chore: config editor (#5878)

The goal is to have a single place where we actually write files

In a follow-up PR, will move everything config related in a dedicated
module and move the helpers in a dedicated file

Author: jif-oai

codex-rs/app-server/src/codex_message_processor.rs

@@ -74,9 +74,7 @@ use codex_core::config::Config;
 use codex_core::config::ConfigOverrides;
 use codex_core::config::ConfigToml;
 use codex_core::config::load_config_as_toml;
-use codex_core::config_edit::CONFIG_KEY_EFFORT;
-use codex_core::config_edit::CONFIG_KEY_MODEL;
-use codex_core::config_edit::persist_overrides_and_clear_if_none;
+use codex_core::config_edit::ConfigEditsBuilder;
 use codex_core::default_client::get_codex_user_agent;
 use codex_core::exec::ExecParams;
 use codex_core::exec_env::create_env;
@@ -689,19 +687,12 @@ impl CodexMessageProcessor {
             model,
             reasoning_effort,
         } = params;
-        let effort_str = reasoning_effort.map(|effort| effort.to_string());
 
-        let overrides: [(&[&str], Option<&str>); 2] = [
-            (&[CONFIG_KEY_MODEL], model.as_deref()),
-            (&[CONFIG_KEY_EFFORT], effort_str.as_deref()),
-        ];
-
-        match persist_overrides_and_clear_if_none(
-            &self.config.codex_home,
-            self.config.active_profile.as_deref(),
-            &overrides,
-        )
-        .await
+        match ConfigEditsBuilder::new(&self.config.codex_home)
+            .with_profile(self.config.active_profile.as_deref())
+            .set_model(model.as_deref(), reasoning_effort)
+            .apply()
+            .await
         {
             Ok(()) => {
                 let response = SetDefaultModelResponse {};
@@ -710,7 +701,7 @@ impl CodexMessageProcessor {
             Err(err) => {
                 let error = JSONRPCErrorError {
                     code: INTERNAL_ERROR_CODE,
-                    message: format!("failed to persist overrides: {err}"),
+                    message: format!("failed to persist model selection: {err}"),
                     data: None,
                 };
                 self.outgoing.send_error(request_id, error).await;

codex-rs/cli/src/mcp_cmd.rs

@@ -11,7 +11,7 @@ use codex_core::config::Config;
 use codex_core::config::ConfigOverrides;
 use codex_core::config::find_codex_home;
 use codex_core::config::load_global_mcp_servers;
-use codex_core::config::write_global_mcp_servers;
+use codex_core::config_edit::ConfigEditsBuilder;
 use codex_core::config_types::McpServerConfig;
 use codex_core::config_types::McpServerTransportConfig;
 use codex_core::features::Feature;
@@ -263,7 +263,10 @@ async fn run_add(config_overrides: &CliConfigOverrides, add_args: AddArgs) -> Re
 
     servers.insert(name.clone(), new_entry);
 
-    write_global_mcp_servers(&codex_home, &servers)
+    ConfigEditsBuilder::new(&codex_home)
+        .replace_mcp_servers(&servers)
+        .apply()
+        .await
         .with_context(|| format!("failed to write MCP servers to {}", codex_home.display()))?;
 
     println!("Added global MCP server '{name}'.");
@@ -321,7 +324,10 @@ async fn run_remove(config_overrides: &CliConfigOverrides, remove_args: RemoveAr
     let removed = servers.remove(&name).is_some();
 
     if removed {
-        write_global_mcp_servers(&codex_home, &servers)
+        ConfigEditsBuilder::new(&codex_home)
+            .replace_mcp_servers(&servers)
+            .apply()
+            .await
             .with_context(|| format!("failed to write MCP servers to {}", codex_home.display()))?;
     }
 

codex-rs/cli/tests/mcp_list.rs

@@ -2,7 +2,7 @@ use std::path::Path;
 
 use anyhow::Result;
 use codex_core::config::load_global_mcp_servers;
-use codex_core::config::write_global_mcp_servers;
+use codex_core::config_edit::ConfigEditsBuilder;
 use codex_core::config_types::McpServerTransportConfig;
 use predicates::prelude::PredicateBooleanExt;
 use predicates::str::contains;
@@ -59,7 +59,9 @@ async fn list_and_get_render_expected_output() -> Result<()> {
         }
         other => panic!("unexpected transport: {other:?}"),
     }
-    write_global_mcp_servers(codex_home.path(), &servers)?;
+    ConfigEditsBuilder::new(codex_home.path())
+        .replace_mcp_servers(&servers)
+        .apply_blocking()?;
 
     let mut list_cmd = codex_command(codex_home.path())?;
     let list_output = list_cmd.args(["mcp", "list"]).output()?;
@@ -149,7 +151,9 @@ async fn get_disabled_server_shows_single_line() -> Result<()> {
         .get_mut("docs")
         .expect("docs server should exist after add");
     docs.enabled = false;
-    write_global_mcp_servers(codex_home.path(), &servers)?;
+    ConfigEditsBuilder::new(codex_home.path())
+        .replace_mcp_servers(&servers)
+        .apply_blocking()?;
 
     let mut get_cmd = codex_command(codex_home.path())?;
     let get_output = get_cmd.args(["mcp", "get", "docs"]).output()?;