diff --git a/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-chart.vue b/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-chart.vue
index ec27f2bdb..4666cbbd7 100644
--- a/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-chart.vue
+++ b/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-chart.vue
@@ -1,6 +1,7 @@
 <script setup lang="ts">
 import type { IOSpan, IOSubsystem, IOTurn } from '@proj-airi/stage-shared'
 
+import { IOSubsystems } from '@proj-airi/stage-shared'
 import { useElementBounding, useElementSize, useEventListener } from '@vueuse/core'
 import { computed, ref, watch } from 'vue'
 
@@ -131,8 +132,8 @@ const layout = computed(() => {
   const gapAnnotations: GapAnnotation[] = []
   let y = 0
 
-  const subsystemOrder: IOSubsystem[] = ['tts', 'playback']
-  const ttsSubsystems = new Set<IOSubsystem>(['tts', 'playback'])
+  const subsystemOrder: IOSubsystem[] = [IOSubsystems.TTS, IOSubsystems.Playback]
+  const ttsSubsystems = new Set<IOSubsystem>([IOSubsystems.TTS, IOSubsystems.Playback])
   let isFirstTurn = true
 
   for (const turn of turns.value) {
@@ -146,7 +147,10 @@ const layout = computed(() => {
     }
     isFirstTurn = false
 
-    const llmSpans = turnSpans.filter(s => s.subsystem === 'llm').sort((a, b) => a.startTs - b.startTs)
+    const llmSpans = turnSpans.filter(s => s.subsystem === IOSubsystems.LLM).sort((a, b) => a.startTs - b.startTs)
+    const auxiliarySpans = turnSpans
+      .filter(s => s.subsystem !== IOSubsystems.LLM && !ttsSubsystems.has(s.subsystem))
+      .sort((a, b) => a.startTs - b.startTs)
     const ttsSpanList = turnSpans.filter(s => ttsSubsystems.has(s.subsystem))
 
     const segmentGroups = new Map<string, IOSpan[]>()
@@ -166,7 +170,12 @@ const layout = computed(() => {
       .sort((a, b) => a[0].startTs - b[0].startTs)
 
     for (const span of llmSpans) {
-      rows.push({ type: 'span', span, turn, subsystem: 'llm', y })
+      rows.push({ type: 'span', span, turn, subsystem: IOSubsystems.LLM, y })
+      y += ROW_HEIGHT
+    }
+
+    for (const span of auxiliarySpans) {
+      rows.push({ type: 'span', span, turn, subsystem: span.subsystem, y })
       y += ROW_HEIGHT
     }
 
@@ -512,6 +521,28 @@ function spanLabel(span: IOSpan): string {
   const subsystemLabel = SUBSYSTEM_CONFIG_MAP.get(span.subsystem)?.label ?? ''
   return `${subsystemLabel} / ${span.name}`
 }
+
+function formatMetaValue(value: unknown): string {
+  if (value == null)
+    return ''
+  if (typeof value === 'object')
+    return JSON.stringify(value)
+  return String(value)
+}
+
+function tooltipMetaEntries(span: IOSpan) {
+  const tooltipKeys = Array.isArray(span.meta.tooltipKeys)
+    ? span.meta.tooltipKeys.filter((key): key is string => typeof key === 'string')
+    : []
+
+  return tooltipKeys
+    .map(key => [key, span.meta[key]] as const)
+    .filter(([, value]) => value !== undefined && value !== '')
+    .map(([key, value]) => ({
+      label: key,
+      value: formatMetaValue(value),
+    }))
+}
 </script>
 
 <template>
@@ -831,6 +862,19 @@ function spanLabel(span: IOSpan): string {
         <div v-if="hoveredSpan.span.meta.chunk_reason" :class="['text-amber-300/80 mt-0.5']">
           chunk: {{ hoveredSpan.span.meta.chunk_reason }}
         </div>
+        <div
+          v-if="tooltipMetaEntries(hoveredSpan.span).length > 0"
+          :class="['mt-1.5 pt-1.5 border-t border-neutral-700/80 flex flex-col gap-0.5']"
+        >
+          <div
+            v-for="entry in tooltipMetaEntries(hoveredSpan.span)"
+            :key="entry.label"
+            :class="['grid grid-cols-[auto_1fr] gap-x-2 text-neutral-300']"
+          >
+            <span :class="['text-neutral-500']">{{ entry.label }}</span>
+            <span :class="['font-mono text-neutral-100 truncate']">{{ entry.value }}</span>
+          </div>
+        </div>
       </div>
     </Teleport>
   </div>
diff --git a/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-controls.vue b/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-controls.vue
index 87437138e..3801887ae 100644
--- a/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-controls.vue
+++ b/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-controls.vue
@@ -3,7 +3,7 @@ import type { IOSubsystem } from '@proj-airi/stage-shared'
 
 import { Button } from '@proj-airi/ui'
 
-import { SUBSYSTEM_CONFIG_MAP } from '../io-tracer-types'
+import { SUBSYSTEM_CONFIG_MAP, SUBSYSTEM_CONFIGS } from '../io-tracer-types'
 
 defineProps<{
   isRecording: boolean
@@ -20,10 +20,10 @@ const emit = defineEmits<{
   exportOtlp: []
 }>()
 
-const ttsSubsystems: { subsystem: IOSubsystem, label: string }[] = [
-  { subsystem: 'tts', label: 'TTS' },
-  { subsystem: 'playback', label: 'Play' },
-]
+const subsystemFilters = SUBSYSTEM_CONFIGS.map(config => ({
+  subsystem: config.subsystem,
+  label: config.label,
+}))
 </script>
 
 <template>
@@ -31,8 +31,8 @@ const ttsSubsystems: { subsystem: IOSubsystem, label: string }[] = [
     <Button
       :class="[
         'flex items-center gap-1.5',
-        isRecording ? 'text-red-500' : '',
       ]"
+      :variant="isRecording ? 'danger' : 'primary'"
       @click="emit('toggleRecording')"
     >
       <div
@@ -60,11 +60,11 @@ const ttsSubsystems: { subsystem: IOSubsystem, label: string }[] = [
       Fit
     </Button>
 
-    <!-- TTS Subsystem Toggles -->
+    <!-- Subsystem Toggles -->
     <div :class="['w-px h-4 bg-neutral-200 dark:bg-neutral-700 mx-1']" />
-    <span :class="['text-2.5 text-neutral-400']">TTS:</span>
+    <span :class="['text-2.5 text-neutral-400']">Subsystems:</span>
     <button
-      v-for="item in ttsSubsystems"
+      v-for="item in subsystemFilters"
       :key="item.subsystem"
       :class="[
         'text-2.5 px-1.5 py-0.5 rounded',
diff --git a/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-detail.vue b/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-detail.vue
index 174caa628..7a5262430 100644
--- a/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-detail.vue
+++ b/packages/stage-pages/src/pages/devtools/io-tracer/components/io-tracer-detail.vue
@@ -83,6 +83,22 @@ const metaEntries = computed(() => {
     }))
 })
 
+const eventEntries = computed(() => {
+  const span = props.span
+  if (!span)
+    return []
+
+  return (span.events ?? []).map(event => ({
+    name: event.name,
+    relativeTime: fmtMs(event.timeTs - span.startTs),
+    meta: Object.entries(event.meta)
+      .map(([key, value]) => ({
+        key: key.includes('.') ? key.split('.').at(-1)! : key,
+        value: typeof value === 'object' ? JSON.stringify(value) : String(value),
+      })),
+  }))
+})
+
 function copyValue(value: string) {
   navigator.clipboard.writeText(value)
 }
@@ -197,6 +213,42 @@ function copyValue(value: string) {
         </div>
       </div>
 
+      <!-- Events -->
+      <div v-if="eventEntries.length > 0">
+        <div :class="['text-neutral-500 font-medium mb-1.5 uppercase tracking-wider text-2.5']">
+          Events
+        </div>
+        <div :class="['flex flex-col gap-1.5']">
+          <div
+            v-for="entry in eventEntries"
+            :key="`${entry.name}:${entry.relativeTime}`"
+            :class="[
+              'rounded border border-neutral-100 dark:border-neutral-800',
+              'bg-neutral-50 dark:bg-neutral-800/60',
+              'p-1.5',
+            ]"
+          >
+            <div :class="['flex items-center justify-between gap-2']">
+              <span :class="['font-mono text-2.5 truncate']">{{ entry.name }}</span>
+              <span :class="['font-mono text-2.5 text-neutral-400 flex-shrink-0']">+{{ entry.relativeTime }}</span>
+            </div>
+            <div
+              v-if="entry.meta.length > 0"
+              :class="['mt-1 flex flex-col gap-0.5']"
+            >
+              <div
+                v-for="item in entry.meta"
+                :key="item.key"
+                :class="['grid grid-cols-[auto_1fr] gap-x-2']"
+              >
+                <span :class="['text-neutral-400 text-2.5']">{{ item.key }}</span>
+                <span :class="['font-mono text-2.5 truncate']">{{ item.value }}</span>
+              </div>
+            </div>
+          </div>
+        </div>
+      </div>
+
       <!-- Metadata -->
       <div v-if="metaEntries.length > 0">
         <div :class="['text-neutral-500 font-medium mb-1.5 uppercase tracking-wider text-2.5']">
diff --git a/packages/stage-pages/src/pages/devtools/io-tracer/io-tracer-types.ts b/packages/stage-pages/src/pages/devtools/io-tracer/io-tracer-types.ts
index 683fdc575..fd3072a62 100644
--- a/packages/stage-pages/src/pages/devtools/io-tracer/io-tracer-types.ts
+++ b/packages/stage-pages/src/pages/devtools/io-tracer/io-tracer-types.ts
@@ -13,6 +13,7 @@ export interface SubsystemConfig {
 export const SUBSYSTEM_CONFIGS: SubsystemConfig[] = [
   { subsystem: IOSubsystems.ASR, label: 'ASR', color: '#3b82f6', bgColor: '#3b82f618', icon: 'i-lucide:mic' },
   { subsystem: IOSubsystems.LLM, label: 'LLM', color: '#a855f7', bgColor: '#a855f718', icon: 'i-lucide:brain' },
+  { subsystem: IOSubsystems.StreamingControl, label: 'Streaming Control', color: '#06b6d4', bgColor: '#06b6d418', icon: 'i-lucide:radio-tower' },
   { subsystem: IOSubsystems.TTS, label: 'TTS', color: '#22c55e', bgColor: '#22c55e18', icon: 'i-lucide:audio-lines' },
   { subsystem: IOSubsystems.Playback, label: 'Playback', color: '#f87171', bgColor: '#f8717118', icon: 'i-lucide:play' },
 ]
diff --git a/packages/stage-shared/src/perf/io-trace.ts b/packages/stage-shared/src/perf/io-trace.ts
index bd23edefb..0781c46e7 100644
--- a/packages/stage-shared/src/perf/io-trace.ts
+++ b/packages/stage-shared/src/perf/io-trace.ts
@@ -1,6 +1,7 @@
 export const IOSubsystems = {
   ASR: 'asr',
   LLM: 'llm',
+  StreamingControl: 'streaming-control',
   TTS: 'tts',
   Playback: 'playback',
 } as const
@@ -10,6 +11,7 @@ export const IOSpanNames = {
   InteractionTurn: 'Interaction turn',
   SpeechRecognition: 'Speech recognition',
   LLMInference: 'LLM inference',
+  StreamingControlDispatch: 'Streaming control dispatch',
   TTSSynthesis: 'TTS synthesis',
   AudioPlayback: 'Audio playback',
 } as const
@@ -22,10 +24,22 @@ export const IOAttributes = {
 
   // Non-standard
   Subsystem: `${customPrefix}.subsystem`,
+  TooltipKeys: `${customPrefix}.tooltip.keys`,
   LLM_TTFT: `${customPrefix}.llm.time_to_first_token`,
   ASRText: `${customPrefix}.asr.text`,
   ASRAbort: `${customPrefix}.asr.abort`,
   LLMTextLength: `${customPrefix}.llm.text_length`,
+  StreamingControlCallName: `${customPrefix}.streaming_control.call_name`,
+  StreamingControlHandlerCount: `${customPrefix}.streaming_control.handler_count`,
+  StreamingControlMatched: `${customPrefix}.streaming_control.matched`,
+  StreamingControlParameter: `${customPrefix}.streaming_control.parameter`,
+  StreamingControlParsed: `${customPrefix}.streaming_control.parsed`,
+  StreamingControlParserName: `${customPrefix}.streaming_control.parser_name`,
+  StreamingControlReason: `${customPrefix}.streaming_control.reason`,
+  StreamingControlRawToken: `${customPrefix}.streaming_control.raw_token`,
+  StreamingControlTokenLength: `${customPrefix}.streaming_control.token_length`,
+  StreamingControlTokenType: `${customPrefix}.streaming_control.token_type`,
+  StreamingControlTurnId: `${customPrefix}.streaming_control.turn_id`,
   TTSSegmentId: `${customPrefix}.tts.segment_id`,
   TTSText: `${customPrefix}.tts.text`,
   TTSChunkReason: `${customPrefix}.tts.chunk_reason`,
@@ -38,8 +52,26 @@ export const IOEvents = {
   // Non-standard
   LLMFirstToken: `${customPrefix}.llm.first_token`,
   ASRSentenceEnd: `${customPrefix}.asr.sentence_end`,
+  StreamingControlHandlerEnd: `${customPrefix}.streaming_control.handler_end`,
+  StreamingControlHandlerError: `${customPrefix}.streaming_control.handler_error`,
+  StreamingControlHandlerStart: `${customPrefix}.streaming_control.handler_start`,
+  StreamingControlParsed: `${customPrefix}.streaming_control.parsed`,
+  StreamingControlRejected: `${customPrefix}.streaming_control.rejected`,
+  StreamingControlSignalHandlerError: `${customPrefix}.streaming_control.signal_handler_error`,
 } as const
 
+/**
+ * Event captured inside an IO tracing span.
+ */
+export interface IOSpanEvent {
+  /** OTel event name. */
+  name: string
+  /** Event timestamp in milliseconds. */
+  timeTs: number
+  /** Event attributes normalized for the devtools UI. */
+  meta: Record<string, unknown>
+}
+
 export interface IOSpan {
   id: string
   traceId: string
@@ -51,6 +83,8 @@ export interface IOSpan {
   subsystem: IOSubsystem
   name: string
   meta: Record<string, any>
+  /** OTel events attached to the span. */
+  events?: IOSpanEvent[]
 }
 
 export interface IOTurn {
diff --git a/packages/stage-ui/src/stores/devtools/io-tracer.ts b/packages/stage-ui/src/stores/devtools/io-tracer.ts
index 75cab71e2..ca9fe0489 100644
--- a/packages/stage-ui/src/stores/devtools/io-tracer.ts
+++ b/packages/stage-ui/src/stores/devtools/io-tracer.ts
@@ -14,7 +14,11 @@ const MAX_TURNS = 50
 function attrsToMeta(attrs: Attributes): Record<string, any> {
   const meta: Record<string, any> = {}
   for (const [key, value] of Object.entries(attrs)) {
-    const shortKey = key.includes('.') ? key.split('.').at(-1)! : key
+    const shortKey = key === IOAttributes.TooltipKeys
+      ? 'tooltipKeys'
+      : key.includes('.')
+        ? key.split('.').at(-1)!
+        : key
     meta[shortKey] = value
   }
   return meta
@@ -124,6 +128,11 @@ export const useIOTracerStore = defineStore('devtools:io-tracer', () => {
 
     const turn = getOrCreateTurn()
     const meta = attrsToMeta(readable.attributes)
+    const events = readable.events.map(event => ({
+      name: event.name,
+      timeTs: hrTimeToMilliseconds(event.time),
+      meta: attrsToMeta(event.attributes ?? {}),
+    }))
 
     for (const event of readable.events) {
       const eventAttrs = event.attributes ?? {}
@@ -153,6 +162,7 @@ export const useIOTracerStore = defineStore('devtools:io-tracer', () => {
       startTs: startMs,
       endTs: endMs,
       meta,
+      events,
     }
 
     turn.spans.push(ioSpan)