fix(experimental): tighten paging guards and event payload typing

packages/experimental/client-ui-perf/src/client/PerfView.tsx

@@ -1734,7 +1734,7 @@ function stepRows(options: StepRowsOptions): ReactNode[] {
     const gap = gaps.get(step.step)
     const visibleGap = gap !== undefined && gap >= STEP_GAP_MIN_MS ? gap : undefined
     const expanded = open[step.step] === true
-    const hasAnswer = step.answerBody !== null && step.answerBody !== undefined
+    const hasAnswer = step.answerBody !== null
     const hasDetail = step.calls.length > 0 || hasAnswer
     const rowClass: (string | undefined)[] = []
     if (hasDetail) rowClass.push(css.stepRowClickable)

packages/experimental/client-ui-perf/src/client/index.ts

@@ -102,23 +102,17 @@ export function apply(ctx: Context): void {
           if (pending !== undefined) return pending
           const task = (async (): Promise<LoadOlderResult> => {
             const before = perf.getSnapshot()
-            let changed = false
-            const stop = perf.subscribe(() => { changed = true })
-            try {
-              // A view can mount before the Session finishes opening; paging before
-              // that is a no-op, so wait for open unless the view is gone.
-              await whenOpened(session, lifecycle.signal)
-              if (lifecycle.signal.aborted) return 'retry'
-              if (session.getSnapshot().loadingOlder) return 'retry'
-              await session.loadOlder()
-              if (changed || perf.getSnapshot() !== before) return 'grew'
-              const after = session.getSnapshot()
-              // A page can grow the Session window without adding a perf node. Only
-              // an exhausted Session may hide the trigger; otherwise keep it retryable.
-              return after.hasMore ? 'retry' : 'exhausted'
-            } finally {
-              stop()
-            }
+            // A view can mount before the Session finishes opening; paging before
+            // that is a no-op, so wait for open unless the view is gone.
+            await whenOpened(session, lifecycle.signal)
+            if (lifecycle.signal.aborted) return 'retry'
+            if (session.getSnapshot().loadingOlder) return 'retry'
+            await session.loadOlder()
+            if (perf.getSnapshot() !== before) return 'grew'
+            const after = session.getSnapshot()
+            // A page can grow the Session window without adding a perf node. Only
+            // an exhausted Session may hide the trigger; otherwise keep it retryable.
+            return after.hasMore ? 'retry' : 'exhausted'
           })()
           const promise = task.finally(() => { pages.delete(binding) })
           pages.set(binding, promise)

packages/experimental/client-ui-perf/src/client/perf-event.ts

@@ -5,7 +5,7 @@ import type {
 } from '@deepseek-ai/dsh-client-ui-conversation/client'
 import type {} from '@deepseek-ai/dsh-compaction/types'
 import type {} from '@deepseek-ai/dsh-tools'
-import type { LlmRetryEventData } from '@deepseek-ai/dsh-llm-retry/types'
+
 import type {} from '@deepseek-ai/dsh-user-approval/types'
 import type { SessionEventMap } from '@deepseek-ai/dsh-session/types'
 import type { PerfEventMetrics } from './perf-contract.ts'
@@ -13,9 +13,15 @@ import type { PerfEventMetrics } from './perf-contract.ts'
 /** Event shape a Conversation Definition receives. */
 type MatchEvent = Parameters<ConversationNodeDefinition['match']>[0]
 
-/** Payload of an event whose type is known to the caller. */
-function dataOf<T>(event: MatchEvent): T {
-  return (event as MatchEvent & { data: T }).data
+/**
+ * Payload of an event whose type is known to the caller.
+ * @param event - event seen by the Definition match.
+ * @param type - event discriminant already narrowed by the caller.
+ * @returns the typed event payload.
+ */
+function dataOf<K extends keyof SessionEventMap>(event: MatchEvent, type: K): SessionEventMap[K] {
+  void type
+  return (event as MatchEvent & { type: K; data: SessionEventMap[K] }).data
 }
 
 /**
@@ -113,7 +119,7 @@ export function eventMetrics(event: MatchEvent, location: ConversationLocation |
   }
   const eventType: string = event.type
   if (eventType === 'request/context') {
-    const data = dataOf<SessionEventMap['request/context']>(event)
+    const data = dataOf(event, 'request/context')
     return {
       ...base,
       kind: 'request-context',
@@ -124,7 +130,7 @@ export function eventMetrics(event: MatchEvent, location: ConversationLocation |
     }
   }
   if (eventType === 'llm/retry') {
-    const data = dataOf<LlmRetryEventData>(event)
+    const data = dataOf(event, 'llm/retry')
     return {
       ...base,
       kind: 'model-retry',
@@ -138,7 +144,7 @@ export function eventMetrics(event: MatchEvent, location: ConversationLocation |
     }
   }
   if (eventType === 'assistant/attempt') {
-    const data = dataOf<{ turn: number; step: number }>(event)
+    const data = dataOf(event, 'assistant/attempt')
     return {
       ...base,
       kind: 'model-attempt',
@@ -148,20 +154,18 @@ export function eventMetrics(event: MatchEvent, location: ConversationLocation |
     }
   }
   if (eventType === 'user/message') {
-    const data = dataOf<{
-      source: { kind: string }
-      content: readonly { type: string; text?: string }[]
-    }>(event)
-    if (data.source.kind !== 'runtime-context' && data.source.kind !== 'time-context') return null
+    const data = dataOf(event, 'user/message')
+    const kind: string = data.source.kind
+    if (kind !== 'runtime-context' && kind !== 'time-context') return null
     return {
       ...base,
       kind: 'context-refresh',
-      status: data.source.kind,
+      status: kind,
       chars: contentChars(data.content),
     }
   }
   if (eventType === 'approval/asked') {
-    const data = dataOf<{ toolName: string; reason?: string }>(event)
+    const data = dataOf(event, 'approval/asked')
     return {
       ...base,
       kind: 'approval',
@@ -171,7 +175,7 @@ export function eventMetrics(event: MatchEvent, location: ConversationLocation |
     }
   }
   if (eventType === 'approval/decided') {
-    const data = dataOf<{ outcome: string }>(event)
+    const data = dataOf(event, 'approval/decided')
     return { ...base, kind: 'approval', status: data.outcome }
   }
   return null

packages/experimental/client-ui-perf/tests/perf-plugin.client.spec.ts

@@ -450,14 +450,12 @@ describe('browser plugin registration', () => {
     const injectEntry = bench.entries()[0]!.inject as ((sessionId: SessionId) => PerfViewInjected) | undefined
     const injected = injectEntry!(SID)
     bench.setHasMore(true)
-    const gate = Promise.withResolvers<undefined>()
-    bench.loadOlder.mockImplementationOnce(() => gate.promise)
+    bench.loadOlder.mockImplementationOnce(() => undefined)
     const first = injected.loadOlder()
     const second = injected.loadOlder()
     expect(second).toBe(first)
     await Promise.resolve()
     expect(bench.loadOlder).toHaveBeenCalledTimes(1)
-    gate.resolve(undefined)
     expect(await first).toBe('retry')
     expect(bench.loadOlder).toHaveBeenCalledTimes(1)