Steward 0.1.0 (in development): a DHCPv4 server with a web UI, API and CLI

Subnets served per interface, pools, reservations, options at three
levels, leases in SQLite saved before the ACK, ping and decline conflict
checks, validated changes with history and undo, users and tokens, an
audit log, a Kea importer, a sandboxed systemd unit and Debian packages.
Tested with real udhcpc and dhcpcd clients in Docker (scripts/e2e.sh).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/static/assets/pages/subnets.js

@@ -0,0 +1,45 @@
+// The subnets, and the New subnet dialog.
+import { h, mount, table, modal, errorBox, badge } from "../ui.js";
+import { get, change, can } from "../api.js";
+import { usageBar, subnetForm, fmtSeconds, subnetLabel } from "../widgets.js";
+
+export async function render(el, params, query) {
+  const subnets = await get("/subnets");
+  const poolsText = (s) => s.pools.length ? s.pools.map((p) => p.start + "-" + p.end).join(", ") : "–";
+  mount(el,
+    h("div", { class: "page-head" },
+      h("div", { class: "grow" }, h("h1", null, "Subnets"),
+        h("div", { class: "muted" }, "Each subnet is served on one interface: only clients on that interface get its addresses.")),
+      can("config", true) ? h("div", { class: "actions" }, h("button", { class: "primary", onclick: () => newSubnet() }, "New subnet")) : null),
+    h("div", { class: "panel" }, table([
+      { label: "Subnet", render: (s) => h("a", { href: "#/subnets/" + s.id }, subnetLabel(s)) },
+      { label: "Interface", render: (s) => h("span", { class: "mono" }, s.interface) },
+      { label: "Pools", render: (s) => h("span", { class: "mono small" }, poolsText(s)) },
+      { label: "In use", render: (s) => usageBar(s.usage) },
+      { label: "Reserved", class: "num", tdClass: "num", render: (s) => String(s.usage.reservations) },
+      { label: "Lease time", render: (s) => s.lease_time ? fmtSeconds(s.lease_time) : h("span", { class: "muted" }, "default") },
+      { label: "", render: (s) => s.disabled ? badge("disabled", "off") : null },
+    ], subnets, { empty: "No subnets yet. Add one for each network Steward should serve." })));
+  if (query.get("new") === "1" && can("config", true)) newSubnet();
+}
+
+export async function newSubnet() {
+  const settings = await get("/settings");
+  const form = await subnetForm(null, settings);
+  const err = h("div");
+  const res = await modal("New subnet", h("div", null, form, err), [
+    { label: "Cancel", value: null },
+    { label: "Add subnet", kind: "primary", onclick: async () => {
+      mount(err);
+      try {
+        const r = await change("POST", "/subnets", form.values());
+        location.hash = "#/subnets/" + (r.object ? r.object.id : "");
+        return true;
+      } catch (e) {
+        mount(err, errorBox(e));
+        return false;
+      }
+    } },
+  ], { wide: true, sticky: true });
+  return res;
+}