diff --git a/frontend/src/screens/SignIn.tsx b/frontend/src/screens/SignIn.tsx
index 88afd82..47712e0 100644
--- a/frontend/src/screens/SignIn.tsx
+++ b/frontend/src/screens/SignIn.tsx
@@ -1,9 +1,10 @@
 // Sign in (SD-0001 §5.2) — the single email + one-time-code flow behind both doors. Step 1
-// requests a code; step 2 verifies it. Honest copy states which door framing applies and,
-// after verify, whether the account was created or resumed (PUC-3). storefront routing is
-// handled by App on success.
-import { useState } from "react";
-import { requestCode, verifyCode, type VerifyResult } from "../api";
+// requests a code; step 2 verifies it. Honest copy for every §5.2 state; storefront routing
+// is handled by App on success. Visuals per the ui/designs export (hf-signin).
+import { useEffect, useState } from "react";
+import { requestCode, verifyCode, type ApiError, type VerifyResult } from "../api";
+import CodeInput from "../ui/CodeInput";
+import { AuthCard, Banner, Field, Footer, PrimaryButton, Screen, TopBar, Wordmark } from "../ui/kit";
 
 type Door = "signup" | "login";
 
@@ -13,99 +14,175 @@ interface Props {
   onBack: () => void;
 }
 
+function useCooldown(): [number, (s: number) => void] {
+  const [left, setLeft] = useState(0);
+  const ticking = left > 0;
+  useEffect(() => {
+    if (!ticking) return;
+    const t = setInterval(() => setLeft((v) => Math.max(0, v - 1)), 1000);
+    return () => clearInterval(t);
+  }, [ticking]);
+  return [left, setLeft];
+}
+
 export default function SignIn({ door, onAuthed, onBack }: Props) {
   const [step, setStep] = useState<"email" | "code">("email");
   const [email, setEmail] = useState("");
   const [code, setCode] = useState("");
   const [busy, setBusy] = useState(false);
-  const [error, setError] = useState<string | null>(null);
+  const [fieldError, setFieldError] = useState<string | null>(null);
+  const [codeError, setCodeError] = useState<string | null>(null);
+  const [bannerError, setBannerError] = useState<ApiError | null>(null);
+  const [cooldown, setCooldown] = useCooldown();
 
-  const heading = door === "signup" ? "Create your storefront" : "Log in";
+  function applyError(err: ApiError) {
+    setFieldError(null);
+    setCodeError(null);
+    setBannerError(null);
+    if (err.code === "invalid_email") setFieldError(err.message);
+    else if (err.code === "resend_cooldown") setCooldown(err.retry_after_s ?? 60);
+    else if (err.code === "code_mismatch" || err.code === "code_expired") setCodeError(err.message);
+    else setBannerError(err); // delivery_failed, code_exhausted, unexpected
+  }
 
-  async function submitEmail(e: React.FormEvent) {
-    e.preventDefault();
+  async function sendCode(): Promise<boolean> {
     setBusy(true);
-    setError(null);
+    setFieldError(null);
+    setBannerError(null);
     const err = await requestCode(email);
     setBusy(false);
     if (err) {
-      setError(err.message);
-      return;
+      applyError(err);
+      return err.code === "resend_cooldown"; // a cooldown still means a code is out there
     }
-    setStep("code");
+    setCooldown(60);
+    return true;
+  }
+
+  async function submitEmail(e: React.FormEvent) {
+    e.preventDefault();
+    if (await sendCode()) {
+      setCode("");
+      setCodeError(null);
+      setStep("code");
+    }
+  }
+
+  async function resend() {
+    setCodeError(null);
+    setCode("");
+    await sendCode();
   }
 
   async function submitCode(e: React.FormEvent) {
     e.preventDefault();
     setBusy(true);
-    setError(null);
+    setCodeError(null);
+    setBannerError(null);
     const res = await verifyCode(email, code);
     setBusy(false);
     if (!res.ok) {
-      setError(res.error.message);
+      applyError(res.error);
       return;
     }
     onAuthed(res.result);
   }
 
-  if (step === "email") {
-    return (
-      <main>
-        <header>
-          <strong>ecomm</strong>
-          <button type="button" onClick={onBack}>
-            Back
-          </button>
-        </header>
-        <form onSubmit={submitEmail}>
-          <h1>{heading}</h1>
-          <label>
-            Email
-            <input
-              type="email"
-              value={email}
-              autoFocus
-              required
-              onChange={(ev) => setEmail(ev.target.value)}
-            />
-          </label>
-          <p>We'll email you a one-time code. That's all we need.</p>
-          {error && <p role="alert">{error}</p>}
-          <button type="submit" disabled={busy}>
-            {busy ? "Sending…" : "Send code"}
-          </button>
-        </form>
-      </main>
-    );
-  }
+  const heading = door === "signup" ? "Create your storefront" : "Log in";
+  const sub =
+    door === "signup"
+      ? "Enter your email to begin. There's no password to create."
+      : "Enter your email and we'll send a one-time code to sign in.";
 
   return (
-    <main>
-      <header>
-        <strong>ecomm</strong>
-        <button type="button" onClick={() => setStep("email")}>
-          Wrong address?
-        </button>
-      </header>
-      <form onSubmit={submitCode}>
-        <h1>Enter your code</h1>
-        <p>We sent a code to {email}.</p>
-        <label>
-          Code
-          <input
-            inputMode="numeric"
-            autoComplete="one-time-code"
-            value={code}
-            autoFocus
-            required
-            onChange={(ev) => setCode(ev.target.value)}
-          />
-        </label>
-        {error && <p role="alert">{error}</p>}
-        <button type="submit" disabled={busy}>
-          {busy ? "Checking…" : "Continue"}
-        </button>
-      </form>
-    </main>
+    <Screen horizon>
+      <TopBar
+        left={<Wordmark size={22} />}
+        right={
+          <button type="button" className="lk lk--mute" onClick={onBack}>
+            ← Back
+          </button>
+        }
+      />
+      <main className="screen__main">
+        <AuthCard>
+          {step === "email" ? (
+            <form onSubmit={submitEmail} style={{ display: "contents" }}>
+              <div>
+                <h1>{heading}</h1>
+                <p className="card__sub">{sub}</p>
+              </div>
+              {bannerError && (
+                <Banner title="We couldn't send the code">
+                  The email didn't go out. Try again in a moment — nothing was lost.
+                </Banner>
+              )}
+              <Field
+                label="Email"
+                error={fieldError}
+                inputProps={{
+                  type: "email",
+                  value: email,
+                  placeholder: "you@example.com",
+                  autoFocus: true,
+                  required: true,
+                  autoComplete: "email",
+                  onChange: (ev) => setEmail(ev.target.value),
+                }}
+              />
+              <div style={{ display: "flex", flexDirection: "column", gap: 12 }}>
+                <PrimaryButton busy={busy} disabled={cooldown > 0}>
+                  {busy ? "Sending…" : cooldown > 0 ? `Resend in ${cooldown}s` : "Send code"}
+                </PrimaryButton>
+                <p className="note">
+                  We'll email you a one-time code. That's all we need — no password, ever.
+                </p>
+              </div>
+            </form>
+          ) : (
+            <form onSubmit={submitCode} style={{ display: "contents" }}>
+              <div>
+                <h1>Check your email</h1>
+                <p className="card__sub">
+                  We sent a 6-digit code to <span style={{ color: "var(--wv-starlight)" }}>{email}</span>.{" "}
+                  <button type="button" className="lk" onClick={() => setStep("email")}>
+                    Wrong address?
+                  </button>
+                </p>
+              </div>
+              {bannerError && (
+                <Banner title={bannerError.code === "code_exhausted" ? "Too many attempts" : "Something went wrong"}>
+                  {bannerError.code === "code_exhausted"
+                    ? "That code is no longer valid. Request a fresh one to keep going."
+                    : bannerError.message}
+                </Banner>
+              )}
+              <div style={{ display: "flex", flexDirection: "column", gap: 10 }}>
+                <CodeInput value={code} onChange={setCode} error={!!codeError} />
+                {codeError && (
+                  <p className="note note--attn" role="alert">
+                    {codeError}
+                  </p>
+                )}
+              </div>
+              <div style={{ display: "flex", flexDirection: "column", gap: 12 }}>
+                <PrimaryButton busy={busy}>{busy ? "Checking…" : "Continue"}</PrimaryButton>
+                <div style={{ display: "flex", justifyContent: "space-between", alignItems: "center" }}>
+                  <p className="note">Good for 10 minutes.</p>
+                  {cooldown > 0 ? (
+                    <span className="note">Resend in {cooldown}s</span>
+                  ) : (
+                    <button type="button" className="lk" onClick={resend}>
+                      Resend code
+                    </button>
+                  )}
+                </div>
+              </div>
+            </form>
+          )}
+        </AuthCard>
+      </main>
+      <Footer />
+    </Screen>
   );
 }