Merge remote-tracking branch 'origin/staging' into codex/fix-rectification-focus-baseline

# Conflicts:
#	docs/BUG_HISTORY.md

frontend/src/app/globals.css

@@ -272,7 +272,6 @@ button:disabled { cursor: default; opacity: .45; }
 }
 
 @media (max-width: 767px) {
-  .conversation.is-empty { display: block; }
   .brand-row { padding: 0 4px; }
   .brand-mark { width: 26px; height: 26px; }
   .session-nav { overflow: hidden; }
@@ -327,7 +326,7 @@ button:disabled { cursor: default; opacity: .45; }
 .app-loading-error { background: var(--color-canvas-soft); }
 .app-loading-error .app-loading-content { padding: 28px; border: 1px solid var(--color-border); background: var(--color-canvas); border-color: var(--color-border); border-radius: var(--radius-lg); box-shadow: var(--shadow-elevated); }
 
-.group\/sidebar-provider[data-viewport] { height: 100dvh; min-height: 0; overflow: hidden; }
+.group\/sidebar-provider[data-viewport] { height: 100vh; height: 100dvh; min-height: 0; overflow: hidden; }
 .chat-app { width: 100%; height: 100%; min-height: 0; overflow: hidden; display: grid; background: var(--color-canvas); grid-template-columns: minmax(0, 1fr); }
 .sidebar { position: relative; width: 100%; height: 100%; min-width: 0; min-height: 0; overflow: hidden; display: flex; flex-direction: column; border-right: 1px solid var(--sidebar-border); color: var(--sidebar-foreground); padding: var(--space-5) var(--space-3) 0; background: var(--sidebar-background); backdrop-filter: saturate(130%) blur(20px); }
 [data-sidebar="header"] { flex: 0 0 auto; }
@@ -910,7 +909,13 @@ input:not([class^="ant-"]):not([class*=" ant-"]):not(.ant-picker input):disabled
   [data-sidebar="rail"] { display: none; }
   .chat-panel { grid-template-rows: calc(64px + env(safe-area-inset-top)) minmax(0, 1fr) auto; }
   .chat-header { gap: 10px; padding: max(0px, env(safe-area-inset-top)) var(--space-3) 0; }
-  .conversation.is-empty { padding: var(--space-5) var(--space-4); }
+  .conversation.is-empty {
+    display: block;
+    place-items: initial;
+    overflow-y: auto;
+    -webkit-overflow-scrolling: touch;
+    padding: var(--space-5) var(--space-4);
+  }
   .welcome { padding: var(--space-6) 0 var(--space-10); }
   .welcome > .onboarding-message:first-child .message-bubble p { font-size: var(--type-display-sm); }
   .starter-list { grid-template-columns: 1fr; grid-template-rows: auto; }
@@ -1218,43 +1223,36 @@ input:not([class^="ant-"]):not([class*=" ant-"]):not(.ant-picker input):disabled
 }
 
 .starter-theme-accordion {
-  display: flex;
   min-width: 0;
-  overflow: hidden;
-  border: 1px solid var(--color-border);
-  border-radius: var(--radius-xl);
-  background: var(--color-canvas-soft);
+  display: grid;
+  grid-template-columns: repeat(3, minmax(0, 1fr));
+  gap: var(--space-3);
 }
 
 .starter-theme-card {
   position: relative;
   min-width: 0;
-  min-height: 170px;
-  flex: 1 1 0;
+  min-height: 156px;
   display: grid;
   grid-template-columns: minmax(0, 1fr) 20px;
   align-items: end;
   gap: var(--space-3);
   padding: var(--space-5);
-  border: 0;
-  border-right: 1px solid var(--color-border);
-  background: transparent;
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-lg);
+  background: var(--color-canvas-soft);
   cursor: pointer;
   text-align: left;
-  transition: background-color 150ms ease-out;
-}
-
-.starter-theme-card:last-child {
-  border-right: 0;
+  transition: border-color 180ms ease-out, background-color 180ms ease-out, box-shadow 180ms ease-out, transform 180ms var(--ease-out);
 }
 
 .starter-theme-card:not(:disabled):active {
   background: color-mix(in srgb, var(--color-action-soft) 56%, var(--color-canvas));
 }
 
-.starter-theme-card:not(:disabled):active .starter-arrow {
-  color: var(--color-action);
-  transform: translate(2px, -2px);
+.starter-theme-card:focus-visible {
+  border-color: color-mix(in srgb, var(--color-action) 38%, var(--color-border));
+  box-shadow: var(--shadow-soft);
 }
 
 @media (hover: hover) {
@@ -1278,7 +1276,7 @@ input:not([class^="ant-"]):not([class*=" ant-"]):not(.ant-picker input):disabled
 }
 
 .starter-content span {
-  max-width: 245px;
+  max-width: none;
   overflow: visible;
   color: var(--color-ink);
   font-family: var(--font-display);
@@ -1334,21 +1332,11 @@ input:not([class^="ant-"]):not([class*=" ant-"]):not(.ant-picker input):disabled
   }
 
   .starter-theme-accordion {
-    display: grid;
     grid-template-columns: repeat(2, minmax(0, 1fr));
   }
 
   .starter-theme-card {
-    min-height: 136px;
-    border-bottom: 1px solid var(--color-border);
-  }
-
-  .starter-theme-card:nth-child(2n) {
-    border-right: 0;
-  }
-
-  .starter-theme-card:nth-last-child(-n + 2) {
-    border-bottom: 0;
+    min-height: 142px;
   }
 }
 
@@ -1394,17 +1382,12 @@ input:not([class^="ant-"]):not([class*=" ant-"]):not(.ant-picker input):disabled
   }
 
   .starter-theme-accordion {
-    display: grid;
+    grid-template-columns: 1fr;
+    gap: var(--space-3);
   }
 
   .starter-theme-card {
-    min-height: 116px;
-    border-right: 0;
-    border-bottom: 1px solid var(--color-border);
-  }
-
-  .starter-theme-card:last-child {
-    border-bottom: 0;
+    min-height: 112px;
   }
 
   .starter-content span {