From 3bc36cef7de7fb5cb82d7a7cf004a4c9e2a5d638 Mon Sep 17 00:00:00 2001
From: Peter Steinberger <steipete@gmail.com>
Date: Mon, 2 Mar 2026 13:43:04 +0000
Subject: [PATCH] fix(slack): correct typed message event overloads (#31701)

---
 src/slack/monitor/events/messages.test.ts | 22 ++++++++++++++++++++++
 src/slack/monitor/events/messages.ts      | 18 ++++++++++++------
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/src/slack/monitor/events/messages.test.ts b/src/slack/monitor/events/messages.test.ts
index b59b26c1633..4b7cc40386d 100644
--- a/src/slack/monitor/events/messages.test.ts
+++ b/src/slack/monitor/events/messages.test.ts
@@ -192,4 +192,26 @@ describe("registerSlackMessageEvents", () => {
     expect(handleSlackMessage).toHaveBeenCalledTimes(2);
     expect(messageQueueMock).not.toHaveBeenCalled();
   });
+
+  it("applies subtype system-event handling for message.channels events", async () => {
+    messageQueueMock.mockClear();
+    messageAllowMock.mockReset().mockResolvedValue([]);
+    const { channelHandler, handleSlackMessage } = createMessageHandlers({
+      dmPolicy: "open",
+      channelType: "channel",
+    });
+
+    expect(channelHandler).toBeTruthy();
+
+    await channelHandler!({
+      event: {
+        ...makeChangedEvent({ channel: "C1", user: "U1" }),
+        channel_type: "channel",
+      },
+      body: {},
+    });
+
+    expect(handleSlackMessage).not.toHaveBeenCalled();
+    expect(messageQueueMock).toHaveBeenCalledTimes(1);
+  });
 });
diff --git a/src/slack/monitor/events/messages.ts b/src/slack/monitor/events/messages.ts
index d63ce780d30..6891b18c3b9 100644
--- a/src/slack/monitor/events/messages.ts
+++ b/src/slack/monitor/events/messages.ts
@@ -102,12 +102,18 @@ export function registerSlackMessageEvents(params: {
   });
   // Slack may dispatch channel/group message subscriptions under typed event
   // names. Register explicit handlers so both delivery styles are supported.
-  ctx.app.event("message.channels", async ({ event, body }: SlackEventMiddlewareArgs) => {
-    await handleIncomingMessageEvent({ event, body });
-  });
-  ctx.app.event("message.groups", async ({ event, body }: SlackEventMiddlewareArgs) => {
-    await handleIncomingMessageEvent({ event, body });
-  });
+  ctx.app.event(
+    "message.channels",
+    async ({ event, body }: SlackEventMiddlewareArgs<"message.channels">) => {
+      await handleIncomingMessageEvent({ event, body });
+    },
+  );
+  ctx.app.event(
+    "message.groups",
+    async ({ event, body }: SlackEventMiddlewareArgs<"message.groups">) => {
+      await handleIncomingMessageEvent({ event, body });
+    },
+  );
 
   ctx.app.event("app_mention", async ({ event, body }: SlackEventMiddlewareArgs<"app_mention">) => {
     try {