feat(desktop): polish composer pill toward reference look

Solid foreground-on-background send/voice-conversation circle (black-on-white
in light, white-on-black in dark) anchors the right edge as the primary CTA
instead of the orange theme primary. Bumps the primary control to 2.125rem so
it visually outranks the ghost mic/plus controls. Opens up the surface padding
(0.625rem x / 0.5rem y) so the input row breathes around its controls, and
nudges the corner radius from 20 to 24px for a slightly pill-ier silhouette.
LiquidGlass distortion is preserved.

apps/desktop/src/app/chat/composer/controls.tsx

@@ -8,6 +8,15 @@ import type { ChatBarState, VoiceStatus } from './types'
 
 export const ICON_BTN = 'size-(--composer-control-size) shrink-0 rounded-full'
 export const GHOST_ICON_BTN = cn(ICON_BTN, 'text-muted-foreground hover:bg-accent hover:text-foreground')
+// Send/voice-conversation primary: solid foreground-on-background circle
+// (reads as black-on-white in light mode, white-on-black in dark mode) to
+// match the reference composer's high-contrast CTA. Keeps the pill itself
+// neutral and lets the action visually dominate the row.
+export const PRIMARY_ICON_BTN = cn(
+  'size-(--composer-control-primary-size,var(--composer-control-size)) shrink-0 rounded-full p-0',
+  'bg-foreground text-background hover:bg-foreground/90',
+  'disabled:bg-foreground/30 disabled:text-background disabled:opacity-100'
+)
 
 interface ConversationProps {
   active: boolean
@@ -51,7 +60,7 @@ export function ComposerControls({
       {showVoicePrimary ? (
         <Button
           aria-label="Start voice conversation"
-          className={cn(ICON_BTN, 'p-0')}
+          className={PRIMARY_ICON_BTN}
           disabled={disabled}
           onClick={() => {
             triggerHaptic('open')
@@ -66,7 +75,7 @@ export function ComposerControls({
       ) : (
         <Button
           aria-label={busy ? 'Stop' : 'Send'}
-          className={cn(ICON_BTN, 'p-0')}
+          className={PRIMARY_ICON_BTN}
           disabled={disabled || !canSubmit}
           type="submit"
         >

apps/desktop/src/app/chat/composer/hooks/use-composer-glass-tweaks.ts

@@ -20,13 +20,13 @@ const COMPOSER_GLASS_TWEAKS: ComposerGlassTweakOutputs = {
   liquid: {
     aberrationIntensity: 0.95,
     blurAmount: 0.072,
-    cornerRadius: 20,
+    cornerRadius: 24,
     displacementScale: 46,
     elasticity: 0,
     mode: 'standard',
     saturation: 128
   },
-  liquidKey: ['standard', '0.950', '0.072', '20', '46', '0.00', '128'].join(':'),
+  liquidKey: ['standard', '0.950', '0.072', '24', '46', '0.00', '128'].join(':'),
   showLibraryRims: false
 }
 

apps/desktop/src/app/chat/composer/index.tsx

@@ -951,7 +951,7 @@ export function ChatBar({
           <div className="relative w-full">
             <div
               className={cn(
-                'composer-liquid-shell-wrap absolute inset-0 isolate overflow-hidden rounded-(--composer-glass-radius,20px) transition-opacity duration-200 ease-out',
+                'composer-liquid-shell-wrap absolute inset-0 isolate overflow-hidden rounded-(--composer-glass-radius,24px) transition-opacity duration-200 ease-out',
                 'group-has-data-[state=open]/composer:rounded-t-none',
                 scrolledUp ? COMPOSER_SCROLLED_DIM_CLASS : 'opacity-100'
               )}
@@ -1044,7 +1044,7 @@ export function ChatBarFallback() {
     <div
       className={cn(COMPOSER_SHELL_CLASS, 'bg-linear-to-b from-transparent to-background/55')}
       data-slot="composer-root"
-      style={{ '--composer-active-radius': '1.25rem' } as CSSProperties}
+      style={{ '--composer-active-radius': '1.5rem' } as CSSProperties}
     >
       <div className="relative isolate h-(--composer-fallback-height) w-full overflow-hidden rounded-(--composer-active-radius) border border-input/70 shadow-composer">
         <div aria-hidden className={COMPOSER_FROST_CLASS} />

apps/desktop/src/app/chat/composer/liquid-glass-overrides.css

@@ -62,12 +62,12 @@
   width: 100% !important;
   height: 100% !important;
   padding: 0 !important;
-  border-radius: var(--composer-glass-radius, 20px) !important;
+  border-radius: var(--composer-glass-radius, 24px) !important;
   box-shadow: none !important;
 }
 
 .composer-liquid-shell > .glass > .glass__warp {
-  border-radius: var(--composer-glass-radius, 20px) !important;
+  border-radius: var(--composer-glass-radius, 24px) !important;
 }
 
 .composer-liquid-shell > .glass > div {

apps/desktop/src/styles.css

@@ -125,10 +125,15 @@
     --composer-target-width: 68%;
     --composer-max-width: 56rem;
     --composer-control-size: 2rem;
+    /* Send / voice-conversation circle is one notch larger than the ghost
+     * controls so the primary CTA visually anchors the right edge. */
+    --composer-control-primary-size: 2.125rem;
     --composer-control-gap: 0.375rem;
     --composer-row-gap: 0.375rem;
-    --composer-surface-pad-x: 0.5rem;
-    --composer-surface-pad-y: 0.375rem;
+    /* Reference-clean padding: enough breathing room around the input row
+     * that the pill no longer feels cramped against its controls. */
+    --composer-surface-pad-x: 0.625rem;
+    --composer-surface-pad-y: 0.5rem;
     --composer-input-min-height: 2rem;
     --composer-input-max-height: 9.375rem;
     --composer-input-inline-min-width: 8rem;