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

[waleedlatif1]

Summary

• Capture the installing user's Slack authed_user.id at OAuth connect time (via better-auth tokens.raw) and tag the credential's accountId with a usr_ marker
• Scope the channel selector to the credential owner's own Slack membership using users.conversations (bot groups:read) — private channels the owner isn't a member of are hidden, even when the bot has access (Slack Marketplace privacy requirement)
• Public channels unaffected; legacy credentials and BYO bot tokens fall back to the existing is_member behavior (no regression for existing connections)
• Fail closed if membership can't be verified; follow cursor pagination so the channel list is complete

Type of Change

• Bug fix

Testing

Tested manually

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		May 28, 2026 10:42pm

[cursor]

PR Summary

Medium Risk
Changes OAuth credential identity format and channel-selector privacy logic; mis-parsing or API failures could hide private channels or affect re-connect behavior, though legacy paths are preserved.

Overview
Slack channel picker now limits private channels to those the OAuth installer belongs to (Slack Marketplace privacy), instead of any private channel the bot can see.

On new Slack OAuth connects, auth.ts embeds the installing user’s authed_user.id in the credential accountId via a usr_ marker. The channels API reads that id, loads the installer’s private channels with users.conversations, and only shows private channels in that set; if that lookup fails, all private channels are hidden (fail closed). Legacy credentials and direct bot tokens still use the prior bot is_member behavior.

Channel listing now paginates conversations.list / users.conversations (cursor, capped pages) and logs when results may be truncated.

^{Reviewed by Cursor Bugbot for commit be61b2d. Configure here.}

[greptile-apps]

Greptile Summary

This PR scopes private Slack channel visibility to the installing user's own workspace membership, satisfying Slack Marketplace's privacy requirement that a private channel must only be shown to a user whose Slack account is a member — even when the bot has been invited.

• auth.ts: At OAuth connect time, authed_user.id is captured from tokens.raw and embedded in accountId behind a usr_ marker (${teamId}-usr_${userId}-${uuid}). Legacy credentials that lack the marker are left unchanged, so existing connections see no behaviour change.
• route.ts: For new credentials, the accountId is parsed to extract the installing user's Slack ID, which drives a users.conversations?user= call to build the allowed private-channel set. Private channels are shown only when the user is a member; if the membership fetch fails the handler fails closed (hides all private channels). Public channels are unaffected in all code paths.
• Pagination is now fully followed via a bounded loop (SLACK_MAX_PAGES = 10, 200 channels/page), with a truncated flag surfaced in logs when the cap is hit.

Confidence Score: 5/5

Safe to merge. Both changed files are well-contained, backward-compatible, and the new code paths all have explicit fallbacks.

The auth change is purely additive — new credentials get the usr_ marker, legacy credentials are untouched. The channel-filtering logic is correctly fail-closed (empty set on error), pagination is bounded and the truncated flag is surfaced in logs, and the regex correctly narrowed to [UW] user IDs as addressed in prior review rounds. No data loss, no broken code paths.

No files require special attention.

Important Files Changed

Filename	Overview
apps/sim/app/api/tools/slack/channels/route.ts	Adds installer-scoped private channel filtering via users.conversations, full cursor pagination with a bounded loop and truncated sentinel, and a DB lookup to extract the scoped user ID from the credential's accountId. Logic is well-structured with correct fail-closed behavior and legacy-credential fallback.
apps/sim/lib/auth/auth.ts	Tags new Slack OAuth credentials with a usr_<userId> marker in accountId by reading tokens.raw.authed_user.id. Falls back to the existing user_id / bot_id / 'bot' format when authed_user is absent, preserving full backward compatibility with legacy credentials.

Sequence Diagram

sequenceDiagram
    participant Client
    participant Route as channels/route.ts
    participant DB as Database
    participant SlackBot as Slack API (bot token)
    participant SlackUser as Slack API (users.conversations)

    Client->>Route: POST /api/tools/slack/channels
    Route->>Route: authorizeCredentialUse()
    Route->>DB: "SELECT accountId WHERE id = resolvedCredentialId"
    DB-->>Route: accountId (e.g. T123-usr_U456-uuid)
    Route->>Route: parseScopedSlackUserId(accountId) → scopedUserId

    Route->>SlackBot: conversations.list (paginated, ≤10 pages)
    SlackBot-->>Route: all bot-accessible channels

    alt scopedUserId present (new credentials)
        Route->>SlackUser: "users.conversations?user=scopedUserId&types=private_channel"
        SlackUser-->>Route: private channels user is a member of
        Route->>Route: "allowedPrivateChannelIds = Set(user private channels)"
    else legacy credential or BYO bot token
        Route->>Route: use is_member fallback
    end

    Route->>Route: filter private channels against allowedPrivateChannelIds
    Route->>Route: public channels always pass
    Route-->>Client: "{ channels: [...] }"

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[waleedlatif1]

@greptile

[waleedlatif1]

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^{Reviewed by Cursor Bugbot for commit be61b2d. Configure here.}