🤖 fix: clear todos on stream end with smart reconnection handling

[ammar-agent]

Problem

TODOs were not being cleared when streams ended, causing stale todos to persist in the UI until the next user message. Additionally, on page reload, TODOs were incorrectly reconstructed from history even for completed streams.

The challenge: We need different behavior for two reload scenarios:

• Reconnection during active stream: Should reconstruct TODOs (work in progress)
• Reload after completed stream: Should NOT reconstruct TODOs (clean slate)

Solution

1. Clear TODOs on stream end

Modified cleanupStreamState() to clear currentTodos when streams complete (end/abort/error). TODOs are now truly stream-scoped.

2. Smart reconstruction on reload

Key insight: Check buffered events for stream-start to detect active streams.

• loadHistoricalMessages() now accepts hasActiveStream parameter
• WorkspaceStore checks buffered events before loading history
• Active stream (hasActiveStream=true) → Reconstruct TODOs ✅
• Completed stream (hasActiveStream=false) → Don't reconstruct TODOs ✅
• agentStatus always reconstructed (persists across sessions) ✅

3. Improved separation of concerns

Centralized tool persistence logic in processToolResult:

• Added context parameter: "streaming" | "historical"
• loadHistoricalMessages no longer knows about specific tool behaviors
• Each tool declares its own persistence policy in one place

Implementation

WorkspaceStore checks for active streams:

const pendingEvents = this.pendingStreamEvents.get(workspaceId) ?? [];
const hasActiveStream = pendingEvents.some(
  (event) => "type" in event && event.type === "stream-start"
);
aggregator.loadHistoricalMessages(historicalMsgs, hasActiveStream);

StreamingMessageAggregator handles context:

loadHistoricalMessages(messages: CmuxMessage[], hasActiveStream = false) {
  const context = hasActiveStream ? "streaming" : "historical";
  // Process tool results with context
  this.processToolResult(toolName, input, output, context);
}

processToolResult decides based on tool + context:

private processToolResult(toolName, input, output, context: "streaming" | "historical") {
  // TODOs: stream-scoped (only during streaming)
  if (toolName === "todo_write" && context === "streaming") {
    this.currentTodos = args.todos;
  }
  
  // agentStatus: persistent (always reconstruct)
  if (toolName === "status_set") {
    this.agentStatus = { emoji, message, url };
  }
}

Testing

Comprehensive test coverage for the full todo lifecycle:

✅ Clear todos on stream end
✅ Clear todos on stream abort
✅ Reconstruct todos when hasActiveStream=true (reconnection)
✅ Don't reconstruct todos when hasActiveStream=false (completed)
✅ Always reconstruct agentStatus (persists across sessions)
✅ Clear todos on new user message

All 146 message-related tests pass.

Behavior Matrix

Scenario	TODOs	agentStatus
During streaming	✅ Visible	✅ Visible
Stream ends	❌ Cleared	✅ Persists
Reload (active stream)	✅ Reconstructed	✅ Reconstructed
Reload (completed)	❌ Not reconstructed	✅ Reconstructed
New user message	❌ Cleared	❌ Cleared

Key Insight

The reconnection scenario is the critical edge case: when a user reloads during an active stream, historical messages contain completed tool calls from the current stream, and buffered events contain stream-start. In this case, we should reconstruct TODOs to show work in progress.

This is fundamentally different from reloading after stream completion, where TODOs should remain cleared.

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