feat: merge remote models instead of destructing (#7997)

- merge remote models instead of destructing
- make config values have more precedent over remote values

codex-rs/core/tests/suite/remote_models.rs

@@ -41,6 +41,7 @@ use core_test_support::skip_if_no_network;
 use core_test_support::skip_if_sandbox;
 use core_test_support::wait_for_event;
 use core_test_support::wait_for_event_match;
+use pretty_assertions::assert_eq;
 use serde_json::json;
 use tempfile::TempDir;
 use tokio::time::Duration;
@@ -298,6 +299,108 @@ async fn remote_models_apply_remote_base_instructions() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn remote_models_preserve_builtin_presets() -> Result<()> {
+    skip_if_no_network!(Ok(()));
+    skip_if_sandbox!(Ok(()));
+
+    let server = MockServer::start().await;
+    let remote_model = test_remote_model("remote-alpha", ModelVisibility::List, 0);
+    let models_mock = mount_models_once(
+        &server,
+        ModelsResponse {
+            models: vec![remote_model.clone()],
+            etag: String::new(),
+        },
+    )
+    .await;
+
+    let codex_home = TempDir::new()?;
+    let mut config = load_default_config_for_test(&codex_home);
+    config.features.enable(Feature::RemoteModels);
+
+    let auth = CodexAuth::from_api_key("dummy");
+    let provider = ModelProviderInfo {
+        base_url: Some(format!("{}/v1", server.uri())),
+        ..built_in_model_providers()["openai"].clone()
+    };
+    let manager = ModelsManager::with_provider(
+        codex_core::auth::AuthManager::from_auth_for_testing(auth),
+        provider,
+    );
+
+    manager
+        .refresh_available_models(&config)
+        .await
+        .expect("refresh succeeds");
+
+    let available = manager.list_models(&config).await;
+    let remote = available
+        .iter()
+        .find(|model| model.model == "remote-alpha")
+        .expect("remote model should be listed");
+    let mut expected_remote: ModelPreset = remote_model.into();
+    expected_remote.is_default = true;
+    assert_eq!(*remote, expected_remote);
+    assert!(
+        available
+            .iter()
+            .any(|model| model.model == "gpt-5.1-codex-max"),
+        "builtin presets should remain available after refresh"
+    );
+    assert_eq!(
+        models_mock.requests().len(),
+        1,
+        "expected a single /models request"
+    );
+
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn remote_models_hide_picker_only_models() -> Result<()> {
+    skip_if_no_network!(Ok(()));
+    skip_if_sandbox!(Ok(()));
+
+    let server = MockServer::start().await;
+    let remote_model = test_remote_model("codex-auto-balanced", ModelVisibility::Hide, 0);
+    mount_models_once(
+        &server,
+        ModelsResponse {
+            models: vec![remote_model],
+            etag: String::new(),
+        },
+    )
+    .await;
+
+    let codex_home = TempDir::new()?;
+    let mut config = load_default_config_for_test(&codex_home);
+    config.features.enable(Feature::RemoteModels);
+
+    let auth = CodexAuth::create_dummy_chatgpt_auth_for_testing();
+    let provider = ModelProviderInfo {
+        base_url: Some(format!("{}/v1", server.uri())),
+        ..built_in_model_providers()["openai"].clone()
+    };
+    let manager = ModelsManager::with_provider(
+        codex_core::auth::AuthManager::from_auth_for_testing(auth),
+        provider,
+    );
+
+    let selected = manager.get_model(&None, &config).await;
+    assert_eq!(selected, "gpt-5.1-codex-max");
+
+    let available = manager.list_models(&config).await;
+    assert!(
+        available
+            .iter()
+            .all(|model| model.model != "codex-auto-balanced"),
+        "hidden models should not appear in the picker list"
+    );
+
+    Ok(())
+}
+
 async fn wait_for_model_available(
     manager: &Arc<ModelsManager>,
     slug: &str,
@@ -362,3 +465,32 @@ where
         conversation_manager,
     })
 }
+
+fn test_remote_model(slug: &str, visibility: ModelVisibility, priority: i32) -> ModelInfo {
+    ModelInfo {
+        slug: slug.to_string(),
+        display_name: format!("{slug} display"),
+        description: Some(format!("{slug} description")),
+        default_reasoning_level: ReasoningEffort::Medium,
+        supported_reasoning_levels: vec![ReasoningEffortPreset {
+            effort: ReasoningEffort::Medium,
+            description: ReasoningEffort::Medium.to_string(),
+        }],
+        shell_type: ConfigShellToolType::ShellCommand,
+        visibility,
+        minimal_client_version: ClientVersion(0, 1, 0),
+        supported_in_api: true,
+        priority,
+        upgrade: None,
+        base_instructions: None,
+        supports_reasoning_summaries: false,
+        support_verbosity: false,
+        default_verbosity: None,
+        apply_patch_tool_type: None,
+        truncation_policy: TruncationPolicyConfig::bytes(10_000),
+        supports_parallel_tool_calls: false,
+        context_window: None,
+        reasoning_summary_format: ReasoningSummaryFormat::None,
+        experimental_supported_tools: Vec::new(),
+    }
+}