diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f6f74ad..8f63292 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -58,6 +58,8 @@ jobs:
           fi
       - name: go vet
         run: go vet ./...
+      - name: consumer boundary guard
+        run: bash ./scripts/check-consumer-boundaries.sh
 
   # -------------------------------------------------------------------------
   # Lint — golangci-lint covers most static checks.
diff --git a/Makefile b/Makefile
index 3983bf9..8df768b 100644
--- a/Makefile
+++ b/Makefile
@@ -27,7 +27,7 @@ GOVULNCHECK := $(GOBIN_DIR)/govulncheck
 # ---------------------------------------------------------------------------
 # Phony declarations (alphabetical).
 # ---------------------------------------------------------------------------
-.PHONY: all bench build ci clean cover fmt help lint lint-fix \
+.PHONY: all bench boundary-guard build ci clean cover fmt help lint lint-fix \
         security test test-10x test-race tidy version vet
 
 # ---------------------------------------------------------------------------
@@ -74,6 +74,9 @@ fmt: ## Format source files (gofumpt + goimports).
 vet: ## Run go vet.
 	go vet ./...
 
+boundary-guard: ## Fail if the SDK imports support engines or Hawk private packages.
+	bash ./scripts/check-consumer-boundaries.sh
+
 lint: ## Run golangci-lint.
 	@command -v $(GOLANGCI) >/dev/null 2>&1 || (echo "install: go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@latest" && exit 1)
 	$(GOLANGCI) run ./... --timeout=5m
@@ -93,7 +96,7 @@ tidy: ## Tidy go.mod / go.sum.
 # ---------------------------------------------------------------------------
 # Composite gate used by CI and pre-push.
 # ---------------------------------------------------------------------------
-ci: tidy fmt vet lint test-race security ## Run everything CI runs.
+ci: tidy fmt vet boundary-guard lint test-race security ## Run everything CI runs.
 	@echo "All CI checks passed."
 
 # ---------------------------------------------------------------------------
diff --git a/README.md b/README.md
index a4fa09c..9479fb5 100644
--- a/README.md
+++ b/README.md
@@ -50,6 +50,13 @@ fmt.Println(resp.Response)
 
 See the [examples/](examples/) directory for complete runnable examples.
 
+## Ecosystem Boundaries
+
+- `hawk-sdk-go` is a consumer of Hawk public APIs and contracts.
+- Do not import support engine repos such as `eyrie`, `yaad`, `tok`, `trace`, `sight`, or `inspect`.
+- Do not import `hawk/internal/*` or removed legacy path `hawk/shared/types`.
+- Cross-repo shared vocabulary should come from Hawk public surfaces or `hawk-core-contracts`, not engine internals.
+
 ## API Reference
 
 ### Client Methods
diff --git a/lefthook.yml b/lefthook.yml
index ba5700d..7d5bdaf 100644
--- a/lefthook.yml
+++ b/lefthook.yml
@@ -110,3 +110,18 @@ commit-msg:
           echo "  full guide: https://www.conventionalcommits.org/"
           exit 1
         fi
+
+    strip-co-authored-by:
+      run: |
+        # Strip Co-authored-by: trailers that AI tools (Claude, Cursor, etc.) add.
+        # This enforces the rule that commits list only the human author.
+        sed '/^[Cc]o-[Aa]uthored-[Bb]y:/d' "{1}" > "{1}.tmp" && mv "{1}.tmp" "{1}"
+
+# ---------------------------------------------------------------------------
+# prepare-commit-msg — strip AI co-author trailers after tools inject them.
+# ---------------------------------------------------------------------------
+prepare-commit-msg:
+  commands:
+    strip-co-authored-by:
+      run: |
+        sed '/^[Cc]o-[Aa]uthored-[Bb]y:/d' "{1}" > "{1}.tmp" && mv "{1}.tmp" "{1}"
diff --git a/scripts/check-consumer-boundaries.sh b/scripts/check-consumer-boundaries.sh
new file mode 100644
index 0000000..6bcb872
--- /dev/null
+++ b/scripts/check-consumer-boundaries.sh
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+cd "$ROOT_DIR"
+
+violations="$(
+  grep -RInE --include='*.go' \
+    'github\.com/GrayCodeAI/(eyrie|inspect|sight|tok|trace|yaad)(/|")|github\.com/GrayCodeAI/hawk/(internal/|shared/types)' \
+    . || true
+)"
+
+if [[ -n "${violations}" ]]; then
+  echo "forbidden Hawk consumer imports found:"
+  echo "${violations}"
+  echo
+  echo "hawk-sdk-go must depend on Hawk public APIs/contracts only; do not import support engines, hawk/internal, or removed hawk/shared/types"
+  exit 1
+fi
+
+echo "consumer boundary guard passed"