fix(cloud-agent-sdk): recover stale WebSocket connections on tab resume#1919
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fix(cloud-agent-sdk): recover stale WebSocket connections on tab resume#1919
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Add application-level ping/pong staleness detection for WebSocket connections that silently die when tabs are backgrounded. On tab resume, sends a ping and reconnects if no response within 5s. - base-connection: visibilitychange/pageshow/online handlers, ping timeout, proactive ticket refresh before reconnect - cloud-agent-transport/cli-live-transport: snapshot refetch on reconnect via onReconnected callback - session.ts: route completed sessions to historical transport - CloudAgentProvider: determine isLive from DO execution status
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Code Review SummaryStatus: 4 Issues Found | Recommendation: Address before merge Overview
Fix these issues in Kilo Cloud Issue Details (click to expand)WARNING
Other Observations (not in diff)Issues found in unchanged code that cannot receive inline comments:
Files Reviewed (8 files)
Reviewed by gpt-5.4-20260305 · 595,751 tokens |
…ction
Address review feedback on stale WebSocket recovery:
- Remove ws.send('ping') — server never responds; staleness detection
now relies on server heartbeats canceling the timeout
- Make staleness timeout configurable (stalenessTimeoutMs) so the
transport layer that knows the heartbeat interval controls the value
- Increase default from 5s to 30s to exceed server heartbeat intervals
- Track lastMessageTime to skip the check when a recent message proves
the connection is alive
- Wire heartbeatTimeoutMs through cloud-agent-connection
- disconnect() now removes visibility/pageshow/online listeners,
fixing a leak when transports disconnect without calling destroy()
jeanduplessis
approved these changes
Apr 2, 2026
…minated union
Replace the flat { cloudAgentSessionId, isLive } shape with a
discriminated union ('remote' | 'cloud-agent' | 'read-only') so
transport routing is explicit and type-safe. Simplify session
resolution in CloudAgentProvider by removing the runtime-state
liveness check. Add runtime exhaustive check in pickTransportFactory.
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Summary
Fixes half-open WebSocket connections in cloud agent sessions. When a user backgrounds a tab and returns after the TCP socket has silently died,
onclosenever fires and the session appears frozen. This adds application-level staleness detection and recovery.Connection layer (
base-connection.ts):visibilitychange,pageshow(BFCache), andonlineeventsrefreshAndConnect), fixing expired JWT failures on reconnectdestroy()Transport layer (
cloud-agent-transport.ts,cli-live-transport.ts):onReconnectedcallback refetches the session snapshot and replays it into the sink, avoiding blank screens after reconnectionSession routing (
session.ts,CloudAgentProvider.tsx):pickTransportFactorynow checksresolved.isLivefor Cloud Agent sessions — completed sessions route to the read-only historical transport instead of opening a live WebSocketresolveSessionqueriesgetWithRuntimeStateto determine actual session liveness from execution status, instead of hardcodingisLive: trueVerification
npx jest src/lib/cloud-agent-sdk/ --no-coverage— 18 suites, 551 tests, all passpnpm typecheck— passes, no errors[Connection]messagesVisual Changes
N/A
Reviewer Notes
[Connection]messages in dev: All connection log lines appear in pairs due to React StrictMode double-mounting effects. This is expected in development only and does not occur in production."ping") gracefully.isLivedetection inCloudAgentProvider.tsxhandles multiple edge cases (terminal execution, active execution, null execution with/withoutinitiatedAt). TheinitiatedAtheuristic covers the case where the DO has cleaned up the execution record after completion.