fix(web): refresh todos panel from buffered events on reconnect#69
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pufit merged 1 commit intoMay 13, 2026
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handleSessionStatus rebuilds streamingBlocks from the WS buffer when a client reconnects mid-turn (page refresh, WS drop, tab backgrounded), but it never updated currentTodos. The todos panel was driven only by the persisted-history extractor (extractTodosFromMessages on switchSession) plus the live tool_use handler. If a TodoWrite landed in the buffer between the last persisted assistant turn and the live reconnect, the panel froze on the older snapshot from the persisted history while the underlying messages already had the newer todos. Add extractTodosFromBuffer alongside extractTodosFromMessages and call it from handleSessionStatus. Returns null when no top-level TodoWrite is in the buffer so the caller preserves whatever was already set from persisted history. Unlike extractTodosFromMessages it does not skip the all-completed case so the panel can show the final state and let its own 5s auto-hide animate. Repro before the fix: 1. Start a session that runs many TodoWrite calls in one turn. 2. Refresh the browser tab in the middle of the turn. 3. Panel sticks at the latest persisted TodoWrite even though new ones keep arriving in the buffer and (later) on the live stream.
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User-reported glitch: "I ask for something and there is no response, then I ask again and it answers to the previous question." Five reliability PRs (#63 shorthand-schema, #64 synthetic done, #65 stale sdk_session_id, #66 idle timeout, #67 sticky session) each close one underlying cause. Two gaps remain that none of those PRs cover. Gap 1: client-side send silently drops payloads. web/src/api/websocket.ts checked readyState === OPEN and no-op'd otherwise. The 3s reconnect window leaves a hole: send() returns to the caller and chatStore.sendMessage has already optimistically appended the user message and set isStreaming=true. The user thinks the agent is thinking but the message never reached the server, so the next reply lands against a stale prompt. Track readyState explicitly. CONNECTING or reconnect-scheduled now queues the payload (bounded to 5 entries; oldest evicted) and flushes from onopen. CLOSED-without-reconnect and CLOSING return 'dropped' so the caller can revert. chatStore.sendMessage pops the optimistic user message on 'dropped' and surfaces an inline assistant error so the user can retry. Gap 2: gateway initial-bind never replayed the broadcaster buffer. The switch_session handler already shipped session_status with buffered_events on session switch, but the initial-connect handshake at server.py:286-311 didn't. Reload mid-turn (or a transient 3s WS drop) and the in-flight stream was lost from the client's view even though the events sat in broadcaster._session_buffers waiting to be replayed. Lift the duplicated send-status construction into _send_session_status and call it from both branches. Initial-bind gates on broadcaster.is_buffering so idle sessions stay silent; switch_session calls unconditionally so the client refreshes is_running/status on every selection. The frontend handleSessionStatus already restores streamingBlocks, panels, todos, and interaction state from the buffer (handled by #69), so this is purely additive at the gateway. Tests: - 9 new asserts in tests/test_gateway_ws.py covering the helper output, the initial-bind gate, the switch_session regression path, and a load-fidelity check for buffer ordering. - Full pytest run: 444 pass, 2 skip, 2 pre-existing failures unrelated (test_bootstrap docker-env detection and test_cli_upgrade docker mode, both noted in notes/repo-conventions/nerve.md). - web/ tsc --noEmit clean, npm run build clean. Out of scope (followups, not blocking): - Stale-listener cleanup on swallowed send_json exceptions (server.py:298-301). - Application-level message_received ack from engine after sessions.add_message. - _session_locks TTL on session archive.
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Summary
Fixes #68. The todos panel in the web UI froze on a stale snapshot when a client reconnected in the middle of an active turn (page refresh, WS drop, tab backgrounded long enough to drop). New
TodoWritecalls kept landing in the WS buffer and on the persisted history, but the panel kept showing the count from the lastTodoWritethat was persisted before the reconnect.Cause
handleSessionStatusrebuildsstreamingBlocksfrommsg.buffered_eventsviaapplyStreamEvent, but never updatescurrentTodos. The onlycurrentTodoswriters were:handleToolUse(only runs while WS is live, not during buffer replay), andextractTodosFromMessages(hydrated)inswitchSession(only sees persisted DB messages).Any
TodoWritethat arrived in the buffer for an in-flight turn before the reconnect bypassed both writers.Fix
extractTodosFromBuffer(events)next toextractTodosFromMessages. Walks the buffered events backward, returns the latest top-levelTodoWriteinput, ornullif there isn't one. Filters out sub-agent (parent_tool_use_id) entries to match the live handler's behaviour.handleSessionStatusafter rebuildingblocks. UpdatecurrentTodosonly when the helper returns non-null; otherwise preserve whatever was already set from persisted history.extractTodosFromBufferdoes not skip the all-completed case (unlikeextractTodosFromMessages), so the panel can show the final state and let its own 5s auto-hide animate.Test plan
npx tsc --noEmitclean inweb/.npm run buildclean inweb/.TodoWritecalls in one turn, refresh the browser mid-turn, confirm the panel reflects the latest todos rather than the persisted snapshot.Notes
No new unit tests;
web/src/has no test framework configured. Happy to add one in a follow-up if a runner gets wired in.[no-changeset: allow](no changeset infra in this repo).