diff --git a/README.md b/README.md
index d02634d..158d747 100644
--- a/README.md
+++ b/README.md
@@ -35,9 +35,10 @@ the GitHub Security tab.
 
 Inspect is a Hawk support engine. Keep the dependency edge one-way:
 
-- use `hawk-core-contracts` for any cross-repo shared contracts
+- use `hawk-core-contracts` for any cross-repo shared contracts (severity/finding vocabulary)
 - do not import `hawk/internal/*`
 - do not import removed legacy path `hawk/shared/types`; use `hawk-core-contracts/types`
+- do not import other engines (`eyrie`, `yaad`, `tok`, `trace`, `sight`) — engines are peers, not dependencies
 
 ## Quick Start
 
diff --git a/scripts/check-ecosystem-boundaries.sh b/scripts/check-ecosystem-boundaries.sh
old mode 100644
new mode 100755
index 57f81ba..2f0b2f5
--- a/scripts/check-ecosystem-boundaries.sh
+++ b/scripts/check-ecosystem-boundaries.sh
@@ -4,10 +4,17 @@ set -euo pipefail
 ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 cd "$ROOT_DIR"
 
+FORBIDDEN_HAWK='github\.com/GrayCodeAI/hawk/(internal/|shared/types)'
+FORBIDDEN_ENGINES='github\.com/GrayCodeAI/(eyrie|yaad|tok|trace|sight)(/|")'
+
+exit_code=0
+
 if command -v rg >/dev/null 2>&1; then
-  violations="$(rg -n 'github\.com/GrayCodeAI/hawk/(internal/|shared/types)' --glob '*.go' . || true)"
+  violations="$(rg -n "$FORBIDDEN_HAWK" --glob '*.go' . || true)"
+  engine_violations="$(rg -n "$FORBIDDEN_ENGINES" --glob '*.go' . || true)"
 else
-  violations="$(grep -rn --include='*.go' -E 'github\.com/GrayCodeAI/hawk/(internal/|shared/types)' . || true)"
+  violations="$(grep -rn --include='*.go' -E "$FORBIDDEN_HAWK" . || true)"
+  engine_violations="$(grep -rn --include='*.go' -E "$FORBIDDEN_ENGINES" . || true)"
 fi
 
 if [[ -n "${violations}" ]]; then
@@ -15,7 +22,19 @@ if [[ -n "${violations}" ]]; then
   echo "${violations}"
   echo
   echo "support repos must use hawk-core-contracts or local contracts, not hawk/internal or removed hawk/shared/types"
-  exit 1
+  exit_code=1
+fi
+
+if [[ -n "${engine_violations}" ]]; then
+  echo "forbidden cross-engine imports found:"
+  echo "${engine_violations}"
+  echo
+  echo "support engines must not import other engines directly — they are peers, not dependencies"
+  exit_code=1
+fi
+
+if [[ $exit_code -ne 0 ]]; then
+  exit $exit_code
 fi
 
 echo "ecosystem boundary guard passed"