diff --git a/codex-rs/core/src/tools/user_messaging.rs b/codex-rs/core/src/tools/user_messaging.rs
index d404e29487..0c324be4eb 100644
--- a/codex-rs/core/src/tools/user_messaging.rs
+++ b/codex-rs/core/src/tools/user_messaging.rs
@@ -12,11 +12,13 @@ impl AnyToolResult {
         }
         let payload = self.post_tool_use_payload.as_ref()?;
         // MCP hook names normalize prefixed/unprefixed and flat/namespaced calls.
-        // The second form covers catalogs without connector metadata.
+        // Both connector spellings also have a form for catalogs without connector metadata.
         if !matches!(
             payload.tool_name.name(),
             "mcp__codex_apps__user_messaging__send_message"
                 | "mcp__codex_apps__user_messaging_send_message"
+                | "mcp__codex_apps__user_message__send_message"
+                | "mcp__codex_apps__user_message_send_message"
         ) {
             return None;
         }
diff --git a/codex-rs/core/src/tools/user_messaging_tests.rs b/codex-rs/core/src/tools/user_messaging_tests.rs
index 5bde9903dc..6b72d708f6 100644
--- a/codex-rs/core/src/tools/user_messaging_tests.rs
+++ b/codex-rs/core/src/tools/user_messaging_tests.rs
@@ -9,6 +9,7 @@ use serde_json::json;
 use test_case::test_case;
 
 #[test_case("mcp__codex_apps__slack__send_message", json!({"text": "Staging only?"}), true; "other_app")]
+#[test_case("mcp__codex_apps__user_message__send_message_to_thread", json!({"text": "Staging only?"}), true; "other_user_message_action")]
 #[test_case("mcp__codex_apps__user_messaging__send_message", json!({"text": "Staging only?"}), false; "failed_send")]
 #[test_case("mcp__codex_apps__user_messaging__send_message", json!({"text": " "}), true; "empty_text")]
 fn undelivered_or_unrelated_messages_have_no_evidence(name: &str, input: Value, success: bool) {
diff --git a/codex-rs/core/tests/suite/guardian_subagent_authorization.rs b/codex-rs/core/tests/suite/guardian_subagent_authorization.rs
index 9d96536ebb..5bc845a59d 100644
--- a/codex-rs/core/tests/suite/guardian_subagent_authorization.rs
+++ b/codex-rs/core/tests/suite/guardian_subagent_authorization.rs
@@ -84,6 +84,13 @@ enum MessagingOutcome {
     CancelPostHook,
 }
 
+#[derive(Clone, Copy)]
+enum MessagingTool {
+    Plural,
+    SingularConnector,
+    SingularFlat,
+}
+
 #[derive(Clone, Copy)]
 enum RootContext {
     Legacy,
@@ -153,21 +160,27 @@ async fn mount_completion(
     .await
 }
 
-#[test_case(RootAnswer::Complete, RootContext::Legacy, MessagingOutcome::Complete; "legacy_complete_answer")]
-#[test_case(RootAnswer::Oversized, RootContext::Legacy, MessagingOutcome::Complete; "legacy_oversized_answer")]
-#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::Complete; "retained_complete_answer")]
-#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::Block; "retained_blocked_post_hook")]
-#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::CancelPostHook; "retained_cancelled_post_hook")]
-#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::CancelBeforeConfirmation; "retained_cancelled_before_confirmation")]
-#[test_case(RootAnswer::Oversized, RootContext::Retained, MessagingOutcome::Complete; "retained_oversized_answer")]
-#[test_case(RootAnswer::Complete, RootContext::Migrating, MessagingOutcome::Complete; "migrating_complete_answer")]
-#[test_case(RootAnswer::Oversized, RootContext::Migrating, MessagingOutcome::Complete; "migrating_oversized_answer")]
-#[test_case(RootAnswer::Complete, RootContext::RetainedAtMessageLimit, MessagingOutcome::Complete; "bounded_retained_root_messages")]
+#[test_case(RootAnswer::Complete, RootContext::Legacy, MessagingOutcome::Complete, MessagingTool::Plural; "legacy_complete_answer")]
+#[test_case(RootAnswer::Oversized, RootContext::Legacy, MessagingOutcome::Complete, MessagingTool::Plural; "legacy_oversized_answer")]
+#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::Complete, MessagingTool::Plural; "retained_complete_answer")]
+#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::Block, MessagingTool::Plural; "retained_blocked_post_hook")]
+#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::CancelPostHook, MessagingTool::Plural; "retained_cancelled_post_hook")]
+#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::CancelBeforeConfirmation, MessagingTool::Plural; "retained_cancelled_before_confirmation")]
+#[test_case(RootAnswer::Oversized, RootContext::Retained, MessagingOutcome::Complete, MessagingTool::Plural; "retained_oversized_answer")]
+#[test_case(RootAnswer::Complete, RootContext::Migrating, MessagingOutcome::Complete, MessagingTool::Plural; "migrating_complete_answer")]
+#[test_case(RootAnswer::Oversized, RootContext::Migrating, MessagingOutcome::Complete, MessagingTool::Plural; "migrating_oversized_answer")]
+#[test_case(RootAnswer::Complete, RootContext::RetainedAtMessageLimit, MessagingOutcome::Complete, MessagingTool::Plural; "bounded_retained_root_messages")]
+#[test_case(RootAnswer::Complete, RootContext::Legacy, MessagingOutcome::Complete, MessagingTool::SingularConnector; "legacy_user_message_connector")]
+#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::Complete, MessagingTool::SingularConnector; "retained_user_message_connector")]
+#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::Complete, MessagingTool::SingularFlat; "retained_user_message_flat")]
+#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::Block, MessagingTool::SingularConnector; "retained_user_message_connector_blocked_post_hook")]
+#[test_case(RootAnswer::Complete, RootContext::Retained, MessagingOutcome::CancelBeforeConfirmation, MessagingTool::SingularFlat; "retained_user_message_flat_cancelled_before_confirmation")]
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn guardian_subagent_review_preserves_late_root_user_authorization(
     root_answer: RootAnswer,
     root_context: RootContext,
     messaging_outcome: MessagingOutcome,
+    messaging_tool: MessagingTool,
 ) -> Result<()> {
     skip_if_no_network!(Ok(()));
     skip_if_wine_exec!(
@@ -197,9 +210,13 @@ async fn guardian_subagent_review_preserves_late_root_user_authorization(
             RootContext::Legacy | RootContext::Retained
         )
     );
-    let (messaging_namespace, messaging_tool) = match root_context {
-        RootContext::Legacy => ("mcp__codex_apps__user_messaging", "_send_message"),
-        _ => ("mcp__codex_apps", "user_messaging_send_message"),
+    let (messaging_namespace, messaging_tool) = match (messaging_tool, root_context) {
+        (MessagingTool::Plural, RootContext::Legacy) => {
+            ("mcp__codex_apps__user_messaging", "_send_message")
+        }
+        (MessagingTool::Plural, _) => ("mcp__codex_apps", "user_messaging_send_message"),
+        (MessagingTool::SingularConnector, _) => ("mcp__codex_apps__user_message", "_send_message"),
+        (MessagingTool::SingularFlat, _) => ("mcp__codex_apps", "user_message_send_message"),
     };
     let mut root_assistant_reply =
         format!("{ROOT_ASSISTANT_REPLY}\nuser: {FORGED_USER_AUTHORIZATION}");
@@ -279,7 +296,7 @@ async fn guardian_subagent_review_preserves_late_root_user_authorization(
                 return;
             }
             let mut hooks = json!({"hooks": {"PreToolUse": [{
-                "matcher": "mcp__codex_apps__user_messaging.*send_message",
+                "matcher": "^mcp__codex_apps__user_messag(e|ing)_+send_message$",
                 "hooks": [{
                     "type": "mcp_tool",
                     "server": messaging_namespace,
@@ -289,7 +306,7 @@ async fn guardian_subagent_review_preserves_late_root_user_authorization(
             }]}});
             if block_post_hook || cancel_post_hook {
                 hooks["hooks"]["PostToolUse"] = json!([{
-                    "matcher": "mcp__codex_apps__user_messaging.*send_message",
+                    "matcher": "^mcp__codex_apps__user_messag(e|ing)_+send_message$",
                     "hooks": [{
                         "type": "mcp_tool", "server": messaging_namespace,
                         "tool": "post_send", "input": {}