src/components/BoardActivity.test.tsx

@@ -0,0 +1,32 @@
+import { describe, it, expect } from 'vitest'
+import { render, screen } from '@testing-library/react'
+import { BoardActivity } from './BoardActivity'
+import type { NodeActivityEntry } from '@/lib/useCollective'
+
+const entry = (over: Partial<NodeActivityEntry>): NodeActivityEntry => ({
+  teamId: 't1',
+  kind: 'flash',
+  label: 'Flashed to 0x80F0000',
+  ts: 'T',
+  ...over,
+})
+
+describe('BoardActivity', () => {
+  it('shows an empty hint when there is no activity', () => {
+    render(<BoardActivity activity={[]} />)
+    expect(screen.getByTestId('board-activity-empty')).toBeInTheDocument()
+  })
+
+  it('renders entries newest-first with resolved team names', () => {
+    render(
+      <BoardActivity
+        activity={[entry({ label: 'Flashed to 0x80F0000' }), entry({ kind: 'thinking', label: 'Agent started' })]}
+        nameFor={(id) => (id === 't1' ? 'Team Rocket' : id)}
+      />,
+    )
+    const items = screen.getByTestId('board-activity').querySelectorAll('li')
+    expect(items).toHaveLength(2)
+    expect(items[0]).toHaveTextContent('Flashed to 0x80F0000')
+    expect(screen.getAllByText('Team Rocket')).toHaveLength(2)
+  })
+})

src/components/BoardActivity.tsx

@@ -0,0 +1,47 @@
+import type { NodeActivityEntry } from '@/lib/useCollective'
+import type { NodeActivityKind } from '@/types'
+import { cn } from '@/lib/utils'
+
+const KIND_DOT: Record<NodeActivityKind, string> = {
+  thinking: 'bg-muted-foreground',
+  tool: 'bg-amber',
+  flash: 'bg-primary',
+  error: 'bg-destructive',
+  response: 'bg-teal',
+}
+
+export interface BoardActivityProps {
+  activity: NodeActivityEntry[]
+  /** Resolve a teamId to a display name (falls back to the id). */
+  nameFor?: (teamId: string) => string
+}
+
+/** Instructor-facing rolling feed of real on-device agent activity across boards. */
+export function BoardActivity({ activity, nameFor }: BoardActivityProps) {
+  if (activity.length === 0) {
+    return (
+      <p data-testid="board-activity-empty" className="font-mono text-[11px] text-muted-foreground">
+        No board activity yet — boards report generate / compile / flash here as teams work.
+      </p>
+    )
+  }
+  return (
+    <ul data-testid="board-activity" className="space-y-1.5">
+      {activity.map((e, i) => (
+        <li key={i} className="flex items-center gap-2 font-mono text-[11px]">
+          <span className={cn('w-1.5 h-1.5 rounded-full shrink-0', KIND_DOT[e.kind])} />
+          <span className="text-muted-foreground shrink-0">{nameFor ? nameFor(e.teamId) : e.teamId}</span>
+          <span
+            className={cn(
+              'truncate',
+              e.kind === 'error' && 'text-destructive',
+              e.kind === 'flash' && 'text-foreground font-medium',
+            )}
+          >
+            {e.label}
+          </span>
+        </li>
+      ))}
+    </ul>
+  )
+}

src/lib/useCollective.test.ts

@@ -13,7 +13,7 @@ const team = (id: string): TeamSnapshot => ({
   updatedAt: '2026-07-27T13:00:00.000Z',
 })
 
-const empty: CollectiveState = { teams: {}, submissions: {} }
+const empty: CollectiveState = { teams: {}, submissions: {}, nodes: {}, activity: [] }
 
 describe('collectiveReducer', () => {
   it('seeds from a snapshot', () => {
@@ -46,4 +46,35 @@ describe('collectiveReducer', () => {
     const next = collectiveReducer(empty, { type: 'score:new', teamId: 'ghost', total: 1 })
     expect(next).toBe(empty)
   })
+
+  it('tracks per-team board online status on node:status', () => {
+    const next = collectiveReducer(empty, { type: 'node:status', teamId: 'a', online: true })
+    expect(next.nodes.a).toBe(true)
+    const off = collectiveReducer(next, { type: 'node:status', teamId: 'a', online: false })
+    expect(off.nodes.a).toBe(false)
+  })
+
+  it('prepends node:activity to a bounded, most-recent-first feed', () => {
+    const first = collectiveReducer(empty, {
+      type: 'node:activity',
+      teamId: 'a',
+      kind: 'thinking',
+      label: 'Agent started',
+      ts: 'T1',
+    })
+    const second = collectiveReducer(first, {
+      type: 'node:activity',
+      teamId: 'a',
+      kind: 'flash',
+      label: 'Flashed to 0x80F0000',
+      ts: 'T2',
+    })
+    expect(second.activity.map((e) => e.label)).toEqual(['Flashed to 0x80F0000', 'Agent started'])
+  })
+
+  it('preserves node status/activity across a fresh snapshot', () => {
+    const withNode = collectiveReducer(empty, { type: 'node:status', teamId: 'a', online: true })
+    const next = collectiveReducer(withNode, { type: 'snapshot', teams: [team('a')], submissions: [] })
+    expect(next.nodes.a).toBe(true)
+  })
 })

src/lib/useCollective.ts

@@ -1,13 +1,25 @@
 import { useEffect, useReducer, useRef, useState } from 'react'
 import { openCollective, getTeams, getSubmissions } from './api'
-import type { TeamSnapshot, SubmissionSummary, WsEvent } from '@/types'
+import type { TeamSnapshot, SubmissionSummary, WsEvent, NodeActivityKind } from '@/types'
+
+export interface NodeActivityEntry {
+  teamId: string
+  kind: NodeActivityKind
+  label: string
+  ts: string
+}
 
 export interface CollectiveState {
   teams: Record<string, TeamSnapshot>
   submissions: Record<string, SubmissionSummary>
+  /** teamId → board online. */
+  nodes: Record<string, boolean>
+  /** rolling board-activity feed, most-recent-first, bounded. */
+  activity: NodeActivityEntry[]
 }
 
-const empty: CollectiveState = { teams: {}, submissions: {} }
+const MAX_ACTIVITY = 40
+const empty: CollectiveState = { teams: {}, submissions: {}, nodes: {}, activity: [] }
 
 export function collectiveReducer(state: CollectiveState, event: WsEvent): CollectiveState {
   switch (event.type) {
@@ -16,7 +28,7 @@ export function collectiveReducer(state: CollectiveState, event: WsEvent): Colle
       event.teams.forEach((t) => (teams[t.id] = t))
       const submissions: Record<string, SubmissionSummary> = {}
       event.submissions.forEach((s) => (submissions[s.teamId] = s))
-      return { teams, submissions }
+      return { ...state, teams, submissions }
     }
     case 'team:update':
       return { ...state, teams: { ...state.teams, [event.team.id]: event.team } }
@@ -33,6 +45,16 @@ export function collectiveReducer(state: CollectiveState, event: WsEvent): Colle
         submissions: { ...state.submissions, [event.teamId]: { ...existing, scored: true } },
       }
     }
+    case 'node:status':
+      return { ...state, nodes: { ...state.nodes, [event.teamId]: event.online } }
+    case 'node:activity':
+      return {
+        ...state,
+        activity: [
+          { teamId: event.teamId, kind: event.kind, label: event.label, ts: event.ts },
+          ...state.activity,
+        ].slice(0, MAX_ACTIVITY),
+      }
     default:
       return state
   }
@@ -43,6 +65,8 @@ export type CollectiveStatus = 'connecting' | 'live' | 'polling'
 export interface Collective {
   teams: TeamSnapshot[]
   submissions: Record<string, SubmissionSummary>
+  nodes: Record<string, boolean>
+  activity: NodeActivityEntry[]
   status: CollectiveStatus
 }
 
@@ -93,5 +117,5 @@ export function useCollective(code: string): Collective {
   }, [code])
 
   const teams = Object.values(state.teams).sort((a, b) => a.name.localeCompare(b.name))
-  return { teams, submissions: state.submissions, status }
+  return { teams, submissions: state.submissions, nodes: state.nodes, activity: state.activity, status }
 }

src/pages/Admin.tsx

@@ -1,6 +1,7 @@
 import { Link } from 'react-router-dom'
 import { AccessGate } from '@/components/AccessGate'
 import { TeamCard } from '@/components/TeamCard'
+import { BoardActivity } from '@/components/BoardActivity'
 import { useCollective } from '@/lib/useCollective'
 import { useNow } from '@/lib/useNow'
 import { cn } from '@/lib/utils'
@@ -15,11 +16,13 @@ function Stat({ label, value }: { label: string; value: number | string }) {
 }
 
 function AdminBoard({ code }: { code: string }) {
-  const { teams, submissions, status } = useCollective(code)
+  const { teams, submissions, nodes, activity, status } = useCollective(code)
   const now = useNow()
   const connected = teams.filter((t) => t.deviceConnected).length
+  const boardsLive = Object.values(nodes).filter(Boolean).length
   const submittedCount = Object.keys(submissions).length
   const judgedCount = Object.values(submissions).filter((s) => s.scored).length
+  const nameFor = (id: string) => teams.find((t) => t.id === id)?.name || id
 
   return (
     <main className="min-h-screen bg-background">
@@ -40,13 +43,19 @@ function AdminBoard({ code }: { code: string }) {
       </header>
 
       <section className="px-8 py-8 max-w-6xl mx-auto space-y-6">
-        <div className="grid grid-cols-2 md:grid-cols-4 gap-px bg-border rounded-md overflow-hidden">
+        <div className="grid grid-cols-2 md:grid-cols-5 gap-px bg-border rounded-md overflow-hidden">
           <Stat label="Teams" value={teams.length} />
           <Stat label="Connected" value={connected} />
+          <Stat label="Boards live" value={boardsLive} />
           <Stat label="Submitted" value={submittedCount} />
           <Stat label="Judged" value={judgedCount} />
         </div>
 
+        <div className="border border-border rounded-md p-4 space-y-2">
+          <div className="font-mono text-[10px] uppercase tracking-widest text-muted-foreground">Board activity</div>
+          <BoardActivity activity={activity} nameFor={nameFor} />
+        </div>
+
         {teams.length === 0 ? (
           <p className="text-sm text-muted-foreground">No teams have checked in yet.</p>
         ) : (