fix(antigravity): wrap cross-format requests in the v1internal envelope

The gemini:generate_content URL hook rewrites any Antigravity endpoint to
/v1internal:generateContent, but only the same-format passthrough and the two
OpenAI decision paths ever built the matching envelope. A Claude Messages or
Gemini client therefore reached the standard family planner, picked up the
rewritten URL, and posted a bare Gemini body that upstream rejects with
"Invalid JSON payload received. Unknown name \"contents\"" -- four retries
across every account, then a 503 that names none of this.

Route the standard family through the shared v1internal builder the same way
gemini_cli already is, so the URL and the body come from one decision. The
OpenAI-image-to-Gemini path cannot carry an envelope at all, so it now skips
Antigravity candidates instead of sending a request upstream can only reject.

Also stop treating a configured proxy as locally unsupported. The execution
plan carries the proxy itself, and the generic and Vertex gates moved to
transport_proxy_is_locally_supported long ago; Antigravity kept rejecting on
proxy.is_some(), which no longer matches how the local runtime executes. A
proxy that resolves to no route still disqualifies the request, and transport
profiles stay unsupported because the v1internal payload never carries one.

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

apps/aether-gateway/src/ai_serving/planner/specialized/image/request.rs

@@ -9,6 +9,7 @@ use crate::ai_serving::planner::candidate_preparation::{
 };
 use crate::ai_serving::planner::spec_metadata::local_openai_image_spec_metadata;
 use crate::ai_serving::pure::normalize_openai_image_request_with_options;
+use crate::ai_serving::transport::antigravity::is_antigravity_provider_transport;
 use crate::ai_serving::transport::{
     build_grok_browser_headers, build_grok_upstream_url, build_openai_image_headers,
     build_openai_image_upstream_url, build_standard_provider_request_headers,
@@ -338,6 +339,25 @@ async fn resolve_local_openai_image_to_gemini_candidate_payload_parts(
     let candidate = &attempt.eligible.candidate;
     let transport = &attempt.eligible.transport;
     let provider_api_format = "gemini:generate_content";
+
+    // The gemini:generate_content URL hook rewrites an Antigravity endpoint to
+    // /v1internal:, and this image path has no v1internal envelope to match it.
+    // Skip the candidate instead of posting a bare Gemini body that upstream
+    // would only reject.
+    if is_antigravity_provider_transport(transport) {
+        mark_skipped_local_openai_image_candidate(
+            state,
+            input,
+            trace_id,
+            candidate,
+            attempt.candidate_index,
+            &attempt.candidate_id,
+            "transport_unsupported",
+        )
+        .await;
+        return None;
+    }
+
     let effective_headers = input.effective_headers(&parts.headers);
 
     let prepared_candidate = match prepare_header_authenticated_candidate(

apps/aether-gateway/src/ai_serving/planner/standard/family/request.rs

@@ -4,6 +4,10 @@ use std::sync::Arc;
 use aether_contracts::ResolvedTransportProfile;
 use serde_json::Value;
 
+use crate::ai_serving::planner::antigravity::{
+    build_antigravity_v1internal_provider_request, AntigravityV1InternalRequestError,
+    AntigravityV1InternalRequestInput, ANTIGRAVITY_V1INTERNAL_ENVELOPE_NAME,
+};
 use crate::ai_serving::planner::candidate_preparation::{
     prepare_header_authenticated_candidate, prepare_header_authenticated_candidate_from_auth,
     OauthPreparationContext,
@@ -26,6 +30,7 @@ use crate::ai_serving::planner::standard::{
     openai_provider_request_contract_failure_extra_data, openai_responses_reasoning_replay_policy,
     request_body_build_failure_extra_data, request_conversion_failure_extra_data,
 };
+use crate::ai_serving::transport::antigravity::is_antigravity_provider_transport;
 use crate::ai_serving::transport::kiro::{
     build_kiro_provider_headers, build_kiro_provider_request_body,
     is_kiro_claude_messages_transport, KiroProviderHeadersInput, KiroRequestAuth,
@@ -837,6 +842,29 @@ pub(crate) async fn resolve_local_standard_candidate_payload_parts(
         .await);
     }
 
+    if normalized_provider_api_format == "gemini:generate_content"
+        && is_antigravity_provider_transport(transport)
+    {
+        return Ok(build_antigravity_cross_format_payload_parts(
+            state,
+            parts,
+            trace_id,
+            body_json,
+            input,
+            attempt,
+            transport,
+            spec_metadata.api_format,
+            provider_api_format,
+            prepared_candidate.mapped_model,
+            prepared_candidate.auth_header,
+            prepared_candidate.auth_value,
+            provider_request_body,
+            upstream_is_stream,
+            redaction.redacted,
+        )
+        .await);
+    }
+
     if normalized_provider_api_format == "gemini:generate_content"
         && is_gemini_cli_provider_transport(transport)
     {
@@ -963,6 +991,145 @@ fn apply_transport_request_body_semantics(
     )
 }
 
+#[allow(clippy::too_many_arguments)]
+async fn build_antigravity_cross_format_payload_parts(
+    state: &AppState,
+    parts: &http::request::Parts,
+    trace_id: &str,
+    original_body_json: &serde_json::Value,
+    input: &LocalStandardDecisionInput,
+    attempt: &LocalStandardCandidateAttempt,
+    transport: &Arc<GatewayProviderTransportSnapshot>,
+    client_api_format: &str,
+    provider_api_format: &str,
+    mapped_model: String,
+    auth_header: String,
+    auth_value: String,
+    gemini_request_body: Value,
+    upstream_is_stream: bool,
+    request_redacted: bool,
+) -> Option<LocalStandardCandidatePayloadParts> {
+    let candidate = &attempt.eligible.candidate;
+    let effective_headers = input.effective_headers(&parts.headers);
+    let resolved =
+        match build_antigravity_v1internal_provider_request(AntigravityV1InternalRequestInput {
+            state,
+            parts,
+            transport,
+            trace_id,
+            mapped_model: &mapped_model,
+            provider_api_format,
+            auth_header: &auth_header,
+            auth_value: &auth_value,
+            request_headers: effective_headers,
+            original_request_body: original_body_json,
+            gemini_request_body: &gemini_request_body,
+            upstream_is_stream,
+            same_format: false,
+        })
+        .await
+        {
+            Ok(resolved) => resolved,
+            Err(AntigravityV1InternalRequestError::TransportUnsupported) => {
+                mark_skipped_local_standard_candidate(
+                    state,
+                    input,
+                    trace_id,
+                    candidate,
+                    attempt.candidate_index,
+                    &attempt.candidate_id,
+                    "transport_unsupported",
+                )
+                .await;
+                return None;
+            }
+            Err(AntigravityV1InternalRequestError::EnvelopeUnsupported) => {
+                mark_skipped_local_standard_candidate_with_extra_data(
+                    state,
+                    input,
+                    trace_id,
+                    candidate,
+                    attempt.candidate_index,
+                    &attempt.candidate_id,
+                    "provider_request_body_build_failed",
+                    request_body_build_failure_extra_data(
+                        original_body_json,
+                        client_api_format,
+                        provider_api_format,
+                    ),
+                )
+                .await;
+                return None;
+            }
+            Err(AntigravityV1InternalRequestError::UpstreamUrlUnavailable) => {
+                mark_skipped_local_standard_candidate_with_failure_diagnostic(
+                    state,
+                    input,
+                    trace_id,
+                    candidate,
+                    attempt.candidate_index,
+                    &attempt.candidate_id,
+                    "upstream_url_missing",
+                    CandidateFailureDiagnostic::upstream_url_missing(
+                        client_api_format,
+                        provider_api_format,
+                        "standard_family_antigravity_url",
+                    ),
+                )
+                .await;
+                return None;
+            }
+            Err(AntigravityV1InternalRequestError::HeaderRulesApplyFailed) => {
+                mark_skipped_local_standard_candidate_with_failure_diagnostic(
+                    state,
+                    input,
+                    trace_id,
+                    candidate,
+                    attempt.candidate_index,
+                    &attempt.candidate_id,
+                    "transport_header_rules_apply_failed",
+                    CandidateFailureDiagnostic::header_rules_apply_failed(
+                        client_api_format,
+                        provider_api_format,
+                        "standard_family_antigravity_headers",
+                    ),
+                )
+                .await;
+                return None;
+            }
+        };
+
+    let mut provider_request_headers = resolved.headers.headers;
+    apply_codex_openai_special_headers(
+        &mut provider_request_headers,
+        &resolved.body,
+        effective_headers,
+        resolved.transport.provider.provider_type.as_str(),
+        provider_api_format,
+        Some(trace_id),
+        resolved.transport.key.decrypted_auth_config.as_deref(),
+    );
+    request_identity_response_encoding_when_redacted(
+        &mut provider_request_headers,
+        request_redacted,
+    );
+
+    Some(LocalStandardCandidatePayloadParts {
+        auth_header: resolved.headers.auth_header,
+        auth_value: resolved.headers.auth_value,
+        mapped_model,
+        provider_api_format: provider_api_format.to_string(),
+        provider_request_body: resolved.body,
+        provider_request_headers,
+        upstream_url: resolved.upstream_url,
+        upstream_is_stream,
+        envelope_name: Some(ANTIGRAVITY_V1INTERNAL_ENVELOPE_NAME),
+        transport: resolved.transport,
+        transport_profile: None,
+        request_redacted,
+    })
+}
+
 #[allow(clippy::too_many_arguments)]
 async fn build_gemini_cli_cross_format_payload_parts(
     state: &AppState,

apps/aether-gateway/src/tests/architecture/ai_serving.rs

@@ -2893,6 +2893,22 @@ fn ai_serving_standard_attempts_consume_eligible_local_candidates_without_transp
         );
     }
 
+    let standard_family_request = read_workspace_file(
+        "apps/aether-gateway/src/ai_serving/planner/standard/family/request.rs",
+    );
+    for pattern in [
+        "is_antigravity_provider_transport(",
+        "build_antigravity_v1internal_provider_request(",
+        "is_gemini_cli_provider_transport(",
+        "build_gemini_cli_v1internal_provider_request(",
+    ] {
+        assert!(
+            standard_family_request.contains(pattern),
+            "standard family request preparation should build v1internal envelopes through {pattern} \
+             so a cross-format client never posts a bare Gemini body to a v1internal URL"
+        );
+    }
+
     let provider_transport_standard =
         read_workspace_file("crates/aether-provider/transport/src/standard/mod.rs");
     for pattern in [

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

@@ -1,6 +1,7 @@
 use serde_json::Value;
 
 use super::super::snapshot::GatewayProviderTransportSnapshot;
+use super::super::transport_proxy_is_locally_supported;
 use super::auth::{
     resolve_local_antigravity_request_auth, AntigravityRequestAuth, AntigravityRequestAuthSupport,
     AntigravityRequestAuthUnsupportedReason, ANTIGRAVITY_PROVIDER_TYPE,
@@ -87,11 +88,11 @@ pub fn classify_local_antigravity_request_support(
             AntigravityRequestSideUnsupportedReason::UnsupportedBodyRules,
         );
     }
-    if transport.provider.proxy.is_some()
+    // A configured proxy is carried by the execution plan itself, so it only
-        || transport.endpoint.proxy.is_some()
+    // disqualifies the local request when it cannot be resolved into a usable
-        || transport.key.proxy.is_some()
+    // snapshot. Transport profiles stay unsupported because the v1internal
-        || transport.key.fingerprint.is_some()
+    // payload never carries one.
-    {
+    if !transport_proxy_is_locally_supported(transport) || transport.key.fingerprint.is_some() {
         return AntigravityRequestSideSupport::Unsupported(
             AntigravityRequestSideUnsupportedReason::UnsupportedNetworkConfig,
         );
@@ -114,3 +115,145 @@ pub fn classify_local_antigravity_request_support(
 
     AntigravityRequestSideSupport::Supported(AntigravityRequestSideSpec { auth, request_type })
 }
+
+#[cfg(test)]
+mod tests {
+    use serde_json::json;
+
+    use super::super::request::AntigravityEnvelopeRequestType;
+    use super::{
+        classify_local_antigravity_request_support, AntigravityRequestSideSupport,
+        AntigravityRequestSideUnsupportedReason,
+    };
+    use crate::snapshot::{
+        GatewayProviderTransportEndpoint, GatewayProviderTransportKey,
+        GatewayProviderTransportProvider, GatewayProviderTransportSnapshot,
+    };
+
+    fn sample_transport() -> GatewayProviderTransportSnapshot {
+        GatewayProviderTransportSnapshot {
+            provider: GatewayProviderTransportProvider {
+                id: "provider-1".to_string(),
+                name: "Antigravity".to_string(),
+                provider_type: "antigravity".to_string(),
+                website: None,
+                is_active: true,
+                keep_priority_on_conversion: false,
+                enable_format_conversion: true,
+                concurrent_limit: None,
+                max_retries: None,
+                proxy: None,
+                request_timeout_secs: None,
+                stream_first_byte_timeout_secs: None,
+                config: None,
+            },
+            endpoint: GatewayProviderTransportEndpoint {
+                id: "endpoint-1".to_string(),
+                provider_id: "provider-1".to_string(),
+                api_format: "gemini:generate_content".to_string(),
+                api_family: Some("gemini".to_string()),
+                endpoint_kind: Some("generate_content".to_string()),
+                is_active: true,
+                base_url: "https://daily-cloudcode-pa.googleapis.com".to_string(),
+                header_rules: None,
+                body_rules: None,
+                max_retries: None,
+                custom_path: None,
+                config: None,
+                format_acceptance_config: None,
+                proxy: None,
+            },
+            key: GatewayProviderTransportKey {
+                id: "key-1".to_string(),
+                provider_id: "provider-1".to_string(),
+                name: "key".to_string(),
+                auth_type: "oauth".to_string(),
+                is_active: true,
+                api_formats: Some(vec!["gemini:generate_content".to_string()]),
+                auth_type_by_format: None,
+                allow_auth_channel_mismatch_formats: None,
+                allowed_models: None,
+                capabilities: None,
+                rate_multipliers: None,
+                global_priority_by_format: None,
+                expires_at_unix_secs: None,
+                proxy: None,
+                fingerprint: None,
+                upstream_metadata: None,
+                decrypted_api_key: "__placeholder__".to_string(),
+                decrypted_auth_config: Some(
+                    r#"{"provider_type":"antigravity","refresh_token":"rt","cloudaicompanionProject":"project-1"}"#
+                        .to_string(),
+                ),
+            },
+        }
+    }
+
+    fn classify(transport: &GatewayProviderTransportSnapshot) -> AntigravityRequestSideSupport {
+        classify_local_antigravity_request_support(
+            transport,
+            &json!({"contents": []}),
+            AntigravityEnvelopeRequestType::Agent,
+        )
+    }
+
+    fn assert_unsupported_network_config(support: AntigravityRequestSideSupport) {
+        assert_eq!(
+            support,
+            AntigravityRequestSideSupport::Unsupported(
+                AntigravityRequestSideUnsupportedReason::UnsupportedNetworkConfig,
+            )
+        );
+    }
+
+    #[test]
+    fn a_resolvable_tunnel_node_proxy_keeps_the_envelope_supported() {
+        let mut transport = sample_transport();
+        transport.provider.proxy = Some(json!({
+            "enabled": true,
+            "node_id": "702d158b-a432-4694-94cc-3bec13dbbc20",
+        }));
+
+        assert!(matches!(
+            classify(&transport),
+            AntigravityRequestSideSupport::Supported(_)
+        ));
+    }
+
+    #[test]
+    fn a_resolvable_url_proxy_keeps_the_envelope_supported() {
+        for proxy_owner in ["provider", "endpoint", "key"] {
+            let mut transport = sample_transport();
+            let proxy = Some(json!({"enabled": true, "url": "http://127.0.0.1:17000"}));
+            match proxy_owner {
+                "provider" => transport.provider.proxy = proxy,
+                "endpoint" => transport.endpoint.proxy = proxy,
+                _ => transport.key.proxy = proxy,
+            }
+
+            assert!(
+                matches!(
+                    classify(&transport),
+                    AntigravityRequestSideSupport::Supported(_)
+                ),
+                "a {proxy_owner} proxy should not disqualify the antigravity envelope"
+            );
+        }
+    }
+
+    #[test]
+    fn a_proxy_without_a_route_still_disqualifies_the_envelope() {
+        let mut transport = sample_transport();
+        transport.provider.proxy = Some(json!({"enabled": true}));
+
+        assert_unsupported_network_config(classify(&transport));
+    }
+
+    #[test]
+    fn a_key_fingerprint_still_disqualifies_the_envelope() {
+        let mut transport = sample_transport();
+        transport.key.fingerprint = Some(json!({"transport_profile": "chrome"}));
+
+        assert_unsupported_network_config(classify(&transport));
+    }
+}