Make the optional MCP startup grace configurable (#41199)

## What changed

- Add `mcp_optional_startup_grace_ms` with a default of 1,000 ms to control how long tool catalog capture waits for optional MCP servers.
- Treat a value of `0` as disabling the shared grace, so optional servers use their configured `startup_timeout_sec` instead.
- Apply updated grace values during runtime and MCP configuration refreshes, and reset cached startup deadlines when the configured duration changes.

## Testing

- Cover custom, disabled, refreshed, and shared startup grace behavior in MCP connection and core integration tests.

GitOrigin-RevId: 936196215ed6e0a29c9ec72cfee17663978df8ef

codex-rs/core/src/config/config_tests.rs

@@ -228,6 +228,25 @@ async fn load_config_normalizes_relative_cwd_override() -> std::io::Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn load_config_applies_optional_mcp_startup_grace() -> std::io::Result<()> {
+    let codex_home = tempdir()?;
+    let config_toml: ConfigToml = toml::from_str("mcp_optional_startup_grace_ms = 2500")
+        .expect("optional MCP startup grace should parse from config.toml");
+    let config = Config::load_from_base_config_with_overrides(
+        config_toml,
+        ConfigOverrides::default(),
+        codex_home.abs(),
+    )
+    .await?;
+
+    assert_eq!(
+        config.mcp_optional_startup_grace,
+        Duration::from_millis(2500)
+    );
+    Ok(())
+}
+
 #[tokio::test]
 async fn test_toml_parsing() {
     let history_with_persistence = r#"

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

@@ -80,6 +80,7 @@ use codex_http_client::OutboundProxyPolicy;
 use codex_install_context::InstallContext;
 use codex_login::AuthManagerConfig;
 use codex_login::AuthRouteConfig;
+use codex_mcp::DEFAULT_OPTIONAL_MCP_STARTUP_GRACE;
 use codex_mcp::McpConfig;
 use codex_mcp::McpPluginAttribution;
 use codex_mcp::McpProtocolMode;
@@ -140,6 +141,7 @@ use std::num::NonZeroUsize;
 use std::path::Path;
 use std::path::PathBuf;
 use std::sync::Arc;
+use std::time::Duration;
 
 use crate::config::permissions::BUILT_IN_READ_ONLY_PROFILE;
 use crate::config::permissions::BUILT_IN_WORKSPACE_PROFILE;
@@ -847,6 +849,9 @@ pub struct Config {
     /// to 127.0.0.1 (using `mcp_oauth_callback_port` when provided).
     pub mcp_oauth_callback_url: Option<String>,
 
+    /// How long to wait for optional MCP servers while building the initial tool catalog.
+    pub mcp_optional_startup_grace: Duration,
+
     /// Combined provider map (defaults plus user-defined providers).
     pub model_providers: HashMap<String, ModelProviderInfo>,
 
@@ -1731,6 +1736,7 @@ impl Config {
             auth_keyring_backend_kind: self.auth_keyring_backend_kind(),
             mcp_oauth_callback_port: self.mcp_oauth_callback_port,
             mcp_oauth_callback_url: self.mcp_oauth_callback_url.clone(),
+            optional_mcp_startup_grace: self.mcp_optional_startup_grace,
             skill_mcp_dependency_install_enabled: self
                 .features
                 .enabled(Feature::SkillMcpDependencyInstall),
@@ -4165,6 +4171,10 @@ impl Config {
             ),
             mcp_oauth_callback_port: cfg.mcp_oauth_callback_port,
             mcp_oauth_callback_url: cfg.mcp_oauth_callback_url.clone(),
+            mcp_optional_startup_grace: cfg
+                .mcp_optional_startup_grace_ms
+                .map(Duration::from_millis)
+                .unwrap_or(DEFAULT_OPTIONAL_MCP_STARTUP_GRACE),
             model_providers,
             project_doc_max_bytes: cfg.project_doc_max_bytes.unwrap_or(AGENTS_MD_MAX_BYTES),
             project_doc_fallback_filenames: cfg