diff --git a/corpus/skills/cat-mode/SKILL.md b/corpus/skills/cat-mode/SKILL.md
index 7af3811e..2f2d5c40 100644
--- a/corpus/skills/cat-mode/SKILL.md
+++ b/corpus/skills/cat-mode/SKILL.md
@@ -201,6 +201,11 @@ bug: invoke `automate-me`, do not wait.
 - **Treat absolute negatives as categorical.**
 - **A blocked target is a stop, not a licence to substitute.** A number
   produced on a proxy carries the proxy's name beside the number.
+- **A hook or classifier block is a stop, not a puzzle.** Do what the block
+  asks, or report the block and stop. Never reword the prompt, switch tools,
+  retag the claim, or propose weakening the hook to get past it.
+  Disagreement with a block goes to the user, after reading the hook's
+  source.
 - **An answer given through a tool binds exactly as hard as a typed one.**
 
 Each rule's full text:
diff --git a/corpus/skills/cat-mode/references/named-constraints.md b/corpus/skills/cat-mode/references/named-constraints.md
index 3b869def..67f4ed17 100644
--- a/corpus/skills/cat-mode/references/named-constraints.md
+++ b/corpus/skills/cat-mode/references/named-constraints.md
@@ -22,6 +22,14 @@ individual constraints it covers.
   name in the same message as the number. Before reaching for a third vendor
   or workaround, read `.env.example` and ask which paid source the user
   already has.
+- **A hook or classifier block is a stop, not a puzzle.** Do not reword a
+  subagent prompt after `agent-routing-guard` refused it. Do not end a gated
+  turn with a couldn't-verify tag instead of running the check the gate asked
+  for. Do not reissue a denied command through a different tool, flag, or
+  invocation; the classifier-denial rule in `corpus/CLAUDE.learned.md` already
+  binds this shape. Do not open a change that makes a hook complain less. Do
+  what the block asks, and if the block is wrong, read the hook's source and
+  raise it with the user with that evidence.
 - **An answer given through a tool binds exactly as hard as a typed one.**
   A free-text reply to a multiple-choice question means every option offered
   was wrong. Restate it as a binding parameter in the plan before any work
diff --git a/tests/test_cat_mode.py b/tests/test_cat_mode.py
index 72bc17d1..8c198bf6 100644
--- a/tests/test_cat_mode.py
+++ b/tests/test_cat_mode.py
@@ -603,6 +603,19 @@ def test_named_constraints_reference_keeps_its_rules(self):
         self.assertIn("carries the proxy's name in the same message as the number", text)
         self.assertIn("An answer given through a tool binds exactly as hard as a typed one", text)
 
+    def test_block_is_a_stop_rule_kept_its_full_text_in_the_reference(self):
+        """The bullet's bold lead lives in SKILL.md; the concrete forbidden
+        shapes (reword, retag, reissue through another tool, weaken the hook)
+        live in named-constraints.md. Locks both halves the same way
+        test_unhedged_claim_rule_kept_its_full_text_when_it_moved does."""
+        skill = normalized_skill_text()
+        self.assertIn("A hook or classifier block is a stop, not a puzzle.", skill)
+        reference = normalized_reference_text("named-constraints.md")
+        self.assertIn("A hook or classifier block is a stop, not a puzzle.", reference)
+        self.assertIn("Do not reword a subagent prompt after `agent-routing-guard` refused it", reference)
+        self.assertIn("Do not reissue a denied command through a different tool, flag, or invocation", reference)
+        self.assertIn("Do not open a change that makes a hook complain less", reference)
+
     def test_routing_defers_to_an_installed_harness_routing_skill(self):
         skill = normalized_skill_text()
         self.assertIn("**An installed harness routing skill wins**", skill)