fix(activity): bell glyph for unread + larger row state icon

The unread mini-dot stacked on the AgentStateDot competed with the dot
itself for the eye and read like a status badge on the agent state.
Replace it with a small BellDot glyph at the icon's top-right corner so
the unread cue rhymes with the bell button on ThreadRow — one unread
vocabulary across both surfaces.

While here, bump the row state icon to a new 'lg' AgentStateDot size
(18px) so the green check sits center-of-mass in its 32px column instead
of floating small and high. Bump the WorktreeEventRow Plus glyph to
match.

Co-authored-by: Orca <help@stably.ai>

src/renderer/src/components/AgentStateDot.tsx

@@ -44,7 +44,7 @@ export function agentStateLabel(state: AgentDotState): string {
 
 type Props = {
   state: AgentDotState
-  size?: 'sm' | 'md'
+  size?: 'sm' | 'md' | 'lg'
   className?: string
 }
 
@@ -53,9 +53,12 @@ export const AgentStateDot = React.memo(function AgentStateDot({
   size = 'sm',
   className
 }: Props): React.JSX.Element {
-  const box = size === 'md' ? 'h-3 w-3' : 'h-2.5 w-2.5'
-  const inner = size === 'md' ? 'size-2' : 'size-1.5'
-  const icon = size === 'md' ? 'size-3' : 'size-2.5'
+  // Why ('lg' size): the Activity page renders this in its own 32px column
+  // alongside text rows, where 'md' (12px) reads small and floats. 'lg' (18px)
+  // sits center of mass in that cell.
+  const box = size === 'lg' ? 'h-[18px] w-[18px]' : size === 'md' ? 'h-3 w-3' : 'h-2.5 w-2.5'
+  const inner = size === 'lg' ? 'size-3' : size === 'md' ? 'size-2' : 'size-1.5'
+  const icon = size === 'lg' ? 'size-[18px]' : size === 'md' ? 'size-3' : 'size-2.5'
 
   if (state === 'working') {
     return (

src/renderer/src/components/activity/ActivityPrototypePage.tsx

@@ -352,22 +352,22 @@ function AgentEventRow({
         event.unread && 'bg-accent/20'
       )}
     >
-      <div className="flex justify-center pt-1">
+      <div className="flex items-center justify-center pt-0.5">
         <span className="relative inline-flex">
-          {/* Why: anchor the unread dot to the icon's own bounding box (not the
-              24×24 cell) so it tracks the icon's top-left corner regardless of
-              icon size. The previous absolute -left-1 top-1 inside a size-6 box
-              landed visibly off-center against the centered AgentStateDot. */}
+          {/* Why (bell as unread glyph): visually rhymes with the Bell button on
+              ThreadRow so both surfaces share one unread vocabulary. Sits at
+              the icon's top-right corner with a fill-background halo so the
+              bell reads cleanly against the row's tinted unread background. */}
           {event.unread ? (
-            <span
-              className="absolute -top-1 -left-1 size-2 rounded-full bg-primary ring-2 ring-background"
+            <BellDot
+              className="absolute -top-1.5 -right-2 size-3.5 text-primary fill-background"
               aria-hidden
             />
           ) : null}
           <Tooltip>
             <TooltipTrigger asChild>
               <span className="inline-flex">
-                <AgentStateDot state={dotState} size="md" />
+                <AgentStateDot state={dotState} size="lg" />
               </span>
             </TooltipTrigger>
             <TooltipContent side="top" sideOffset={4}>
@@ -454,17 +454,17 @@ function WorktreeEventRow({
         event.unread && 'bg-accent/20'
       )}
     >
-      <div className="flex justify-center pt-0.5">
+      <div className="flex items-center justify-center pt-0.5">
         <span className="relative inline-flex text-muted-foreground">
-          {/* Why: see AgentEventRow — anchor the unread dot to the icon, not the
-              cell, so it lines up at the icon's top-left corner. */}
+          {/* Why: see AgentEventRow — bell at the icon's top-right matches the
+              unread vocabulary used on ThreadRow. */}
           {event.unread ? (
-            <span
-              className="absolute -top-1 -left-1 size-2 rounded-full bg-primary ring-2 ring-background"
+            <BellDot
+              className="absolute -top-1.5 -right-2 size-3.5 text-primary fill-background"
               aria-hidden
             />
           ) : null}
-          <Plus className="size-4" />
+          <Plus className="size-[18px]" />
         </span>
       </div>
       <div className="min-w-0">