feat(web): add turn-duration event display

web/src/chat/normalizeAgent.ts

@@ -232,6 +232,20 @@ export function normalizeAgentRecord(
                 meta
             }
         }
+        if (data.type === 'system' && data.subtype === 'turn_duration') {
+            return {
+                id: messageId,
+                localId,
+                createdAt,
+                role: 'event',
+                content: {
+                    type: 'turn-duration',
+                    durationMs: asNumber(data.durationMs) ?? 0
+                },
+                isSidechain: false,
+                meta
+            }
+        }
         return null
     }
 

web/src/chat/presentation.ts

@@ -7,6 +7,14 @@ export function formatUnixTimestamp(value: number): string {
     return date.toLocaleString()
 }
 
+function formatDuration(ms: number): string {
+    const seconds = ms / 1000
+    if (seconds < 60) return `${seconds.toFixed(1)}s`
+    const mins = Math.floor(seconds / 60)
+    const secs = Math.round(seconds % 60)
+    return `${mins}m ${secs}s`
+}
+
 export type EventPresentation = {
     icon: string | null
     text: string
@@ -46,6 +54,10 @@ export function getEventPresentation(event: AgentEvent): EventPresentation {
     if (event.type === 'message') {
         return { icon: null, text: typeof event.message === 'string' ? event.message : 'Message' }
     }
+    if (event.type === 'turn-duration') {
+        const ms = typeof event.durationMs === 'number' ? event.durationMs : 0
+        return { icon: '⏱️', text: `Turn: ${formatDuration(ms)}` }
+    }
     try {
         return { icon: null, text: JSON.stringify(event) }
     } catch {

web/src/chat/types.ts

@@ -15,6 +15,7 @@ export type AgentEvent =
     | { type: 'limit-reached'; endsAt: number }
     | { type: 'ready' }
     | { type: 'api-error'; retryAttempt: number; maxRetries: number; error: unknown }
+    | { type: 'turn-duration'; durationMs: number }
     | ({ type: string } & Record<string, unknown>)
 
 export type ToolResultPermission = {