oauth: invert macOS debug keyring env flag semantics

Rename CODEX_MCP_OAUTH_KEYRING_DEBUG_ALLOW to
CODEX_MCP_OAUTH_KEYRING_DEBUG_DISABLE and flip the logic so that
setting CODEX_MCP_OAUTH_KEYRING_DEBUG_DISABLE=1 disables keyring
access in debug builds on macOS. Update the error message accordingly.

codex-rs/rmcp-client/src/oauth.rs

@@ -50,6 +50,7 @@ use tokio::sync::Mutex;
 use crate::find_codex_home::find_codex_home;
 
 const KEYRING_SERVICE: &str = "Codex MCP Credentials";
+const MCP_OAUTH_KEYRING_DEBUG_DISABLE_ENV_VAR: &str = "CODEX_MCP_OAUTH_KEYRING_DEBUG_DISABLE";
 const REFRESH_SKEW_MILLIS: u64 = 30_000;
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
@@ -95,6 +96,12 @@ pub(crate) fn load_oauth_tokens(
     url: &str,
     store_mode: OAuthCredentialsStoreMode,
 ) -> Result<Option<StoredOAuthTokens>> {
+    if keyring_load_disabled_in_debug() {
+        return Err(anyhow::anyhow!(
+            "MCP OAuth keyring access is disabled in debug because {MCP_OAUTH_KEYRING_DEBUG_DISABLE_ENV_VAR} is set."
+        ));
+    }
+
     let keyring_store = DefaultKeyringStore;
     match store_mode {
         OAuthCredentialsStoreMode::Auto => {
@@ -116,6 +123,12 @@ pub(crate) fn has_oauth_tokens(
     Ok(load_oauth_tokens(server_name, url, store_mode)?.is_some())
 }
 
+fn keyring_load_disabled_in_debug() -> bool {
+    cfg!(debug_assertions)
+        && cfg!(target_os = "macos")
+        && std::env::var_os(MCP_OAUTH_KEYRING_DEBUG_DISABLE_ENV_VAR).is_some_and(|v| v == "1")
+}
+
 fn refresh_expires_in_from_timestamp(tokens: &mut StoredOAuthTokens) {
     let Some(expires_at) = tokens.expires_at else {
         return;

docs/config.md

@@ -12,6 +12,8 @@ Codex can connect to MCP servers configured in `~/.codex/config.toml`. See the c
 
 - https://developers.openai.com/codex/config-reference
 
+On macOS debug builds, Codex skips reading MCP OAuth tokens from the system keychain to avoid repeated access prompts. Set `CODEX_MCP_OAUTH_KEYRING_DEBUG_ALLOW=1` to allow keychain reads when debugging.
+
 ## Notify
 
 Codex can run a notification hook when the agent finishes a turn. See the configuration reference for the latest notification settings: