Fix 2 of plans/2026-07-11-concurrent-task-execution.md. sendMessage's SSE
callback mutated the global messages/currentSession stores unconditionally,
assuming only one task's turn is ever in flight. It isn't — the backend runs
every /chat request as its own goroutine with no serialization. Switching to
a different task while a previous one was still streaming let that
background stream's later events (tool_use, text_delta, ..., and worst of
all 'done''s currentSession.set) get applied to whatever the operator is now
looking at: corrupting another task's transcript, or yanking the view back
to the one they left.
- Captures the session a stream belongs to (openedFor at call time, updated
to the real id once the 'session' event assigns one) and checks
$currentSession still matches before every messages/error/streaming
mutation. The task keeps running server-side regardless — dropped events
just mean the live view isn't watching it; navigating back re-hydrates via
REST, same as already happens for auto-continuation.
- The 'session' event itself only claims currentSession if the operator
hasn't already navigated elsewhere since the call started (comparing
against openedFor, which is null for a brand-new task).
- loadSessionMessages/newChat now reset `streaming` to false unconditionally
on navigation — needed so the new guard can't leave a DIFFERENT task's view
stuck showing streaming=true (which would also silently stop startPolling's
loop from ever applying updates, since it bails while $streaming is true).
Known residual gap, not fixed here (matches the plan's "contained fix, not a
rearchitecture" scope): activeController is still a single global slot, so
starting a new task while another is mid-stream, then clicking "New task"
again, aborts whichever stream that slot last pointed at rather than only
the one being left. A genuine multi-session controller/store is the
plan's deferred "stretch" fix, not required for correctness here.
Verified live: started Task A with a deliberately slow 4-tool-call turn,
switched to an existing Task B mid-stream — Task B's transcript stayed
correct with zero A-originated entries and the input was NOT stuck disabled.
Task A kept running and completed normally server-side (status=done, full
6-tool transcript, 5-entity graph); navigating back loaded its complete,
uncorrupted result via REST.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
dtoro
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