diff --git a/docs/checks/check-structure.sh b/docs/checks/check-structure.sh
new file mode 100755
index 0000000..9c057b6
--- /dev/null
+++ b/docs/checks/check-structure.sh
@@ -0,0 +1,95 @@
+#!/usr/bin/env bash
+# Structure pin for docs/structure-pass. Exit 0 only when ownership, calendar home,
+# UX demotion, TEST-SPEC honesty, and Gate A lock phrases all hold.
+set -euo pipefail
+ROOT="$(cd "$(dirname "$0")/../.." && pwd)"
+cd "$ROOT"
+fail=0
+
+ok() { printf 'OK  %s\n' "$1"; }
+bad() { printf 'FAIL %s\n' "$1"; fail=1; }
+
+# Ownership table only (AGENTS §0), not casual mentions elsewhere.
+ownership_block=$(awk '/^## 0\. Where each doc lives$/,/^## /{if(/^## 0/) next; if(/^## / && !/^## 0/) exit; print}' AGENTS.md)
+# Include through end of table: stop at next ## that is not 0
+ownership_block=$(awk '
+  /^## 0\. Where each doc lives$/ {p=1; next}
+  /^## / && p {exit}
+  p {print}
+' AGENTS.md)
+
+for doc in 'docs/UX-DESIGN.md' 'deploy/INVENTORY.md' 'docs/TEST-SPEC.md'; do
+  if printf '%s\n' "$ownership_block" | grep -Fq "\`$doc\`"; then
+    ok "AGENTS §0 lists $doc"
+  else
+    bad "AGENTS §0 ownership missing $doc"
+  fi
+done
+
+if grep -Eqi 'non-normative|not normative' docs/UX-DESIGN.md \
+  && grep -Eq 'UX\.md' docs/UX-DESIGN.md; then
+  ok "UX-DESIGN demoted to non-normative and points at UX.md"
+else
+  bad "UX-DESIGN header must say non-normative and point at UX.md"
+fi
+if grep -Eqi 'phone and PC|signed UX' docs/UX-DESIGN.md; then
+  ok "UX-DESIGN defers to phone+PC / signed UX"
+else
+  bad "UX-DESIGN must defer to phone+PC matrix / signed UX.md"
+fi
+
+if grep -Eq 'Gate A.*Docs freeze|Docs freeze' docs/IMPL-PLAN.md \
+  && grep -Eq 'Gate B' docs/IMPL-PLAN.md \
+  && grep -Eq 'Gate C' docs/IMPL-PLAN.md; then
+  ok "IMPL-PLAN owns Gates meanings"
+else
+  bad "IMPL-PLAN must contain Gates A/B/C meanings"
+fi
+
+agents_gate_rows=$(grep -cE '^\| Gate [ABC] \|' AGENTS.md || true)
+if [[ "$agents_gate_rows" -eq 0 ]]; then
+  ok "AGENTS has no Gates meanings table rows"
+else
+  bad "AGENTS still has $agents_gate_rows Gates table rows; move meanings to IMPL-PLAN"
+fi
+if grep -Fq 'docs/IMPL-PLAN.md' AGENTS.md; then
+  ok "AGENTS points at IMPL-PLAN for phase/gate depth"
+else
+  bad "AGENTS must point at docs/IMPL-PLAN.md for gate/phase depth"
+fi
+
+if grep -Eqi 'not (yet )?on (this branch|main)|Phase 0 deliverable|when (the )?code lands|targets until|do not (exist|treat).*(present|checked.in)' docs/TEST-SPEC.md; then
+  ok "TEST-SPEC states harness paths are targets until code lands"
+else
+  bad "TEST-SPEC §2 must say frontend/e2e and backend/tests are targets until code exists"
+fi
+
+if grep -Eqi 'Phase 0 deliverable|not (yet )?in (the )?tree|aspirational|scaffold target' deploy/docker-compose.yml docs/DEPLOYMENT.md; then
+  ok "deploy docs label missing tree paths as Phase 0 targets"
+else
+  bad "compose or DEPLOYMENT must label frontend/backend Dockerfiles as Phase 0 targets"
+fi
+
+while IFS= read -r phrase; do
+  [[ -z "$phrase" ]] && continue
+  if grep -Fq "$phrase" AGENTS.md; then
+    ok "lock phrase present: $phrase"
+  else
+    bad "missing lock phrase in AGENTS.md: $phrase"
+  fi
+done <<'LOCKS'
+bdft = sqft × thickness_in
+SLAB-UAT-*
+WOO_BASE_URL
+https://
+authoritative for math
+Confidence 0.7
+draft → calibrated → ready → publishing → published
+LOCKS
+
+if [[ "$fail" -ne 0 ]]; then
+  printf '\ncheck-structure: FAILED\n'
+  exit 1
+fi
+printf '\ncheck-structure: PASSED\n'
+exit 0