[2.x] Tags: `discussion_count` / `last_posted_discussion_id` not updated when a pending discussion is approved

[linkrobins]

Reproduced on

A clean Flarum 2.0.0-rc.4 install with only flarum/tags and flarum/approval enabled (plus flarum/flags, an approval dependency), MariaDB 11. The control case below confirms the normal path is unaffected.

Description

When flarum/approval is active, content created pending approval is treated as is_private until approved. flarum/tags' UpdateTagMetadata correctly skips private content, so a pending discussion does not update tag metadata. But when the discussion is later approved, nothing recomputes the tag — so the tag's discussion_count and last_posted_discussion_id are left permanently unset/stale even though the discussion is now public.

Steps to reproduce

1. Fresh Flarum 2.0.0-rc.4; enable Tags + Approval.
2. Create a (non-restricted) tag. Grant the Members group startDiscussion but not discussion.startWithoutApproval, so members' new discussions require approval.
3. As a member, start a discussion with that tag. It is created pending: is_approved = false, and approval marks it is_private = true.
4. As an admin/mod, approve it: PATCH /api/posts/{firstPostId} with { "data": { "attributes": { "isApproved": true } } }.

Expected

After approval, the tag's discussion_count and last_posted_discussion_id reflect the now-visible discussion.

Actual

The discussion becomes is_approved = true, is_private = false, fully visible — but the tag's discussion_count is still 0 and last_posted_discussion_id is still null. The /tags page shows a wrong count and no "latest discussion" for that tag. Replies gated by replyWithoutApproval are affected the same way.

Minimal reproduction output (core + tags + approval only):

A) member posts   -> is_approved=false, is_private=true  -> tag count=0, last_posted_discussion_id=NULL
   admin approves -> is_approved=true,  is_private=false -> tag count=0, last_posted_discussion_id=NULL   <- bug
B) control: admin auto-approved post -> tag count=1, last_posted_discussion_id set   (normal path works)

Root cause

• Flarum\Approval\Listener\UnapproveNewContent::markUnapprovedContentAsPrivate() — unapproved content is treated as is_private.
• Flarum\Tags\Listener\UpdateTagMetadata::updateTags() gates both the discussion_count change and setLastPostedDiscussion() behind ! $discussion->is_private, so pending content is (correctly) skipped on Started / Posted.
• On approval, Flarum\Approval\Listener\UpdateDiscussionAfterPostApproval (handling PostWasApproved) refreshes the discussion's and author's counts, but never touches tag metadata — and UpdateTagMetadata does not subscribe to PostWasApproved / PostWasUnapproved.

So no code path updates tag metadata when content transitions from pending to approved.

Suggested fix

Have UpdateTagMetadata subscribe to PostWasApproved (and PostWasUnapproved) and recompute the affected tags' discussion_count + last_posted_discussion_id (e.g. refreshLastPostedDiscussion() plus a recount), with the matching decrement on unapprove/reject.

Related

• fix(approval): PostWasApproved event triggered incorrectly #3930 / fix(1.x,approval): correct PostWasApproved event trigger condition #3925 corrected when PostWasApproved fires, but not tag metadata.
• Tag discussion count doesn't adjust when deleting first/only post of the discussion #3252 fixed tag discussion_count on first/only-post deletion — a similar gap in the same listener.

Versions

• Flarum core / tags / approval: 2.0.0-rc.4
• PHP 8.x, MariaDB 11