Reduce the surface of collaboration modes (#20149)

Collaboration modes were slightly invasive both into ThreadManager
construction and ModelProvider

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

@@ -5,13 +5,14 @@ use crate::tools::context::ToolPayload;
 use crate::tools::handlers::parse_arguments;
 use crate::tools::registry::ToolHandler;
 use crate::tools::registry::ToolKind;
+use codex_protocol::config_types::ModeKind;
 use codex_protocol::request_user_input::RequestUserInputArgs;
 use codex_tools::REQUEST_USER_INPUT_TOOL_NAME;
 use codex_tools::normalize_request_user_input_args;
 use codex_tools::request_user_input_unavailable_message;
 
 pub struct RequestUserInputHandler {
-    pub default_mode_request_user_input: bool,
+    pub available_modes: Vec<ModeKind>,
 }
 
 impl ToolHandler for RequestUserInputHandler {
@@ -46,9 +47,7 @@ impl ToolHandler for RequestUserInputHandler {
         }
 
         let mode = session.collaboration_mode().await.mode;
-        if let Some(message) =
-            request_user_input_unavailable_message(mode, self.default_mode_request_user_input)
-        {
+        if let Some(message) = request_user_input_unavailable_message(mode, &self.available_modes) {
             return Err(FunctionCallError::RespondToModel(message));
         }
 

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

@@ -23,7 +23,7 @@ async fn multi_agent_v2_request_user_input_rejects_subagent_threads() {
     });
 
     let result = RequestUserInputHandler {
-        default_mode_request_user_input: true,
+        available_modes: Vec::new(),
     }
     .handle(ToolInvocation {
         session: Arc::new(session),

codex-rs/core/src/tools/spec.rs

@@ -166,7 +166,7 @@ pub(crate) fn build_specs_with_discoverable_tools(
     let shell_command_handler = Arc::new(ShellCommandHandler::from(config.shell_command_backend));
     let request_permissions_handler = Arc::new(RequestPermissionsHandler);
     let request_user_input_handler = Arc::new(RequestUserInputHandler {
-        default_mode_request_user_input: config.default_mode_request_user_input,
+        available_modes: config.request_user_input_available_modes.clone(),
     });
     let deferred_dynamic_tools = dynamic_tools
         .iter()