codex-rs/codex-mcp/src/client_capabilities.rs

use std::collections::HashMap;

use codex_protocol::mcp::ClientMcpExtensions;
use codex_protocol::mcp::MCP_APP_UI_EXTENSION_ID;
use codex_protocol::mcp::OPENAI_ELICITATION_EXTENSION_ID;
use codex_protocol::mcp::OPENAI_FORM_EXTENSION_ID;
use codex_protocol::mcp::OPENAI_STANDARD_FORM_INPUT_EXTENSION_ID;
use serde_json::Map;
use serde_json::Value;

/// Restricts verification to the host-owned plugin service, even when another server uses its name.
pub(crate) fn server_mcp_extensions(
    extensions: &ClientMcpExtensions,
    server_name: &str,
    server: Option<&crate::catalog::ResolvedMcpServer>,
) -> ClientMcpExtensions {
    let plugin_service = server.is_some_and(|server| {
        server
            .source()
            .is_host_owned_apps(server_name, server.config())
    });
    ClientMcpExtensions::new(extensions.iter().map(|(id, settings)| {
        let mut settings = settings.clone();
        if !plugin_service
            && id == OPENAI_ELICITATION_EXTENSION_ID
            && let Some(settings) = settings.as_object_mut()
        {
            settings.remove("userVerification");
        }
        (id.to_string(), settings)
    }))
}

/// Selects the MCP extensions Codex supports from those declared by the app-server host.
///
/// App-server clients may declare unrelated extensions. Codex retains only the
/// trusted extension namespaces it knows how to project downstream. The
/// legacy form capability is normalized into the same extension map.
pub fn client_mcp_extensions(
    extensions: Option<&HashMap<String, Value>>,
    legacy_openai_form_elicitation: bool,
) -> ClientMcpExtensions {
    let mut selected = extensions
        .into_iter()
        .flat_map(HashMap::iter)
        .filter(|(id, _)| {
            matches!(
                id.as_str(),
                OPENAI_FORM_EXTENSION_ID
                    | OPENAI_ELICITATION_EXTENSION_ID
                    | OPENAI_STANDARD_FORM_INPUT_EXTENSION_ID
                    | MCP_APP_UI_EXTENSION_ID
            )
        })
        .map(|(id, value)| (id.clone(), value.clone()))
        .collect::<HashMap<_, _>>();
    if let Some(settings) = selected
        .get_mut(OPENAI_ELICITATION_EXTENSION_ID)
        .and_then(Value::as_object_mut)
    {
        settings.retain(|key, _| key == "form");
    }
    if legacy_openai_form_elicitation {
        selected
            .entry(OPENAI_FORM_EXTENSION_ID.to_string())
            .or_insert_with(|| Value::Object(Map::new()));
    }
    ClientMcpExtensions::new(selected)
}

#[cfg(test)]
#[path = "client_capabilities_tests.rs"]
mod tests;