Editor: Do not apply Block Hooks when generating post excerpts.

[MarcinDudekDev]

What / why

Since r59523 (Core-61074, WP 6.8), the_content carries a Block Hooks callback at priority 8 —
apply_block_hooks_to_content, swapped for apply_block_hooks_to_content_from_post_object
in r59838 (Core-61074, Core-62716). wp_trim_excerpt() already unhooks do_blocks (r56560 / Core-58682
and wp_filter_content_tags (r55850 / Core-56588) around its inner apply_filters( 'the_content' )
call, but the priority-8 callback was never unhooked. Three consequences:

• Hooked-block markup leaks into excerpts as plain text. The callback wraps content in a
  temporary core/post-content wrapper block so first_child/last_child hooked blocks have
  an anchor; the algorithm serializes them into the content, do_blocks is unhooked so they can
  never render, and wp_strip_all_tags() strips the `` delimiters — leaving the markup a
  hooked block carries via the hooked_block filter as literal excerpt text.
  Reproduced: excerpt goes from `'Visible text.'` to `'Visible text. LEAKED HOOKED TEXT'`.
• Guaranteed wasted work — a parse_blocks() traversal, get_hooked_blocks(), the
  hooked_block_types/hooked_block filters, and a _wp_ignored_hooked_blocks meta read on
  every generated excerpt, for output that can never be visible.
• Wrong post context — the callback resolves context via get_post() (current loop post),
  not the post passed to wp_trim_excerpt(), so off-loop excerpts read the wrong post's
  _wp_ignored_hooked_blocks suppression.

The change

Unhook and conditionally restore apply_block_hooks_to_content_from_post_object (priority 8)
inside wp_trim_excerpt(), mirroring the existing do_blocks/wp_filter_content_tags dance and
the identical unhook core already performs in insert_hooked_blocks_into_rest_response()
(blocks.php:1559-1573). A site that deliberately unhooked the callback is left unchanged.

Testing

• Six new PHPUnit tests in tests/phpunit/tests/formatting/wpTrimExcerpt.php: callback unhooked
  during the inner the_content run; restored afterwards; not resurrected when previously
  unhooked; Block Hooks algorithm does not run (spied via hooked_block_types, which only fires
  inside the algorithm); hooked-block markup does not leak into the excerpt; Block Hooks still
  apply to a subsequent real the_content run.
• Negative control: the same reproduction on the code path without the fix yields the leaked
  excerpt 'Visible text. LEAKED HOOKED TEXT', confirming the bug on trunk.
• 5283 tests pass across the formatting / post / query / REST-posts / feed groups (sequential
  sweep); PHPCS clean.

Trac ticket: https://core.trac.wordpress.org/ticket/66110

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code (Anthropic), Devin (Cognition)
Model(s): Claude Opus 4.8 (orchestration/review), Devin (implementation)
Used for: root-cause analysis, patch + test authorship, git fact-checking, and full test sweep; reviewed and taken responsibility for by the contributor.

---

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[westonruter]

This looks good to me. However, I will request a review from @ockham since he introduced this function to begin with.