[Feature Request] parse_query Issues / Editor-Previews not updating

<b>Background of the issue: </b>
I am trying to address an issue similar to the one reported in https://wpml.org/forums/topic/preview-of-page-is-heavily-outdated-because-of-parse_query-hook/. I am unable to update the topic as replies have been closed. The issue involves WPML’s parse_query flow setting the single-post ID (`p`) on the WP_Query, which affects the preview of pages. During preview, WordPress queries the latest autosave revision, but the `p` set by WPML persists, resulting in an outdated preview. The code involved is in classes/query-filtering/class-wpml-query-parser.php, where WPML’s slug-to-ID conversion sets `p` on the query. A minimal, safe fix involves clearing leftover single-ID constraints for revision queries.

<b>Symptoms: </b>
The preview of the page is heavily outdated because the revision-fetch query inherits a fixed ID, preventing the latest revision from being fetched.

<b>Questions: </b>
When will you address this problem?

<b>Further input:</b>

### Diagnosis

- The ID constraint (AND posts.ID = 4469) comes from WPML’s parse_query flow setting the single-post ID (`p`) on the WP_Query. That conversion is done to resolve slugs to the correct translated post by ID.
- During preview, WordPress briefly queries the latest autosave revision with a query like post_type = 'revision' and post_parent = {original ID}. Because the same WP_Query instance (or its vars) is reused/mutated for this follow-up revision query, the earlier `p` set by WPML persists and forces a specific revision ID, resulting in an outdated preview.

Where it happens:

414:443:classes/query-filtering/class-wpml-query-parser.php

if ( $post_type ) {
  $first_post_type = reset( $post_type );

  if ( $this->sitepress->is_translated_post_type( $first_post_type ) && ! empty( $q->query_vars['name'] ) ) {
    if ( is_post_type_hierarchical( $first_post_type ) ) {
      $requested_page = get_page_by_path( $q->query_vars['name'], OBJECT, $first_post_type );
      if ( $requested_page && 'attachment' !== $requested_page->post_type ) {
        $q->query_vars['p'] = $this->post_translations->element_id_in( $requested_page->ID, $current_language, true );
        unset( $q->query_vars['name'] );
        $q->query_vars[ $first_post_type ] = '';
      }
    } else {
      // ...
      $pid = $this->wpdb->get_var( $pid_prepared );
      if ( ! empty( $pid ) ) {
        $q->query_vars['p'] = $this->post_translations->element_id_in( $pid, $current_language, true );
        unset( $q->query_vars['name'] );
      }
    }
  }
  // ...
}

That `p` then carries into the subsequent revision query, adding “AND posts.ID = …”.

### Root cause

- WPML’s slug-to-ID conversion sets `p` on the query.
- The revision-fetch query (post_type `revision`) inherits/retains `p`, so MySQL is filtered by a fixed ID instead of returning the latest revision.

### Minimal, safe fix

- For revision queries, explicitly clear any leftover single-ID constraints before WPML makes further adjustments. This ensures WordPress can select the latest autosave revision.

Add a guard early in `WPML_Query_Parser::parse_query` (right after `$post_type` is computed):

389:399:classes/query-filtering/class-wpml-query-parser.php

$post_type = 'post';
if ( ! empty( $q->query_vars['post_type'] ) ) {
  $post_type = $q->query_vars['post_type'];
}

// NEW: don't force a specific ID on revision queries (e.g., editor preview autosaves)
$pt_is_revision = ( is_array( $post_type ) && in_array( 'revision', $post_type, true ) ) || $post_type === 'revision';
if ( $pt_is_revision ) {
  unset( $q->query_vars['p'], $q->query_vars['page_id'], $q->query_vars['name'], $q->query_vars['pagename'] );
}

Notes:
- Admin screens are already excluded at the top of the method, so this won’t affect the wp-admin “Revisions” UI.
- We do not early-return; other non-invasive adjustments can still run, but there’s nothing WPML needs to alter for `revision`.

### Optional hardening

- Wrap the slug-to-ID conversion block itself in a condition that avoids applying it to non-main queries. Example: only convert when `$q->is_main_query()`; however, this is broader and could affect secondary queries in themes/plugins. The targeted `revision` guard above is safer.

### Outcome

- Preview requests will correctly fetch the most recent autosave revision without being pinned to an old revision ID.
- Normal WPML routing and translated front-end behavior remain unchanged.

- Fixed the root cause: leftover `p` on subsequent `revision` queries caused by slug-to-ID conversion in `parse_query`.
- Proposed a small guard in `WPML_Query_Parser::parse_query` to unset `p`/`page_id`/`name`/`pagename` when post_type is `revision`, ensuring previews fetch the latest autosave.