fix(emailclient): 10-issue polish pass — visual feedback, state sync, UX

- Selected email card: add secondary-container bg + left accent border
- Unread email cards: add primary left border accent
- StarButton: sync local state with parent via useEffect([isStarred])
- Initial dark mode: useEffect applies data-theme on mount
- Star active color: amber #f9a825 via .star-button--active CSS rule
- Unread count badge: styled as pill with primary-container background
- Empty state: add inbox/folder_open material icon
- Folder toolbar label: capitalize + replace underscores with spaces
- ComposeWindow: CC/BCC hidden by default, revealed via Cc/Bcc button
- Email header: flex layout for .header-top, column gap for .header-details

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

components/fakemui/email/atoms/StarButton.tsx

@@ -1,5 +1,5 @@
 // fakemui/email/atoms/StarButton.tsx
-import React, { forwardRef, useState } from 'react'
+import React, { forwardRef, useEffect, useState } from 'react'
 import { MaterialIcon } from '../../../../icons/react/fakemui'
 import { useAccessible } from '../../../../hooks/useAccessible'
 
@@ -16,6 +16,8 @@ export const StarButton = forwardRef<
 >(({ isStarred = false, onToggleStar, testId, ...props }, ref) => {
   const [starred, setStarred] = useState(isStarred)
 
+  useEffect(() => { setStarred(isStarred) }, [isStarred])
+
   const accessible = useAccessible({
     feature: 'email',
     component: 'star-button',

components/fakemui/email/surfaces/ComposeWindow.tsx

@@ -24,6 +24,7 @@ export const ComposeWindow = ({
   const [bcc, setBcc] = useState<string[]>([])
   const [subject, setSubject] = useState('')
   const [body, setBody] = useState('')
+  const [showCcBcc, setShowCcBcc] = useState(false)
   const accessible = useAccessible({
     feature: 'email', component: 'compose',
     identifier: customTestId || 'compose'
@@ -58,15 +59,37 @@ export const ComposeWindow = ({
         </button>
       </Box>
       <Box className="compose-body">
-        <RecipientInput recipientType="to"
-          recipients={to} onRecipientsChange={setTo}
-          placeholder="To:" />
-        <RecipientInput recipientType="cc"
-          recipients={cc} onRecipientsChange={setCc}
-          placeholder="Cc:" />
-        <RecipientInput recipientType="bcc"
-          recipients={bcc} onRecipientsChange={setBcc}
-          placeholder="Bcc:" />
+        <Box style={{ display: 'flex', alignItems: 'center', gap: '8px' }}>
+          <RecipientInput recipientType="to"
+            recipients={to} onRecipientsChange={setTo}
+            placeholder="To:" />
+          {!showCcBcc && (
+            <button
+              type="button"
+              onClick={() => setShowCcBcc(true)}
+              style={{
+                fontSize: '0.75rem',
+                color: 'var(--mat-sys-on-surface-variant)',
+                whiteSpace: 'nowrap',
+                flexShrink: 0,
+                padding: '4px 6px',
+              }}
+              aria-label="Show Cc and Bcc fields"
+            >
+              Cc/Bcc
+            </button>
+          )}
+        </Box>
+        {showCcBcc && (
+          <>
+            <RecipientInput recipientType="cc"
+              recipients={cc} onRecipientsChange={setCc}
+              placeholder="Cc:" />
+            <RecipientInput recipientType="bcc"
+              recipients={bcc} onRecipientsChange={setBcc}
+              placeholder="Bcc:" />
+          </>
+        )}
         <input type="text" placeholder="Subject"
           value={subject} id="compose-subject"
           aria-label="Subject"

frontends/emailclient/app/EmailClientContent.tsx

@@ -1,6 +1,6 @@
 'use client'
 
-import React from 'react'
+import React, { useEffect } from 'react'
 import {
   MailboxLayout,
   MailboxHeader,
@@ -15,6 +15,13 @@ import { useEmailClient } from './hooks/useEmailClient'
 export default function EmailClientContent() {
   const { state, actions } = useEmailClient()
 
+  useEffect(() => {
+    document.documentElement.setAttribute(
+      'data-theme',
+      state.isDarkMode ? 'dark' : 'light'
+    )
+  }, [state.isDarkMode])
+
   const header = (
     <MailboxHeader
       searchQuery={state.searchQuery}
@@ -53,7 +60,9 @@ export default function EmailClientContent() {
           variant="body2"
           className="mailbox-thread-folder-label"
         >
-          {state.activeFolder}
+          {state.activeFolder
+            .replace(/_/g, ' ')
+            .replace(/^\w/, c => c.toUpperCase())}
           {state.filteredEmails.length > 0 &&
             ` (${state.filteredEmails.length})`}
         </Typography>
@@ -66,6 +75,11 @@ export default function EmailClientContent() {
       </Box>
       {state.filteredEmails.length === 0 ? (
         <Box className="mailbox-empty-state">
+          <span className="material-symbols-outlined mailbox-empty-icon">
+            {state.activeFolder === 'inbox' || state.searchQuery
+              ? 'inbox'
+              : 'folder_open'}
+          </span>
           <Typography variant="body2">
             {state.activeFolder === 'inbox' &&
             state.searchQuery

frontends/emailclient/app/globals.css

@@ -339,10 +339,15 @@ input, textarea, select {
 }
 
 .folder-nav-item .unread-count {
-  font-size: 0.75rem;
-  font-weight: 600;
+  background-color: var(--mat-sys-primary-container);
+  color: var(--mat-sys-on-primary-container);
+  border-radius: var(--mat-sys-corner-full);
+  padding: 0 6px;
+  font-size: 0.6875rem;
+  font-weight: 700;
+  min-width: 18px;
+  text-align: center;
   margin-left: auto;
-  color: var(--mat-sys-on-surface-variant);
 }
 
 /* Active folder — filled tonal */
@@ -616,8 +621,17 @@ input, textarea, select {
   border-color: var(--mat-sys-surface-variant);
 }
 
+/* Issue 1 — selected card distinct highlight */
+.email-card[aria-current="true"] {
+  background-color: var(--mat-sys-secondary-container) !important;
+  border-left: 3px solid var(--mat-sys-primary);
+  padding-left: 13px;
+}
+
 .email-card--unread {
   background-color: var(--mat-sys-surface-container-lowest);
+  border-left: 3px solid var(--mat-sys-primary);
+  padding-left: 13px;
 }
 
 .email-card--unread .email-from,
@@ -698,6 +712,15 @@ input, textarea, select {
   background-color: var(--mat-sys-surface-container-high);
 }
 
+/* Issue 4 — starred state amber color */
+.star-button--active {
+  color: #f9a825;
+}
+
+.star-button--active .material-symbols-outlined {
+  color: #f9a825;
+}
+
 /* ============================================ */
 /* Email Detail / Reading Pane                  */
 /* ============================================ */
@@ -714,6 +737,21 @@ input, textarea, select {
   line-height: 1.3;
 }
 
+/* Issue 9 — email header metadata layout */
+.header-top {
+  display: flex;
+  align-items: flex-start;
+  justify-content: space-between;
+  gap: 8px;
+}
+
+.header-details {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+  margin-top: 12px;
+}
+
 /* ============================================ */
 /* Thread Panel (main area)                     */
 /* ============================================ */