feat(ext/setup): polished passphrase entry UX

Setup wizard step 3 now has self-explanatory passphrase feedback:

- Strength meter: 5 segments with smooth color transitions
  (very-weak/weak/fair/good/strong). Tier 4 gets a subtle glow.
- Nuanced label (lowercase, tracked): "very weak" / "weak" / "fair" /
  "good" / "strong" — color-matched to each tier.
- Entropy readout line: "~10^N guesses — <time to crack>" with
  tiered shorthand (trivial / minutes-on-GPU / hours-to-days /
  years-on-consumer / beyond consumer / uncrackable).
- Live char counter in the strength row.
- Eye toggle buttons on both passphrase fields. Flip type="password"
  <-> type="text" without re-render, preserving focus + cursor.
- Live match indicator (✓ / ✗) between the confirm field and its eye
  toggle. Updates per keystroke.
- Create button gate widened: now requires score >= 3 AND confirm
  field filled AND confirm matches. Disabled button carries a
  tooltip saying which condition failed.
- Contextual help box above the passphrase field explaining the
  "long phrase > complex password" idea + the score >= 3 threshold.

All live-update paths (counter, label, entropy, match indicator,
button gate) go through updateStrengthUi() which targets the DOM
directly — no full re-render, so focus/cursor survive every keystroke.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

extension/setup.html

@@ -51,21 +51,21 @@
     .strength-bar {
       display: flex;
       gap: 3px;
-      margin-top: 6px;
+      margin-top: 8px;
     }
 
     .strength-bar .seg {
       flex: 1;
-      height: 4px;
+      height: 5px;
       background: #21262d;
-      border-radius: 2px;
+      border-radius: 3px;
-      transition: background 0.2s;
+      transition: background 0.25s ease, box-shadow 0.25s ease;
     }
 
     /* zxcvbn score-driven colors. Higher-scored bars light up earlier bars too. */
     .strength-bar.s0 .seg.i0 { background: #f85149; }
     .strength-bar.s1 .seg.i0,
-    .strength-bar.s1 .seg.i1 { background: #db6d28; }
+    .strength-bar.s1 .seg.i1 { background: #f08d49; }
     .strength-bar.s2 .seg.i0,
     .strength-bar.s2 .seg.i1,
     .strength-bar.s2 .seg.i2 { background: #d29922; }
@@ -73,14 +73,101 @@
     .strength-bar.s3 .seg.i1,
     .strength-bar.s3 .seg.i2,
     .strength-bar.s3 .seg.i3 { background: #3fb950; }
-    .strength-bar.s4 .seg { background: #3fb950; }
+    .strength-bar.s4 .seg {
+      background: #56d364;
+      box-shadow: 0 0 4px rgba(86, 211, 100, 0.4);
+    }
 
+    .strength-row {
+      display: flex;
+      justify-content: space-between;
+      align-items: baseline;
+      margin-top: 5px;
+    }
     .strength-label {
       font-size: 11px;
-      margin-top: 3px;
+      margin: 0;
+      text-transform: lowercase;
+      letter-spacing: 0.03em;
+      transition: color 0.2s ease;
+    }
+    .strength-label.s-very-weak { color: #f85149; }
+    .strength-label.s-weak      { color: #f08d49; }
+    .strength-label.s-fair      { color: #d29922; }
+    .strength-label.s-good      { color: #3fb950; }
+    .strength-label.s-strong    { color: #56d364; font-weight: 600; }
+
+    .char-counter {
+      font-size: 10px;
+      color: #6e7681;
+      margin: 0;
+      font-variant-numeric: tabular-nums;
+    }
+
+    .entropy-line {
+      font-size: 10px;
+      color: #8b949e;
+      margin-top: 2px;
+      font-family: "SF Mono", "JetBrains Mono", monospace;
+      min-height: 1em;
+    }
+
+    .pass-help {
+      background: #0d1117;
+      border: 1px solid #21262d;
+      border-left: 2px solid #1f6feb;
+      border-radius: 4px;
+      padding: 8px 12px;
+      font-size: 11px;
+      color: #8b949e;
+      line-height: 1.55;
+      margin: 10px 0;
+    }
+    .pass-help strong { color: #c9d1d9; }
+
+    .passphrase-field {
+      position: relative;
+    }
+    .passphrase-field input {
+      padding-right: 76px;   /* room for match indicator + eye button */
+    }
+    .eye-btn {
+      position: absolute;
+      right: 6px;
+      top: 50%;
+      transform: translateY(-50%);
+      height: 24px;
+      padding: 0 8px;
+      background: transparent;
+      border: 1px solid #30363d;
+      border-radius: 3px;
+      color: #8b949e;
+      cursor: pointer;
+      font-size: 10px;
+      font-family: inherit;
+      text-transform: lowercase;
+      letter-spacing: 0.03em;
+    }
+    .eye-btn:hover { color: #c9d1d9; border-color: #484f58; }
+
+    .match-indicator {
+      position: absolute;
+      right: 50px;
+      top: 50%;
+      transform: translateY(-50%);
+      font-size: 16px;
+      line-height: 1;
+      pointer-events: none;
+      transition: color 0.15s ease, opacity 0.15s ease;
+    }
+    .match-indicator.ok  { color: #3fb950; }
+    .match-indicator.bad { color: #f85149; }
+
+    /* Primary button explicitly dims when disabled so the gate is obvious. */
+    .btn-primary:disabled {
+      opacity: 0.45;
+      cursor: not-allowed;
     }
-    .strength-label.weak   { color: #f85149; }
-    .strength-label.strong { color: #3fb950; }
 
     .success-box {
       background: #0d1b0e;

extension/src/setup/setup.ts

@@ -38,6 +38,9 @@ interface WizardState {
   passphraseConfirm: string;
   // zxcvbn meter state — -1 means "not yet scored" (empty passphrase).
   passphraseScore: number;
+  passphraseGuessesLog10: number;   // -1 before first rating
+  passphraseVisible: boolean;
+  confirmVisible: boolean;
   referenceImageBytes: Uint8Array | null;
   creating: boolean;
   error: string | null;
@@ -56,6 +59,9 @@ const state: WizardState = {
   passphrase: '',
   passphraseConfirm: '',
   passphraseScore: -1,
+  passphraseGuessesLog10: -1,
+  passphraseVisible: false,
+  confirmVisible: false,
   referenceImageBytes: null,
   creating: false,
   error: null,
@@ -73,9 +79,11 @@ function escapeHtml(s: string): string {
     .replace(/"/g, '"');
 }
 
-/// Call the SW to score a passphrase with zxcvbn. Returns a score in [0, 4]
+interface Strength { score: number; guessesLog10: number }
-/// per the zxcvbn convention, or -1 if the message round-trip failed.
+
-function ratePassphrase(passphrase: string): Promise<number> {
+/// Call the SW to score a passphrase with zxcvbn. Returns score in [0, 4]
+/// and guesses_log10, or -1 on both if the round-trip failed.
+function ratePassphrase(passphrase: string): Promise<Strength> {
   return new Promise((resolve) => {
     try {
       chrome.runtime.sendMessage(
@@ -84,20 +92,23 @@ function ratePassphrase(passphrase: string): Promise<number> {
           if (chrome.runtime.lastError) {
             // eslint-disable-next-line no-console
             console.warn('[relicario setup] rate_passphrase lastError:', chrome.runtime.lastError);
-            resolve(-1); return;
+            resolve({ score: -1, guessesLog10: -1 }); return;
           }
           if (!response?.ok) {
             // eslint-disable-next-line no-console
             console.warn('[relicario setup] rate_passphrase rejected by SW:', response);
-            resolve(-1); return;
+            resolve({ score: -1, guessesLog10: -1 }); return;
           }
-          resolve(response.data?.score ?? -1);
+          resolve({
+            score: response.data?.score ?? -1,
+            guessesLog10: response.data?.guesses_log10 ?? -1,
+          });
         },
       );
     } catch (err) {
       // eslint-disable-next-line no-console
       console.warn('[relicario setup] rate_passphrase threw:', err);
-      resolve(-1);
+      resolve({ score: -1, guessesLog10: -1 });
     }
   });
 }
@@ -105,36 +116,101 @@ function ratePassphrase(passphrase: string): Promise<number> {
 /// 150ms debounce around the rate_passphrase call so we don't hammer the SW
 /// on every keystroke. The last invocation wins.
 let rateDebounceTimer: ReturnType<typeof setTimeout> | null = null;
-function scheduleRate(passphrase: string, onScore: (score: number) => void): void {
+function scheduleRate(passphrase: string, onResult: (s: Strength) => void): void {
   if (rateDebounceTimer !== null) clearTimeout(rateDebounceTimer);
   rateDebounceTimer = setTimeout(async () => {
     rateDebounceTimer = null;
-    if (!passphrase) { onScore(-1); return; }
+    if (!passphrase) { onResult({ score: -1, guessesLog10: -1 }); return; }
-    onScore(await ratePassphrase(passphrase));
+    onResult(await ratePassphrase(passphrase));
   }, 150);
 }
 
+const STRENGTH_LABELS: Record<number, { text: string; cls: string }> = {
+  0: { text: 'very weak',   cls: 's-very-weak' },
+  1: { text: 'weak',        cls: 's-weak' },
+  2: { text: 'fair',        cls: 's-fair' },
+  3: { text: 'good',        cls: 's-good' },
+  4: { text: 'strong',      cls: 's-strong' },
+};
+
+/// Render the entropy readout as "~10^N guesses to crack" or a friendlier
+/// shorthand for large values. Returns empty string when no data.
+function entropyText(guessesLog10: number): string {
+  if (guessesLog10 < 0) return '';
+  const rounded = Math.round(guessesLog10);
+  if (rounded < 6)  return `~10^${rounded} guesses — trivially crackable`;
+  if (rounded < 9)  return `~10^${rounded} guesses — minutes on a single GPU`;
+  if (rounded < 12) return `~10^${rounded} guesses — hours to days on a GPU`;
+  if (rounded < 15) return `~10^${rounded} guesses — years on consumer hardware`;
+  if (rounded < 20) return `~10^${rounded} guesses — beyond consumer-hardware reach`;
+  return `~10^${rounded} guesses — effectively uncrackable`;
+}
+
 /// Update just the meter DOM without a full re-render (so the input keeps
-/// focus and the user's cursor position is preserved).
+/// focus and the user's cursor position is preserved). Also updates the
+/// char counter and confirm-match indicator live.
 function updateStrengthUi(): void {
   const bar = document.getElementById('strength-bar');
   const label = document.getElementById('strength-label');
+  const entropy = document.getElementById('entropy-line');
+  const counter = document.getElementById('passphrase-counter');
+  const matchInd = document.getElementById('match-indicator');
   const create = document.getElementById('create-btn') as HTMLButtonElement | null;
+
   const score = state.passphraseScore;
+  const guessesLog10 = state.passphraseGuessesLog10;
+
   if (bar) bar.className = `strength-bar${score >= 0 ? ` s${score}` : ''}`;
+
   if (label) {
     if (score < 0) {
       label.className = 'strength-label';
       label.innerHTML = '&nbsp;';
-    } else if (score >= 3) {
-      label.className = 'strength-label strong';
-      label.textContent = 'Strong enough';
     } else {
-      label.className = 'strength-label weak';
+      const meta = STRENGTH_LABELS[score] ?? STRENGTH_LABELS[0];
-      label.textContent = 'Too weak';
+      label.className = `strength-label ${meta.cls}`;
+      label.textContent = meta.text;
     }
   }
-  if (create) create.disabled = state.creating || score < 3;
+
+  if (entropy) {
+    const txt = entropyText(guessesLog10);
+    entropy.textContent = txt;
+    entropy.style.visibility = txt ? 'visible' : 'hidden';
+  }
+
+  if (counter) {
+    const n = state.passphrase.length;
+    counter.textContent = n === 0 ? '' : `${n} character${n === 1 ? '' : 's'}`;
+  }
+
+  if (matchInd) {
+    const p = state.passphrase;
+    const c = state.passphraseConfirm;
+    if (!p || !c) {
+      matchInd.className = 'match-indicator';
+      matchInd.textContent = '';
+    } else if (p === c) {
+      matchInd.className = 'match-indicator ok';
+      matchInd.textContent = '✓';
+    } else {
+      matchInd.className = 'match-indicator bad';
+      matchInd.textContent = '✗';
+    }
+  }
+
+  const matchOk = !state.passphraseConfirm || state.passphrase === state.passphraseConfirm;
+  if (create) {
+    const disabled = state.creating || score < 3 || !state.passphraseConfirm || !matchOk;
+    create.disabled = disabled;
+    create.title = disabled
+      ? (score < 3
+          ? 'passphrase must score "good" or better'
+          : !state.passphraseConfirm ? 'confirm your passphrase'
+          : !matchOk ? 'passphrases do not match'
+          : '')
+      : '';
+  }
 }
 
 // --- Render ---
@@ -320,17 +396,34 @@ function attachStep2(): void {
 
 function renderStep3(): string {
   const score = state.passphraseScore;
+  const guessesLog10 = state.passphraseGuessesLog10;
   const hasScore = score >= 0;
   const meterClass = hasScore ? `s${score}` : '';
-  const labelClass = hasScore ? (score >= 3 ? 'strong' : 'weak') : '';
+  const labelMeta = hasScore ? STRENGTH_LABELS[score] : null;
-  const labelText = !hasScore
+  const labelClass = labelMeta?.cls ?? '';
-    ? '&nbsp;'
+  const labelText = labelMeta?.text ?? '&nbsp;';
-    : (score >= 3 ? 'Strong enough' : 'Too weak');
+  const entropy = entropyText(guessesLog10);
-  const gateDisabled = state.creating || score < 3;
+
+  const p = state.passphrase;
+  const c = state.passphraseConfirm;
+  const matchState = !p || !c ? '' : p === c ? 'ok' : 'bad';
+  const matchGlyph = matchState === 'ok' ? '✓' : matchState === 'bad' ? '✗' : '';
+
+  const pType = state.passphraseVisible ? 'text' : 'password';
+  const cType = state.confirmVisible ? 'text' : 'password';
+  const pToggle = state.passphraseVisible ? 'hide' : 'show';
+  const cToggle = state.confirmVisible ? 'hide' : 'show';
+
+  const matchOk = !c || p === c;
+  const gateDisabled = state.creating || score < 3 || !c || !matchOk;
+
+  const nChars = p.length;
+  const counterText = nChars === 0 ? '' : `${nChars} character${nChars === 1 ? '' : 's'}`;
 
   return `
     <div class="wizard-step">
       <h3>create vault</h3>
+
       <div class="form-group">
         <label class="label">carrier image (JPEG)</label>
         <div class="file-drop ${state.carrierImageBytes ? 'has-file' : ''}" id="file-drop">
@@ -341,9 +434,18 @@ function renderStep3(): string {
         </div>
         <p class="muted" style="margin-top:4px;">A 256-bit secret will be steganographically embedded in this image.</p>
       </div>
+
+      <div class="pass-help">
+        A long phrase of unrelated words is stronger than a short complex password.
+        Your vault needs <strong>good</strong> (score&nbsp;≥&nbsp;3) to continue.
+      </div>
+
       <div class="form-group">
         <label class="label" for="passphrase">passphrase</label>
-        <input id="passphrase" type="password" value="${escapeHtml(state.passphrase)}" placeholder="enter a strong passphrase" autocomplete="new-password">
+        <div class="passphrase-field">
+          <input id="passphrase" type="${pType}" value="${escapeHtml(p)}" placeholder="enter a strong passphrase" autocomplete="new-password">
+          <button type="button" class="eye-btn" id="eye-btn" aria-label="toggle passphrase visibility">${pToggle}</button>
+        </div>
         <div class="strength-bar ${meterClass}" id="strength-bar" aria-hidden="true">
           <div class="seg i0"></div>
           <div class="seg i1"></div>
@@ -351,12 +453,22 @@ function renderStep3(): string {
           <div class="seg i3"></div>
           <div class="seg i4"></div>
         </div>
-        <p class="strength-label ${labelClass}" id="strength-label">${labelText}</p>
+        <div class="strength-row">
+          <p class="strength-label ${labelClass}" id="strength-label">${labelText}</p>
+          <p class="char-counter" id="passphrase-counter">${escapeHtml(counterText)}</p>
+        </div>
+        <p class="entropy-line" id="entropy-line" style="visibility:${entropy ? 'visible' : 'hidden'};">${escapeHtml(entropy || ' ')}</p>
       </div>
+
       <div class="form-group">
         <label class="label" for="passphrase-confirm">confirm passphrase</label>
-        <input id="passphrase-confirm" type="password" value="${escapeHtml(state.passphraseConfirm)}" placeholder="re-enter passphrase" autocomplete="new-password">
+        <div class="passphrase-field">
+          <input id="passphrase-confirm" type="${cType}" value="${escapeHtml(c)}" placeholder="re-enter passphrase" autocomplete="new-password">
+          <span class="match-indicator ${matchState}" id="match-indicator">${matchGlyph}</span>
+          <button type="button" class="eye-btn" id="confirm-eye-btn" aria-label="toggle confirm visibility">${cToggle}</button>
+        </div>
       </div>
+
       <div class="form-actions">
         <button class="btn" id="back-btn">back</button>
         <button class="btn btn-primary" id="create-btn" ${gateDisabled ? 'disabled' : ''}>
@@ -387,16 +499,41 @@ function attachStep3(): void {
 
   // Track passphrase changes inline (no full re-render) so the input keeps focus.
   // zxcvbn score is computed via the SW on a 150ms debounce — see scheduleRate.
-  document.getElementById('passphrase')?.addEventListener('input', (e) => {
+  const passInput = document.getElementById('passphrase') as HTMLInputElement | null;
+  passInput?.addEventListener('input', (e) => {
     state.passphrase = (e.target as HTMLInputElement).value;
-    scheduleRate(state.passphrase, (score) => {
+    // Update char counter + match indicator + button gate immediately on every keystroke.
-      state.passphraseScore = score;
+    updateStrengthUi();
+    // Score updates on the 150ms debounce to avoid SW hammering.
+    scheduleRate(state.passphrase, (s) => {
+      state.passphraseScore = s.score;
+      state.passphraseGuessesLog10 = s.guessesLog10;
       updateStrengthUi();
     });
   });
 
-  document.getElementById('passphrase-confirm')?.addEventListener('input', (e) => {
+  const confirmInput = document.getElementById('passphrase-confirm') as HTMLInputElement | null;
+  confirmInput?.addEventListener('input', (e) => {
     state.passphraseConfirm = (e.target as HTMLInputElement).value;
+    updateStrengthUi();
+  });
+
+  // Eye toggles — flip the input type and label without a full re-render so
+  // focus + cursor position survive the click.
+  document.getElementById('eye-btn')?.addEventListener('click', () => {
+    state.passphraseVisible = !state.passphraseVisible;
+    if (passInput) passInput.type = state.passphraseVisible ? 'text' : 'password';
+    const btn = document.getElementById('eye-btn');
+    if (btn) btn.textContent = state.passphraseVisible ? 'hide' : 'show';
+    passInput?.focus();
+  });
+
+  document.getElementById('confirm-eye-btn')?.addEventListener('click', () => {
+    state.confirmVisible = !state.confirmVisible;
+    if (confirmInput) confirmInput.type = state.confirmVisible ? 'text' : 'password';
+    const btn = document.getElementById('confirm-eye-btn');
+    if (btn) btn.textContent = state.confirmVisible ? 'hide' : 'show';
+    confirmInput?.focus();
   });
 
   document.getElementById('back-btn')?.addEventListener('click', () => {
@@ -423,7 +560,9 @@ function attachStep3(): void {
     // Re-rate synchronously in case the button was clicked before the
     // debounced rater fired. Defence in depth — the button is already
     // disabled in the UI when score < 3 (audit H3).
-    state.passphraseScore = await ratePassphrase(state.passphrase);
+    const strength = await ratePassphrase(state.passphrase);
+    state.passphraseScore = strength.score;
+    state.passphraseGuessesLog10 = strength.guessesLog10;
     if (state.passphraseScore < 3) {
       state.error = 'Passphrase is too weak (zxcvbn score must be ≥ 3).';
       render();