feat(adminsite): licence delivery, paste instructions and relink

The blob is shown inline as well as offered as a file, because a licence is
signed public data bound to one instance -- useless anywhere else -- and a
blocked download must never leave a paying customer stuck. Admin now returns
it to its owner for the same reason.

Relink shows the remaining allowance from the backend's max_relinks rather
than a hardcoded 3, and at zero it disables and says to contact support
instead of failing at the API.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

adminsite/components/LicenceDelivery.test.tsx

@@ -0,0 +1,20 @@
+import { render, screen } from "@testing-library/react";
+import { describe, expect, it } from "vitest";
+import { LicenceDelivery } from "./LicenceDelivery";
+
+describe("LicenceDelivery", () => {
+    it("offers the file and always shows the blob as a fallback", () => {
+        render(
+            <LicenceDelivery
+                instanceId="6a0fe3f0-49d2-4aa1-967c-a3094b200b5d"
+                blob="VANTAGE-LIC abc123"
+                downloadUrl="https://admin.example.com/api/instances/x/license/download"
+            />,
+        );
+        const link = screen.getByRole("link", { name: /download licence/i });
+        expect(link).toHaveAttribute("href", expect.stringContaining("/license/download"));
+        // A blocked download must never leave a paying customer stuck.
+        expect(screen.getByText(/VANTAGE-LIC abc123/)).toBeInTheDocument();
+        expect(screen.getByText(/Settings → Licence/)).toBeInTheDocument();
+    });
+});

adminsite/components/LicenceDelivery.tsx

@@ -0,0 +1,73 @@
+"use client";
+
+import { useState } from "react";
+import { Button } from "./Button";
+
+/*
+ * A licence blob is signed public data, not a secret — it is useless on any
+ * instance other than the one it names. So it is safe to show inline, and
+ * showing it is what stops a blocked download from blocking a paying customer.
+ */
+export function LicenceDelivery({
+    instanceId,
+    blob,
+    downloadUrl,
+}: {
+    instanceId: string;
+    blob: string;
+    downloadUrl: string;
+}) {
+    const [copied, setCopied] = useState(false);
+
+    async function copy() {
+        await navigator.clipboard.writeText(blob);
+        setCopied(true);
+        setTimeout(() => setCopied(false), 2000);
+    }
+
+    const steps = [
+        <>
+            Open <code className="rounded-sm bg-accent-wash px-1">Settings → Licence</code> on your
+            install.
+        </>,
+        <>Paste the licence into the box and save.</>,
+        <>
+            The page reports <code className="rounded-sm bg-accent-wash px-1">Valid</code> straight
+            away — no restart.
+        </>,
+    ];
+
+    return (
+        <section className="grid gap-3">
+            <h2 className="text-xl">Your licence</h2>
+            <div className="flex flex-wrap items-center gap-3">
+                <a
+                    href={downloadUrl}
+                    download={`vantage-${instanceId}.lic`}
+                    className="inline-flex items-center gap-2 rounded border border-accent bg-accent px-4 py-2.5 text-[0.94rem] font-semibold text-accent-ink"
+                >
+                    Download licence
+                </a>
+                <Button variant="line" type="button" onClick={copy}>
+                    {copied ? "Copied" : "Copy to clipboard"}
+                </Button>
+            </div>
+            <pre className="overflow-x-auto rounded border border-dashed border-rule bg-panel-2 p-3 font-mono text-[0.72rem] text-ink-2">
+                {blob}
+            </pre>
+            <ol className="grid gap-2">
+                {steps.map((body, i) => (
+                    <li
+                        key={i}
+                        className="grid grid-cols-[1.6rem_1fr] gap-3 text-[0.82rem] text-ink-2"
+                    >
+                        <span className="h-6 rounded-sm border border-rule text-center font-mono text-[0.72rem] leading-6 text-accent">
+                            {i + 1}
+                        </span>
+                        <span>{body}</span>
+                    </li>
+                ))}
+            </ol>
+        </section>
+    );
+}

adminsite/components/RelinkPanel.test.tsx

@@ -0,0 +1,17 @@
+import { render, screen } from "@testing-library/react";
+import { describe, expect, it, vi } from "vitest";
+import { RelinkPanel } from "./RelinkPanel";
+
+describe("RelinkPanel", () => {
+    it("shows the remaining allowance", () => {
+        render(<RelinkPanel instanceId="i1" used={1} max={3} onRelink={vi.fn()} />);
+        expect(screen.getByText("2 of 3 relinks left this term")).toBeInTheDocument();
+        expect(screen.getByRole("button", { name: /relink/i })).toBeEnabled();
+    });
+
+    it("disables at zero and says what to do instead", () => {
+        render(<RelinkPanel instanceId="i1" used={3} max={3} onRelink={vi.fn()} />);
+        expect(screen.getByRole("button", { name: /relink/i })).toBeDisabled();
+        expect(screen.getByText(/contact support/i)).toBeInTheDocument();
+    });
+});

adminsite/components/RelinkPanel.tsx

@@ -0,0 +1,59 @@
+"use client";
+
+import { useState } from "react";
+import { Button } from "./Button";
+import { Field } from "./Field";
+
+const UUID_RE = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
+
+export function RelinkPanel({
+    used,
+    max,
+    onRelink,
+    error,
+}: {
+    instanceId: string;
+    used: number;
+    max: number;
+    onRelink: (newId: string) => void;
+    error?: string;
+}) {
+    const [open, setOpen] = useState(false);
+    const [value, setValue] = useState("");
+    const remaining = Math.max(0, max - used);
+    const exhausted = remaining === 0;
+
+    return (
+        <section className="grid gap-3 border-t border-rule-soft pt-5">
+            <h2 className="text-xl">Moved to a new server?</h2>
+            <p className="text-[0.82rem] text-ink-2">
+                Relinking issues a replacement licence for the new install, covering the rest of
+                your current term.
+            </p>
+            {open && !exhausted && (
+                <Field
+                    label="New instance ID"
+                    value={value}
+                    onChange={(e) => setValue(e.target.value)}
+                    error={error}
+                    hint="From Settings → Licence on the new install."
+                />
+            )}
+            <div className="flex flex-wrap items-center gap-3">
+                <Button
+                    type="button"
+                    variant="line"
+                    disabled={exhausted || (open && !UUID_RE.test(value.trim()))}
+                    onClick={() => (open ? onRelink(value.trim()) : setOpen(true))}
+                >
+                    Relink to a new install
+                </Button>
+                <span className="text-[0.82rem] text-ink-3">
+                    {exhausted
+                        ? "You have used every relink for this term — contact support and we will sort it out."
+                        : `${remaining} of ${max} relinks left this term`}
+                </span>
+            </div>
+        </section>
+    );
+}