feat(onboarding): 5 clickable mnemonic suggestions per letter

- Dot words: ≤3 letters (was ≤2) — two-letter words like "go/it" were too limiting
- Dash words: ≥4 letters (unchanged in practice)
- Added DOT_WORDS and DASH_WORDS banks (~60 and ~200 words)
- suggestPhrases() generates 5 random valid suggestions per letter
- MnemonicBuilder shows clickable suggestion pills; "↻ new" refreshes them
- Selected suggestion highlights in gold; user can still type their own

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/src/components/MnemonicBuilder.tsx

@@ -1,5 +1,5 @@
-import { useState } from 'react'
-import { NOVICE_LETTERS, MORSE, validatePhrase } from '../lib/morse'
+import { useState, useEffect } from 'react'
+import { NOVICE_LETTERS, MORSE, validatePhrase, suggestPhrases } from '../lib/morse'
 
 type Props = {
   token: string
@@ -13,6 +13,7 @@ export function MnemonicBuilder({ token, onComplete }: Props) {
   const [phrase, setPhrase] = useState('')
   const [saving, setSaving] = useState(false)
   const [error, setError] = useState<string | null>(null)
+  const [suggestions, setSuggestions] = useState<string[]>([])
 
   const letter = LETTERS[index]
   const pattern = MORSE[letter] ?? ''
@@ -20,6 +21,12 @@ export function MnemonicBuilder({ token, onComplete }: Props) {
   const display = pattern.split('').map(c => c === '.' ? '·' : '—').join(' ')
   const validation = phrase.trim() ? validatePhrase(phrase.trim(), letter) : null
 
+  useEffect(() => {
+    setSuggestions(suggestPhrases(letter, 5))
+    setPhrase('')
+    setError(null)
+  }, [letter])
+
   async function save() {
     if (!validation?.valid) return
     setSaving(true)
@@ -47,8 +54,6 @@ export function MnemonicBuilder({ token, onComplete }: Props) {
       onComplete()
     } else {
       setIndex(i => i + 1)
-      setPhrase('')
-      setError(null)
     }
   }
 
@@ -88,14 +93,14 @@ export function MnemonicBuilder({ token, onComplete }: Props) {
         Create your mnemonic phrase:
       </label>
       <p style={{ fontSize: '0.85rem', color: 'var(--color-brown)', marginBottom: '0.5rem' }}>
-        {pattern.length} word{pattern.length !== 1 ? 's' : ''} — short words (1-2 letters) for dots,
-        long words (3+ letters) for dashes.
+        {pattern.length} word{pattern.length !== 1 ? 's' : ''} —
+        {' '}≤3 letters for dots · (short), 4+ letters for dashes — (long).
       </p>
       <input
         type="text"
         value={phrase}
         onChange={e => { setPhrase(e.target.value); setError(null) }}
-        placeholder={`${pattern.length} word${pattern.length !== 1 ? 's' : ''}, e.g. "${examplePhrase(pattern)}"`}
+        placeholder={`e.g. "${examplePhrase(pattern)}"`}
         disabled={saving}
         style={{ marginBottom: '0.5rem' }}
       />
@@ -115,6 +120,61 @@ export function MnemonicBuilder({ token, onComplete }: Props) {
         <p style={{ color: 'crimson', fontSize: '0.9rem', marginBottom: '0.5rem' }}>{error}</p>
       )}
 
+      {/* Suggestions */}
+      <div style={{ marginTop: '0.75rem', marginBottom: '1rem' }}>
+        <div style={{
+          display: 'flex',
+          alignItems: 'center',
+          gap: '0.5rem',
+          marginBottom: '0.4rem',
+        }}>
+          <span style={{ fontSize: '0.85rem', color: 'var(--color-brown)' }}>
+            Suggestions — click to use:
+          </span>
+          <button
+            type="button"
+            onClick={() => setSuggestions(suggestPhrases(letter, 5))}
+            disabled={saving}
+            style={{
+              padding: '0.1rem 0.4rem',
+              fontSize: '0.8rem',
+              background: 'none',
+              border: '1px solid var(--color-brown)',
+              borderRadius: '0.25rem',
+              cursor: 'pointer',
+              color: 'var(--color-brown)',
+              lineHeight: 1.4,
+            }}
+          >
+            ↻ new
+          </button>
+        </div>
+        <div style={{ display: 'flex', flexDirection: 'column', gap: '0.35rem' }}>
+          {suggestions.map(s => (
+            <button
+              key={s}
+              type="button"
+              onClick={() => { setPhrase(s); setError(null) }}
+              disabled={saving}
+              style={{
+                padding: '0.35rem 0.7rem',
+                fontSize: '0.9rem',
+                fontFamily: 'var(--font-mono)',
+                background: phrase === s ? 'var(--color-gold)' : 'var(--color-parchment)',
+                border: `1px solid ${phrase === s ? 'var(--color-gold)' : '#c8a96e'}`,
+                borderRadius: '0.25rem',
+                cursor: 'pointer',
+                color: 'var(--color-forest)',
+                textAlign: 'left',
+                transition: 'background 0.1s',
+              }}
+            >
+              {s}
+            </button>
+          ))}
+        </div>
+      </div>
+
       {/* Actions */}
       <div style={{ display: 'flex', gap: '0.75rem', marginTop: '1rem' }}>
         <button
@@ -139,5 +199,5 @@ export function MnemonicBuilder({ token, onComplete }: Props) {
 
 // Generate a simple example phrase for the placeholder
 function examplePhrase(pattern: string): string {
-  return pattern.split('').map(c => c === '.' ? 'go' : 'WALKING').join(' ')
+  return pattern.split('').map(c => c === '.' ? 'run' : 'WALK').join(' ')
 }

client/src/lib/morse.test.ts

@@ -3,10 +3,13 @@ import {
   MORSE,
   NOVICE_LETTERS,
   OPERATOR_WORDS,
+  DOT_WORDS,
+  DASH_WORDS,
   wpmToTiming,
   DEFAULT_WPM,
   DEFAULT_TIMING,
   validatePhrase,
+  suggestPhrases,
   pickChallenge,
 } from './morse'
 
@@ -71,16 +74,65 @@ describe('wpmToTiming', () => {
   })
 })
 
+describe('DOT_WORDS and DASH_WORDS', () => {
+  it('all DOT_WORDS are 3 letters or less', () => {
+    DOT_WORDS.forEach(w => expect(w.length).toBeLessThanOrEqual(3))
+  })
+  it('all DASH_WORDS are 4 letters or more', () => {
+    DASH_WORDS.forEach(w => expect(w.length).toBeGreaterThanOrEqual(4))
+  })
+  it('has at least 30 DOT_WORDS', () => expect(DOT_WORDS.length).toBeGreaterThanOrEqual(30))
+  it('has at least 30 DASH_WORDS', () => expect(DASH_WORDS.length).toBeGreaterThanOrEqual(30))
+})
+
+describe('suggestPhrases', () => {
+  it('returns 5 suggestions for A (.-)', () => {
+    const s = suggestPhrases('A', 5)
+    expect(s).toHaveLength(5)
+  })
+  it('each suggestion has correct word count', () => {
+    const s = suggestPhrases('S', 5) // S = ...  (3 words)
+    s.forEach(phrase => expect(phrase.split(' ')).toHaveLength(3))
+  })
+  it('suggestions for E are single words ≤3 letters', () => {
+    const s = suggestPhrases('E', 5)
+    s.forEach(phrase => {
+      expect(phrase.split(' ')).toHaveLength(1)
+      expect(phrase.length).toBeLessThanOrEqual(3)
+    })
+  })
+  it('returns empty array for unknown letter', () => {
+    expect(suggestPhrases('$', 5)).toEqual([])
+  })
+})
+
 describe('validatePhrase', () => {
   it('accepts valid phrase for E (.)', () => {
     expect(validatePhrase('go', 'E')).toEqual({ valid: true })
   })
+  it('accepts 3-letter dot word', () => {
+    expect(validatePhrase('run', 'E')).toEqual({ valid: true })
+  })
   it('accepts valid phrase for A (.-)', () => {
     expect(validatePhrase('go WALKING', 'A')).toEqual({ valid: true })
   })
   it('accepts valid phrase for S (...)', () => {
     expect(validatePhrase('go go go', 'S')).toEqual({ valid: true })
   })
+  it('rejects 4-letter word in dot position', () => {
+    const r = validatePhrase('walk go go', 'S')
+    expect(r.valid).toBe(false)
+  })
+  it('accepts 3-letter word in dot position', () => {
+    expect(validatePhrase('run', 'E')).toEqual({ valid: true })
+  })
+  it('rejects 3-letter word in dash position', () => {
+    const r = validatePhrase('go go', 'A') // A=.- so second word must be 4+ letters
+    expect(r.valid).toBe(false)
+  })
+  it('accepts 4-letter word in dash position', () => {
+    expect(validatePhrase('go walk', 'A')).toEqual({ valid: true })
+  })
   it('rejects wrong word count', () => {
     const r = validatePhrase('go go', 'S')
     expect(r.valid).toBe(false)
@@ -90,10 +142,6 @@ describe('validatePhrase', () => {
     const r = validatePhrase('WALKING go go', 'S')
     expect(r.valid).toBe(false)
   })
-  it('rejects short word for dash position', () => {
-    const r = validatePhrase('go go', 'A')
-    expect(r.valid).toBe(false)
-  })
   it('rejects unknown letter', () => {
     expect(validatePhrase('test', '1')).toEqual({ valid: false, message: 'Unknown letter' })
   })

client/src/lib/morse.ts

@@ -46,6 +46,68 @@ export interface ValidationResult {
   message?: string
 }
 
+// Words for mnemonic suggestions
+export const DOT_WORDS = [
+  'go','do','be','see','run','fly','set','try','can','the','win','get',
+  'top','sky','sun','sea','war','key','age','all','now','one','big','far',
+  'low','red','old','hot','new','day','eat','ice','joy','leg','man','out',
+  'pay','put','raw','sad','shy','son','tap','tin','toe','toy','two','use',
+  'way','you','aim','air','ask','bit','cut','dry','fun','god','had','hit',
+  'its','law','log','lot','mad','mix','net','not','odd','pet','row','she',
+]
+
+export const DASH_WORDS = [
+  'walk','sail','camp','hunt','fire','bold','fast','tall','dark','wide',
+  'long','deep','hard','warm','cool','loud','slow','sure','true','real',
+  'free','gold','star','wave','wind','lion','hawk','rock','iron','rise',
+  'lead','dare','race','grow','find','make','keep','know','call','glow',
+  'best','blue','book','burn','calm','care','cave','city','coal','code',
+  'cold','cook','cost','cure','dawn','deal','deck','dive','door','down',
+  'drum','dust','earn','east','edge','epic','face','fact','fair','fall',
+  'fame','farm','fate','feel','feet','fill','fine','firm','fish','flag',
+  'flow','food','form','fort','game','gate','gear','give','goal','good',
+  'gray','grin','grow','gulf','gust','hail','hair','hall','hand','harm',
+  'hawk','head','heal','heat','help','high','hike','hill','hold','hole',
+  'home','hook','hope','horn','host','huge','idea','iron','jest','join',
+  'jump','just','kill','kind','king','kiss','lake','lamp','land','lane',
+  'last','late','leaf','leap','lend','lift','like','line','link','live',
+  'lock','lone','look','love','lure','main','make','many','mark','mast',
+  'meal','mean','meet','mind','mine','miss','mist','more','most','move',
+  'much','must','name','need','next','none','noon','note','pain','pale',
+  'park','part','pass','path','peak','pick','pile','plan','play','plot',
+  'plow','pole','pond','pool','port','pour','pull','push','race','rain',
+  'rank','read','reed','rest','ride','ring','rise','risk','road','roam',
+  'roar','rock','roll','roof','room','rope','rose','ruin','rule','rush',
+  'rust','sage','sale','sand','save','seal','seat','sell','send','ship',
+  'shop','shot','shut','side','silk','sing','sink','site','skip','soak',
+  'soar','soul','soup','span','spin','spot','spur','star','stay','stem',
+  'step','stir','stop','take','tale','talk','tame','tank','task','tell',
+  'tent','term','test','than','that','them','they','tide','time','toll',
+  'tone','tool','toss','tour','town','trek','trim','trip','tune','turn',
+  'veil','vine','vote','wail','wait','wake','wall','warn','wash','wave',
+  'weed','week','well','went','wide','wife','wild','will','wind','wine',
+  'wing','wire','wise','wish','wolf','wood','wool','word','work','worn',
+  'yarn','yell','zone','zoom',
+]
+
+export function suggestPhrases(letter: string, count: number): string[] {
+  const upper = letter.toUpperCase()
+  const pattern = MORSE[upper]
+  if (!pattern) return []
+  const elements = pattern.split('')
+  const results: string[] = []
+  const seen = new Set<string>()
+  for (let attempt = 0; attempt < count * 30 && results.length < count; attempt++) {
+    const words = elements.map(el => {
+      const pool = el === '.' ? DOT_WORDS : DASH_WORDS
+      return pool[Math.floor(Math.random() * pool.length)]
+    })
+    const phrase = words.join(' ')
+    if (!seen.has(phrase)) { seen.add(phrase); results.push(phrase) }
+  }
+  return results
+}
+
 export function validatePhrase(phrase: string, letter: string): ValidationResult {
   const upper = letter.toUpperCase()
   const pattern = /^[A-Z]$/.test(upper) ? MORSE[upper] : undefined
@@ -63,12 +125,12 @@ export function validatePhrase(phrase: string, letter: string): ValidationResult
 
   for (let i = 0; i < words.length; i++) {
     const isDot = elements[i] === '.'
-    const isShort = words[i].length <= 2
+    const isShort = words[i].length <= 3
     if (isDot && !isShort) {
-      return { valid: false, message: `Word "${words[i]}" should be short (1-2 chars) for a dot` }
+      return { valid: false, message: `"${words[i]}" is too long for a dot — use 3 letters or less` }
     }
     if (!isDot && isShort) {
-      return { valid: false, message: `Word "${words[i]}" should be longer (3+ chars) for a dash` }
+      return { valid: false, message: `"${words[i]}" is too short for a dash — use 4+ letters` }
     }
   }