feat(slack): scope private channel visibility to installing user (#4779)

* feat(slack): scope private channel visibility to installing user

* improvement(slack): warn on usr_ marker parse miss, drop dead bot prefix

* chore(slack): trim verbose comment

apps/sim/app/api/tools/slack/channels/route.ts

@@ -1,4 +1,7 @@
+import { db } from '@sim/db'
+import { account } from '@sim/db/schema'
 import { createLogger } from '@sim/logger'
+import { eq } from 'drizzle-orm'
 import { type NextRequest, NextResponse } from 'next/server'
 import { slackChannelsSelectorContract } from '@/lib/api/contracts/selectors/slack'
 import { parseRequest } from '@/lib/api/server'
@@ -20,6 +23,29 @@ interface SlackChannel {
   is_member: boolean
 }
 
+/**
+ * Extracts the installing user's Slack id from credentials connected after the
+ * privacy fix, which `auth.ts` tags with a `usr_` marker
+ * (`${teamId}-usr_${installerUserId}-${uuid}`). Legacy credentials encode the
+ * bot id with no marker and return null, so the caller keeps the existing
+ * `is_member` filter — no regression.
+ */
+const SCOPED_USER_ID_PATTERN =
+  /-usr_([UW][A-Z0-9]+)-[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i
+
+function parseScopedSlackUserId(accountId: string): string | null {
+  const match = SCOPED_USER_ID_PATTERN.exec(accountId)
+  if (match) return match[1]
+  // Marker present but unparseable — surface it rather than silently falling
+  // back to the bot `is_member` filter and bypassing the privacy scope.
+  if (accountId.includes('-usr_')) {
+    logger.warn('Slack accountId carries usr_ marker but did not parse; using is_member fallback', {
+      accountId,
+    })
+  }
+  return null
+}
+
 export const POST = withRouteHandler(async (request: NextRequest) => {
   try {
     const requestId = generateRequestId()
@@ -32,6 +58,7 @@ export const POST = withRouteHandler(async (request: NextRequest) => {
 
     let accessToken: string
     let isBotToken = false
+    let scopedUserId: string | null = null
 
     if (credential.startsWith('xoxb-')) {
       accessToken = credential
@@ -65,11 +92,25 @@ export const POST = withRouteHandler(async (request: NextRequest) => {
       }
       accessToken = resolvedToken
       logger.info('Using OAuth token for Slack API')
+
+      if (authz.resolvedCredentialId) {
+        const [accountRow] = await db
+          .select({ accountId: account.accountId })
+          .from(account)
+          .where(eq(account.id, authz.resolvedCredentialId))
+          .limit(1)
+        if (accountRow) {
+          scopedUserId = parseScopedSlackUserId(accountRow.accountId)
+        }
+      }
     }
 
-    let data
+    let data: SlackConversationsResult
     try {
       data = await fetchSlackChannels(accessToken, true)
+      if (data.truncated) {
+        logger.warn('conversations.list hit pagination cap; channel list may be incomplete')
+      }
       logger.info('Successfully fetched channels including private channels')
     } catch (error) {
       if (isBotToken) {
@@ -96,17 +137,49 @@ export const POST = withRouteHandler(async (request: NextRequest) => {
       }
     }
 
-    const channels = (data.channels || [])
-      .filter((channel: SlackChannel) => {
-        const canAccess = !channel.is_archived && (channel.is_member || !channel.is_private)
-
-        if (!canAccess) {
-          logger.debug(
-            `Filtering out channel: ${channel.name} (archived: ${channel.is_archived}, private: ${channel.is_private}, member: ${channel.is_member})`
+    /**
+     * Slack Marketplace privacy: a private channel may only be shown to a user
+     * whose own Slack account is a member, even when the bot has been invited.
+     * `users.conversations?user=` returns the channels the bot AND that user
+     * share, giving us the allowed set. Public channels are never restricted.
+     * Without a scoped user id (legacy credentials), fall back to bot membership.
+     */
+    let allowedPrivateChannelIds: Set<string> | null = null
+    if (scopedUserId) {
+      try {
+        const userPrivate = await fetchUserPrivateChannels(accessToken, scopedUserId)
+        allowedPrivateChannelIds = new Set(userPrivate.channels.map((c) => c.id))
+        if (userPrivate.truncated) {
+          logger.warn(
+            'users.conversations hit pagination cap; some private channels the user belongs to may be hidden',
+            { scopedUserId }
           )
         }
+        logger.info('Scoped private channels to installing user membership', {
+          scopedUserId,
+          allowedCount: allowedPrivateChannelIds.size,
+        })
+      } catch (scopeError) {
+        // Fail closed: if membership can't be verified, hide all private channels.
+        logger.warn('Failed to scope private channels to user, hiding all private channels', {
+          error: (scopeError as Error).message,
+        })
+        allowedPrivateChannelIds = new Set()
+      }
+    }
 
-        return canAccess
+    const channels = (data.channels || [])
+      .filter((channel: SlackChannel) => {
+        if (channel.is_archived) return false
+
+        if (channel.is_private) {
+          if (allowedPrivateChannelIds) {
+            return allowedPrivateChannelIds.has(channel.id)
+          }
+          return channel.is_member
+        }
+
+        return true
       })
       .filter((channel: SlackChannel) => {
         const validation = validateAlphanumericId(channel.id, 'channelId', 50)
@@ -141,6 +214,7 @@ export const POST = withRouteHandler(async (request: NextRequest) => {
       private: channels.filter((c: { isPrivate: boolean }) => c.isPrivate).length,
       public: channels.filter((c: { isPrivate: boolean }) => !c.isPrivate).length,
       tokenType: isBotToken ? 'bot_token' : 'oauth',
+      userScoped: !!scopedUserId,
     })
     return NextResponse.json({ channels })
   } catch (error) {
@@ -152,35 +226,86 @@ export const POST = withRouteHandler(async (request: NextRequest) => {
   }
 })
 
-async function fetchSlackChannels(accessToken: string, includePrivate = true) {
-  const url = new URL('https://slack.com/api/conversations.list')
+const SLACK_PAGE_LIMIT = 200
+const SLACK_MAX_PAGES = 10
 
-  if (includePrivate) {
-    url.searchParams.append('types', 'public_channel,private_channel')
-  } else {
-    url.searchParams.append('types', 'public_channel')
-  }
+interface SlackConversationsResult {
+  channels: SlackChannel[]
+  truncated: boolean
+}
+
+/**
+ * Lists Slack conversations, following `response_metadata.next_cursor` so the
+ * full set is returned. Bounded by `SLACK_MAX_PAGES`; sets `truncated` rather
+ * than silently dropping channels when the cap is hit.
+ */
+async function fetchAllConversations(
+  method: 'conversations.list' | 'users.conversations',
+  accessToken: string,
+  params: Record<string, string>
+): Promise<SlackConversationsResult> {
+  const channels: SlackChannel[] = []
+  let cursor: string | undefined
+  let truncated = false
+
+  for (let page = 0; page < SLACK_MAX_PAGES; page++) {
+    const url = new URL(`https://slack.com/api/${method}`)
+    for (const [key, value] of Object.entries(params)) {
+      url.searchParams.append(key, value)
+    }
+    url.searchParams.append('limit', String(SLACK_PAGE_LIMIT))
+    if (cursor) {
+      url.searchParams.append('cursor', cursor)
+    }
+
+    const response = await fetch(url.toString(), {
+      method: 'GET',
+      headers: { Authorization: `Bearer ${accessToken}` },
+    })
+
+    if (!response.ok) {
+      throw new Error(`Slack API error: ${response.status} ${response.statusText}`)
+    }
+
+    const data = await response.json()
 
-  url.searchParams.append('exclude_archived', 'true')
-  url.searchParams.append('limit', '200')
+    if (!data.ok) {
+      throw new Error(data.error || `Failed to fetch ${method}`)
+    }
 
-  const response = await fetch(url.toString(), {
-    method: 'GET',
-    headers: {
-      Authorization: `Bearer ${accessToken}`,
-      'Content-Type': 'application/json',
-    },
-  })
+    if (Array.isArray(data.channels)) {
+      channels.push(...data.channels)
+    }
 
-  if (!response.ok) {
-    throw new Error(`Slack API error: ${response.status} ${response.statusText}`)
+    cursor = data.response_metadata?.next_cursor?.trim() || undefined
+    if (!cursor) {
+      return { channels, truncated }
+    }
+    if (page === SLACK_MAX_PAGES - 1) {
+      truncated = true
+    }
   }
 
-  const data = await response.json()
+  return { channels, truncated }
+}
 
-  if (!data.ok) {
-    throw new Error(data.error || 'Failed to fetch channels')
-  }
+async function fetchSlackChannels(
+  accessToken: string,
+  includePrivate = true
+): Promise<SlackConversationsResult> {
+  return fetchAllConversations('conversations.list', accessToken, {
+    types: includePrivate ? 'public_channel,private_channel' : 'public_channel',
+    exclude_archived: 'true',
+  })
+}
 
-  return data
+async function fetchUserPrivateChannels(
+  accessToken: string,
+  userId: string
+): Promise<SlackConversationsResult> {
+  return fetchAllConversations('users.conversations', accessToken, {
+    user: userId,
+    types: 'private_channel',
+    exclude_archived: 'true',
+  })
 }

apps/sim/lib/auth/auth.ts

@@ -2532,17 +2532,36 @@ export const auth = betterAuth({
               }
 
               const teamId = data.team_id || 'unknown'
-              const userId = data.user_id || data.bot_id || 'bot'
               const teamName = data.team || 'Slack Workspace'
 
-              const uniqueId = `${teamId}-${userId}`
+              /**
+               * Tag the accountId with the installing user's Slack id (from the OAuth
+               * v2 `authed_user.id`, preserved on `tokens.raw`) behind a `usr_` marker.
+               * The channels selector uses it to scope private-channel visibility to
+               * the installer's own Slack membership, per Slack Marketplace rules. The
+               * marker disambiguates it from a legacy bot id (same `U.../B...` shape);
+               * absent it, we keep the legacy format and today's behavior.
+               */
+              const authedUser = tokens.raw?.authed_user as { id?: string } | undefined
+              const installerUserId = authedUser?.id
+              const userSegment = installerUserId
+                ? `usr_${installerUserId}`
+                : data.user_id || data.bot_id || 'bot'
 
-              logger.info('Slack credential identifier', { teamId, userId, uniqueId, teamName })
+              const uniqueId = `${teamId}-${userSegment}`
+
+              logger.info('Slack credential identifier', {
+                teamId,
+                userSegment,
+                uniqueId,
+                teamName,
+                hasInstallerId: !!installerUserId,
+              })
 
               return {
                 id: `${uniqueId}-${generateId()}`,
                 name: teamName,
-                email: `${teamId}-${userId}@slack.bot`,
+                email: `${uniqueId}@slack.bot`,
                 emailVerified: false,
                 createdAt: new Date(),
                 updatedAt: new Date(),