diff --git a/product/skills/admin-bypass-sweep/SKILL.md b/product/skills/admin-bypass-sweep/SKILL.md
index becb9df3..bc6b6ec1 100644
--- a/product/skills/admin-bypass-sweep/SKILL.md
+++ b/product/skills/admin-bypass-sweep/SKILL.md
@@ -223,18 +223,48 @@ fate — merged or genuinely blocked — is decided.
 ## Step 6: Prove the final state
 
 Before reporting results, re-query every PR number touched — do not trust
-running tallies kept during execution:
+running tallies kept during execution. A merged tally may not be computed
+from `gh pr view` state alone; GitHub's PR state is not proof that the PR's
+merge commit reached the trunk.
 
 ```bash
+verify="engine/hooks/gh-write-verification/verify_pr_landed_on_trunk.sh"
+trunk="<trunk-branch>"  # for example, master
+
 for pr in <all touched PR numbers>; do
-  gh pr view $pr --repo <owner>/<repo> --json number,state,mergedAt,title \
-    --jq '"#\(.number)\t\(.state)\t\(.mergedAt // "-")\t\(.title)"'
+  title="$(gh pr view "$pr" --repo <owner>/<repo> --json number,title \
+    --jq '"#\(.number)\t\(.title)"')" || title="#${pr}\t<title unavailable>"
+
+  verifier_status=0
+  verifier_output="$("$verify" --repo <owner>/<repo> "$pr" "$trunk" 2>&1)" || verifier_status=$?
+
+  case "$verifier_status" in
+    0)
+      printf '%s\tmerged\t%s\n' "$title" "$verifier_output"
+      ;;
+    1)
+      printf '%s\tmerged-but-not-on-trunk\t%s\n' "$title" "$verifier_output"
+      ;;
+    3)
+      printf '%s\tunchecked\t%s\n' "$title" "$verifier_output"
+      ;;
+    *)
+      printf '%s\tunchecked\tverify_pr_landed_on_trunk.sh exited %s: %s\n' \
+        "$title" "$verifier_status" "$verifier_output"
+      ;;
+  esac
 done
 ```
 
-Report merged count, blocked count, and the specific PR numbers/titles in
-each bucket — a summary count alone hides which specific work is still
-stuck.
+Branch only on `engine/hooks/gh-write-verification/verify_pr_landed_on_trunk.sh`
+exit codes: exit 0 is `merged`, exit 1 is `merged-but-not-on-trunk`, and
+exit 3 is `unchecked`. Exit 3 is never reported as merged. Only exit 0
+increments the merged count; exit 1 and exit 3 must be counted in their own
+buckets and named with their PR numbers/titles.
+
+Report merged count, merged-but-not-on-trunk count, unchecked count, blocked
+count, and the specific PR numbers/titles in each bucket — a summary count
+alone hides which specific work is still stuck.
 
 ## Why this exists
 
diff --git a/product/skills/admin-bypass-sweep/tests/stack_branch_landing_fixture.md b/product/skills/admin-bypass-sweep/tests/stack_branch_landing_fixture.md
new file mode 100644
index 00000000..78afb031
--- /dev/null
+++ b/product/skills/admin-bypass-sweep/tests/stack_branch_landing_fixture.md
@@ -0,0 +1,29 @@
+# Stack-branch landing fixture
+
+PR #1789 was reported by GitHub as merged after it landed against a stack
+branch instead of the trunk.
+
+Old Step 6 input:
+
+```text
+#1789	MERGED	2026-09-09T10:11:12Z	Retarget child stack branch
+```
+
+Old Step 6 outcome:
+
+```text
+merged
+```
+
+New Step 6 verifier result:
+
+```text
+exit 1
+FAIL: PR #1789 in owner/repo reports MERGED but abc123 is not on origin/master
+```
+
+New Step 6 outcome:
+
+```text
+merged-but-not-on-trunk
+```
diff --git a/product/skills/admin-bypass-sweep/tests/test_step_6_verifier_tally.py b/product/skills/admin-bypass-sweep/tests/test_step_6_verifier_tally.py
new file mode 100644
index 00000000..486b8409
--- /dev/null
+++ b/product/skills/admin-bypass-sweep/tests/test_step_6_verifier_tally.py
@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+from __future__ import annotations
+
+import re
+import unittest
+from pathlib import Path
+
+SKILL_DIR = Path(__file__).resolve().parents[1]
+SKILL = (SKILL_DIR / "SKILL.md").read_text(encoding="utf-8")
+FIXTURE = (Path(__file__).resolve().parent / "stack_branch_landing_fixture.md").read_text(encoding="utf-8")
+
+
+def step_6() -> str:
+    match = re.search(r"^## Step 6:.*?(?=^## )", SKILL, re.M | re.S)
+    if match is None:
+        raise AssertionError("Step 6 section not found")
+    return match.group(0)
+
+
+class TestStep6VerifierTally(unittest.TestCase):
+    def setUp(self) -> None:
+        self.step = step_6()
+        self.compact_step = " ".join(self.step.split())
+
+    def test_step_6_names_the_trunk_ancestry_verifier(self):
+        self.assertIn("engine/hooks/gh-write-verification/verify_pr_landed_on_trunk.sh", self.step)
+
+    def test_step_6_maps_all_documented_status_codes(self):
+        for code, outcome in (
+            ("exit 0", "merged"),
+            ("exit 1", "merged-but-not-on-trunk"),
+            ("exit 3", "unchecked"),
+        ):
+            self.assertIn(code, self.step)
+            self.assertIn(outcome, self.step)
+
+    def test_gh_pr_view_state_alone_cannot_drive_the_merged_tally(self):
+        self.assertIn("A merged tally may not be computed from `gh pr view` state alone", self.compact_step)
+        self.assertNotIn("state,mergedAt", self.step)
+        self.assertIn("Only exit 0 increments the merged count", self.compact_step)
+
+    def test_exit_3_is_never_merged(self):
+        self.assertIn("Exit 3 is never reported as merged", self.step)
+
+    def test_stack_branch_fixture_is_no_longer_counted_as_merged(self):
+        self.assertIn("#1789\tMERGED", FIXTURE)
+        self.assertIn("Old Step 6 outcome:\n\n```text\nmerged\n```", FIXTURE)
+        self.assertIn("exit 1", FIXTURE)
+        self.assertIn("New Step 6 outcome:\n\n```text\nmerged-but-not-on-trunk\n```", FIXTURE)
+
+
+if __name__ == "__main__":
+    unittest.main()