diff --git a/CLAUDE.md b/CLAUDE.md
index 3684a84..78319c6 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -23,6 +23,7 @@ Without Docker (native stack: uvicorn `--reload` on :5000, Vite HMR on **:8020**
 ```bash
 src/dev/devenv.sh setup     # backend venv (src/backend/.venv), npm ci for frontend + e2e, Mailpit binary into src/.devenv/bin
 src/dev/devenv.sh start     # idempotent; waits until everything answers. Also: stop | restart | status | logs [service] | reset (wipes DB + uploads)
+src/dev/devenv.sh seed      # sample users (admin, alice, bob, carol @example.com), an open and a closed order; local only, idempotent
 cd src/frontend && npx tsc --noEmit                # type checking (vite build does not run tsc)
 ```
 
diff --git a/src/dev/devenv.sh b/src/dev/devenv.sh
index 418a8fc..ab9ac71 100755
--- a/src/dev/devenv.sh
+++ b/src/dev/devenv.sh
@@ -2,7 +2,7 @@
 # Native dev stack (no Docker): backend (uvicorn --reload), frontend (Vite HMR, proxies /api), Mailpit.
 # App: http://localhost:8020  API: http://localhost:8020/api (or :5000 directly)  Mailpit: http://localhost:8025
 #
-# Usage: src/dev/devenv.sh setup|start|stop|restart|status|logs [service]|reset
+# Usage: src/dev/devenv.sh setup|start|stop|restart|status|logs [service]|reset|seed
 set -euo pipefail
 
 SRC_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
@@ -135,6 +135,12 @@ cmd_reset() {
   if ((was_running)); then cmd_start; fi
 }
 
+# Sample users/orders via the API (src/dev/seed.mjs); local stack only, idempotent.
+cmd_seed() {
+  is_running backend || cmd_start
+  (cd "$E2E_DIR" && node "$SRC_DIR/dev/seed.mjs")
+}
+
 case "${1:-}" in
   setup) cmd_setup ;;
   start) cmd_start ;;
@@ -143,5 +149,6 @@ case "${1:-}" in
   status) cmd_status ;;
   logs) cmd_logs "${2:-}" ;;
   reset) cmd_reset ;;
-  *) echo "Usage: $0 setup|start|stop|restart|status|logs [mailpit|backend|frontend]|reset" >&2; exit 2 ;;
+  seed) cmd_seed ;;
+  *) echo "Usage: $0 setup|start|stop|restart|status|logs [mailpit|backend|frontend]|reset|seed" >&2; exit 2 ;;
 esac
diff --git a/src/dev/seed.mjs b/src/dev/seed.mjs
new file mode 100644
index 0000000..155bf42
--- /dev/null
+++ b/src/dev/seed.mjs
@@ -0,0 +1,39 @@
+// Seeds the local dev stack with sample users, orders and submissions (run via `src/dev/devenv.sh seed`).
+// Goes through the public API + Mailpit like a real user, so it only works against a stack with Mailpit,
+// and refuses any BASE_URL that is not localhost.
+import { BASE_URL, ADMIN_EMAIL, api, createOrder, signIn, submit } from "../e2e/lib.mjs";
+
+if (!/^https?:\/\/(localhost|127\.0\.0\.1)(:|\/|$)/.test(BASE_URL)) {
+  console.error(`Refusing to seed ${BASE_URL}: dev seed data is for local stacks only.`);
+  process.exit(1);
+}
+
+const SEED_TITLE = "Burger Friday";
+
+const admin = await signIn(ADMIN_EMAIL);
+const existing = await api("/api/orders/me?limit=100", { userId: admin.userId });
+if (existing.orders?.some((o) => o.title === SEED_TITLE)) {
+  console.log("Seed data already present, nothing to do.");
+  process.exit(0);
+}
+
+const [alice, bob, carol] = await Promise.all(["alice", "bob", "carol"].map((n) => signIn(`${n}@example.com`)));
+
+// Open order with a mix of submission states
+const open = await createOrder(admin.userId, { title: SEED_TITLE, description: "Order by **11:30**, pickup at noon." });
+const a = await submit(alice.userId, open.id, { burger: "Classic", sides: ["Fries"] });
+await submit(bob.userId, open.id, { burger: "Veggie", sides: ["Fries", "Side salad"] });
+await submit(carol.userId, open.id, { burger: "Cheeseburger" });
+await api(`/api/orders/${open.id}/admin/submissions/${a.id}/status`, {
+  userId: admin.userId,
+  method: "PUT",
+  body: { accepted: true, paid: true },
+});
+
+// Closed order, owned by alice, where the admin participated
+const closed = await createOrder(alice.userId, { title: "Pizza Wednesday", description: "Done." });
+await submit(admin.userId, closed.id, { burger: "Classic" });
+await submit(bob.userId, closed.id, { burger: "Veggie", sides: ["Side salad"] });
+await api(`/api/orders/${closed.id}/admin/status`, { userId: alice.userId, method: "PUT", body: { closed: true } });
+
+console.log(`Seeded. Admin ${ADMIN_EMAIL}, users alice/bob/carol@example.com. Open ${BASE_URL}/order/${open.id}`);