From 2ff5c179178917fa5a0637364048017960ed2ff1 Mon Sep 17 00:00:00 2001
From: Peter Steinberger <steipete@gmail.com>
Date: Sun, 15 Feb 2026 01:13:11 +0000
Subject: [PATCH] refactor(slack): dedupe member join/leave handlers

---
 src/slack/monitor/events/members.ts | 119 ++++++++++++----------------
 1 file changed, 51 insertions(+), 68 deletions(-)

diff --git a/src/slack/monitor/events/members.ts b/src/slack/monitor/events/members.ts
index cf7b5b03e..1b7decdfd 100644
--- a/src/slack/monitor/events/members.ts
+++ b/src/slack/monitor/events/members.ts
@@ -8,83 +8,66 @@ import { resolveSlackChannelLabel } from "../channel-config.js";
 export function registerSlackMemberEvents(params: { ctx: SlackMonitorContext }) {
   const { ctx } = params;
 
+  const handleMemberChannelEvent = async (params: {
+    verb: "joined" | "left";
+    event: SlackMemberChannelEvent;
+    body: unknown;
+  }) => {
+    try {
+      if (ctx.shouldDropMismatchedSlackEvent(params.body)) {
+        return;
+      }
+      const payload = params.event;
+      const channelId = payload.channel;
+      const channelInfo = channelId ? await ctx.resolveChannelName(channelId) : {};
+      const channelType = payload.channel_type ?? channelInfo?.type;
+      if (
+        !ctx.isChannelAllowed({
+          channelId,
+          channelName: channelInfo?.name,
+          channelType,
+        })
+      ) {
+        return;
+      }
+      const userInfo = payload.user ? await ctx.resolveUserName(payload.user) : {};
+      const userLabel = userInfo?.name ?? payload.user ?? "someone";
+      const label = resolveSlackChannelLabel({
+        channelId,
+        channelName: channelInfo?.name,
+      });
+      const sessionKey = ctx.resolveSlackSystemEventSessionKey({
+        channelId,
+        channelType,
+      });
+      enqueueSystemEvent(`Slack: ${userLabel} ${params.verb} ${label}.`, {
+        sessionKey,
+        contextKey: `slack:member:${params.verb}:${channelId ?? "unknown"}:${payload.user ?? "unknown"}`,
+      });
+    } catch (err) {
+      ctx.runtime.error?.(danger(`slack ${params.verb} handler failed: ${String(err)}`));
+    }
+  };
+
   ctx.app.event(
     "member_joined_channel",
     async ({ event, body }: SlackEventMiddlewareArgs<"member_joined_channel">) => {
-      try {
-        if (ctx.shouldDropMismatchedSlackEvent(body)) {
-          return;
-        }
-        const payload = event as SlackMemberChannelEvent;
-        const channelId = payload.channel;
-        const channelInfo = channelId ? await ctx.resolveChannelName(channelId) : {};
-        const channelType = payload.channel_type ?? channelInfo?.type;
-        if (
-          !ctx.isChannelAllowed({
-            channelId,
-            channelName: channelInfo?.name,
-            channelType,
-          })
-        ) {
-          return;
-        }
-        const userInfo = payload.user ? await ctx.resolveUserName(payload.user) : {};
-        const userLabel = userInfo?.name ?? payload.user ?? "someone";
-        const label = resolveSlackChannelLabel({
-          channelId,
-          channelName: channelInfo?.name,
-        });
-        const sessionKey = ctx.resolveSlackSystemEventSessionKey({
-          channelId,
-          channelType,
-        });
-        enqueueSystemEvent(`Slack: ${userLabel} joined ${label}.`, {
-          sessionKey,
-          contextKey: `slack:member:joined:${channelId ?? "unknown"}:${payload.user ?? "unknown"}`,
-        });
-      } catch (err) {
-        ctx.runtime.error?.(danger(`slack join handler failed: ${String(err)}`));
-      }
+      await handleMemberChannelEvent({
+        verb: "joined",
+        event: event as SlackMemberChannelEvent,
+        body,
+      });
     },
   );
 
   ctx.app.event(
     "member_left_channel",
     async ({ event, body }: SlackEventMiddlewareArgs<"member_left_channel">) => {
-      try {
-        if (ctx.shouldDropMismatchedSlackEvent(body)) {
-          return;
-        }
-        const payload = event as SlackMemberChannelEvent;
-        const channelId = payload.channel;
-        const channelInfo = channelId ? await ctx.resolveChannelName(channelId) : {};
-        const channelType = payload.channel_type ?? channelInfo?.type;
-        if (
-          !ctx.isChannelAllowed({
-            channelId,
-            channelName: channelInfo?.name,
-            channelType,
-          })
-        ) {
-          return;
-        }
-        const userInfo = payload.user ? await ctx.resolveUserName(payload.user) : {};
-        const userLabel = userInfo?.name ?? payload.user ?? "someone";
-        const label = resolveSlackChannelLabel({
-          channelId,
-          channelName: channelInfo?.name,
-        });
-        const sessionKey = ctx.resolveSlackSystemEventSessionKey({
-          channelId,
-          channelType,
-        });
-        enqueueSystemEvent(`Slack: ${userLabel} left ${label}.`, {
-          sessionKey,
-          contextKey: `slack:member:left:${channelId ?? "unknown"}:${payload.user ?? "unknown"}`,
-        });
-      } catch (err) {
-        ctx.runtime.error?.(danger(`slack leave handler failed: ${String(err)}`));
-      }
+      await handleMemberChannelEvent({
+        verb: "left",
+        event: event as SlackMemberChannelEvent,
+        body,
+      });
     },
   );
 }