register all mcp tools with namespace (#17404)

stacked on #17402.

MCP tools returned by `tool_search` (deferred tools) get registered in
our `ToolRegistry` with a different format than directly available
tools. this leads to two different ways of accessing MCP tools from our
tool catalog, only one of which works for each. fix this by registering
all MCP tools with the namespace format, since this info is already
available.

also, direct MCP tools are registered to responsesapi without a
namespace, while deferred MCP tools have a namespace. this means we can
receive MCP `FunctionCall`s in both formats from namespaces. fix this by
always registering MCP tools with namespace, regardless of deferral
status.

make code mode track `ToolName` provenance of tools so it can map the
literal JS function name string to the correct `ToolName` for
invocation, rather than supporting both in core.

this lets us unify to a single canonical `ToolName` representation for
each MCP tool and force everywhere to use that one, without supporting
fallbacks.

codex-rs/code-mode/src/runtime/callbacks.rs

@@ -15,7 +15,13 @@ pub(super) fn tool_callback(
     args: v8::FunctionCallbackArguments,
     mut retval: v8::ReturnValue<v8::Value>,
 ) {
-    let tool_name = args.data().to_rust_string_lossy(scope);
+    let tool_index = match args.data().to_rust_string_lossy(scope).parse::<usize>() {
+        Ok(tool_index) => tool_index,
+        Err(_) => {
+            throw_type_error(scope, "invalid tool callback data");
+            return;
+        }
+    };
     let input = if args.length() == 0 {
         Ok(None)
     } else {
@@ -36,6 +42,22 @@ pub(super) fn tool_callback(
     let promise = resolver.get_promise(scope);
 
     let resolver = v8::Global::new(scope, resolver);
+    let tool_name = {
+        let Some(state) = scope.get_slot::<RuntimeState>() else {
+            throw_type_error(scope, "runtime state unavailable");
+            return;
+        };
+        let Some(tool_name) = state
+            .enabled_tools
+            .get(tool_index)
+            .map(|tool| tool.tool_name.clone())
+        else {
+            throw_type_error(scope, "tool callback data is out of range");
+            return;
+        };
+        tool_name
+    };
+
     let Some(state) = scope.get_slot_mut::<RuntimeState>() else {
         throw_type_error(scope, "runtime state unavailable");
         return;

codex-rs/code-mode/src/runtime/globals.rs

@@ -53,10 +53,10 @@ fn build_tools_object<'s>(
         .map(|state| state.enabled_tools.clone())
         .unwrap_or_default();
 
-    for tool in enabled_tools {
+    for (tool_index, tool) in enabled_tools.iter().enumerate() {
         let name = v8::String::new(scope, &tool.global_name)
             .ok_or_else(|| "failed to allocate tool name".to_string())?;
-        let function = tool_function(scope, &tool.tool_name)?;
+        let function = tool_function(scope, tool_index)?;
         tools.set(scope, name.into(), function.into());
     }
     Ok(tools)
@@ -116,9 +116,9 @@ where
 
 fn tool_function<'s>(
     scope: &mut v8::PinScope<'s, '_>,
-    tool_name: &str,
+    tool_index: usize,
 ) -> Result<v8::Local<'s, v8::Function>, String> {
-    let data = v8::String::new(scope, tool_name)
+    let data = v8::String::new(scope, &tool_index.to_string())
         .ok_or_else(|| "failed to allocate tool callback data".to_string())?;
     let template = v8::FunctionTemplate::builder(tool_callback)
         .data(data.into())

codex-rs/code-mode/src/runtime/mod.rs

@@ -9,6 +9,7 @@ use std::sync::OnceLock;
 use std::sync::mpsc as std_mpsc;
 use std::thread;
 
+use codex_protocol::ToolName;
 use serde_json::Value as JsonValue;
 use tokio::sync::mpsc;
 
@@ -62,7 +63,7 @@ pub(crate) enum TurnMessage {
     ToolCall {
         cell_id: String,
         id: String,
-        name: String,
+        name: ToolName,
         input: Option<JsonValue>,
     },
     Notify {
@@ -87,7 +88,7 @@ pub(crate) enum RuntimeEvent {
     YieldRequested,
     ToolCall {
         id: String,
-        name: String,
+        name: ToolName,
         input: Option<JsonValue>,
     },
     Notify {