[codex] Remove unused legacy shell tools (#22246)

## Why

Recent session history showed no active use of the raw `shell`,
`local_shell`, or `container.exec` execution surfaces. Keeping those
handlers/specs wired into core leaves duplicate shell execution paths
alongside the supported `shell_command` and unified exec tools.

## What changed

- Removed the raw `shell` handler/spec and its `ShellToolCallParams`
protocol helper.
- Removed the legacy `local_shell` and `container.exec` handler/spec
plumbing while preserving persisted-history compatibility for old
response items.
- Normalized model/config `default` and `local` shell selections to
`shell_command`.
- Pruned tests that exercised removed raw-shell/local-shell/apply-patch
variants and kept coverage on `shell_command`, unified exec, and
freeform `apply_patch`.

## Verification

- `git diff --check`
- `cargo test -p codex-protocol`
- `cargo test -p codex-tools`
- `cargo test -p codex-core tools::handlers::shell`
- `cargo test -p codex-core tools::spec`
- `cargo test -p codex-core tools::router`
- `cargo test -p codex-core
active_call_preserves_triggering_command_context`
- `cargo test -p codex-core guardian_tests`
- `cargo test -p codex-core --test all shell_serialization`
- `cargo test -p codex-core --test all apply_patch_cli`
- `cargo test -p codex-core --test all shell_command_`
- `cargo test -p codex-core --test all local_shell`
- `cargo test -p codex-core --test all otel::`
- `cargo test -p codex-core --test all hooks::`
- `just fix -p codex-core`
- `just fix -p codex-tools`

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

@@ -2,7 +2,6 @@ use crate::tools::code_mode::execute_spec::create_code_mode_tool;
 use crate::tools::handlers::ApplyPatchHandler;
 use crate::tools::handlers::CodeModeExecuteHandler;
 use crate::tools::handlers::CodeModeWaitHandler;
-use crate::tools::handlers::ContainerExecHandler;
 use crate::tools::handlers::CreateGoalHandler;
 use crate::tools::handlers::DynamicToolHandler;
 use crate::tools::handlers::ExecCommandHandler;
@@ -10,7 +9,6 @@ use crate::tools::handlers::ExecCommandHandlerOptions;
 use crate::tools::handlers::GetGoalHandler;
 use crate::tools::handlers::ListMcpResourceTemplatesHandler;
 use crate::tools::handlers::ListMcpResourcesHandler;
-use crate::tools::handlers::LocalShellHandler;
 use crate::tools::handlers::McpHandler;
 use crate::tools::handlers::PlanHandler;
 use crate::tools::handlers::ReadMcpResourceHandler;
@@ -19,7 +17,6 @@ use crate::tools::handlers::RequestPluginInstallHandler;
 use crate::tools::handlers::RequestUserInputHandler;
 use crate::tools::handlers::ShellCommandHandler;
 use crate::tools::handlers::ShellCommandHandlerOptions;
-use crate::tools::handlers::ShellHandler;
 use crate::tools::handlers::TestSyncHandler;
 use crate::tools::handlers::ToolSearchHandler;
 use crate::tools::handlers::UpdateGoalHandler;
@@ -39,7 +36,6 @@ use crate::tools::handlers::multi_agents_v2::ListAgentsHandler as ListAgentsHand
 use crate::tools::handlers::multi_agents_v2::SendMessageHandler as SendMessageHandlerV2;
 use crate::tools::handlers::multi_agents_v2::SpawnAgentHandler as SpawnAgentHandlerV2;
 use crate::tools::handlers::multi_agents_v2::WaitAgentHandler as WaitAgentHandlerV2;
-use crate::tools::handlers::shell_spec::ShellToolOptions;
 use crate::tools::handlers::view_image_spec::ViewImageToolOptions;
 use crate::tools::hosted_spec::WebSearchToolOptions;
 use crate::tools::hosted_spec::create_image_generation_tool;
@@ -252,14 +248,6 @@ fn collect_handler_tools(
         let include_environment_id =
             matches!(config.environment_mode, ToolEnvironmentMode::Multiple);
         match &config.shell_type {
-            ConfigShellToolType::Default => {
-                handlers.push(Arc::new(ShellHandler::new(ShellToolOptions {
-                    exec_permission_approvals_enabled,
-                })));
-            }
-            ConfigShellToolType::Local => {
-                handlers.push(Arc::new(LocalShellHandler::new()));
-            }
             ConfigShellToolType::UnifiedExec => {
                 handlers.push(Arc::new(ExecCommandHandler::new(
                     ExecCommandHandlerOptions {
@@ -271,7 +259,9 @@ fn collect_handler_tools(
                 handlers.push(Arc::new(WriteStdinHandler));
             }
             ConfigShellToolType::Disabled => {}
-            ConfigShellToolType::ShellCommand => {
+            ConfigShellToolType::Default
+            | ConfigShellToolType::Local
+            | ConfigShellToolType::ShellCommand => {
                 handlers.push(Arc::new(ShellCommandHandler::new(
                     ShellCommandHandlerOptions {
                         backend_config: config.shell_command_backend,
@@ -287,34 +277,15 @@ fn collect_handler_tools(
         && config.shell_type != ConfigShellToolType::Disabled
     {
         match &config.shell_type {
-            ConfigShellToolType::Default => {
-                handlers.push(Arc::new(ContainerExecHandler));
-                handlers.push(Arc::new(LocalShellHandler::default()));
-                handlers.push(Arc::new(ShellCommandHandler::from(
-                    config.shell_command_backend,
-                )));
-            }
-            ConfigShellToolType::Local => {
-                handlers.push(Arc::new(ShellHandler::default()));
-                handlers.push(Arc::new(ContainerExecHandler));
-                handlers.push(Arc::new(ShellCommandHandler::from(
-                    config.shell_command_backend,
-                )));
-            }
             ConfigShellToolType::UnifiedExec => {
-                handlers.push(Arc::new(ShellHandler::default()));
-                handlers.push(Arc::new(ContainerExecHandler));
-                handlers.push(Arc::new(LocalShellHandler::default()));
                 handlers.push(Arc::new(ShellCommandHandler::from(
                     config.shell_command_backend,
                 )));
             }
-            ConfigShellToolType::ShellCommand => {
-                handlers.push(Arc::new(ShellHandler::default()));
-                handlers.push(Arc::new(ContainerExecHandler));
-                handlers.push(Arc::new(LocalShellHandler::default()));
-            }
-            ConfigShellToolType::Disabled => {}
+            ConfigShellToolType::Default
+            | ConfigShellToolType::Local
+            | ConfigShellToolType::ShellCommand
+            | ConfigShellToolType::Disabled => {}
         }
     }