The Flow Debugger trace arm was recorded when a traced write was ISSUED, not
when the DCL acknowledged it. A write the device rejected (or that timed out)
left the arm standing for the whole TraceArmWindowSeconds (30 s), so the next
unrelated subscription update on that attribute was stamped with the debugger's
execution id and spawned a traced, parented run — the debugger drew a "device
echo" of a write that never landed.
The write's continuation runs off the actor's dispatcher, so it cannot touch
_traceArms directly; it Tells self a new DisarmTrace message instead, handled in
a Receive<>. The disarm is keyed on the writer's execution id, so a late failure
cannot steal an arm a newer traced write has since taken.
Claude-Session: https://claude.ai/code/session_01NcMG6xXdsJbmD2wYAgkK29
Flow Debugger (design 2026-09-05 §5.3): a traced SetStaticAttributeCommand on a data-sourced
attribute records (attribute → writer, expiry) for TraceArmWindowSeconds (new option,
default 30, validated > 0); the next DCL echo for that attribute is published with the
writer's SourceExecutionId + Trace whatever its value, and the arm is consumed once. Static
writes publish Trace directly. Untraced writes never arm (pinned).
Claude-Session: https://claude.ai/code/session_01GSLkkHKz9JrAtmJjmQK3cP
Joseph Doherty