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PRFlow keeps one Slack message per merge request and updates it in place as the MR progresses. Comment sync does the same for the review conversation: every comment on the MR becomes a threaded reply under that message, so the Slack thread mirrors the discussion as it happens.
Slack thread showing a PRFlow merge request message with a review comment synced as a threaded reply, quoting the comment text and attributing it to the commenter's username

A review comment synced into the Slack thread under the MR message.

Reviewers keep commenting where they always have — in GitLab or GitHub — and teammates who live in Slack follow the whole conversation from the thread. The channel itself stays clean: comments only ever go to the thread, never posted as separate channel messages.

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How it works

Each synced comment is a threaded reply that preserves the comment text (up to 2,000 characters) and attributes it to the commenter’s GitLab or GitHub username. The thread stays in step with the source: Sync is one-way, from GitLab/GitHub into Slack. PRFlow has read-only access to your code platform, so replying in the Slack thread does not post anything back to the merge request.

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What gets synced

GitLab — comments on merge requests, both general comments and inline diff comments. Notes on issues, commits, and snippets are ignored. Comments arrive via the Note Hook webhook, and PRFlow’s polling fallback catches comments a missed webhook delivery would have dropped. GitHub — pull request comments from the Conversation tab, inline review comments on the diff, and the summary body submitted with a review. Comments on plain issues are ignored. Approved and changes-requested summaries include that state in text in the reply, while the outcome also updates the PR message. Editing a review summary updates its reply; GitHub sends no event when a review is deleted, so the delete row above applies to comments, not summaries.

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Good to know

  • Each routing rule controls new replies. In the rule editor, choose All comments to post every comment, Hide bot comments to skip bots PRFlow recognizes and marks Hidden, or No comments to create no new replies. New rules start on Hide bot comments.
  • Changing modes is prospective. A skipped comment is not backfilled if you later choose a more permissive mode. Replies that were already posted still receive edits and deletions, regardless of the rule’s current mode.
  • The pull or merge request card stays authoritative. Skipping a reply does not stop the card from tracking review state, CI, or unresolved-thread counts from GitHub or GitLab.
  • Comments need a parent message. If an MR has no Slack message — for example, the project was connected to PRFlow after the MR was opened, or the comment was made while the MR was still a draft — the comment is not posted, and it is not posted retroactively.
  • Exactly one reply per source object. Duplicate or concurrently delivered webhook events never produce a second reply. A GitHub review summary and its inline comments are distinct source objects, so each appears as its own reply.
  • See data handling for how PRFlow retains notification data while delivering and synchronizing updates.

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Setup

Comment sync is available for every project you map to a Slack channel, on every plan. Open a routing rule’s Notifications section to choose its comment mode. New to PRFlow? Start with the quickstart.

GitLab integration

Webhook events, API calls, data handling, and security details.

GitHub integration

The one-click GitHub App: events, permissions, and setup.
Questions? Reach us at hello@prflow.dev.