif ct in ("input_image", "image_url"):
+                                iu = c.get("image_url") or c.get("url", {})
+                                url = iu.get("url", iu) if isinstance(iu, dict) else iu
+                                if isinstance(url, str) and url.startswith("data:"):
+                                    mime, _, b64 = url.partition(";base64,")
+                                    mime = mime.replace("data:", "") or "image/png"
+                                    parts.append({"inlineData": {"mimeType": mime, "data": b64}})
+                                else:
+                                    parts.append({"text": str(url)})
+                    elif isinstance(content, str):
+                        parts.append({"text": content})
+                    if parts:
+                        contents.append({"role": role, "parts": parts})
+                elif t == "function_call":
+                    call_id = item.get("call_id") or item.get("id") or f"call_{uuid.uuid4().hex[:24]}"
+                    fname = item.get("name", "")
+                    if call_id and fname:
+                        tool_call_names[call_id] = fname
+                    args = item.get("arguments", "{}")
+                    if isinstance(args, str):
+                        try:
+                            args = json.loads(args)
+                        except Exception:
+                            args = {}
+                    fc_part = {"functionCall": {"name": fname, "args": args, "id": call_id}}
+                    stored_sig = _gemini_get_sig(f"fc:{call_id}") or _gemini_get_sig(f"fc:{fname}")
+                    if stored_sig:
+                        fc_part["thoughtSignature"] = stored_sig
+                        fc_part["thought_signature"] = stored_sig
+                    else:
+                        fc_part["thought_signature"] = "skip_thought_signature_validator"
+                    contents.append({"role": "model", "parts": [fc_part]})
+                elif t == "function_call_output":
+                    call_id = item.get("call_id", item.get("id", ""))
+                    output = item.get("output", "")
+                    fname = item.get("name", "") or tool_call_names.get(call_id, "")
+                    resp_part = {"functionResponse": {"name": fname or "unknown", "response": {"result": str(output)}}}
+                    if call_id:
+                        resp_part["functionResponse"]["id"] = call_id
+                    contents.append({"role": "user", "parts": [resp_part]})
+
+        sanitized = []
+        last_user_text = None
+        last_role = None
+        for content in contents:
+            role = content.get("role")
+            parts = [p for p in content.get("parts", []) if isinstance(p, dict)]
+            if not parts:
+                continue
+            has_function_call = any("functionCall" in p for p in parts)
+            has_function_response = any("functionResponse" in p for p in parts)
+            text_key = "\n".join([p.get("text", "") for p in parts if "text" in p]).strip()
+
+            if has_function_call or has_function_response:
+                sanitized.append({"role": role, "parts": parts})
+                last_role = role
+                continue
+
+            if role == "user" and text_key and text_key == last_user_text:
+                continue
+
+            if role == last_role and role in ("user", "model") and sanitized:
+                last_parts = sanitized[-1].get("parts", [])
+                last_has_tool = any("functionCall" in p or "functionResponse" in p for p in last_parts)
+                if not last_has_tool:
+                    sanitized[-1].setdefault("parts", []).extend(parts)
+                    if role == "user" and text_key:
+                        last_user_text = text_key
+                    last_role = role
+                    continue
+
+            sanitized.append({"role": role, "parts": parts})
+            if role == "user" and text_key:
+                last_user_text = text_key
+            last_role = role
+
+        while sanitized and sanitized[0].get("role") != "user":
+            sanitized.pop(0)
+
+        contents = sanitized
+
+        instructions = body.get("instructions", "").strip()
+        ag_identity = "You are Antigravity, a powerful agentic AI coding assistant designed by the Google Deepmind team working on Advanced Agentic Coding.\nYou are pair programming with a USER to solve their coding task. The task may require creating a new codebase, modifying or debugging an existing codebase, or simply answering a question.\n**Absolute paths only**\n**Proactiveness**"
+        system_parts = [{"text": ag_identity}, {"text": "\n--- [SYSTEM_PROMPT_END] ---"}]
+        if instructions:
+            system_parts.append({"text": instructions})
+
+        gen_config = {"maxOutputTokens": body.get("max_output_tokens", 64000), "stopSequences": ["\n\nHuman:", "[DONE]"]}
+        if body.get("temperature") is not None:
+            gen_config["temperature"] = body["temperature"]
+        if body.get("top_p") is not None:
+            gen_config["topP"] = body["top_p"]
+
+        _is_claude_model = "claude" in model.lower()
+        _is_claude_thinking = _is_claude_model and "thinking" in model.lower()
+
+        if REASONING_ENABLED and REASONING_EFFORT != "none":
+            if _is_claude_thinking:
+                budget = {"low": 8192, "medium": 16384, "high": 32768}.get(REASONING_EFFORT, 16384)
+                gen_config["thinkingConfig"] = {"include_thoughts": True, "thinking_budget": budget}
+                if gen_config.get("maxOutputTokens", 0) <= budget:
+                    gen_config["maxOutputTokens"] = 64000
+            elif not _is_claude_model:
+                budget = {"low": 2048, "medium": 8192, "high": 24576}.get(REASONING_EFFORT, 8192)
+                gen_config["thinkingConfig"] = {"includeThoughts": True, "thinkingBudget": budget}
+
+        oa_tools = body.get("tools", [])
+        gemini_tools = []
+        if oa_tools:
+            func_decls = []
+            for tool in oa_tools:
+                ttype = tool.get("type", "function")
+                fname = tool.get("name", "")
+                if ttype == "function":
+                    fn = tool.get("function", tool)
+                    name = fn.get("name", fname)
+                    desc = fn.get("description", "")
+                    params = fn.get("parameters", fn.get("input_schema", {}))
+                    func_decls.append({"name": name, "description": desc, "parameters": params})
+                elif fname:
+                    func_decls.append({"name": fname, "description": tool.get("description", ""), "parameters": tool.get("parameters", {"type": "object", "properties": {}})})
+            if func_decls:
+                gemini_tools = [{"functionDeclarations": func_decls}]
+
+        contents = _gemini_reattach_sigs(contents)
+
+        ag_key = _antigravity_loop_key(self._session_id)
+        with _ANTIGRAVITY_LOOP_TRACKER_LOCK:
+            if ag_key not in _ANTIGRAVITY_LOOP_TRACKER:
+                _ANTIGRAVITY_LOOP_TRACKER[ag_key] = {
+                    "latest_user_hash": None, "nudge_injected": False, "latest_user_appended": False,
+                    "tool_calls_for_request": 0, "repeated_tool": False, "force_finalize": False,
+                    "last_tool": None, "last_tool_count": 0,
+                }
+            ag_state = _ANTIGRAVITY_LOOP_TRACKER[ag_key]
+
+        latest_user = ""
+        if isinstance(input_data, list):
+            for item in reversed(input_data):
+                if item.get("type") == "message" and item.get("role") == "user":
+                    c = item.get("content", "")
+                    if isinstance(c, str):
+                        latest_user = c
+                    elif isinstance(c, list):
+                        latest_user = "\n".join(p.get("text", p.get("input_text", "")) for p in c if isinstance(p, dict))
+                    break
+            if latest_user:
+                latest_norm = " ".join(latest_user.strip().split())[:200]
+                latest_user_hash = hashlib.sha256(latest_norm.encode()).hexdigest()[:16]
+                if latest_user_hash != ag_state.get("latest_user_hash"):
+                    ag_state["latest_user_hash"] = latest_user_hash
+                    ag_state["nudge_injected"] = False
+                    ag_state["latest_user_appended"] = False
+                    ag_state["tool_calls_for_request"] = 0
+                    ag_state["repeated_tool"] = False
+                    ag_state["force_finalize"] = False
+                    ag_state["last_tool"] = None
+                    ag_state["last_tool_count"] = 0
+            n_tool_calls = sum(1 for it in input_data if isinstance(it, dict) and it.get("type") == "function_call")
+            ag_state["tool_calls_for_request"] = n_tool_calls
+            last_tool_key = None
+            for item in reversed(input_data):
+                if isinstance(item, dict) and item.get("type") == "function_call":
+                    fname = item.get("name", "")
+                    args_str = json.dumps(item.get("arguments", {}), sort_keys=True)[:100]
+                    last_tool_key = f"{fname}:{args_str}"
+                    break
+            if last_tool_key:
+                if last_tool_key == ag_state.get("last_tool"):
+                    ag_state["last_tool_count"] = ag_state.get("last_tool_count", 0) + 1
+                    if ag_state["last_tool_count"] >= 5:
+                        ag_state["repeated_tool"] = True
+                        ag_state["force_finalize"] = True
+                else:
+                    ag_state["last_tool"] = last_tool_key
+                    ag_state["last_tool_count"] = 1
+
+        if ag_state.get("force_finalize"):
+            contents.append({"role": "user", "parts": [{"text": "STOP CALLING TOOLS. APPLY THE FINAL EDIT OR SUMMARIZE WHAT BLOCKED YOU. DO NOT CALL ANY MORE TOOLS."}]})
+
+        if not _antigravity_is_simple_user(latest_user):
+            contents.insert(0, {"role": "user", "parts": [{"text": _GEMINI_AGENT_GUARDRAIL}]})
+
+        request_body = {"contents": contents, "safetySettings": [
+            {"category": "HARM_CATEGORY_HARASSMENT", "threshold": "OFF"},
+            {"category": "HARM_CATEGORY_HATE_SPEECH", "threshold": "OFF"},
+            {"category": "HARM_CATEGORY_SEXUALLY_EXPLICIT", "threshold": "OFF"},
+            {"category": "HARM_CATEGORY_DANGEROUS_CONTENT", "threshold": "OFF"},
+            {"category": "HARM_CATEGORY_CIVIC_INTEGRITY", "threshold": "OFF"},
+        ]}
+        request_body["systemInstruction"] = {"role": "user", "parts": system_parts}
+        if gen_config:
+            request_body["generationConfig"] = gen_config
+        if gemini_tools:
+            request_body["tools"] = gemini_tools
+        if _is_claude_model and gemini_tools:
+            request_body["toolConfig"] = {"functionCallingConfig": {"mode": "VALIDATED"}}
+
+        import platform as _plat
+        _os_name = _plat.system().lower()
+        _os_arch = _plat.machine().lower().replace("x86_64", "x64").replace("aarch64", "arm64")
+        _fetched_ver = _ensure_antigravity_version()
+        _ag_ua = f"antigravity/{_fetched_ver} {_os_name}/{_os_arch}"
+        headers = {
+            "Content-Type": "application/json",
+            "Authorization": f"Bearer {access_token}",
+            "User-Agent": _ag_ua,
+            "X-Client-Name": "antigravity",
+            "X-Client-Version": _ensure_antigravity_client_version(),
+            "x-goog-api-client": "gl-node/18.18.2 fire/0.8.6 grpc/1.10.x",
+        }
+
+        wrapped = {
+            "project": project_id,
+            "model": model,
+            "requestType": "agent",
+            "userAgent": _ag_ua,
+            "requestId": f"agent-{uuid.uuid4().hex[:12]}",
+            "request": request_body,
+        }
+        wrapped["request"]["sessionId"] = f"{uuid.uuid4().hex}{int(time.time()*1000)}"
+
+        _allow_staging = os.environ.get("ALLOW_ANTIGRAVITY_STAGING", "0") == "1"
+        _antigravity_endpoints = [
+            "https://daily-cloudcode-pa.googleapis.com",
+            "https://daily-cloudcode-pa.sandbox.googleapis.com",
+            "https://cloudcode-pa.googleapis.com",
+        ]
+        if _allow_staging:
+            _antigravity_endpoints.append("https://autopush-cloudcode-pa.sandbox.googleapis.com")
+
+        body_b = json.dumps(wrapped).encode()
+        print(f"[{self._session_id}] [antigravity-v2] model={model} stream={stream} contents={len(contents)} tools={bool(gemini_tools)} project={project_id} ver={_versions[0]}", file=sys.stderr)
+        try:
+            debug_path = os.path.join(_LOG_DIR, f"antigravity-v2-request-{self._session_id}.json")
+            with open(debug_path, "w") as dbg:
+                json.dump(wrapped, dbg, indent=2)
+        except Exception:
+            pass
+
+        upstream = None
+        chosen_ep = None
+        global _antigravity_preferred_endpoint
+        with _antigravity_endpoint_lock:
+            _pref = _antigravity_preferred_endpoint
+        ordered = ([_pref] + [e for e in _antigravity_endpoints if e != _pref]) if _pref and _pref in _antigravity_endpoints else list(_antigravity_endpoints)
+
+        _all_404 = True
+        for ep in ordered:
+            action = "streamGenerateContent" if stream else "generateContent"
+            url_suffix = f"v1internal:{action}?alt=sse" if stream else f"v1internal:{action}"
+            target = f"{ep}/{url_suffix}"
+            req = urllib.request.Request(target, data=body_b, headers=headers)
+            try:
+                upstream = urllib.request.urlopen(req, timeout=_upstream_timeout(body, stream))
+                chosen_ep = ep
+                _all_404 = False
+                with _antigravity_endpoint_lock:
+                    _antigravity_preferred_endpoint = ep
+                break
+            except urllib.error.HTTPError as e:
+                err_body = e.read().decode()
+                err_class = _classify_antigravity_error(e.code, err_body)
+                print(f"[{self._session_id}] [antigravity-v2] {ep.replace('https://','')} {e.code} class={err_class} body={err_body[:300]}", file=sys.stderr)
+                if e.code != 404:
+                    _all_404 = False
+                if e.code in (400, 404):
+                    try:
+                        debug_path = os.path.join(_LOG_DIR, f"antigravity-v2-{e.code}.json")
+                        with open(debug_path, "w") as dbg:
+                            json.dump({"endpoint": ep, "url": target, "model": model, "wrapped": wrapped, "error": err_body}, dbg, indent=2)
+                    except Exception:
+                        pass
+                    if e.code == 400:
+                        return self.send_json(e.code, {"error": {"type": "upstream_error", "message": _sanitize_err_body(err_body)}})
+                if err_class in ("auth_permanent", "service_disabled", "forbidden", "account_banned", "validation_required"):
+                    return self.send_json(e.code, {"error": {"type": "upstream_error", "message": _sanitize_err_body(err_body)}})
+                if err_class in ("quota_exhausted", "rate_limited"):
+                    pool = _google_antigravity_pool
+                    _, acct = _get_google_account(OAUTH_PROVIDER)
+                    if acct:
+                        reset_s = _parse_rate_limit_reset(err_body)
+                        cooldown = reset_s if reset_s and reset_s > 10 else 60
+                        pool.mark_rate_limited(acct, cooldown)
+                    return self.send_json(e.code, {"error": {"type": "upstream_error", "message": _sanitize_err_body(err_body)}})
+                if ep == ordered[-1] and not _all_404:
+                    return self.send_json(e.code, {"error": {"type": "upstream_error", "message": _sanitize_err_body(err_body)}})
+                continue
+            except Exception as e:
+                _all_404 = False
+                print(f"[{self._session_id}] [antigravity-v2] {ep.replace('https://','')} conn failed: {e}", file=sys.stderr)
+                if ep == ordered[-1]:
+                    return self.send_json(502, {"error": {"type": "proxy_error", "message": str(e)}})
+                continue
+
+        if _all_404 and upstream is None:
+            print(f"[{self._session_id}] [antigravity-v2] all endpoints 404, invalidating version cache and re-fetching", file=sys.stderr)
+            global _antigravity_version_validated
+            with _antigravity_version_lock:
+                _antigravity_version_validated = False
+                _antigravity_version_checked = 0
+            _new_ver = _ensure_antigravity_version()
+            if _new_ver != _fetched_ver:
+                print(f"[{self._session_id}] [antigravity-v2] version changed {_fetched_ver} -> {_new_ver}, retrying", file=sys.stderr)
+                _ag_ua_new = f"antigravity/{_new_ver} {_os_name}/{_os_arch}"
+                headers["User-Agent"] = _ag_ua_new
+                wrapped["userAgent"] = _ag_ua_new
+                body_b = json.dumps(wrapped).encode()
+                for ep in ordered:
+                    action = "streamGenerateContent" if stream else "generateContent"
+                    url_suffix = f"v1internal:{action}?alt=sse" if stream else f"v1internal:{action}"
+                    target = f"{ep}/{url_suffix}"
+                    req = urllib.request.Request(target, data=body_b, headers=headers)
+                    try:
+                        upstream = urllib.request.urlopen(req, timeout=_upstream_timeout(body, stream))
+                        chosen_ep = ep
+                        with _antigravity_endpoint_lock:
+                            _antigravity_preferred_endpoint = ep
+                        break
+                    except urllib.error.HTTPError as e:
+                        err_body = e.read().decode()
+                        print(f"[{self._session_id}] [antigravity-v2-retry] {ep.replace('https://','')} {e.code}", file=sys.stderr)
+                        if e.code == 400:
+                            return self.send_json(e.code, {"error": {"type": "upstream_error", "message": _sanitize_err_body(err_body)}})
+                        if ep == ordered[-1]:
+                            return self.send_json(e.code, {"error": {"type": "upstream_error", "message": _sanitize_err_body(err_body)}})
+                        continue
+                    except Exception as e:
+                        if ep == ordered[-1]:
+                            return self.send_json(502, {"error": {"type": "proxy_error", "message": str(e)}})
+                        continue
+
+        if upstream is None:
+            return self.send_json(502, {"error": {"type": "proxy_error", "message": "All endpoints failed"}})
+
+        if stream:
+            self._forward_gemini_sse(upstream, model, body, input_data, tracker)
+        else:
+            self._forward_gemini_json(upstream, model, body, input_data)
+
     def _handle_gemini_oauth(self, body, model, stream, tracker=None):
         input_data = body.get("input", "")
         policy = provider_policy()
@@ -5553,6 +6037,9 @@ class Handler(http.server.BaseHTTPRequestHandler):
                         resp_part["functionResponse"]["id"] = call_id
                     contents.append({"role": "user", "parts": [resp_part]})
 
+        # CRITICAL FIX: Sanitize contents while PRESERVING functionCall -> functionResponse alternation.
+        # Google's Gemini API REQUIRES: functionCall (role=model) must be immediately followed by functionResponse (role=user).
+        # We NEVER merge, skip, or reorder tool-related messages.
         if OAUTH_PROVIDER.startswith("google") and "claude" not in model.lower():
             sanitized = []
             last_user_text = None
@@ -5562,18 +6049,40 @@ class Handler(http.server.BaseHTTPRequestHandler):
                 parts = [p for p in content.get("parts", []) if isinstance(p, dict)]
                 if not parts:
                     continue
+                # Check if this content has functionCall or functionResponse - these MUST be preserved as-is
+                has_function_call = any("functionCall" in p for p in parts)
+                has_function_response = any("functionResponse" in p for p in parts)
                 text_key = "\n".join([p.get("text", "") for p in parts if "text" in p]).strip()
+                
+                # Tool calls/responses are NEVER merged or skipped - they must maintain strict order
+                if has_function_call or has_function_response:
+                    sanitized.append({"role": role, "parts": parts})
+                    continue
+                
+                # For plain text messages only: skip duplicate consecutive user text
                 if role == "user" and text_key and text_key == last_user_text:
                     continue
+                
+                # Merge consecutive same-role TEXT-ONLY messages (no tool content)
                 if role == last_role and role in ("user", "model") and sanitized:
-                    sanitized[-1].setdefault("parts", []).extend(parts)
+                    last_parts = sanitized[-1].get("parts", [])
-                else:
+                    # Only merge if the last message is also text-only (no functionCall/functionResponse)
-                    sanitized.append({"role": role, "parts": parts})
+                    last_has_tool = any("functionCall" in p or "functionResponse" in p for p in last_parts)
+                    if not last_has_tool:
+                        sanitized[-1].setdefault("parts", []).extend(parts)
+                        if role == "user" and text_key:
+                            last_user_text = text_key
+                        continue
+                
+                sanitized.append({"role": role, "parts": parts})
                 if role == "user" and text_key:
                     last_user_text = text_key
                 last_role = role
+            
+            # Trim leading non-user messages (Google expects conversation to start with user)
             while sanitized and sanitized[0].get("role") != "user":
                 sanitized.pop(0)
+            # Trim trailing non-user messages (must end with user turn for continuation)
             while sanitized and sanitized[-1].get("role") != "user":
                 sanitized.pop()
             contents = sanitized