Extract MCP into codex-mcp crate (#15919)

- Split MCP runtime/server code out of `codex-core` into the new
`codex-mcp` crate. New/moved public structs/types include `McpConfig`,
`McpConnectionManager`, `ToolInfo`, `ToolPluginProvenance`,
`CodexAppsToolsCacheKey`, and the `McpManager` API
(`codex_mcp::mcp::McpManager` plus the `codex_core::mcp::McpManager`
wrapper/shim). New/moved functions include `with_codex_apps_mcp`,
`configured_mcp_servers`, `effective_mcp_servers`,
`collect_mcp_snapshot`, `collect_mcp_snapshot_from_manager`,
`qualified_mcp_tool_name_prefix`, and the MCP auth/skill-dependency
helpers. Why: this creates a focused MCP crate boundary and shrinks
`codex-core` without forcing every consumer to migrate in the same PR.

- Move MCP server config schema and persistence into `codex-config`.
New/moved structs/enums include `AppToolApproval`,
`McpServerToolConfig`, `McpServerConfig`, `RawMcpServerConfig`,
`McpServerTransportConfig`, `McpServerDisabledReason`, and
`codex_config::ConfigEditsBuilder`. New/moved functions include
`load_global_mcp_servers` and
`ConfigEditsBuilder::replace_mcp_servers`/`apply`. Why: MCP TOML
parsing/editing is config ownership, and this keeps config
validation/round-tripping (including per-tool approval overrides and
inline bearer-token rejection) in the config crate instead of
`codex-core`.

- Rewire `codex-core`, app-server, and plugin call sites onto the new
crates. Updated `Config::to_mcp_config(&self, plugins_manager)`,
`codex-rs/core/src/mcp.rs`, `codex-rs/core/src/connectors.rs`,
`codex-rs/core/src/codex.rs`,
`CodexMessageProcessor::list_mcp_server_status_task`, and
`utils/plugins/src/mcp_connector.rs` to build/pass the new MCP
config/runtime types. Why: plugin-provided MCP servers still merge with
user-configured servers, and runtime auth (`CodexAuth`) is threaded into
`with_codex_apps_mcp` / `collect_mcp_snapshot` explicitly so `McpConfig`
stays config-only.

codex-rs/config/src/mcp_edit.rs

@@ -0,0 +1,253 @@
+use std::collections::BTreeMap;
+use std::fs;
+use std::io::ErrorKind;
+use std::path::Path;
+use std::path::PathBuf;
+
+use tokio::task;
+use toml::Value as TomlValue;
+use toml_edit::DocumentMut;
+use toml_edit::Item as TomlItem;
+use toml_edit::Table as TomlTable;
+use toml_edit::value;
+
+use crate::AppToolApproval;
+use crate::CONFIG_TOML_FILE;
+use crate::McpServerConfig;
+use crate::McpServerTransportConfig;
+
+pub async fn load_global_mcp_servers(
+    codex_home: &Path,
+) -> std::io::Result<BTreeMap<String, McpServerConfig>> {
+    let config_path = codex_home.join(CONFIG_TOML_FILE);
+    let raw = match tokio::fs::read_to_string(&config_path).await {
+        Ok(raw) => raw,
+        Err(err) if err.kind() == ErrorKind::NotFound => return Ok(BTreeMap::new()),
+        Err(err) => return Err(err),
+    };
+    let parsed = toml::from_str::<TomlValue>(&raw)
+        .map_err(|err| std::io::Error::new(ErrorKind::InvalidData, err))?;
+    let Some(servers_value) = parsed.get("mcp_servers") else {
+        return Ok(BTreeMap::new());
+    };
+
+    ensure_no_inline_bearer_tokens(servers_value)?;
+
+    servers_value
+        .clone()
+        .try_into()
+        .map_err(|err| std::io::Error::new(ErrorKind::InvalidData, err))
+}
+
+fn ensure_no_inline_bearer_tokens(value: &TomlValue) -> std::io::Result<()> {
+    let Some(servers_table) = value.as_table() else {
+        return Ok(());
+    };
+
+    for (server_name, server_value) in servers_table {
+        if let Some(server_table) = server_value.as_table()
+            && server_table.contains_key("bearer_token")
+        {
+            let message = format!(
+                "mcp_servers.{server_name} uses unsupported `bearer_token`; set `bearer_token_env_var`."
+            );
+            return Err(std::io::Error::new(ErrorKind::InvalidData, message));
+        }
+    }
+
+    Ok(())
+}
+
+pub struct ConfigEditsBuilder {
+    codex_home: PathBuf,
+    mcp_servers: Option<BTreeMap<String, McpServerConfig>>,
+}
+
+impl ConfigEditsBuilder {
+    pub fn new(codex_home: &Path) -> Self {
+        Self {
+            codex_home: codex_home.to_path_buf(),
+            mcp_servers: None,
+        }
+    }
+
+    pub fn replace_mcp_servers(mut self, servers: &BTreeMap<String, McpServerConfig>) -> Self {
+        self.mcp_servers = Some(servers.clone());
+        self
+    }
+
+    pub async fn apply(self) -> std::io::Result<()> {
+        task::spawn_blocking(move || self.apply_blocking())
+            .await
+            .map_err(|err| {
+                std::io::Error::other(format!("config persistence task panicked: {err}"))
+            })?
+    }
+
+    fn apply_blocking(self) -> std::io::Result<()> {
+        let config_path = self.codex_home.join(CONFIG_TOML_FILE);
+        let mut doc = read_or_create_document(&config_path)?;
+        if let Some(servers) = self.mcp_servers.as_ref() {
+            replace_mcp_servers(&mut doc, servers);
+        }
+        fs::create_dir_all(&self.codex_home)?;
+        fs::write(config_path, doc.to_string())
+    }
+}
+
+fn read_or_create_document(config_path: &Path) -> std::io::Result<DocumentMut> {
+    match fs::read_to_string(config_path) {
+        Ok(raw) => raw
+            .parse::<DocumentMut>()
+            .map_err(|err| std::io::Error::new(ErrorKind::InvalidData, err)),
+        Err(err) if err.kind() == ErrorKind::NotFound => Ok(DocumentMut::new()),
+        Err(err) => Err(err),
+    }
+}
+
+fn replace_mcp_servers(doc: &mut DocumentMut, servers: &BTreeMap<String, McpServerConfig>) {
+    let root = doc.as_table_mut();
+    if servers.is_empty() {
+        root.remove("mcp_servers");
+        return;
+    }
+
+    let mut table = TomlTable::new();
+    table.set_implicit(true);
+    for (name, config) in servers {
+        table.insert(name, serialize_mcp_server(config));
+    }
+    root.insert("mcp_servers", TomlItem::Table(table));
+}
+
+fn serialize_mcp_server(config: &McpServerConfig) -> TomlItem {
+    let mut entry = TomlTable::new();
+    entry.set_implicit(false);
+
+    match &config.transport {
+        McpServerTransportConfig::Stdio {
+            command,
+            args,
+            env,
+            env_vars,
+            cwd,
+        } => {
+            entry["command"] = value(command.clone());
+            if !args.is_empty() {
+                entry["args"] = array_from_strings(args);
+            }
+            if let Some(env) = env
+                && !env.is_empty()
+            {
+                entry["env"] = table_from_pairs(env.iter());
+            }
+            if !env_vars.is_empty() {
+                entry["env_vars"] = array_from_strings(env_vars);
+            }
+            if let Some(cwd) = cwd {
+                entry["cwd"] = value(cwd.to_string_lossy().to_string());
+            }
+        }
+        McpServerTransportConfig::StreamableHttp {
+            url,
+            bearer_token_env_var,
+            http_headers,
+            env_http_headers,
+        } => {
+            entry["url"] = value(url.clone());
+            if let Some(env_var) = bearer_token_env_var {
+                entry["bearer_token_env_var"] = value(env_var.clone());
+            }
+            if let Some(headers) = http_headers
+                && !headers.is_empty()
+            {
+                entry["http_headers"] = table_from_pairs(headers.iter());
+            }
+            if let Some(headers) = env_http_headers
+                && !headers.is_empty()
+            {
+                entry["env_http_headers"] = table_from_pairs(headers.iter());
+            }
+        }
+    }
+
+    if !config.enabled {
+        entry["enabled"] = value(false);
+    }
+    if config.required {
+        entry["required"] = value(true);
+    }
+    if let Some(timeout) = config.startup_timeout_sec {
+        entry["startup_timeout_sec"] = value(timeout.as_secs_f64());
+    }
+    if let Some(timeout) = config.tool_timeout_sec {
+        entry["tool_timeout_sec"] = value(timeout.as_secs_f64());
+    }
+    if let Some(enabled_tools) = &config.enabled_tools
+        && !enabled_tools.is_empty()
+    {
+        entry["enabled_tools"] = array_from_strings(enabled_tools);
+    }
+    if let Some(disabled_tools) = &config.disabled_tools
+        && !disabled_tools.is_empty()
+    {
+        entry["disabled_tools"] = array_from_strings(disabled_tools);
+    }
+    if let Some(scopes) = &config.scopes
+        && !scopes.is_empty()
+    {
+        entry["scopes"] = array_from_strings(scopes);
+    }
+    if let Some(resource) = &config.oauth_resource
+        && !resource.is_empty()
+    {
+        entry["oauth_resource"] = value(resource.clone());
+    }
+    if !config.tools.is_empty() {
+        let mut tools = TomlTable::new();
+        tools.set_implicit(false);
+        let mut tool_entries: Vec<_> = config.tools.iter().collect();
+        tool_entries.sort_by(|(left, _), (right, _)| left.cmp(right));
+        for (name, tool_config) in tool_entries {
+            let mut tool_entry = TomlTable::new();
+            tool_entry.set_implicit(false);
+            if let Some(approval_mode) = tool_config.approval_mode {
+                tool_entry["approval_mode"] = value(match approval_mode {
+                    AppToolApproval::Auto => "auto",
+                    AppToolApproval::Prompt => "prompt",
+                    AppToolApproval::Approve => "approve",
+                });
+            }
+            tools.insert(name, TomlItem::Table(tool_entry));
+        }
+        entry.insert("tools", TomlItem::Table(tools));
+    }
+
+    TomlItem::Table(entry)
+}
+
+fn array_from_strings(values: &[String]) -> TomlItem {
+    let mut array = toml_edit::Array::new();
+    for value in values {
+        array.push(value.clone());
+    }
+    TomlItem::Value(array.into())
+}
+
+fn table_from_pairs<'a, I>(pairs: I) -> TomlItem
+where
+    I: IntoIterator<Item = (&'a String, &'a String)>,
+{
+    let mut entries: Vec<_> = pairs.into_iter().collect();
+    entries.sort_by(|(left, _), (right, _)| left.cmp(right));
+    let mut table = TomlTable::new();
+    table.set_implicit(false);
+    for (key, value_str) in entries {
+        table.insert(key, value(value_str.clone()));
+    }
+    TomlItem::Table(table)
+}
+
+#[cfg(test)]
+#[path = "mcp_edit_tests.rs"]
+mod tests;