diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..fdec8d1
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,32 @@
+# scheduler — the repo's command surface (D-27).
+#
+# There is no venv in this working tree today, even though CLAUDE.md documents
+# `.venv/bin/python -m pytest`. `make test` says so rather than failing with a
+# bare "No such file or directory", and `make setup` creates one.
+#
+# `python3` on this host is 3.8; PYTHON names 3.12 explicitly (D-26).
+
+VENV   := $(CURDIR)/.venv
+PYTHON ?= python3.12
+
+.DEFAULT_GOAL := help
+
+.PHONY: help
+help: ## Show this help
+	@grep -hE '^[a-z][a-z0-9_-]*:.*?## ' $(MAKEFILE_LIST) \
+	  | awk 'BEGIN{FS=":.*?## "}{printf "  \033[36m%-14s\033[0m %s\n", $$1, $$2}'
+
+.PHONY: setup
+setup: ## Create the venv and install the test extra
+	$(PYTHON) -m venv .venv
+	$(VENV)/bin/pip install -e ".[test]"
+
+.PHONY: test
+test: ## Run the test suite
+	@test -x $(VENV)/bin/python || { echo "FAIL — no venv in this tree; run: make setup"; exit 1; }
+	$(VENV)/bin/python -m pytest tests/
+
+# No `lint` target, deliberately. CLAUDE.md states it outright: no linter is
+# configured, no ruff or flake8 config, neither in the dependencies. Per D-27
+# the name is reserved for repos that lint rather than mandated everywhere — a
+# target here could only fail or report clean for something never run.