diff --git a/includes/class-pr-core.php b/includes/class-pr-core.php
index b68aab6..5c5c4fc 100644
--- a/includes/class-pr-core.php
+++ b/includes/class-pr-core.php
@@ -6,9 +6,9 @@ declare(strict_types=1);
  *
  * What: Registers all hooks, runs migrations, boots subsystems.
  * Who calls it: peptide-repo-core.php on plugins_loaded.
- * Dependencies: PR_Core_Migration_Runner, PR_Core_Peptide_CPT, PR_Core_Admin,
- *              PR_Core_Disclaimer, PR_Core_Jsonld, PR_Core_Rest_Controller,
- *              PR_Core_Related_Posts_Section.
+ * Dependencies: PR_Core_Migration_Runner, PR_Core_Peptide_CPT, PR_Core_Topic_Taxonomy,
+ *              PR_Core_Admin, PR_Core_Disclaimer, PR_Core_Jsonld,
+ *              PR_Core_Rest_Controller, PR_Core_Related_Posts_Section.
  *
  * @see peptide-repo-core.php — Bootstrap that instantiates this class.
  * @see ARCHITECTURE.md    — Full data flow diagram.
@@ -31,6 +31,10 @@ class PR_Core {
 		$cpt = new PR_Core_Peptide_CPT();
 		$cpt->register_hooks();
 
+		// Register peptide_topic taxonomy (fires on init).
+		$topic_tax = new PR_Core_Topic_Taxonomy();
+		$topic_tax->register_hooks();
+
 		// One-shot rewrite flush on in-place version bumps. Runs at the very
 		// end of init (priority 999) so all CPTs/taxonomies — ours and
 		// anyone else's — are registered first. Handles updates deployed