refactor(tui): move last-msg elapsed from status bar to prompt right-edge

Status bar ticker was too hot in peripheral vision. The moment the elapsed
value matters is when the prompt returns — so surface it there. Dim
`fmtDuration` next to the GoodVibesHeart, idle-only (hidden while busy),
so quick turns and active streaming stay quiet.

ui-tui/src/components/appChrome.tsx

@@ -55,7 +55,7 @@ function ctxBar(pct: number | undefined, w = 10) {
   return '█'.repeat(filled) + '░'.repeat(w - filled)
 }
 
-function SessionDuration({ lastUserAt, startedAt }: { lastUserAt?: null | number; startedAt: number }) {
+function SessionDuration({ startedAt }: { startedAt: number }) {
   const [now, setNow] = useState(() => Date.now())
 
   useEffect(() => {
@@ -65,9 +65,20 @@ function SessionDuration({ lastUserAt, startedAt }: { lastUserAt?: null | number
     return () => clearInterval(id)
   }, [startedAt])
 
-  const total = fmtDuration(now - startedAt)
+  return fmtDuration(now - startedAt)
+}
 
-  return lastUserAt ? `${fmtDuration(now - lastUserAt)}/${total}` : total
+export function IdleSinceLastMsg({ lastUserAt, t }: { lastUserAt: number; t: Theme }) {
+  const [now, setNow] = useState(() => Date.now())
+
+  useEffect(() => {
+    setNow(Date.now())
+    const id = setInterval(() => setNow(Date.now()), 1000)
+
+    return () => clearInterval(id)
+  }, [lastUserAt])
+
+  return <Text color={t.color.dim}>{fmtDuration(now - lastUserAt)} </Text>
 }
 
 export function GoodVibesHeart({ tick, t }: { tick: number; t: Theme }) {
@@ -100,7 +111,6 @@ export function StatusRule({
   model,
   usage,
   bgCount,
-  lastUserAt,
   sessionStartedAt,
   showCost,
   voiceLabel,
@@ -135,7 +145,7 @@ export function StatusRule({
           {sessionStartedAt ? (
             <Text color={t.color.dim}>
               {' │ '}
-              <SessionDuration lastUserAt={lastUserAt} startedAt={sessionStartedAt} />
+              <SessionDuration startedAt={sessionStartedAt} />
             </Text>
           ) : null}
           {voiceLabel ? <Text color={t.color.dim}> │ {voiceLabel}</Text> : null}
@@ -290,7 +300,6 @@ interface StatusRuleProps {
   busy: boolean
   cols: number
   cwdLabel: string
-  lastUserAt?: null | number
   model: string
   sessionStartedAt?: null | number
   showCost: boolean

ui-tui/src/components/appLayout.tsx

@@ -9,7 +9,7 @@ import { PLACEHOLDER } from '../content/placeholders.js'
 import type { Theme } from '../theme.js'
 import type { DetailsMode } from '../types.js'
 
-import { GoodVibesHeart, StatusRule, StickyPromptTracker, TranscriptScrollbar } from './appChrome.js'
+import { GoodVibesHeart, IdleSinceLastMsg, StatusRule, StickyPromptTracker, TranscriptScrollbar } from './appChrome.js'
 import { FloatingOverlays, PromptZone } from './appOverlays.js'
 import { Banner, Panel, SessionPanel } from './branding.js'
 import { MessageLine } from './messageLine.js'
@@ -188,7 +188,6 @@ const ComposerPane = memo(function ComposerPane({
             busy={ui.busy}
             cols={composer.cols}
             cwdLabel={status.cwdLabel}
-            lastUserAt={status.lastUserAt}
             model={ui.info?.model?.split('/').pop() ?? ''}
             sessionStartedAt={status.sessionStartedAt}
             showCost={ui.showCost}
@@ -243,7 +242,9 @@ const ComposerPane = memo(function ComposerPane({
                 value={composer.input}
               />
 
-              <Box position="absolute" right={0}>
+              <Box flexDirection="row" position="absolute" right={0}>
+                {!ui.busy && status.lastUserAt ? <IdleSinceLastMsg lastUserAt={status.lastUserAt} t={ui.theme} /> : null}
+
                 <GoodVibesHeart t={ui.theme} tick={status.goodVibesTick} />
               </Box>
             </Box>