wip introduce a performance monitor in-app

compose.yml

@@ -213,6 +213,8 @@ services:
       - "7880:7880"
       - "7881:7881"
       - "7882:7882/udp"
+      - "3478:3478/udp"
+      - "30000-30100:30000-30100/udp"
     volumes:
       - ./docker/livekit/config/livekit-server.yaml:/config.yaml
     depends_on:

docker/livekit/config/livekit-server.yaml

@@ -8,3 +8,16 @@ webhook:
   api_key: devkey
   urls:
       - http://app-dev:8000/api/v1.0/rooms/webhooks-livekit/
+
+turn:
+  enabled: true
+  domain: turn.192.168.1.50.nip.io
+  udp_port: 3478
+  tls_port: 0
+  external_tls: false
+  relay_range_start: 30000
+  relay_range_end: 30100
+  allow_restricted_peer_cidrs:
+    - 192.168.0.0/16
+    - 172.16.0.0/12
+

src/frontend/src/features/devtools/MeetDevtools.tsx

@@ -0,0 +1,608 @@
+import { CSSProperties, useState } from 'react'
+import { useConnectionState, useRoomContext } from '@livekit/components-react'
+import { ConnectionState } from 'livekit-client'
+import { StatsSnapshot, TrackRow, useWebRTCStats } from './useWebRTCStats'
+import { readRoomConfig } from './roomConfig'
+import {
+  forceTransport,
+  releaseForcedTransport,
+  Scenario,
+  SCENARIOS,
+  setDownlinkCap,
+  setUplinkCap,
+  stepBitrate,
+  TransportMode,
+  transportModeFromRoute,
+} from './simulation'
+
+const SANS =
+  "-apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif"
+const MONO = 'ui-monospace, SFMono-Regular, Menlo, Consolas, monospace'
+
+const COLOR = {
+  text: '#e8e8e8',
+  muted: '#9a9a9a',
+  faint: '#6f6f6f',
+  hairline: '#2c2d31',
+  border: '#3d3e44',
+  surface: '#1b1c1e',
+  chartBg: '#141517',
+  down: '#f6821f',
+  up: '#5a9cf8',
+  ok: '#10b981',
+  bad: '#f05a4a',
+  busy: '#e5a13c',
+}
+
+const stateColor = (state: ConnectionState): string => {
+  switch (state) {
+    case ConnectionState.Connected:
+      return COLOR.ok
+    case ConnectionState.Reconnecting:
+    case ConnectionState.SignalReconnecting:
+      return COLOR.busy
+    case ConnectionState.Connecting:
+      return COLOR.up
+    case ConnectionState.Disconnected:
+      return COLOR.bad
+  }
+}
+
+const styles: Record<string, CSSProperties> = {
+  toggle: {
+    position: 'fixed',
+    bottom: 12,
+    right: 12,
+    zIndex: 9999,
+    fontFamily: SANS,
+    fontSize: 12,
+    lineHeight: 1,
+    padding: '8px 12px',
+    borderRadius: 999,
+    borderWidth: 1,
+    borderStyle: 'solid',
+    borderColor: COLOR.border,
+    background: COLOR.surface,
+    color: COLOR.text,
+    cursor: 'pointer',
+    boxShadow: '0 2px 10px #0006',
+  },
+  panel: {
+    position: 'fixed',
+    bottom: 12,
+    right: 12,
+    zIndex: 9999,
+    width: 460,
+    maxWidth: 'calc(100vw - 24px)',
+    maxHeight: 'calc(100vh - 24px)',
+    overflowY: 'auto',
+    fontFamily: SANS,
+    fontSize: 11,
+    lineHeight: 1.5,
+    color: COLOR.text,
+    background: COLOR.surface,
+    borderWidth: 1,
+    borderStyle: 'solid',
+    borderColor: COLOR.border,
+    borderRadius: 10,
+    padding: 14,
+    boxShadow: '0 10px 34px #00000080',
+  },
+  sectionTitle: {
+    margin: '14px 0 5px',
+    color: COLOR.faint,
+    textTransform: 'uppercase',
+    letterSpacing: 1.2,
+    fontSize: 9,
+    fontWeight: 600,
+    display: 'flex',
+    justifyContent: 'space-between',
+  },
+  metricsLine: {
+    display: 'flex',
+    alignItems: 'center',
+    gap: 16,
+    margin: '0 0 10px',
+    paddingBottom: 10,
+    borderBottom: `1px solid ${COLOR.hairline}`,
+    fontVariantNumeric: 'tabular-nums',
+  },
+  legend: {
+    display: 'flex',
+    gap: 12,
+    marginTop: 3,
+    color: COLOR.faint,
+    fontSize: 10,
+  },
+  list: { display: 'flex', flexDirection: 'column', maxHeight: '200px', overflowY: 'auto' },
+  listRow: { display: 'flex', gap: 8, padding: '1px 0' },
+  listLabel: { flex: '0 0 34%', color: COLOR.muted },
+  trackRow: {
+    display: 'flex',
+    gap: 8,
+    padding: '3px 0',
+    borderBottom: `1px solid ${COLOR.hairline}`,
+    alignItems: 'baseline',
+  },
+  trackLabel: {
+    flex: '0 0 34%',
+    whiteSpace: 'nowrap',
+    overflow: 'hidden',
+    textOverflow: 'ellipsis',
+  },
+  trackCodec: {
+    flex: '0 0 11%',
+    fontFamily: MONO,
+    fontSize: 10,
+    color: COLOR.muted,
+  },
+  trackKbps: {
+    flex: '0 0 9%',
+    textAlign: 'right',
+    fontVariantNumeric: 'tabular-nums',
+  },
+  trackDetail: { flex: 1, minWidth: 0 },
+  mono: { fontFamily: MONO, fontSize: 10, color: COLOR.muted },
+  button: {
+    fontFamily: SANS,
+    fontSize: 11,
+    padding: '3px 9px',
+    borderRadius: 5,
+    borderWidth: 1,
+    borderStyle: 'solid',
+    borderColor: COLOR.border,
+    background: '#232428',
+    color: COLOR.text,
+    cursor: 'pointer',
+  },
+  buttonActive: { borderColor: COLOR.down, color: COLOR.down },
+  buttonDisabled: { color: COLOR.faint, cursor: 'not-allowed' },
+  row: { display: 'flex', alignItems: 'center', gap: 6, flexWrap: 'wrap' },
+  stepperValue: {
+    minWidth: 92,
+    textAlign: 'center',
+    borderWidth: 1,
+    borderStyle: 'solid',
+    borderColor: COLOR.hairline,
+    borderRadius: 4,
+    padding: '2px 6px',
+    background: COLOR.chartBg,
+    fontVariantNumeric: 'tabular-nums',
+  },
+  close: {
+    background: 'none',
+    border: 'none',
+    color: COLOR.faint,
+    cursor: 'pointer',
+    fontSize: 14,
+  },
+}
+
+const Sparkline = ({ history }: { history: StatsSnapshot[] }) => {
+  const width = 430
+  const height = 54
+  const max = Math.max(...history.map((s) => Math.max(s.upKbps, s.downKbps)), 1)
+  const points = (pick: (s: StatsSnapshot) => number) =>
+    history
+      .map(
+        (s, i) =>
+          `${((i / Math.max(history.length - 1, 1)) * width).toFixed(1)},${(
+            height -
+            (pick(s) / max) * (height - 6) -
+            3
+          ).toFixed(1)}`
+      )
+      .join(' ')
+  return (
+    <>
+      <svg
+        width={width}
+        height={height}
+        role="img"
+        aria-label="Bandwidth over the last minute"
+        style={{
+          display: 'block',
+          background: COLOR.chartBg,
+          borderRadius: 6,
+          border: `1px solid ${COLOR.hairline}`,
+        }}
+      >
+        {history.length >= 2 && (
+          <>
+            <polyline
+              points={points((s) => s.downKbps)}
+              fill="none"
+              stroke={COLOR.down}
+              strokeWidth="1.5"
+            />
+            <polyline
+              points={points((s) => s.upKbps)}
+              fill="none"
+              stroke={COLOR.up}
+              strokeWidth="1.5"
+            />
+          </>
+        )}
+      </svg>
+      {/* Legend outside the plot: text over the lines was unreadable. */}
+      <div style={styles.legend}>
+        <span>
+          <span style={{ color: COLOR.down }}>●</span> down
+        </span>
+        <span>
+          <span style={{ color: COLOR.up }}>●</span> up
+        </span>
+        <span>last 60s · max {Math.round(max)} kbps</span>
+      </div>
+    </>
+  )
+}
+
+const TrackDetail = ({ track }: { track: TrackRow }) => {
+  const parts: Array<{ text: string; tone?: 'warn' | 'muted' }> = []
+  if (track.res) parts.push({ text: track.res })
+  if (track.fps !== undefined) {
+    parts.push({ text: `${Math.round(track.fps)}fps` })
+  }
+  if (track.lossPct !== undefined && track.lossPct > 0) {
+    parts.push({ text: `loss ${track.lossPct.toFixed(1)}%`, tone: 'warn' })
+  }
+  if (track.froze) parts.push({ text: 'freeze', tone: 'warn' })
+  if (track.limitation) {
+    parts.push({ text: `lim:${track.limitation}`, tone: 'warn' })
+  }
+  const layer = track.layer
+  if (layer) {
+    if (layer.availRes && layer.availRes !== track.res) {
+      parts.push({
+        text: `≤${layer.availRes}${layer.layerCount ? `(${layer.layerCount}L)` : ''}`,
+        tone: 'muted',
+      })
+    }
+    if (layer.reason === 'adaptive' && layer.elementRes) {
+      parts.push({ text: `fit:${layer.elementRes}`, tone: 'muted' })
+    } else if (layer.reason === 'bandwidth') {
+      parts.push({ text: 'bw-limited', tone: 'warn' })
+    } else if (layer.reason === 'paused') {
+      parts.push({ text: 'paused:SFU', tone: 'warn' })
+    } else if (layer.reason === 'off-screen') {
+      parts.push({ text: 'off-screen', tone: 'muted' })
+    }
+  }
+  return (
+    <>
+      {parts.map((part, i) => (
+        <span
+          key={part.text}
+          style={
+            part.tone === 'warn'
+              ? { color: COLOR.bad }
+              : part.tone === 'muted'
+                ? { color: COLOR.faint }
+                : {}
+          }
+        >
+          {i > 0 && ' · '}
+          {part.text}
+        </span>
+      ))}
+    </>
+  )
+}
+
+const CapStepper = ({
+  label,
+  hint,
+  valueKbps,
+  onChange,
+}: {
+  label: string
+  hint: string
+  valueKbps: number | null
+  onChange: (kbps: number | null) => void
+}) => (
+  <div style={styles.row}>
+    <span style={{ flex: '0 0 70px' }}>{label}</span>
+    <button
+      type="button"
+      style={styles.button}
+      aria-label={`Decrease ${label} bandwidth`}
+      onClick={() => onChange(stepBitrate(valueKbps, 'decrease'))}
+    >
+      −
+    </button>
+    <span
+      style={{
+        ...styles.stepperValue,
+        ...(valueKbps !== null ? { color: COLOR.down } : {}),
+      }}
+    >
+      {valueKbps === null ? 'unlimited' : `≤ ${valueKbps} kbps`}
+    </span>
+    <button
+      type="button"
+      style={styles.button}
+      aria-label={`Increase ${label} bandwidth`}
+      onClick={() => onChange(stepBitrate(valueKbps, 'increase'))}
+    >
+      +
+    </button>
+    <span style={styles.mono}>{hint}</span>
+  </div>
+)
+
+const TrackList = ({ title, rows }: { title: string; rows: TrackRow[] }) => (
+  <>
+    <div style={styles.sectionTitle}>
+      <span>
+        {title} ({rows.length})
+      </span>
+      <span>
+        {Math.round(rows.reduce((sum, t) => sum + t.kbps, 0))} kbps media
+      </span>
+    </div>
+    <div style={styles.list}>
+      {rows.map((track) => (
+        <div key={track.key} style={styles.trackRow}>
+          <span style={styles.trackLabel}>{track.label}</span>
+          <span style={styles.trackCodec}>{track.codec ?? '–'}</span>
+          <span style={styles.trackKbps}>{Math.round(track.kbps)}</span>
+          <span style={styles.trackDetail}>
+            <TrackDetail track={track} />
+          </span>
+        </div>
+      ))}
+      {rows.length === 0 && <span style={{ color: COLOR.faint }}>none</span>}
+    </div>
+  </>
+)
+
+const MeetDevtools = () => {
+  const room = useRoomContext()
+  const connState = useConnectionState(room)
+  const [open, setOpen] = useState(false)
+  const [firedScenario, setFiredScenario] = useState<string>()
+  const [uplinkCap, setUplinkCapState] = useState<number | null>(null)
+  const [downlinkCap, setDownlinkCapState] = useState<number | null>(null)
+  const { snapshot, history } = useWebRTCStats(room, open)
+
+  const transportMode: TransportMode = transportModeFromRoute(snapshot?.route)
+
+  const fireScenario = (scenario: Scenario) => {
+    setFiredScenario(scenario.id)
+    scenario.run(room).catch((e) => {
+      console.warn('[MeetDevtools] simulateScenario failed', e)
+    })
+    window.setTimeout(
+      () =>
+        setFiredScenario((current) =>
+          current === scenario.id ? undefined : current
+        ),
+      1200
+    )
+  }
+
+  if (!open) {
+    return (
+      <button
+        type="button"
+        style={styles.toggle}
+        onClick={() => setOpen(true)}
+        aria-label="Open WebRTC devtools"
+      >
+        <span style={{ color: stateColor(connState) }}>●</span> rtc
+      </button>
+    )
+  }
+
+  const config = readRoomConfig(room)
+  const published = snapshot?.tracks.filter((t) => t.dir === 'up') ?? []
+  const subscribed = snapshot?.tracks.filter((t) => t.dir === 'down') ?? []
+  const turnProtocols = snapshot?.turnProtocols ?? []
+  const transports: Array<{
+    mode: TransportMode
+    label: string
+    requires?: string
+    title: string
+  }> = [
+    {
+      mode: 'auto',
+      label: 'auto (udp)',
+      title:
+        'clears the server-cached transport preference and relay-only policy, then full reconnect',
+    },
+    {
+      mode: 'tcp',
+      label: 'tcp',
+      title: 'force-tcp — server prefers TCP candidates (ICE/TCP)',
+    },
+    {
+      mode: 'turn-udp',
+      label: 'turn:udp',
+      requires: 'udp',
+      title:
+        'client-side: iceTransportPolicy relay + full reconnect (no server hook exists)',
+    },
+    {
+      mode: 'turn-tcp',
+      label: 'turn:tcp',
+      requires: 'tcp',
+      title: 'force-tcp — lands on TURN/TCP when it is the TCP path',
+    },
+    {
+      mode: 'turn-tls',
+      label: 'turn:tls',
+      requires: 'tls',
+      title: 'force-tls — server switches you to TURN over TLS',
+    },
+  ]
+
+  return (
+    <section style={styles.panel} aria-label="WebRTC devtools">
+      <div style={styles.metricsLine}>
+        <span>
+          <span style={{ color: COLOR.down }}>↓</span> {snapshot?.downKbps ?? 0}{' '}
+          kbps
+        </span>
+        <span>
+          <span style={{ color: COLOR.up }}>↑</span> {snapshot?.upKbps ?? 0}{' '}
+          kbps
+        </span>
+        <span style={{ color: COLOR.muted }}>
+          rtt{' '}
+          <span style={{ color: COLOR.text }}>{snapshot?.rttMs ?? '–'}</span> ms
+        </span>
+        <span style={{ color: COLOR.muted }}>
+          jitter{' '}
+          <span style={{ color: COLOR.text }}>{snapshot?.jitterMs ?? '–'}</span>{' '}
+          ms
+        </span>
+        <span
+          style={{
+            color: stateColor(connState),
+            fontSize: 10,
+            marginLeft: 'auto',
+          }}
+        >
+          ● {connState}
+        </span>
+        <button
+          type="button"
+          style={styles.close}
+          onClick={() => setOpen(false)}
+          aria-label="Close WebRTC devtools"
+        >
+          ✕
+        </button>
+      </div>
+
+      <Sparkline history={history} />
+
+      <div style={styles.sectionTitle}>room configuration (live)</div>
+      <div style={styles.list}>
+        {config.map((entry) => (
+          <div key={entry.label} style={styles.listRow}>
+            <span
+              style={{
+                color:
+                  entry.on === undefined
+                    ? COLOR.faint
+                    : entry.on
+                      ? COLOR.ok
+                      : COLOR.bad,
+              }}
+            >
+              ●
+            </span>
+            <span style={styles.listLabel}>{entry.label}</span>
+            <span>{entry.value}</span>
+          </div>
+        ))}
+      </div>
+
+      <TrackList title="published ↑" rows={published} />
+      <TrackList title="subscribed ↓" rows={subscribed} />
+
+      <div style={styles.sectionTitle}>bandwidth</div>
+      <div style={{ ...styles.list, gap: 4 }}>
+        <CapStepper
+          label="uplink"
+          hint="encoder cap (setParameters)"
+          valueKbps={uplinkCap}
+          onChange={(kbps) => {
+            setUplinkCapState(kbps)
+            void setUplinkCap(room, kbps)
+          }}
+        />
+        <CapStepper
+          label="downlink"
+          hint="SFU limit (subscriber-bandwidth)"
+          valueKbps={downlinkCap}
+          onChange={(kbps) => {
+            setDownlinkCapState(kbps)
+            void setDownlinkCap(room, kbps).catch((e) =>
+              console.warn('[MeetDevtools] downlink cap failed', e)
+            )
+          }}
+        />
+      </div>
+
+      <div style={styles.sectionTitle}>transport</div>
+      <div style={styles.row}>
+        {transports.map(({ mode, label, requires, title }) => {
+          const available = !requires || turnProtocols.includes(requires)
+          const active = transportMode === mode
+          const clickable = available && !active
+          return (
+            <button
+              key={mode}
+              type="button"
+              aria-pressed={active}
+              disabled={!clickable}
+              title={available ? title : `${title} — not configured`}
+              style={{
+                ...styles.button,
+                ...(clickable || active ? {} : styles.buttonDisabled),
+                ...(active ? styles.buttonActive : {}),
+              }}
+              onClick={() => {
+                if (!clickable) return
+                void (
+                  mode === 'auto'
+                    ? releaseForcedTransport(room)
+                    : forceTransport(
+                        room,
+                        mode as 'tcp' | 'turn-udp' | 'turn-tcp' | 'turn-tls'
+                      )
+                ).catch((e) =>
+                  console.warn('[MeetDevtools] transport change failed', e)
+                )
+              }}
+            >
+              {requires && (
+                <span style={{ color: available ? COLOR.ok : COLOR.faint }}>
+                  ●{' '}
+                </span>
+              )}
+              {label}
+            </button>
+          )
+        })}
+        <span style={styles.mono}>
+          route:{' '}
+          {snapshot?.route
+            ? [
+                snapshot.route.protocol,
+                snapshot.route.type,
+                snapshot.route.relayProtocol &&
+                  `relay:${snapshot.route.relayProtocol}`,
+              ]
+                .filter(Boolean)
+                .join('·')
+            : '–'}
+        </span>
+      </div>
+
+      <div style={styles.sectionTitle}>connection scenarios</div>
+      <div style={styles.row}>
+        {SCENARIOS.map((scenario) => (
+          <button
+            key={scenario.id}
+            type="button"
+            title={`${scenario.side}-side simulation — momentary, watch the state dot`}
+            style={{
+              ...styles.button,
+              ...(firedScenario === scenario.id ? styles.buttonActive : {}),
+            }}
+            onClick={() => fireScenario(scenario)}
+          >
+            {scenario.side === 'server' ? '☁ ' : ''}
+            {scenario.label}
+          </button>
+        ))}
+      </div>
+    </section>
+  )
+}
+
+export default MeetDevtools

src/frontend/src/features/devtools/index.tsx

@@ -0,0 +1,15 @@
+import { lazy, Suspense } from 'react'
+
+
+const LazyPanel = import.meta.env.DEV
+  ? lazy(() => import('./MeetDevtools'))
+  : null
+
+export const MeetDevtools = () => {
+  if (!LazyPanel) return null
+  return (
+    <Suspense fallback={null}>
+      <LazyPanel />
+    </Suspense>
+  )
+}

src/frontend/src/features/devtools/roomConfig.ts

@@ -0,0 +1,89 @@
+import { Room } from 'livekit-client'
+
+
+export type ConfigEntry = {
+  label: string
+  value: string
+  /** true = feature actively on, false = off, undefined = informational */
+  on?: boolean
+}
+
+const formatBackupCodec = (backup: unknown): string => {
+  if (backup === undefined || backup === true) return 'auto'
+  if (backup === false) return 'off'
+  if (typeof backup === 'object' && backup !== null && 'codec' in backup) {
+    return String((backup as { codec: unknown }).codec)
+  }
+  return String(backup)
+}
+
+export const readRoomConfig = (room: Room): ConfigEntry[] => {
+  const options = room.options
+  const publish = options.publishDefaults
+  const adaptive = options.adaptiveStream
+
+  const entries: ConfigEntry[] = [
+    {
+      label: 'adaptiveStream',
+      value:
+        typeof adaptive === 'object'
+          ? JSON.stringify(adaptive)
+          : String(!!adaptive),
+      on: !!adaptive,
+    },
+    {
+      label: 'dynacast',
+      value: String(!!options.dynacast),
+      on: !!options.dynacast,
+    },
+    {
+      label: 'e2ee',
+      value: String(room.isE2EEEnabled),
+      on: room.isE2EEEnabled,
+    },
+    {
+      label: 'videoCodec',
+      value: publish?.videoCodec ?? 'default',
+    },
+    {
+      label: 'backupCodec',
+      value: formatBackupCodec(publish?.backupCodec),
+    },
+    {
+      label: 'simulcast',
+      value: String(publish?.simulcast ?? true),
+      on: publish?.simulcast ?? true,
+    },
+    {
+      label: 'audio dtx',
+      value: String(publish?.dtx ?? true),
+      on: publish?.dtx ?? true,
+    },
+    {
+      label: 'audio red',
+      value: String(publish?.red ?? true),
+      on: publish?.red ?? true,
+    },
+    {
+      label: 'quality (local)',
+      value: room.localParticipant.connectionQuality,
+    },
+  ]
+
+  const server = room.serverInfo
+  if (server) {
+    entries.push({
+      label: 'server',
+      value: [
+        server.version && `v${server.version}`,
+        server.region,
+        server.protocol !== undefined && `proto ${server.protocol}`,
+        server.edition !== undefined && `edition ${server.edition}`,
+      ]
+        .filter(Boolean)
+        .join(' · '),
+    })
+  }
+
+  return entries
+}

src/frontend/src/features/devtools/simulation.ts

@@ -0,0 +1,193 @@
+import { Room, Track } from 'livekit-client'
+// Transitive dependency of livekit-client (pinned by it); used only to
+// build the one signal request room.simulateScenario cannot express.
+import { SimulateScenario } from '@livekit/protocol'
+
+/** Shared bandwidth ladder for the −/+ steppers; null = unlimited. */
+export const BITRATE_LADDER_KBPS: Array<number | null> = [
+  null,
+  2000,
+  1000,
+  600,
+  300,
+  150,
+]
+
+export const stepBitrate = (
+  current: number | null,
+  direction: 'decrease' | 'increase'
+): number | null => {
+  const index = BITRATE_LADDER_KBPS.indexOf(current)
+  const safeIndex = index === -1 ? 0 : index
+  const next =
+    direction === 'decrease'
+      ? Math.min(safeIndex + 1, BITRATE_LADDER_KBPS.length - 1)
+      : Math.max(safeIndex - 1, 0)
+  return BITRATE_LADDER_KBPS[next]
+}
+
+const savedEncodings = new WeakMap<RTCRtpSender, Array<number | undefined>>()
+
+export const setUplinkCap = async (
+  room: Room,
+  kbps: number | null
+): Promise<void> => {
+  const senders: RTCRtpSender[] = []
+  room.localParticipant.trackPublications.forEach((pub) => {
+    const track = pub.track
+    if (track?.kind === Track.Kind.Video && track.sender) {
+      senders.push(track.sender)
+    }
+  })
+
+  for (const sender of senders) {
+    const params = sender.getParameters()
+    if (!params.encodings || params.encodings.length === 0) continue
+
+    if (kbps === null) {
+      const original = savedEncodings.get(sender)
+      params.encodings.forEach((encoding, i) => {
+        encoding.maxBitrate = original?.[i]
+      })
+      savedEncodings.delete(sender)
+    } else {
+      if (!savedEncodings.has(sender)) {
+        savedEncodings.set(
+          sender,
+          params.encodings.map((encoding) => encoding.maxBitrate)
+        )
+      }
+      const activeCount =
+        params.encodings.filter((encoding) => encoding.active !== false)
+          .length || 1
+      // Split the budget across active simulcast layers / SVC encoding.
+      const perEncoding = Math.max(
+        30_000,
+        Math.floor((kbps * 1000) / activeCount)
+      )
+      params.encodings.forEach((encoding) => {
+        encoding.maxBitrate = perEncoding
+      })
+    }
+
+    try {
+      await sender.setParameters(params)
+    } catch (e) {
+      console.warn('[MeetDevtools] setParameters failed', e)
+    }
+  }
+}
+
+
+export const setDownlinkCap = (
+  room: Room,
+  kbps: number | null
+): Promise<void> =>
+  room.simulateScenario('subscriber-bandwidth', kbps === null ? 0 : kbps * 1000)
+
+export type Scenario = {
+  id: string
+  label: string
+  /** where the simulation happens */
+  side: 'client' | 'server'
+  run: (room: Room) => Promise<void>
+}
+
+export const SCENARIOS: Scenario[] = [
+  {
+    id: 'resume',
+    label: 'reconnect (resume)',
+    side: 'client',
+    // Replays a signaling WebSocket loss; media keeps flowing, client resumes.
+    run: (room) => room.simulateScenario('signal-reconnect'),
+  },
+  {
+    id: 'resume-fail',
+    label: 'reconnect (resume fails)',
+    side: 'client',
+    // Same, but the next resume attempt fails → exercises the retry ladder.
+    run: (room) => room.simulateScenario('resume-reconnect'),
+  },
+  {
+    id: 'full-reconnect',
+    label: 'full reconnect',
+    side: 'client',
+    // Complete rejoin with brand-new peer connections.
+    run: (room) => room.simulateScenario('full-reconnect'),
+  },
+  {
+    id: 'migration',
+    label: 'server migration',
+    side: 'server',
+    run: (room) => room.simulateScenario('migration'),
+  },
+  {
+    id: 'node-failure',
+    label: 'SFU node failure',
+    side: 'server',
+    run: (room) => room.simulateScenario('node-failure'),
+  },
+  {
+    id: 'server-leave',
+    label: 'server disconnect',
+    side: 'server',
+    // Server-initiated leave: the closest thing to "you got kicked".
+    run: (room) => room.simulateScenario('server-leave'),
+  },
+]
+
+export type TransportMode =
+  | 'auto'
+  | 'tcp'
+  | 'turn-udp'
+  | 'turn-tcp'
+  | 'turn-tls'
+
+const clearServerTransportPreference = (room: Room): Promise<void> =>
+  room.engine.client.sendSimulateScenario(
+    new SimulateScenario({
+      scenario: { case: 'switchCandidateProtocol', value: 0 },
+    })
+  )
+
+const setRelayOnly = (room: Room, relay: boolean) => {
+  room.engine.rtcConfig = {
+    ...room.engine.rtcConfig,
+    iceTransportPolicy: relay ? 'relay' : 'all',
+  }
+}
+
+const settle = () => new Promise((resolve) => setTimeout(resolve, 300))
+
+export const forceTransport = async (
+  room: Room,
+  mode: 'tcp' | 'turn-udp' | 'turn-tcp' | 'turn-tls'
+): Promise<void> => {
+  if (mode === 'turn-udp') {
+    await clearServerTransportPreference(room)
+    setRelayOnly(room, true)
+    await settle()
+    return room.simulateScenario('full-reconnect')
+  }
+  setRelayOnly(room, false)
+  return room.simulateScenario(mode === 'turn-tls' ? 'force-tls' : 'force-tcp')
+}
+
+export const releaseForcedTransport = async (room: Room): Promise<void> => {
+  setRelayOnly(room, false)
+  await clearServerTransportPreference(room)
+  await settle()
+  await room.simulateScenario('full-reconnect')
+}
+
+export const transportModeFromRoute = (route?: {
+  protocol?: string
+  relayProtocol?: string
+}): TransportMode => {
+  // relayProtocol is the client→TURN leg; protocol alone means no relay.
+  if (route?.relayProtocol === 'tls') return 'turn-tls'
+  if (route?.relayProtocol === 'tcp') return 'turn-tcp'
+  if (route?.relayProtocol === 'udp') return 'turn-udp'
+  if (route?.protocol === 'tcp') return 'tcp'
+  return 'auto'
+}

src/frontend/src/features/devtools/useWebRTCStats.ts

@@ -0,0 +1,357 @@
+import { useEffect, useRef, useState } from 'react'
+import { Room, Track } from 'livekit-client'
+
+
+export type LayerInfo = {
+  /** top published layer, e.g. '1280x720' */
+  availRes?: string
+  /** number of published spatial layers (simulcast/SVC), when known */
+  layerCount?: number
+  /** largest attached element size in device px, e.g. '480x270' */
+  elementRes?: string
+  /** why the forwarded layer is below the top one */
+  reason?: 'adaptive' | 'bandwidth' | 'paused' | 'off-screen'
+}
+
+export type TrackRow = {
+  key: string
+  dir: 'up' | 'down'
+  kind: string
+  label: string
+  codec?: string
+  kbps: number
+  fps?: number
+  res?: string
+  lossPct?: number
+  limitation?: string
+  /** subscribed video only: SFU layer forwarding context */
+  layer?: LayerInfo
+  /** this track froze during the last tick */
+  froze?: boolean
+}
+
+export type StatsSnapshot = {
+  ts: number
+  /** wire totals from transport stats (includes headers, RTCP, FEC) */
+  upKbps: number
+  downKbps: number
+  rttMs?: number
+  /** worst inbound RTP jitter across subscribed tracks */
+  jitterMs?: number
+  availableOutKbps?: number
+  /** selected ICE route of the publisher transport (measured, not assumed) */
+  route?: { protocol?: string; type?: string; relayProtocol?: string }
+  /**
+   * relayProtocol values of gathered relay local candidates — i.e. which
+   * client→TURN transports are actually configured (udp/tcp/tls). Empty
+   * when no TURN server is configured.
+   */
+  turnProtocols: string[]
+  tracks: TrackRow[]
+}
+
+type StatDict = Record<string, unknown>
+type Counters = Record<string, number>
+
+const asNumber = (v: unknown): number | undefined =>
+  typeof v === 'number' && Number.isFinite(v) ? v : undefined
+
+const asString = (v: unknown): string | undefined =>
+  typeof v === 'string' ? v : undefined
+
+const shortCodec = (mimeType?: string) =>
+  mimeType ? mimeType.replace(/^(audio|video)\//, '') : undefined
+
+type TrackContext = { label: string; layer?: LayerInfo; publishedH?: number }
+
+/**
+ * msTrackId -> label + subscribed-layer context, rebuilt on every tick.
+ * The "why is this tile blurry" answer needs SDK state (publication +
+ * element size) joined with getStats (forwarded resolution); this is the
+ * SDK-state half.
+ */
+const buildTrackContext = (room: Room) => {
+  const contexts = new Map<string, TrackContext>()
+  room.localParticipant.trackPublications.forEach((pub) => {
+    const id = pub.track?.mediaStreamTrack?.id
+    if (id) contexts.set(id, { label: `local ${pub.source}` })
+  })
+  const dpr = window.devicePixelRatio || 1
+  room.remoteParticipants.forEach((participant) => {
+    // Keep rows scannable: participant names capped at 10 chars.
+    const rawName = participant.name || participant.identity
+    const name = rawName.length > 15 ? `${rawName.slice(0, 15)}.` : rawName
+    participant.trackPublications.forEach((pub) => {
+      const track = pub.track
+      const id = track?.mediaStreamTrack?.id
+      if (!track || !id) return
+      const label = `${name} ${pub.source}`
+      if (track.kind !== Track.Kind.Video) {
+        contexts.set(id, { label })
+        return
+      }
+      let elementRes: string | undefined
+      let elementH: number | undefined
+      for (const element of track.attachedElements) {
+        const w = Math.round(element.clientWidth * dpr)
+        const h = Math.round(element.clientHeight * dpr)
+        if (elementH === undefined || h > elementH) {
+          elementH = h
+          elementRes = `${w}x${h}`
+        }
+      }
+      const dims = pub.dimensions
+      const layers = pub.trackInfo?.layers?.length
+      contexts.set(id, {
+        label,
+        publishedH: dims?.height,
+        layer: {
+          availRes: dims ? `${dims.width}x${dims.height}` : undefined,
+          layerCount: layers && layers > 1 ? layers : undefined,
+          elementRes,
+          reason: !pub.isEnabled
+            ? 'off-screen'
+            : track.streamState === Track.StreamState.Paused
+              ? 'paused'
+              : undefined,
+        },
+      })
+    })
+  })
+  return contexts
+}
+
+/** Decide why a forwarded layer is below the published top layer. */
+const resolveLayerReason = (
+  context: TrackContext,
+  forwardedH: number | undefined
+): LayerInfo | undefined => {
+  const layer = context.layer
+  if (!layer) return undefined
+  if (layer.reason) return layer // off-screen / paused already decided
+  const publishedH = context.publishedH
+  if (!publishedH || !forwardedH || forwardedH >= publishedH * 0.9) {
+    return { ...layer, reason: undefined } // full quality, nothing to explain
+  }
+  // Below top layer: if the element only needs about what we get, it's
+  // adaptiveStream fitting the element; otherwise the SFU is holding back
+  // a layer the element could use — congestion.
+  const elementH = layer.elementRes
+    ? Number(layer.elementRes.split('x')[1])
+    : undefined
+  const adaptive = elementH !== undefined && forwardedH >= elementH * 0.7
+  return { ...layer, reason: adaptive ? 'adaptive' : 'bandwidth' }
+}
+
+export const useWebRTCStats = (
+  room: Room,
+  enabled: boolean,
+  intervalMs = 1000
+) => {
+  // Single source of truth: the snapshot is just the last history entry.
+  const [history, setHistory] = useState<StatsSnapshot[]>([])
+  const prevRef = useRef(new Map<string, Counters>())
+
+  useEffect(() => {
+    if (!enabled) return
+
+    let cancelled = false
+    const prev = prevRef.current
+
+    /** Per-stat counter deltas; returns 0 on the first sighting. */
+    const deltas = (key: string, now: Counters): Counters => {
+      const before = prev.get(key)
+      prev.set(key, now)
+      const out: Counters = {}
+      for (const [name, value] of Object.entries(now)) {
+        out[name] = before?.[name] !== undefined ? value - before[name] : 0
+      }
+      return out
+    }
+
+    const collect = async () => {
+      const reports: Array<{ pc: 'pub' | 'sub'; report: RTCStatsReport }> = []
+      try {
+        // Not public API — see file header.
+        const manager = room.engine?.pcManager
+        const pub = await manager?.publisher?.getStats()
+        if (pub) reports.push({ pc: 'pub', report: pub })
+        const sub = await manager?.subscriber?.getStats()
+        if (sub) reports.push({ pc: 'sub', report: sub })
+      } catch {
+        // Engine not ready or SDK internals changed; panel shows nothing.
+      }
+      if (cancelled || reports.length === 0) return
+
+      const contexts = buildTrackContext(room)
+      const tracks: TrackRow[] = []
+      let upKbps = 0
+      let downKbps = 0
+      let rttMs: number | undefined
+      let jitterMs: number | undefined
+      let availableOutKbps: number | undefined
+      let route: StatsSnapshot['route']
+      const turnProtocols = new Set<string>()
+
+      for (const { pc, report } of reports) {
+        const byId = new Map<string, StatDict>()
+        report.forEach((stat) => byId.set(stat.id as string, stat as StatDict))
+
+        report.forEach((raw) => {
+          const stat = raw as StatDict
+          const type = asString(stat.type)
+          const ts = asNumber(stat.timestamp) ?? Date.now()
+          const key = `${pc}:${asString(stat.id) ?? ''}`
+
+          if (
+            type === 'local-candidate' &&
+            asString(stat.candidateType) === 'relay'
+          ) {
+            // Relay candidates are only gathered when a TURN server is
+            // configured and reachable; relayProtocol says how the client
+            // reaches it (udp/tcp/tls) — a turn:…?transport=udp server
+            // must NOT be presented as a TURN/TLS capability.
+            turnProtocols.add(
+              asString(stat.relayProtocol) ?? asString(stat.protocol) ?? 'udp'
+            )
+          }
+
+          if (type === 'transport') {
+            const d = deltas(key, {
+              sent: asNumber(stat.bytesSent) ?? 0,
+              received: asNumber(stat.bytesReceived) ?? 0,
+              ts,
+            })
+            if (d.ts > 0) {
+              upKbps += Math.max(0, (d.sent * 8) / d.ts)
+              downKbps += Math.max(0, (d.received * 8) / d.ts)
+            }
+          }
+
+          if (type === 'candidate-pair' && stat.nominated === true) {
+            const rtt = asNumber(stat.currentRoundTripTime)
+            if (rtt !== undefined) rttMs = Math.round(rtt * 1000)
+            const available = asNumber(stat.availableOutgoingBitrate)
+            if (available !== undefined && pc === 'pub') {
+              availableOutKbps = Math.round(available / 1000)
+            }
+            if (pc === 'pub') {
+              const local = byId.get(asString(stat.localCandidateId) ?? '')
+              route = {
+                protocol: asString(local?.protocol),
+                type: asString(local?.candidateType),
+                relayProtocol: asString(local?.relayProtocol),
+              }
+            }
+          }
+
+          if (type === 'outbound-rtp' || type === 'inbound-rtp') {
+            const isUp = type === 'outbound-rtp'
+            const kind = asString(stat.kind)
+
+            if (!isUp) {
+              const jitter = asNumber(stat.jitter)
+              if (jitter !== undefined) {
+                const ms = Math.round(jitter * 1000)
+                if (jitterMs === undefined || ms > jitterMs) jitterMs = ms
+              }
+            }
+
+            // Packet loss: reported directly on inbound-rtp; for outbound it
+            // lives on the matching remote-inbound-rtp (what the SFU got).
+            let packetsLost = asNumber(stat.packetsLost) ?? 0
+            if (isUp) {
+              const remote = byId.get(asString(stat.remoteId) ?? '')
+              packetsLost = asNumber(remote?.packetsLost) ?? 0
+            }
+
+            const d = deltas(key, {
+              bytes: asNumber(isUp ? stat.bytesSent : stat.bytesReceived) ?? 0,
+              packets:
+                asNumber(isUp ? stat.packetsSent : stat.packetsReceived) ?? 0,
+              packetsLost,
+              ts,
+              freezeCount: asNumber(stat.freezeCount) ?? 0,
+            })
+
+            const kbps = d.ts > 0 ? Math.max(0, (d.bytes * 8) / d.ts) : 0
+            const lostTotal = d.packetsLost + d.packets
+            const lossPct =
+              lostTotal > 0
+                ? Math.max(0, Math.min(100, (d.packetsLost / lostTotal) * 100))
+                : 0
+
+            // Resolve codec + source track.
+            const codecStat = byId.get(asString(stat.codecId) ?? '')
+            let msTrackId = asString(stat.trackIdentifier)
+            if (!msTrackId && isUp) {
+              const mediaSource = byId.get(asString(stat.mediaSourceId) ?? '')
+              msTrackId = asString(mediaSource?.trackIdentifier)
+            }
+            const rid = asString(stat.rid)
+            const context = msTrackId ? contexts.get(msTrackId) : undefined
+            const baseLabel =
+              context?.label ??
+              `${kind ?? 'media'} ssrc ${asNumber(stat.ssrc) ?? '?'}`
+
+            const width = asNumber(stat.frameWidth)
+            const height = asNumber(stat.frameHeight)
+
+            tracks.push({
+              key,
+              dir: isUp ? 'up' : 'down',
+              kind: kind ?? 'unknown',
+              label: rid ? `${baseLabel} [${rid}]` : baseLabel,
+              codec: shortCodec(asString(codecStat?.mimeType)),
+              kbps,
+              fps: asNumber(stat.framesPerSecond),
+              res: width && height ? `${width}x${height}` : undefined,
+              lossPct,
+              limitation:
+                asString(stat.qualityLimitationReason) === 'none'
+                  ? undefined
+                  : asString(stat.qualityLimitationReason),
+              layer:
+                !isUp && kind === 'video' && context
+                  ? resolveLayerReason(context, height)
+                  : undefined,
+              froze: !isUp && kind === 'video' && d.freezeCount > 0,
+            })
+          }
+        })
+      }
+
+      // Stable order (direction, then label): sorting by bitrate would
+      // reshuffle rows on every tick as kbps fluctuates.
+      tracks.sort((a, b) =>
+        a.dir === b.dir
+          ? a.label.localeCompare(b.label)
+          : a.dir === 'up'
+            ? -1
+            : 1
+      )
+
+      const next: StatsSnapshot = {
+        ts: Date.now(),
+        upKbps: Math.round(upKbps),
+        downKbps: Math.round(downKbps),
+        rttMs,
+        jitterMs,
+        availableOutKbps,
+        route,
+        turnProtocols: Array.from(turnProtocols).sort(),
+        tracks,
+      }
+      setHistory((h) => [...h.slice(-59), next])
+    }
+
+    void collect()
+    const id = window.setInterval(() => void collect(), intervalMs)
+    return () => {
+      cancelled = true
+      window.clearInterval(id)
+    }
+  }, [room, enabled, intervalMs])
+
+  return { snapshot: history[history.length - 1], history }
+}

src/frontend/src/features/rooms/components/Conference.tsx

@@ -43,6 +43,7 @@ import { useSnapshot } from 'valtio'
 import { userPreferencesStore } from '@/stores/userPreferences'
 import { userStore } from '@/stores/user'
 import { WatchMediaDeviceErrors } from './WatchMediaDeviceErrors'
+import { MeetDevtools } from '@/features/devtools'
 import { VOICE_AUDIO_CONSTRAINTS } from '@/features/rooms/livekit/utils/constants'
 
 export const Conference = ({
@@ -298,6 +299,7 @@ export const Conference = ({
           <VideoConference />
           {!isMobile && <InviteDialog mode={mode} />}
           <PictureInPictureConference />
+          <MeetDevtools />
         </LiveKitRoom>
       </Screen>
     </QueryAware>