Forward turn metadata for app-server MCP calls

codex-rs/app-server/src/request_processors/mcp_processor.rs

@@ -402,6 +402,10 @@ impl McpRequestProcessor {
         let thread_id = params.thread_id.clone();
         let (_, thread) = self.load_thread(&thread_id).await?;
         let meta = with_mcp_tool_call_thread_id_meta(params.meta, &thread_id);
+        let meta = with_mcp_tool_call_turn_metadata_meta(
+            meta,
+            thread.current_mcp_request_turn_metadata().await,
+        );
         let request_id = request_id.clone();
 
         tokio::spawn(async move {
@@ -416,6 +420,34 @@ impl McpRequestProcessor {
     }
 }
 
+fn with_mcp_tool_call_turn_metadata_meta(
+    meta: Option<serde_json::Value>,
+    turn_metadata: Option<serde_json::Value>,
+) -> Option<serde_json::Value> {
+    let Some(turn_metadata) = turn_metadata else {
+        return meta;
+    };
+
+    match meta {
+        Some(serde_json::Value::Object(mut map)) => {
+            map.insert(
+                codex_core::X_CODEX_TURN_METADATA_HEADER.to_string(),
+                turn_metadata,
+            );
+            Some(serde_json::Value::Object(map))
+        }
+        None => {
+            let mut map = serde_json::Map::new();
+            map.insert(
+                codex_core::X_CODEX_TURN_METADATA_HEADER.to_string(),
+                turn_metadata,
+            );
+            Some(serde_json::Value::Object(map))
+        }
+        other => other,
+    }
+}
+
 fn with_mcp_tool_call_thread_id_meta(
     meta: Option<serde_json::Value>,
     thread_id: &str,

codex-rs/core/src/codex_thread.rs

@@ -5,6 +5,7 @@ use crate::goals::GoalRuntimeEvent;
 use crate::session::Codex;
 use crate::session::SessionSettingsUpdate;
 use crate::session::SteerInputError;
+use crate::turn_metadata::McpTurnMetadataContext;
 use codex_features::Feature;
 use codex_otel::SessionTelemetry;
 use codex_protocol::config_types::ApprovalsReviewer;
@@ -502,6 +503,18 @@ impl CodexThread {
         self.codex.session.get_config().await
     }
 
+    pub async fn current_mcp_request_turn_metadata(&self) -> Option<serde_json::Value> {
+        let active = self.codex.session.active_turn.lock().await;
+        let (_, active_task) = active.as_ref()?.tasks.first()?;
+        let turn_context = active_task.turn_context.as_ref();
+        turn_context
+            .turn_metadata_state
+            .current_meta_value_for_mcp_request(McpTurnMetadataContext {
+                model: turn_context.model_info.slug.as_str(),
+                reasoning_effort: turn_context.effective_reasoning_effort(),
+            })
+    }
+
     /// Refresh the thread's layer-backed user config state from a caller-supplied
     /// config snapshot. Thread-scoped layers and session-static settings remain
     /// unchanged.