Deduplicate MCP resource operation handling (#36716)

## What changed

- Add a shared runner for MCP resource operation lifecycle events, output serialization, truncation, timing, and error handling.
- Use it for listing resources, listing resource templates, and reading resources.

GitOrigin-RevId: 84cae2e01a096d5b8ed97ea1cb462f01fe2ed1f9

codex-rs/core/src/tools/handlers/mcp_resource.rs

@@ -1,6 +1,8 @@
 use std::collections::HashMap;
+use std::future::Future;
 use std::sync::Arc;
 use std::time::Duration;
+use std::time::Instant;
 
 use codex_mcp::CODEX_APPS_MCP_SERVER_NAME;
 use codex_protocol::items::McpToolCallError;
@@ -8,6 +10,7 @@ use codex_protocol::items::McpToolCallItem;
 use codex_protocol::items::McpToolCallStatus;
 use codex_protocol::items::TurnItem;
 use codex_protocol::mcp::CallToolResult;
+use codex_protocol::models::function_call_output_content_items_to_text;
 use codex_protocol::protocol::TruncationPolicy;
 use codex_utils_output_truncation::truncate_text;
 use rmcp::model::ListResourceTemplatesResult;
@@ -24,6 +27,8 @@ use crate::function_tool::FunctionCallError;
 use crate::session::session::Session;
 use crate::session::turn_context::TurnContext;
 use crate::tools::context::FunctionToolOutput;
+use crate::tools::context::ToolOutput;
+use crate::tools::context::boxed_tool_output;
 use codex_protocol::protocol::McpInvocation;
 
 mod list_mcp_resource_templates;
@@ -280,6 +285,52 @@ async fn emit_tool_call_end(
     session.emit_turn_item_completed(turn, item).await;
 }
 
+async fn run_resource_operation<T>(
+    session: &Arc<Session>,
+    turn: &TurnContext,
+    call_id: &str,
+    invocation: McpInvocation,
+    operation: impl Future<Output = Result<T, FunctionCallError>>,
+) -> Result<Box<dyn ToolOutput>, FunctionCallError>
+where
+    T: Serialize,
+{
+    emit_tool_call_begin(session, turn, call_id, invocation.clone()).await;
+    let start = Instant::now();
+    let result = operation.await.and_then(|payload| {
+        serialize_function_output(payload, turn.model_info.truncation_policy.into())
+    });
+
+    match result {
+        Ok(output) => {
+            let content =
+                function_call_output_content_items_to_text(&output.body).unwrap_or_default();
+            emit_tool_call_end(
+                session,
+                turn,
+                call_id,
+                invocation,
+                start.elapsed(),
+                Ok(call_tool_result_from_content(&content, output.success)),
+            )
+            .await;
+            Ok(boxed_tool_output(output))
+        }
+        Err(error) => {
+            emit_tool_call_end(
+                session,
+                turn,
+                call_id,
+                invocation,
+                start.elapsed(),
+                Err(error.to_string()),
+            )
+            .await;
+            Err(error)
+        }
+    }
+}
+
 fn normalize_optional_string(input: Option<String>) -> Option<String> {
     input.and_then(|value| {
         let trimmed = value.trim().to_string();

codex-rs/core/src/tools/handlers/mcp_resource/list_mcp_resource_templates.rs

@@ -1,13 +1,9 @@
-use std::time::Instant;
-
 use crate::function_tool::FunctionCallError;
 use crate::tools::context::ToolInvocation;
 use crate::tools::context::ToolPayload;
-use crate::tools::context::boxed_tool_output;
 use crate::tools::handlers::mcp_resource_spec::create_list_mcp_resource_templates_tool;
 use crate::tools::registry::CoreToolRuntime;
 use crate::tools::registry::ToolExecutor;
-use codex_protocol::models::function_call_output_content_items_to_text;
 use codex_protocol::protocol::McpInvocation;
 use codex_tools::ToolName;
 use codex_tools::ToolSpec;
@@ -16,15 +12,12 @@ use rmcp::model::PaginatedRequestParams;
 
 use super::ListResourceTemplatesArgs;
 use super::ListResourceTemplatesPayload;
-use super::call_tool_result_from_content;
-use super::emit_tool_call_begin;
-use super::emit_tool_call_end;
 use super::ensure_model_can_access_mcp_server;
 use super::model_can_access_mcp_server;
 use super::normalize_optional_string;
 use super::parse_args_with_default;
 use super::parse_arguments;
-use super::serialize_function_output;
+use super::run_resource_operation;
 
 pub struct ListMcpResourceTemplatesHandler;
 
@@ -82,10 +75,7 @@ impl ListMcpResourceTemplatesHandler {
             arguments: arguments.clone(),
         };
 
-        emit_tool_call_begin(&session, turn.as_ref(), &call_id, invocation.clone()).await;
-        let start = Instant::now();
-
-        let payload_result: Result<ListResourceTemplatesPayload, FunctionCallError> = async {
+        run_resource_operation(&session, turn.as_ref(), &call_id, invocation, async {
             if let Some(server_name) = server.clone() {
                 ensure_model_can_access_mcp_server(turn.as_ref(), &server_name)?;
                 let params = cursor
@@ -117,57 +107,8 @@ impl ListMcpResourceTemplatesHandler {
                     .await;
                 Ok(ListResourceTemplatesPayload::from_all_servers(templates))
             }
-        }
-        .await;
-        let truncation_policy = turn.model_info.truncation_policy.into();
-
-        match payload_result {
-            Ok(payload) => match serialize_function_output(payload, truncation_policy) {
-                Ok(output) => {
-                    let content = function_call_output_content_items_to_text(&output.body)
-                        .unwrap_or_default();
-                    let duration = start.elapsed();
-                    emit_tool_call_end(
-                        &session,
-                        turn.as_ref(),
-                        &call_id,
-                        invocation,
-                        duration,
-                        Ok(call_tool_result_from_content(&content, output.success)),
-                    )
-                    .await;
-                    Ok(boxed_tool_output(output))
-                }
-                Err(err) => {
-                    let duration = start.elapsed();
-                    let message = err.to_string();
-                    emit_tool_call_end(
-                        &session,
-                        turn.as_ref(),
-                        &call_id,
-                        invocation,
-                        duration,
-                        Err(message.clone()),
-                    )
-                    .await;
-                    Err(err)
-                }
-            },
-            Err(err) => {
-                let duration = start.elapsed();
-                let message = err.to_string();
-                emit_tool_call_end(
-                    &session,
-                    turn.as_ref(),
-                    &call_id,
-                    invocation,
-                    duration,
-                    Err(message.clone()),
-                )
-                .await;
-                Err(err)
-            }
-        }
+        })
+        .await
     }
 }
 

codex-rs/core/src/tools/handlers/mcp_resource/list_mcp_resources.rs

@@ -1,13 +1,9 @@
-use std::time::Instant;
-
 use crate::function_tool::FunctionCallError;
 use crate::tools::context::ToolInvocation;
 use crate::tools::context::ToolPayload;
-use crate::tools::context::boxed_tool_output;
 use crate::tools::handlers::mcp_resource_spec::create_list_mcp_resources_tool;
 use crate::tools::registry::CoreToolRuntime;
 use crate::tools::registry::ToolExecutor;
-use codex_protocol::models::function_call_output_content_items_to_text;
 use codex_protocol::protocol::McpInvocation;
 use codex_tools::ToolName;
 use codex_tools::ToolSpec;
@@ -16,15 +12,12 @@ use rmcp::model::PaginatedRequestParams;
 
 use super::ListResourcesArgs;
 use super::ListResourcesPayload;
-use super::call_tool_result_from_content;
-use super::emit_tool_call_begin;
-use super::emit_tool_call_end;
 use super::ensure_model_can_access_mcp_server;
 use super::model_can_access_mcp_server;
 use super::normalize_optional_string;
 use super::parse_args_with_default;
 use super::parse_arguments;
-use super::serialize_function_output;
+use super::run_resource_operation;
 
 pub struct ListMcpResourcesHandler;
 
@@ -82,10 +75,7 @@ impl ListMcpResourcesHandler {
             arguments: arguments.clone(),
         };
 
-        emit_tool_call_begin(&session, turn.as_ref(), &call_id, invocation.clone()).await;
-        let start = Instant::now();
-
-        let payload_result: Result<ListResourcesPayload, FunctionCallError> = async {
+        run_resource_operation(&session, turn.as_ref(), &call_id, invocation, async {
             if let Some(server_name) = server.clone() {
                 ensure_model_can_access_mcp_server(turn.as_ref(), &server_name)?;
                 let params = cursor
@@ -115,57 +105,8 @@ impl ListMcpResourcesHandler {
                     .await;
                 Ok(ListResourcesPayload::from_all_servers(resources))
             }
-        }
-        .await;
-        let truncation_policy = turn.model_info.truncation_policy.into();
-
-        match payload_result {
-            Ok(payload) => match serialize_function_output(payload, truncation_policy) {
-                Ok(output) => {
-                    let content = function_call_output_content_items_to_text(&output.body)
-                        .unwrap_or_default();
-                    let duration = start.elapsed();
-                    emit_tool_call_end(
-                        &session,
-                        turn.as_ref(),
-                        &call_id,
-                        invocation,
-                        duration,
-                        Ok(call_tool_result_from_content(&content, output.success)),
-                    )
-                    .await;
-                    Ok(boxed_tool_output(output))
-                }
-                Err(err) => {
-                    let duration = start.elapsed();
-                    let message = err.to_string();
-                    emit_tool_call_end(
-                        &session,
-                        turn.as_ref(),
-                        &call_id,
-                        invocation,
-                        duration,
-                        Err(message.clone()),
-                    )
-                    .await;
-                    Err(err)
-                }
-            },
-            Err(err) => {
-                let duration = start.elapsed();
-                let message = err.to_string();
-                emit_tool_call_end(
-                    &session,
-                    turn.as_ref(),
-                    &call_id,
-                    invocation,
-                    duration,
-                    Err(message.clone()),
-                )
-                .await;
-                Err(err)
-            }
-        }
+        })
+        .await
     }
 }
 

codex-rs/core/src/tools/handlers/mcp_resource/read_mcp_resource.rs

@@ -1,13 +1,9 @@
-use std::time::Instant;
-
 use crate::function_tool::FunctionCallError;
 use crate::tools::context::ToolInvocation;
 use crate::tools::context::ToolPayload;
-use crate::tools::context::boxed_tool_output;
 use crate::tools::handlers::mcp_resource_spec::create_read_mcp_resource_tool;
 use crate::tools::registry::CoreToolRuntime;
 use crate::tools::registry::ToolExecutor;
-use codex_protocol::models::function_call_output_content_items_to_text;
 use codex_protocol::protocol::McpInvocation;
 use codex_tools::ToolName;
 use codex_tools::ToolSpec;
@@ -16,14 +12,11 @@ use rmcp::model::ReadResourceRequestParams;
 
 use super::ReadResourceArgs;
 use super::ReadResourcePayload;
-use super::call_tool_result_from_content;
-use super::emit_tool_call_begin;
-use super::emit_tool_call_end;
 use super::ensure_model_can_access_mcp_server;
 use super::normalize_required_string;
 use super::parse_args;
 use super::parse_arguments;
-use super::serialize_function_output;
+use super::run_resource_operation;
 
 pub struct ReadMcpResourceHandler;
 
@@ -81,10 +74,7 @@ impl ReadMcpResourceHandler {
             arguments: arguments.clone(),
         };
 
-        emit_tool_call_begin(&session, turn.as_ref(), &call_id, invocation.clone()).await;
-        let start = Instant::now();
-
-        let payload_result: Result<ReadResourcePayload, FunctionCallError> = async {
+        run_resource_operation(&session, turn.as_ref(), &call_id, invocation, async {
             ensure_model_can_access_mcp_server(turn.as_ref(), &server)?;
             let result = mcp
                 .read_resource(&server, ReadResourceRequestParams::new(uri.clone()))
@@ -98,57 +88,8 @@ impl ReadMcpResourceHandler {
                 uri,
                 result,
             })
-        }
-        .await;
-        let truncation_policy = turn.model_info.truncation_policy.into();
-
-        match payload_result {
-            Ok(payload) => match serialize_function_output(payload, truncation_policy) {
-                Ok(output) => {
-                    let content = function_call_output_content_items_to_text(&output.body)
-                        .unwrap_or_default();
-                    let duration = start.elapsed();
-                    emit_tool_call_end(
-                        &session,
-                        turn.as_ref(),
-                        &call_id,
-                        invocation,
-                        duration,
-                        Ok(call_tool_result_from_content(&content, output.success)),
-                    )
-                    .await;
-                    Ok(boxed_tool_output(output))
-                }
-                Err(err) => {
-                    let duration = start.elapsed();
-                    let message = err.to_string();
-                    emit_tool_call_end(
-                        &session,
-                        turn.as_ref(),
-                        &call_id,
-                        invocation,
-                        duration,
-                        Err(message.clone()),
-                    )
-                    .await;
-                    Err(err)
-                }
-            },
-            Err(err) => {
-                let duration = start.elapsed();
-                let message = err.to_string();
-                emit_tool_call_end(
-                    &session,
-                    turn.as_ref(),
-                    &call_id,
-                    invocation,
-                    duration,
-                    Err(message.clone()),
-                )
-                .await;
-                Err(err)
-            }
-        }
+        })
+        .await
     }
 }