fix(codex): restore upstream model discovery

apps/aether-gateway/src/handlers/admin/provider/query/models/mod.rs

@@ -399,7 +399,8 @@ async fn provider_query_read_cached_models(
     let cache_key = format!("upstream_models:{provider_id}:{key_id}");
     let raw = state.runtime_state().kv_get(&cache_key).await.ok()??;
     let parsed = serde_json::from_str::<Vec<Value>>(&raw).ok()?;
-    Some(aggregate_models_for_cache(&parsed))
+    let models = aggregate_models_for_cache(&parsed);
+    (!models.is_empty()).then_some(models)
 }
 
 async fn provider_query_read_provider_cached_models(
@@ -409,7 +410,8 @@ async fn provider_query_read_provider_cached_models(
     let cache_key = format!("{ANTIGRAVITY_PROVIDER_CACHE_KEY_PREFIX}{provider_id}");
     let raw = state.runtime_state().kv_get(&cache_key).await.ok()??;
     let parsed = serde_json::from_str::<Vec<Value>>(&raw).ok()?;
-    Some(aggregate_models_for_cache(&parsed))
+    let models = aggregate_models_for_cache(&parsed);
+    (!models.is_empty()).then_some(models)
 }
 
 async fn provider_query_write_provider_cached_models(
@@ -417,7 +419,11 @@ async fn provider_query_write_provider_cached_models(
     provider_id: &str,
     models: &[Value],
 ) {
-    let Ok(serialized) = serde_json::to_string(&aggregate_models_for_cache(models)) else {
+    let models = aggregate_models_for_cache(models);
+    if models.is_empty() {
+        return;
+    }
+    let Ok(serialized) = serde_json::to_string(&models) else {
         return;
     };
     let cache_key = format!("{ANTIGRAVITY_PROVIDER_CACHE_KEY_PREFIX}{provider_id}");
@@ -577,7 +583,7 @@ async fn provider_query_fetch_models_for_key(
     };
 
     all_errors.extend(outcome.errors);
-    let unique_models = aggregate_models_for_cache(&outcome.cached_models);
+    let unique_models = outcome.legacy_models;
     if outcome.has_success && !unique_models.is_empty() {
         <AppState as ModelFetchRuntimeState>::write_upstream_models_cache(
             state.app(),

apps/aether-gateway/src/model_fetch/runtime.rs

@@ -378,7 +378,7 @@ async fn fetch_and_persist_key_models(
     )
     .await?;
     state
-        .write_upstream_models_cache(&target.provider.id, &target.key.id, &result.cached_models)
+        .write_upstream_models_cache(&target.provider.id, &target.key.id, &result.legacy_models)
         .await;
     sync_provider_model_whitelist_associations(state, &target.provider.id, &filtered_models)
         .await

apps/aether-gateway/src/state/integrations.rs

@@ -469,8 +469,11 @@ impl ModelFetchRuntimeState for AppState {
         key_id: &str,
         cached_models: &[Value],
     ) {
-        let Ok(serialized) = serde_json::to_string(&aggregate_models_for_cache(cached_models))
-        else {
+        let models = aggregate_models_for_cache(cached_models);
+        if models.is_empty() {
+            return;
+        }
+        let Ok(serialized) = serde_json::to_string(&models) else {
             return;
         };
         let cache_key = format!("upstream_models:{provider_id}:{key_id}");

apps/aether-gateway/src/tests/control/admin/provider_query.rs

@@ -537,6 +537,159 @@ async fn gateway_handles_admin_provider_query_models_with_openai_responses_endpo
     execution_runtime_handle.abort();
 }
 
+#[test]
+fn gateway_recovers_codex_slug_only_models_from_an_empty_legacy_cache() {
+    run_provider_query_test(
+        "gateway_recovers_codex_slug_only_models_from_an_empty_legacy_cache",
+        gateway_recovers_codex_slug_only_models_from_an_empty_legacy_cache_impl,
+    );
+}
+
+async fn gateway_recovers_codex_slug_only_models_from_an_empty_legacy_cache_impl() {
+    let execution_runtime_hits = Arc::new(Mutex::new(0usize));
+    let execution_runtime_hits_clone = Arc::clone(&execution_runtime_hits);
+    let execution_runtime = Router::new().route(
+        "/v1/execute/sync",
+        any(move |Json(plan): Json<ExecutionPlan>| {
+            let execution_runtime_hits_inner = Arc::clone(&execution_runtime_hits_clone);
+            async move {
+                *execution_runtime_hits_inner
+                    .lock()
+                    .expect("mutex should lock") += 1;
+                assert_eq!(
+                    plan.url,
+                    "https://chatgpt.com/backend-api/codex/models?client_version=0.144.1"
+                );
+                assert_eq!(plan.provider_api_format, "openai:responses");
+                Json(json!({
+                    "request_id": "req-provider-query-codex-slug-only",
+                    "status_code": 200,
+                    "headers": {
+                        "content-type": "application/json"
+                    },
+                    "body": {
+                        "json_body": {
+                            "models": [{
+                                "slug": "gpt-future-dynamic",
+                                "display_name": "Future Dynamic",
+                                "description": "A model unknown to this Aether build",
+                                "model_messages": {
+                                    "instructions_template": "Follow the dynamic instructions."
+                                },
+                                "api_format": "opaque-upstream-protocol",
+                                "future_capability": {
+                                    "opaque": true,
+                                    "schema_version": 7
+                                }
+                            }]
+                        }
+                    }
+                }))
+            }
+        }),
+    );
+
+    let (execution_runtime_url, execution_runtime_handle) = start_server(execution_runtime).await;
+    let mut provider = sample_provider("provider-codex-dynamic", "Codex Dynamic", 10);
+    provider.provider_type = "codex".to_string();
+    let provider_catalog_repository = Arc::new(InMemoryProviderCatalogReadRepository::seed(
+        vec![provider],
+        vec![sample_endpoint(
+            "endpoint-codex-dynamic",
+            "provider-codex-dynamic",
+            "openai:responses",
+            "https://chatgpt.com/backend-api/codex",
+        )],
+        vec![sample_key(
+            "key-codex-dynamic",
+            "provider-codex-dynamic",
+            "openai:responses",
+            "codex-dynamic-token",
+        )],
+    ));
+
+    let state = build_state_with_execution_runtime_override(execution_runtime_url)
+        .with_data_state_for_tests(GatewayDataState::with_provider_transport_reader_for_tests(
+            provider_catalog_repository,
+            DEVELOPMENT_ENCRYPTION_KEY.to_string(),
+        ));
+    state
+        .runtime_state()
+        .kv_set(
+            "upstream_models:provider-codex-dynamic:key-codex-dynamic",
+            "[]".to_string(),
+            None,
+        )
+        .await
+        .expect("empty legacy cache should seed");
+    let cache_state = state.clone();
+    let gateway = build_router_with_state(state);
+    let (gateway_url, gateway_handle) = start_server(gateway).await;
+
+    for (request_index, expected_from_cache) in [(0usize, false), (1usize, true)] {
+        let response = reqwest::Client::new()
+            .post(format!("{gateway_url}/api/admin/provider-query/models"))
+            .header(crate::constants::GATEWAY_HEADER, "rust-phase3b")
+            .header(TRUSTED_ADMIN_USER_ID_HEADER, "admin-user-123")
+            .header(TRUSTED_ADMIN_USER_ROLE_HEADER, "admin")
+            .header(TRUSTED_ADMIN_SESSION_ID_HEADER, "session-123")
+            .json(&json!({
+                "provider_id": "provider-codex-dynamic",
+                "api_key_id": "key-codex-dynamic"
+            }))
+            .send()
+            .await
+            .expect("request should succeed");
+
+        assert_eq!(response.status(), StatusCode::OK);
+        let payload: serde_json::Value = response.json().await.expect("json body should parse");
+        assert_eq!(payload["success"], json!(true));
+        assert_eq!(payload["data"]["error"], serde_json::Value::Null);
+        assert_eq!(
+            payload["data"]["from_cache"],
+            json!(expected_from_cache),
+            "request {request_index} cache status"
+        );
+        assert_eq!(
+            payload["data"]["models"][0]["id"],
+            json!("gpt-future-dynamic")
+        );
+        assert_eq!(
+            payload["data"]["models"][0]["api_formats"],
+            json!(["openai:responses"])
+        );
+        assert_eq!(
+            payload["data"]["models"][0]["api_format"],
+            json!("opaque-upstream-protocol")
+        );
+        assert_eq!(
+            payload["data"]["models"][0]["model_messages"]["instructions_template"],
+            json!("Follow the dynamic instructions.")
+        );
+        assert_eq!(
+            payload["data"]["models"][0]["future_capability"],
+            json!({"opaque": true, "schema_version": 7})
+        );
+        assert_eq!(
+            *execution_runtime_hits.lock().expect("mutex should lock"),
+            1,
+            "request {request_index} must not cause another upstream fetch"
+        );
+        if request_index == 0 {
+            <AppState as crate::model_fetch::ModelFetchRuntimeState>::write_upstream_models_cache(
+                &cache_state,
+                "provider-codex-dynamic",
+                "key-codex-dynamic",
+                &[],
+            )
+            .await;
+        }
+    }
+
+    gateway_handle.abort();
+    execution_runtime_handle.abort();
+}
+
 #[test]
 fn gateway_handles_admin_provider_query_models_falls_back_to_codex_preset_when_token_invalidated() {
     run_provider_query_test(

crates/aether-model-fetch/src/lib.rs

@@ -16,9 +16,9 @@ pub use logic::{
     endpoint_supports_rust_models_fetch, extract_error_message, json_string_list,
     merge_upstream_metadata, model_catalog_upstream_metadata, parse_models_response,
     parse_models_response_page, parse_windsurf_model_configs_response, preset_models_for_provider,
-    provider_type_uses_preset_models, select_models_fetch_endpoint,
-    selected_models_fetch_endpoints, upstream_metadata_namespace_updates, ModelFetchRunSummary,
-    ModelsFetchPage, ModelsFetchSuccess,
+    project_codex_models_for_legacy_cache, provider_type_uses_preset_models,
+    select_models_fetch_endpoint, selected_models_fetch_endpoints,
+    upstream_metadata_namespace_updates, ModelFetchRunSummary, ModelsFetchPage, ModelsFetchSuccess,
 };
 pub use strategy::{
     fetch_models_from_transports, fetch_models_from_transports_for_client_version,

crates/aether-model-fetch/src/logic.rs

@@ -303,7 +303,7 @@ fn codex_model_identities(model: &Value) -> Result<Vec<&str>, String> {
 
 pub(crate) fn codex_model_identity(model: &Value) -> Option<&str> {
     let object = model.as_object()?;
-    ["id", "slug"].iter().find_map(|field| {
+    ["slug", "id"].iter().find_map(|field| {
         object
             .get(*field)
             .and_then(Value::as_str)
@@ -312,6 +312,67 @@ pub(crate) fn codex_model_identity(model: &Value) -> Option<&str> {
     })
 }
 
+/// Projects opaque Codex cards into the legacy model-cache shape used by permission sync.
+///
+/// The source cards remain untouched. Only formats from transports that actually returned the
+/// card are admitted into `api_formats`; an upstream `api_format` field is protocol data and is
+/// preserved as-is rather than interpreted as an Aether endpoint format.
+pub fn project_codex_models_for_legacy_cache<'a>(
+    successful_transports: impl IntoIterator<Item = (&'a str, &'a [Value])>,
+) -> Vec<Value> {
+    let mut projected = BTreeMap::<String, serde_json::Map<String, Value>>::new();
+
+    for (endpoint_api_format, models) in successful_transports {
+        let api_format = normalize_api_format(endpoint_api_format);
+        if api_format.is_empty() {
+            continue;
+        }
+
+        for model in models {
+            let Some(model_id) = codex_model_identity(model).map(ToOwned::to_owned) else {
+                continue;
+            };
+            let Some(source) = model.as_object() else {
+                continue;
+            };
+
+            let entry = projected.entry(model_id.clone()).or_insert_with(|| {
+                let mut card = source.clone();
+                card.insert("id".to_string(), Value::String(model_id));
+                // `api_formats` is Aether's routing projection. Never inherit a similarly named
+                // opaque upstream field when constructing this legacy view.
+                card.insert("api_formats".to_string(), Value::Array(Vec::new()));
+                card
+            });
+            let mut formats = entry
+                .get("api_formats")
+                .and_then(Value::as_array)
+                .map(|items| {
+                    items
+                        .iter()
+                        .filter_map(Value::as_str)
+                        .map(str::trim)
+                        .filter(|value| !value.is_empty())
+                        .map(ToOwned::to_owned)
+                        .collect::<BTreeSet<_>>()
+                })
+                .unwrap_or_default();
+            formats.insert(api_format.clone());
+            entry.insert(
+                "api_formats".to_string(),
+                Value::Array(
+                    sorted_api_formats(formats)
+                        .into_iter()
+                        .map(Value::String)
+                        .collect(),
+                ),
+            );
+        }
+    }
+
+    projected.into_values().map(Value::Object).collect()
+}
+
 fn valid_codex_model_identity(value: &str) -> bool {
     !value.is_empty()
         && value.len() <= 256
@@ -715,9 +776,15 @@ pub fn aggregate_models_for_cache(models: &[Value]) -> Vec<Value> {
             continue;
         };
 
+        let has_api_formats_array = object
+            .get("api_formats")
+            .and_then(Value::as_array)
+            .is_some();
         let entry = aggregated.entry(model_id.to_string()).or_insert_with(|| {
             let mut cloned = object.clone();
-            cloned.remove("api_format");
+            if !has_api_formats_array {
+                cloned.remove("api_format");
+            }
             cloned
         });
 
@@ -734,12 +801,16 @@ pub fn aggregate_models_for_cache(models: &[Value]) -> Vec<Value> {
                     .collect::<BTreeSet<_>>()
             })
             .unwrap_or_default();
-        let legacy_api_format = object
-            .get("api_format")
-            .and_then(Value::as_str)
-            .map(str::trim)
-            .filter(|value| !value.is_empty())
-            .map(ToOwned::to_owned);
+        let legacy_api_format = (!has_api_formats_array)
+            .then(|| {
+                object
+                    .get("api_format")
+                    .and_then(Value::as_str)
+                    .map(str::trim)
+                    .filter(|value| !value.is_empty())
+                    .map(ToOwned::to_owned)
+            })
+            .flatten();
         let existing_formats = entry
             .get("api_formats")
             .and_then(Value::as_array)
@@ -767,7 +838,13 @@ pub fn aggregate_models_for_cache(models: &[Value]) -> Vec<Value> {
         entry.insert("api_formats".to_string(), Value::Array(merged_formats));
 
         for (key, value) in object {
-            if key == "api_format" || entry.contains_key(key) {
+            if key == "api_format" {
+                if has_api_formats_array && !entry.contains_key(key) {
+                    entry.insert(key.clone(), value.clone());
+                }
+                continue;
+            }
+            if entry.contains_key(key) {
                 continue;
             }
             entry.insert(key.clone(), value.clone());
@@ -1082,7 +1159,8 @@ mod tests {
         aggregate_models_for_cache, apply_model_filters, build_gemini_models_url,
         build_models_fetch_url, build_models_fetch_url_for_client_version, merge_upstream_metadata,
         parse_codex_models_response_page, parse_models_response, parse_models_response_page,
-        preset_models_for_provider, selected_models_fetch_endpoints,
+        preset_models_for_provider, project_codex_models_for_legacy_cache,
+        selected_models_fetch_endpoints,
     };
 
     fn sample_endpoint(
@@ -1200,6 +1278,27 @@ mod tests {
         assert!(aggregated[0].get("api_format").is_none());
     }
 
+    #[test]
+    fn aggregate_models_for_cache_preserves_opaque_api_format_on_projected_cards() {
+        let card = json!({
+            "slug": "gpt-slug-only-future",
+            "api_format": "opaque-upstream-protocol",
+            "model_messages": {"instructions_template": "Future instructions"},
+            "future_capability": {"opaque": true}
+        });
+        let cards = vec![card];
+        let projected =
+            project_codex_models_for_legacy_cache([("openai:responses", cards.as_slice())]);
+
+        let aggregated = aggregate_models_for_cache(&projected);
+
+        assert_eq!(aggregated.len(), 1);
+        assert_eq!(aggregated[0]["id"], "gpt-slug-only-future");
+        assert_eq!(aggregated[0]["api_format"], "opaque-upstream-protocol");
+        assert_eq!(aggregated[0]["api_formats"], json!(["openai:responses"]));
+        assert_eq!(aggregated[0]["future_capability"]["opaque"], true);
+    }
+
     #[test]
     fn build_gemini_models_url_preserves_base_query() {
         let url =
@@ -1466,6 +1565,38 @@ mod tests {
         assert_eq!(parsed.cached_models, vec![card]);
     }
 
+    #[test]
+    fn codex_legacy_projector_adds_internal_identity_and_only_successful_endpoint_formats() {
+        let card = json!({
+            "id": "opaque-upstream-id",
+            "slug": "gpt-slug-only-future",
+            "api_format": "opaque-upstream-protocol",
+            "api_formats": ["opaque-upstream-format-list"],
+            "model_messages": {"instructions_template": "Future instructions"},
+            "future_capability": {"opaque": true}
+        });
+        let cards = vec![card.clone()];
+
+        let projected = project_codex_models_for_legacy_cache([
+            ("openai:responses", cards.as_slice()),
+            ("openai:chat", cards.as_slice()),
+        ]);
+
+        assert_eq!(cards, vec![card]);
+        assert_eq!(projected.len(), 1);
+        assert_eq!(projected[0]["id"], "gpt-slug-only-future");
+        assert_eq!(
+            projected[0]["api_formats"],
+            json!(["openai:chat", "openai:responses"])
+        );
+        assert_eq!(projected[0]["api_format"], "opaque-upstream-protocol");
+        assert_eq!(
+            projected[0]["model_messages"]["instructions_template"],
+            "Future instructions"
+        );
+        assert_eq!(projected[0]["future_capability"]["opaque"], true);
+    }
+
     #[test]
     fn strict_codex_parser_rejects_empty_models_array() {
         let error = parse_codex_models_response_page(&json!({"models": []}))

crates/aether-model-fetch/src/strategy.rs

@@ -23,6 +23,7 @@ use crate::logic::{
     aggregate_models_for_cache, codex_model_identity, extract_error_message,
     merge_codex_models_preserving_cards, parse_codex_models_response_page,
     parse_models_response_page, parse_windsurf_model_configs_response, preset_models_for_provider,
+    project_codex_models_for_legacy_cache,
 };
 use crate::transport::{
     build_antigravity_fetch_available_models_plan, build_antigravity_load_code_assist_plan,
@@ -46,7 +47,10 @@ const GOOGLE_CLOUD_PLATFORM_SCOPE: &str = "https://www.googleapis.com/auth/cloud
 #[derive(Debug, Clone, PartialEq)]
 pub struct ModelsFetchOutcome {
     pub fetched_model_ids: Vec<String>,
+    /// Provider response cards. Versioned Codex catalogs remain byte-for-byte opaque here.
     pub cached_models: Vec<Value>,
+    /// Provider cards projected into Aether's legacy admin/runtime-cache shape.
+    pub legacy_models: Vec<Value>,
     pub errors: Vec<String>,
     pub has_success: bool,
     pub upstream_metadata: Option<Value>,
@@ -253,15 +257,21 @@ async fn fetch_standard_models(
     codex_client_version: Option<&str>,
 ) -> Result<ModelsFetchOutcome, String> {
     let mut all_models = Vec::new();
+    let mut successful_codex_catalogs = Vec::<(String, Vec<Value>)>::new();
     let mut errors = Vec::new();
     let mut has_success = false;
     let mut etag = ConsistentValue::default();
     let mut upstream_status = ConsistentValue::default();
+    let is_codex = provider_type.trim().eq_ignore_ascii_case("codex");
 
     for transport in transports {
         match fetch_standard_models_for_transport(runtime, transport, codex_client_version).await {
             Ok(outcome) => {
-                all_models.extend(outcome.cached_models);
+                all_models.extend(outcome.cached_models.iter().cloned());
+                if is_codex && outcome.has_success {
+                    successful_codex_catalogs
+                        .push((transport.endpoint.api_format.clone(), outcome.cached_models));
+                }
                 has_success |= outcome.has_success;
                 if outcome.has_success {
                     etag.observe(outcome.etag);
@@ -275,7 +285,6 @@ async fn fetch_standard_models(
         }
     }
 
-    let is_codex = provider_type.trim().eq_ignore_ascii_case("codex");
     let merged_models = if is_codex {
         merge_codex_models_preserving_cards(&all_models)?
     } else {
@@ -287,6 +296,11 @@ async fn fetch_standard_models(
     let mut outcome = build_success_outcome(merged_models, upstream_metadata, has_success);
     if let Some(model_ids) = codex_model_ids {
         outcome.fetched_model_ids = model_ids;
+        outcome.legacy_models = project_codex_models_for_legacy_cache(
+            successful_codex_catalogs
+                .iter()
+                .map(|(api_format, models)| (api_format.as_str(), models.as_slice())),
+        );
     }
     Ok(outcome
         .with_errors(errors)
@@ -328,7 +342,11 @@ async fn fetch_standard_models_for_transport(
         let body_json =
             execution_result_json_body(&result).map_err(|err| (err, Some(result.status_code)))?;
         let parsed = if is_codex {
-            parse_codex_models_response_page(&body_json)
+            parse_codex_models_response_for_request(
+                &transport.endpoint.api_format,
+                &body_json,
+                codex_client_version,
+            )
         } else {
             parse_models_response_page(&transport.endpoint.api_format, &body_json)
         }
@@ -372,6 +390,19 @@ async fn fetch_standard_models_for_transport(
         .with_upstream_status(upstream_status.finish()))
 }
 
+fn parse_codex_models_response_for_request(
+    endpoint_api_format: &str,
+    body: &Value,
+    codex_client_version: Option<&str>,
+) -> Result<crate::logic::ModelsFetchPage, String> {
+    if codex_client_version.is_none()
+        && (body.is_array() || body.get("data").and_then(Value::as_array).is_some())
+    {
+        return parse_models_response_page(endpoint_api_format, body);
+    }
+    parse_codex_models_response_page(body)
+}
+
 async fn fetch_antigravity_models(
     runtime: &(impl ModelFetchTransportRuntime + ?Sized),
     transport: &GatewayProviderTransportSnapshot,
@@ -425,6 +456,7 @@ async fn fetch_antigravity_models(
     Ok(ModelsFetchOutcome {
         fetched_model_ids: Vec::new(),
         cached_models: Vec::new(),
+        legacy_models: Vec::new(),
         errors,
         has_success: false,
         upstream_metadata: None,
@@ -607,6 +639,7 @@ async fn fetch_vertex_api_key_models(
         return Ok(ModelsFetchOutcome {
             fetched_model_ids: Vec::new(),
             cached_models: Vec::new(),
+            legacy_models: Vec::new(),
             errors: vec!["vertex_ai(api_key): missing api key".to_string()],
             has_success: false,
             upstream_metadata: None,
@@ -666,6 +699,7 @@ async fn fetch_vertex_api_key_models(
     Ok(ModelsFetchOutcome {
         fetched_model_ids: Vec::new(),
         cached_models: Vec::new(),
+        legacy_models: Vec::new(),
         errors,
         has_success,
         upstream_metadata: None,
@@ -683,6 +717,7 @@ async fn fetch_vertex_service_account_models(
         return Ok(ModelsFetchOutcome {
             fetched_model_ids: Vec::new(),
             cached_models: Vec::new(),
+            legacy_models: Vec::new(),
             errors: vec!["vertex_ai(service_account): missing auth_config".to_string()],
             has_success: false,
             upstream_metadata: None,
@@ -753,6 +788,7 @@ async fn fetch_vertex_service_account_models(
     Ok(ModelsFetchOutcome {
         fetched_model_ids: Vec::new(),
         cached_models: Vec::new(),
+        legacy_models: Vec::new(),
         errors,
         has_success,
         upstream_metadata: None,
@@ -1367,9 +1403,11 @@ fn build_success_outcome(
     upstream_metadata: Option<Value>,
     has_success: bool,
 ) -> ModelsFetchOutcome {
+    let legacy_models = cached_models.clone();
     ModelsFetchOutcome {
         fetched_model_ids: collect_model_ids(&cached_models),
         cached_models,
+        legacy_models,
         errors: Vec::new(),
         has_success,
         upstream_metadata,
@@ -1580,7 +1618,8 @@ mod tests {
 
     use super::{
         build_vertex_google_list_url, build_vertex_service_account_list_url,
-        select_model_fetch_strategy, ModelFetchStrategy, ModelFetchStrategyKind,
+        parse_codex_models_response_for_request, select_model_fetch_strategy, ModelFetchStrategy,
+        ModelFetchStrategyKind,
     };
     use crate::transport::ModelFetchTransportRuntime;
     use crate::{fetch_models_from_transports, fetch_models_from_transports_for_client_version};
@@ -1929,6 +1968,30 @@ mod tests {
         assert_eq!(strategy.kind(), ModelFetchStrategyKind::StandardTransport);
     }
 
+    #[test]
+    fn unversioned_codex_parser_accepts_top_level_openai_compatible_array() {
+        let parsed = parse_codex_models_response_for_request(
+            "openai:responses",
+            &json!([{"id": "gpt-array-compatible"}]),
+            None,
+        )
+        .expect("unversioned admin fetch should retain the top-level array fallback");
+
+        assert_eq!(parsed.fetched_model_ids, vec!["gpt-array-compatible"]);
+        assert_eq!(
+            parsed.cached_models[0]["api_formats"],
+            json!(["openai:responses"])
+        );
+
+        let error = parse_codex_models_response_for_request(
+            "openai:responses",
+            &json!([{"id": "gpt-array-compatible"}]),
+            Some("0.145.2"),
+        )
+        .expect_err("versioned catalogs must use the opaque models-array schema");
+        assert!(error.contains("missing models array"));
+    }
+
     #[test]
     fn strategy_selection_uses_preset_catalog_for_claude_code() {
         let mut transport = sample_custom_aiplatform_transport();
@@ -2044,6 +2107,7 @@ mod tests {
             vec!["responses-only", "shared-model"]
         );
         assert_eq!(outcome.cached_models.len(), 2);
+        assert_eq!(outcome.legacy_models, outcome.cached_models);
         assert_eq!(outcome.errors.len(), 1);
         assert!(outcome.errors[0].contains("connection reset"));
         let shared_model = outcome
@@ -2209,6 +2273,16 @@ mod tests {
             "opaque-future-field"
         );
         assert!(outcome.cached_models[0].get("api_formats").is_none());
+        assert_eq!(outcome.legacy_models.len(), 1);
+        assert_eq!(outcome.legacy_models[0]["id"], "gpt-5.6-future");
+        assert_eq!(
+            outcome.legacy_models[0]["api_formats"],
+            json!(["openai:responses"])
+        );
+        assert_eq!(
+            outcome.legacy_models[0]["api_format"],
+            "opaque-future-field"
+        );
         let card = &outcome
             .upstream_metadata
             .as_ref()
@@ -2243,6 +2317,130 @@ mod tests {
         assert_eq!(outcome.fetched_model_ids, vec!["gpt-slug-only-future"]);
         assert_eq!(outcome.cached_models, vec![card]);
         assert!(outcome.cached_models[0].get("id").is_none());
+        assert_eq!(outcome.legacy_models[0]["id"], "gpt-slug-only-future");
+        assert_eq!(
+            outcome.legacy_models[0]["api_formats"],
+            json!(["openai:responses"])
+        );
+        assert_eq!(
+            outcome.legacy_models[0]["future_capability"]["opaque"],
+            true
+        );
+    }
+
+    #[tokio::test]
+    async fn codex_legacy_projection_merges_only_formats_from_successful_transports() {
+        let executed_urls = Arc::new(Mutex::new(Vec::new()));
+        let card = json!({
+            "slug": "gpt-multi-format-future",
+            "api_format": "opaque-upstream-protocol",
+            "future_capability": {"opaque": true}
+        });
+        let runtime = RoutingTestRuntime {
+            executed_urls,
+            routes: vec![
+                (
+                    "chat.example.com/backend-api/codex/models".to_string(),
+                    Ok((200, json!({"models": [card.clone()]}))),
+                ),
+                (
+                    "responses.example.com/backend-api/codex/models".to_string(),
+                    Ok((200, json!({"models": [card.clone()]}))),
+                ),
+                (
+                    "compact.example.com/backend-api/codex/models".to_string(),
+                    Err("compact endpoint unavailable".to_string()),
+                ),
+            ],
+        };
+        let mut chat = sample_codex_transport_for_base(
+            "endpoint-chat",
+            "https://chat.example.com/backend-api/codex",
+        );
+        chat.endpoint.api_format = "openai:chat".to_string();
+        let responses = sample_codex_transport_for_base(
+            "endpoint-responses",
+            "https://responses.example.com/backend-api/codex",
+        );
+        let mut compact = sample_codex_transport_for_base(
+            "endpoint-compact",
+            "https://compact.example.com/backend-api/codex",
+        );
+        compact.endpoint.api_format = "openai:responses:compact".to_string();
+
+        let outcome = fetch_models_from_transports_for_client_version(
+            &runtime,
+            &[chat, responses, compact],
+            Some("0.145.2"),
+        )
+        .await
+        .expect("successful endpoint catalogs should survive a sibling failure");
+
+        assert_eq!(outcome.cached_models, vec![card]);
+        assert_eq!(outcome.legacy_models.len(), 1);
+        assert_eq!(
+            outcome.legacy_models[0]["api_formats"],
+            json!(["openai:chat", "openai:responses"])
+        );
+        assert_eq!(
+            outcome.legacy_models[0]["api_format"],
+            "opaque-upstream-protocol"
+        );
+        assert_eq!(outcome.errors.len(), 1);
+        assert!(outcome.errors[0].contains("compact endpoint unavailable"));
+    }
+
+    #[tokio::test]
+    async fn unversioned_codex_admin_fetch_keeps_openai_compatible_data_fallback() {
+        let executed_urls = Arc::new(Mutex::new(Vec::new()));
+        let runtime = TestRuntime {
+            executed_urls,
+            response_body: json!({
+                "data": [{
+                    "id": "gpt-legacy-compatible",
+                    "future_capability": {"preserved": true}
+                }]
+            }),
+            status_code: 200,
+            response_headers: BTreeMap::new(),
+        };
+
+        let outcome = fetch_models_from_transports(&runtime, &[sample_codex_transport()])
+            .await
+            .expect("unversioned admin fetch should retain the generic parser fallback");
+
+        assert!(outcome.has_success);
+        assert_eq!(outcome.fetched_model_ids, vec!["gpt-legacy-compatible"]);
+        assert_eq!(outcome.cached_models[0]["id"], "gpt-legacy-compatible");
+        assert_eq!(
+            outcome.legacy_models[0]["api_formats"],
+            json!(["openai:responses"])
+        );
+    }
+
+    #[tokio::test]
+    async fn versioned_codex_catalog_does_not_accept_openai_compatible_data_fallback() {
+        let executed_urls = Arc::new(Mutex::new(Vec::new()));
+        let runtime = TestRuntime {
+            executed_urls,
+            response_body: json!({"data": [{"id": "gpt-not-an-opaque-card"}]}),
+            status_code: 200,
+            response_headers: BTreeMap::new(),
+        };
+
+        let outcome = fetch_models_from_transports_for_client_version(
+            &runtime,
+            &[sample_codex_transport()],
+            Some("0.145.2"),
+        )
+        .await
+        .expect("transport failures are returned as observable outcomes");
+
+        assert!(!outcome.has_success);
+        assert!(outcome.cached_models.is_empty());
+        assert!(outcome.legacy_models.is_empty());
+        assert_eq!(outcome.errors.len(), 1);
+        assert!(outcome.errors[0].contains("missing models array"));
     }
 
     #[tokio::test]

crates/aether-model-fetch/src/transport.rs

@@ -973,8 +973,9 @@ mod tests {
         let mut transport = sample_transport("codex", "openai:chat", "oauth");
         transport.endpoint.base_url = "https://chatgpt.com/backend-api/codex".to_string();
         transport.endpoint.header_rules = Some(json!([
-            {"op": "set", "name": "chatgpt-account-id", "value": "spoofed-account"},
-            {"op": "set", "name": "x-openai-fedramp", "value": "false"}
+            {"action": "set", "key": "authorization", "value": "Bearer spoofed-token"},
+            {"action": "set", "key": "chatgpt-account-id", "value": "spoofed-account"},
+            {"action": "set", "key": "x-openai-fedramp", "value": "false"}
         ]));
         transport.key.decrypted_auth_config =
             Some(r#"{"account_id":"account-1","chatgpt_account_is_fedramp":true}"#.to_string());
@@ -1028,8 +1029,8 @@ mod tests {
         let mut transport = sample_transport("codex", "openai:responses", "oauth");
         transport.endpoint.base_url = "https://chatgpt.com/backend-api/codex".to_string();
         transport.endpoint.header_rules = Some(json!([
-            {"op": "set", "name": "user-agent", "value": "codex_cli_rs/0.1.0"},
-            {"op": "remove", "name": "originator"}
+            {"action": "set", "key": "user-agent", "value": "custom-codex-client/0.1.0"},
+            {"action": "drop", "key": "originator"}
         ]));
         transport.key.decrypted_auth_config =
             Some(r#"{"account_id":"account-1","chatgpt_account_is_fedramp":true}"#.to_string());
@@ -1054,10 +1055,6 @@ mod tests {
             plan.headers.get("originator").map(String::as_str),
             Some("codex_cli_rs")
         );
-        assert_eq!(
-            plan.headers.get("originator").map(String::as_str),
-            Some("codex_cli_rs")
-        );
         assert_eq!(
             plan.headers.get("chatgpt-account-id").map(String::as_str),
             Some("account-1")