Summary

The generic message tool's read action cannot read Slack thread replies. When threadId is passed, it is silently ignored and channel-level messages are returned instead.

Status: ✅ Fixed on main, pending release

Fixed by PR #17017 (merged 2026-02-26). The latest release (2026.2.25) was published before the merge. Waiting on the next release to ship the fix. Release requested on the PR.

Steps to reproduce

1. Have a Slack message with thread replies
2. Use the message tool with action: "read", target: "<channel>", threadId: "<thread_ts>"
3. Observe that only channel-level messages are returned, not thread replies

Root cause

In extensions/slack/src/channel.ts, the handleAction for read manually built the readMessages params and did not include threadId:

if (action === "read") {
    return await getSlackRuntime().channel.slack.handleSlackAction({
        action: "readMessages",
        channelId: resolveChannelId(),
        limit,
        before, after, accountId
        // threadId was MISSING
    }, cfg);
}

The underlying readSlackMessages function already supports threadId (calls conversations.replies). The parameter just never reached it.

Fix (PR #17017)

The inline handleAction was replaced with handleSlackMessageAction from plugin-sdk, which properly forwards threadId when includeReadThreadId: true:

actions: {
    handleAction: async (ctx) =>
        await handleSlackMessageAction({
            providerId: meta.id,
            ctx,
            includeReadThreadId: true,
            invoke: async (action, cfg, toolContext) =>
                await getSlackRuntime().channel.slack.handleSlackAction(action, cfg, toolContext),
        }),
},

Environment

• Affected versions: ≤ 2026.2.25
• Fixed on: main (commit d0d83a2)
• Fix release: pending