Instrument environment and plugin resolution paths (#33223)

## What changed

Add named tracing spans around step environment snapshots, capability and
executor plugin resolution, `AGENTS.md` refreshes, and MCP runtime projection
and refresh operations. Skip recording function arguments to keep these spans
focused on timing and execution flow.

GitOrigin-RevId: 73a452ef1b5da6f7f2b00d24421a815c5d514eaf

codex-rs/Cargo.lock

@@ -2628,6 +2628,7 @@ dependencies = [
  "codex-utils-path-uri",
  "serde_json",
  "thiserror 2.0.18",
+ "tracing",
 ]
 
 [[package]]

codex-rs/core-plugins/src/provider.rs

@@ -105,6 +105,7 @@ impl ExecutorPluginProvider {
     }
 
     /// Resolves a plugin and retains the exact filesystem used for package access.
+    #[tracing::instrument(name = "plugins.executor.package.resolve", skip_all)]
     pub async fn resolve_bound(
         &self,
         selected_root: &SelectedCapabilityRoot,

codex-rs/core/src/agents_md_manager.rs

@@ -28,6 +28,7 @@ impl AgentsMdManager {
         }
     }
 
+    #[tracing::instrument(name = "agents_md.refresh", skip_all)]
     pub(crate) async fn refresh(&self, config: &Config, environments: &TurnEnvironmentSnapshot) {
         let selections = environments.to_selections();
         if self.cache.lock().await.selections.as_ref() == Some(&selections) {

codex-rs/core/src/environment_selection.rs

@@ -195,6 +195,7 @@ impl ThreadEnvironments {
         .boxed()
     }
 
+    #[tracing::instrument(name = "environments.snapshot", skip_all)]
     pub(crate) async fn snapshot(&self) -> TurnEnvironmentSnapshot {
         let current = self.environments.load_full();
         let mut turn_environments = Vec::with_capacity(current.len());

codex-rs/core/src/mcp.rs

@@ -100,6 +100,7 @@ impl McpManager {
         .config
     }
 
+    #[tracing::instrument(name = "mcp.runtime_config.project_for_step", skip_all)]
     pub(crate) async fn runtime_config_for_step(
         &self,
         config: &Config,

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

@@ -109,6 +109,7 @@ impl Session {
         clippy::await_holding_invalid_type,
         reason = "MCP runtime comparison and publication must remain serialized"
     )]
+    #[tracing::instrument(name = "mcp.runtime.resolve_for_step", skip_all)]
     pub(crate) async fn mcp_runtime_for_step(
         self: &Arc<Self>,
         turn_context: &TurnContext,
@@ -319,6 +320,7 @@ impl Session {
             .await
     }
 
+    #[tracing::instrument(name = "mcp.runtime.refresh", skip_all)]
     async fn refresh_mcp_servers_inner(
         &self,
         turn_context: &TurnContext,

codex-rs/exec-server/src/resolved_capability.rs

@@ -118,6 +118,7 @@ impl EnvironmentManager {
     /// environment captured for the step carries its exact process-local handle so readiness and
     /// execution cannot come from different registry snapshots. Missing, starting, or failed
     /// environments are omitted. A lazy environment is started for a later step.
+    #[tracing::instrument(name = "capability_roots.resolve", skip_all)]
     pub async fn resolve_selected_capability_roots(
         &self,
         selected_roots: &[SelectedCapabilityRoot],

codex-rs/ext/connectors/Cargo.toml

@@ -20,3 +20,4 @@ codex-plugin = { workspace = true }
 codex-utils-path-uri = { workspace = true }
 serde_json = { workspace = true }
 thiserror = { workspace = true }
+tracing = { workspace = true }

codex-rs/ext/connectors/src/executor_plugin.rs

@@ -31,6 +31,7 @@ pub enum ExecutorPluginConnectorProviderError {
 
 impl ExecutorPluginConnectorProvider {
     /// Returns the connector declarations contributed by `plugin`.
+    #[tracing::instrument(name = "connectors.executor_plugin.declarations.load", skip_all)]
     pub async fn load(
         &self,
         plugin: &ResolvedExecutorPlugin,

codex-rs/ext/mcp/src/executor_plugin.rs

@@ -58,6 +58,7 @@ impl SelectedExecutorPluginMcpContributor {
     /// Successful resolution, including a root that is not a plugin or declares no capabilities,
     /// is cached until the thread state is dropped. Environment availability never invalidates
     /// this cache; it only controls whether the cached metadata is projected into a model step.
+    #[tracing::instrument(name = "mcp.executor_plugin.metadata.load", skip_all)]
     async fn metadata_for_root(
         &self,
         state: &SelectedExecutorPluginMcpState,

codex-rs/ext/mcp/src/executor_plugin/provider.rs

@@ -48,6 +48,7 @@ pub(super) enum ExecutorPluginMcpProviderError {
 
 impl ExecutorPluginMcpProvider {
     /// Returns MCP servers declared by `plugin`, bound to its environment.
+    #[tracing::instrument(name = "mcp.executor_plugin.servers.load", skip_all)]
     pub(super) async fn load(
         &self,
         plugin: &ResolvedExecutorPlugin,