feat: message starter in the contact section

The visitor picks what they need and a prepared email types itself out; one
press opens it in their own mail app with subject and body filled in. The
mailto link is built by a tested pure function (src/domain/email.ts, spec
first) and only in the browser, so the address still never appears in the
page source.

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

apps/web/src/components/home/ContactComposer.tsx

@@ -0,0 +1,171 @@
+"use client";
+
+import * as React from "react";
+import { CONTACT_TOPICS } from "@/src/content/contact";
+import { CONTACT_EMAIL_PARTS } from "@/src/content/site";
+import { assembleEmail, mailtoHref, spellOutEmail } from "@/src/domain/email";
+
+const TYPE_MS = 9;
+const MONO = "font-mono text-[11px] uppercase tracking-[0.2em]";
+
+/** The text typed out so far. Jumps to the full text when motion is reduced. */
+const useTyped = (text: string): string => {
+  const [length, setLength] = React.useState(text.length);
+
+  React.useEffect(() => {
+    if (window.matchMedia("(prefers-reduced-motion: reduce)").matches) {
+      setLength(text.length);
+      return;
+    }
+    setLength(0);
+    const timer = window.setInterval(() => {
+      setLength((current) => {
+        if (current >= text.length) {
+          window.clearInterval(timer);
+          return current;
+        }
+        return Math.min(text.length, current + 3);
+      });
+    }, TYPE_MS);
+    return () => window.clearInterval(timer);
+  }, [text]);
+
+  return text.slice(0, length);
+};
+
+/** Blanks the visitor fills in are set apart from the prepared wording. */
+const withBlanks = (text: string): React.ReactNode =>
+  text.split(/(\[[^\]]*\]?)/).map((part, index) =>
+    part.startsWith("[") ? (
+      <span key={index} className="rounded-sm bg-amber-200/15 text-amber-200">
+        {part}
+      </span>
+    ) : (
+      part
+    ),
+  );
+
+/**
+ * ContactComposer: pick what you need and the email writes itself. One press
+ * opens it in the visitor's own mail app, ready to finish and send. The address
+ * is assembled in the browser, so it never appears in the page source.
+ */
+export const ContactComposer: React.FC = () => {
+  const [topicId, setTopicId] = React.useState(CONTACT_TOPICS[0]?.id ?? "");
+  const [address, setAddress] = React.useState<string | null>(null);
+  const [copied, setCopied] = React.useState(false);
+
+  React.useEffect(() => {
+    setAddress(assembleEmail(CONTACT_EMAIL_PARTS));
+  }, []);
+
+  const topic =
+    CONTACT_TOPICS.find((item) => item.id === topicId) ?? CONTACT_TOPICS[0];
+  const typed = useTyped(topic?.draft.body ?? "");
+
+  if (!topic) return null;
+
+  const done = typed.length === topic.draft.body.length;
+
+  const copy = async () => {
+    if (!address) return;
+    try {
+      await navigator.clipboard.writeText(address);
+      setCopied(true);
+      window.setTimeout(() => setCopied(false), 1800);
+    } catch {
+      // Clipboard access can be refused; the address stays visible to copy by hand.
+    }
+  };
+
+  return (
+    <div className="overflow-hidden rounded-3xl border border-slate-700 bg-slate-950/60 backdrop-blur-sm">
+      <div className="flex items-center justify-between border-b border-slate-800 px-5 py-4 md:px-7">
+        <div className="flex items-center gap-3">
+          <span className="flex gap-1.5" aria-hidden="true">
+            <span className="h-2.5 w-2.5 rounded-full bg-slate-700" />
+            <span className="h-2.5 w-2.5 rounded-full bg-slate-700" />
+            <span className="h-2.5 w-2.5 rounded-full bg-slate-700" />
+          </span>
+          <span className={`${MONO} text-slate-400`}>New message</span>
+        </div>
+        <span className={`${MONO} flex items-center gap-2 text-slate-500`}>
+          <span className="h-1.5 w-1.5 animate-pulse rounded-full bg-emerald-400" />
+          draft
+        </span>
+      </div>
+
+      <div className="border-b border-slate-800 px-5 py-5 md:px-7">
+        <p className={`${MONO} m-0 text-slate-500`}>I need</p>
+        <div className="mt-3 flex flex-wrap gap-2">
+          {CONTACT_TOPICS.map((item) => {
+            const selected = item.id === topic.id;
+            return (
+              <button
+                key={item.id}
+                type="button"
+                aria-pressed={selected}
+                onClick={() => setTopicId(item.id)}
+                className={`rounded-full border px-4 py-2 font-mono text-[11px] uppercase tracking-[0.15em] transition-colors duration-200 ${
+                  selected
+                    ? "border-white bg-white text-slate-900"
+                    : "border-slate-700 text-slate-300 hover:border-slate-400 hover:text-white"
+                }`}
+              >
+                {item.label}
+              </button>
+            );
+          })}
+        </div>
+      </div>
+
+      <dl className="m-0 border-b border-slate-800 px-5 py-4 font-mono text-[12px] leading-relaxed md:px-7 md:text-[13px]">
+        <div className="flex gap-4">
+          <dt className="w-16 shrink-0 text-slate-500">to</dt>
+          <dd className="m-0 text-slate-200">
+            {address ?? spellOutEmail(CONTACT_EMAIL_PARTS)}
+          </dd>
+        </div>
+        <div className="mt-1 flex gap-4">
+          <dt className="w-16 shrink-0 text-slate-500">subject</dt>
+          <dd className="m-0 text-white">{topic.draft.subject}</dd>
+        </div>
+      </dl>
+
+      <div
+        className="min-h-[15.5rem] whitespace-pre-wrap px-5 py-5 font-mono text-[12px] leading-relaxed text-slate-300 md:min-h-[14rem] md:px-7 md:text-[13px]"
+        aria-live="off"
+      >
+        {withBlanks(typed)}
+        <span
+          aria-hidden="true"
+          className={`ml-0.5 inline-block h-[1.05em] w-[0.55em] translate-y-[0.18em] bg-amber-200 ${done ? "animate-pulse" : ""}`}
+        />
+      </div>
+
+      <div className="flex flex-col gap-3 border-t border-slate-800 p-5 sm:flex-row sm:items-center md:px-7">
+        <a
+          href={
+            address ? mailtoHref(CONTACT_EMAIL_PARTS, topic.draft) : "#contact"
+          }
+          className="group inline-flex flex-1 items-center justify-between gap-4 rounded-full bg-white px-7 py-4 font-sans text-[12px] font-bold uppercase tracking-[0.18em] text-slate-900 no-underline transition-transform duration-300 hover:-translate-y-0.5"
+        >
+          Open in my mail app
+          <span
+            aria-hidden="true"
+            className="transition-transform duration-300 group-hover:translate-x-1"
+          >
+            →
+          </span>
+        </a>
+        <button
+          type="button"
+          onClick={copy}
+          className="rounded-full border border-slate-700 px-6 py-4 font-sans text-[12px] font-bold uppercase tracking-[0.18em] text-slate-300 transition-colors duration-200 hover:border-slate-400 hover:text-white"
+        >
+          {copied ? "Copied" : "Copy address"}
+        </button>
+      </div>
+    </div>
+  );
+};