fix(console/agent-sessions): keep prior data during refetch (no flash)

[vaderyang]

Summary

Add placeholderData: (prev) => prev to the three Agent Session list hooks so the Sessions page does an in-place swap on refetch — same behavior as Agent Turns / LLM Calls / Metrics / every other list page.

Why

User report: "Agent Session 界面每次刷新都会重刷整个页面，而不是像其他页面一样看上去重刷幅度很小".

Every other list hook in the app sets placeholderData: (prev) => prev. The Agent Session hooks didn't — so every auto-refresh tick / toolbar key change wiped the cache to undefined, the page rendered its loading skeleton, then the new data dropped in. The user saw a full-page flash where every other page did a smooth swap.

Files

• console/src/hooks/use-agent-sessions.ts — three hooks (useAgentSessions, useAgentSessionDetail, useSessionTurns) each get the same one-liner.

Test plan

• bun test — 111 pass
• bun run build — clean

🤖 Generated with Claude Code

[github-actions]

Summary

Agent run failed (exit 1). See workflow logs.

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🤖 Reviewed by vivi • workflow run

[github-actions]

Summary

This PR adds placeholderData: (prev) => prev to three Agent Session hooks (useAgentSessions, useAgentSessionDetail, useSessionTurns) to eliminate a UI flash during auto-refresh. The fix matches the pattern used in all other list hooks (useAgentTurns, useLlmCalls, useHttpExchanges, useMetrics) and correctly addresses the reported issue. The implementation is correct and follows established patterns. APPROVE

Verified

• Pattern consistency: Confirmed that useAgentTurns:44, useLlmCalls:57, useHttpExchanges:72, useMetrics:15 all use placeholderData: (prev) => prev — the three hooks in this PR now match this pattern
• Infinite query behavior: For useAgentSessions and useSessionTurns, the queryKey includes start/end from toolbar store. When auto-refresh updates the preset (via useAutoRefresh → setPreset), these values change, causing a key transition. Without placeholderData, this would clear cached pages → render loading skeleton → flash; with it, prior pages stay visible until new data arrives
• Detail hook appropriateness: useAgentSessionDetail doesn't subscribe to start/end, but navigation between sessions (same source, different session_id) would benefit from showing the prior session until the new one loads
• Caller compatibility: Checked agent-sessions.tsx:54 and agent-session-detail.tsx:11,19 — the hooks are consumed correctly, and the loading-state predicates (isLoading && items.length === 0, loadingDetail && !detail) already handle the placeholderData case properly (they check for data presence, not just loading state)
• No other hooks missed: Grepped for all useQuery/useInfiniteQuery hooks — all list/timeseries queries now have placeholderData, detail queries (useAgentTurnDetail, useAgentTurnCalls, useLlmCallDetail, useHttpExchange) correctly omit it as they lack time-range dependencies

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🤖 Reviewed by vivi • workflow run