[MCP] Add auth status to MCP servers (#4918)

This adds a queryable auth status for MCP servers which is useful:
1. To determine whether a streamable HTTP server supports auth or not
based on whether or not it supports RFC 8414-3.2
2. Allow us to build a better user experience on top of MCP status

codex-rs/core/src/mcp/auth.rs

@@ -0,0 +1,58 @@
+use std::collections::HashMap;
+
+use anyhow::Result;
+use codex_protocol::protocol::McpAuthStatus;
+use codex_rmcp_client::OAuthCredentialsStoreMode;
+use codex_rmcp_client::determine_streamable_http_auth_status;
+use futures::future::join_all;
+use tracing::warn;
+
+use crate::config_types::McpServerConfig;
+use crate::config_types::McpServerTransportConfig;
+
+pub async fn compute_auth_statuses<'a, I>(
+    servers: I,
+    store_mode: OAuthCredentialsStoreMode,
+) -> HashMap<String, McpAuthStatus>
+where
+    I: IntoIterator<Item = (&'a String, &'a McpServerConfig)>,
+{
+    let futures = servers.into_iter().map(|(name, config)| {
+        let name = name.clone();
+        let config = config.clone();
+        async move {
+            let status = match compute_auth_status(&name, &config, store_mode).await {
+                Ok(status) => status,
+                Err(error) => {
+                    warn!("failed to determine auth status for MCP server `{name}`: {error:?}");
+                    McpAuthStatus::Unsupported
+                }
+            };
+            (name, status)
+        }
+    });
+
+    join_all(futures).await.into_iter().collect()
+}
+
+async fn compute_auth_status(
+    server_name: &str,
+    config: &McpServerConfig,
+    store_mode: OAuthCredentialsStoreMode,
+) -> Result<McpAuthStatus> {
+    match &config.transport {
+        McpServerTransportConfig::Stdio { .. } => Ok(McpAuthStatus::Unsupported),
+        McpServerTransportConfig::StreamableHttp {
+            url,
+            bearer_token_env_var,
+        } => {
+            determine_streamable_http_auth_status(
+                server_name,
+                url,
+                bearer_token_env_var.as_deref(),
+                store_mode,
+            )
+            .await
+        }
+    }
+}

codex-rs/core/src/mcp/mod.rs

@@ -0,0 +1 @@
+pub mod auth;