fix(antigravity): send googleSearch instead of the Gemini 1.5 retrieval tool

The transport boundary rewrote `googleSearch` into the Gemini 1.5-era
`googleSearchRetrieval` spelling before every v1internal call, on the stated
grounds that the private backend rejects `googleSearch` when it is combined
with function declarations. That rewrite breaks grounding on Gemini 3.

Observed on stabey-124 against daily-cloudcode-pa.googleapis.com. A controlled
pair, same model and keys, 5 seconds apart:

- no `web_search_options` -> 200
- with `web_search_options` -> 502 on all three candidates

The outgoing body carried `tools: [{"googleSearchRetrieval": {}}]` and no
function declarations at all, so the documented mixed-tool rationale did not
apply. `request_candidates.error_message` holds what the backend actually
said:

    Malformed function call: call:google_search{query:current UTC date time}
    Malformed function call: call:google:search{query:current UTC date}
    Malformed function call: call:google_search{queries:[current UTC date]}

The model reaches for `google_search`, the legacy declaration binds nothing,
and the turn dies unparsed. CLIProxyAPI sends `googleSearch` to this same
v1internal surface, including alongside function declarations.

Keep folding the snake_case `google_search` alias into the canonical
`googleSearch` key, and leave a request that already spells the tool
`googleSearchRetrieval` untouched.

Co-Authored-By: Claude Opus 5 <[email protected]>

crates/aether-provider/transport/src/antigravity/request.rs

@@ -120,11 +120,18 @@ pub fn build_antigravity_safe_v1internal_request(
     AntigravityRequestEnvelopeSupport::Supported(envelope)
 }
 
-/// Antigravity's private v1internal Gemini surface still uses the legacy
+/// Antigravity's private v1internal Gemini surface takes the same
-/// `googleSearchRetrieval` spelling. The public Gemini converter emits the
+/// `googleSearch` grounding tool as the public one. Only the snake_case alias
-/// newer `googleSearch` spelling, which the private backend rejects when it is
+/// needs folding into the canonical camelCase key.
-/// combined with function declarations. Normalize only at this transport
+///
-/// boundary so public Gemini requests retain their native shape.
+/// This used to rewrite `googleSearch` into the Gemini 1.5-era
+/// `googleSearchRetrieval` spelling. Gemini 3 rejects that: the model emits a
+/// `google_search` call the backend cannot bind to any declared tool, and the
+/// turn dies with `MALFORMED_FUNCTION_CALL`, e.g.
+/// `Malformed function call: call:google_search{query:current UTC date}`
+/// observed against `daily-cloudcode-pa.googleapis.com` with
+/// `tools: [{"googleSearchRetrieval": {}}]` and no function declarations.
+/// CLIProxyAPI sends `googleSearch` to the same v1internal surface.
 fn normalize_antigravity_builtin_tool_names(request: &mut Map<String, Value>) {
     let Some(tools) = request.get_mut("tools").and_then(Value::as_array_mut) else {
         return;
@@ -135,14 +142,9 @@ fn normalize_antigravity_builtin_tool_names(request: &mut Map<String, Value>) {
             continue;
         };
 
-        if let Some(payload) = tool_object.remove("googleSearch") {
-            tool_object
-                .entry("googleSearchRetrieval".to_string())
-                .or_insert(payload);
-        }
         if let Some(payload) = tool_object.remove("google_search") {
             tool_object
-                .entry("googleSearchRetrieval".to_string())
+                .entry("googleSearch".to_string())
                 .or_insert(payload);
         }
     }
@@ -222,6 +224,43 @@ mod tests {
         }
     }
 
+    #[test]
+    fn search_only_request_keeps_the_modern_google_search_spelling() {
+        // Reproduces the live failure: a grounding-only request (no function
+        // declarations) that went out as `googleSearchRetrieval` came back as
+        // `Malformed function call: call:google_search{query:current UTC date}`
+        // from daily-cloudcode-pa.googleapis.com.
+        let request_body = json!({
+            "contents": [
+                { "role": "user", "parts": [{ "text": "today's UTC date?" }] }
+            ],
+            "tools": [{ "googleSearch": {} }]
+        });
+
+        let envelope = match build_antigravity_safe_v1internal_request(
+            &sample_auth(),
+            "request-ant-search-1",
+            "gemini-3.8-flash-high",
+            &request_body,
+            AntigravityEnvelopeRequestType::Agent,
+        ) {
+            AntigravityRequestEnvelopeSupport::Supported(envelope) => envelope,
+            AntigravityRequestEnvelopeSupport::Unsupported(reason) => {
+                panic!("search-only envelope should be supported: {reason:?}")
+            }
+        };
+
+        let tools = envelope["request"]["tools"]
+            .as_array()
+            .expect("tools should survive");
+        assert_eq!(tools.len(), 1, "{tools:?}");
+        assert_eq!(tools[0]["googleSearch"], json!({}));
+        assert!(
+            tools[0].get("googleSearchRetrieval").is_none(),
+            "the Gemini 1.5 spelling must not be reintroduced: {tools:?}"
+        );
+    }
+
     #[test]
     fn real_agent_request_preserves_antigravity_agent_fields() {
         let request_body = json!({
@@ -328,12 +367,9 @@ mod tests {
             .get("include_server_side_tool_invocations")
             .is_none());
         assert!(envelope["request"]["tools"][0]
-            .get("googleSearch")
+            .get("googleSearchRetrieval")
             .is_none());
-        assert_eq!(
+        assert_eq!(envelope["request"]["tools"][0]["googleSearch"], json!({}));
-            envelope["request"]["tools"][0]["googleSearchRetrieval"],
-            json!({})
-        );
         assert_eq!(
             envelope["request"]["tools"][1]["functionDeclarations"][0]["name"],
             "run_command"
@@ -471,7 +507,7 @@ mod tests {
             .get("google_search")
             .is_none());
         assert_eq!(
-            envelope["request"]["tools"][0]["googleSearchRetrieval"],
+            envelope["request"]["tools"][0]["googleSearch"],
             json!({
                 "dynamicRetrievalConfig": {
                     "mode": "MODE_UNSPECIFIED"