fix: propagate OTel context through fan-out branches and emit per-branch spans - #11
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lostbean merged 1 commit intoJun 16, 2026
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…nch spans Three issues caused broken traces for workflows using MapNode/FanOutBranch: 1. Task.async_stream in execute_fan_out_branches (dsl.ex) and MapNode.run spawned child tasks without propagating the current OTel context. Child spans were disconnected from the parent trace. Fixed by capturing the context before spawning and re-attaching via OtelCtx.with_parent_context in each task — the same pattern already used by SpawnAgent. 2. execute_fan_out_branch ran the child node without creating a span, so individual branch executions were invisible to tracing. Now wraps each branch in a TOOL span with the child node name. 3. maybe_complete_fan_out in the workflow strategy transitioned to the next node without finishing the current node span. This left the fan-out node's span open, causing subsequent nodes to incorrectly nest under it instead of being siblings. Added finish_node_span before the transition. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Thanks @Munksgaard! LGTM, merging it |
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Three issues caused broken traces for workflows using MapNode/FanOutBranch:
Task.async_stream in execute_fan_out_branches (dsl.ex) and MapNode.run spawned child tasks without propagating the current OTel context. Child spans were disconnected from the parent trace. Fixed by capturing the context before spawning and re-attaching via OtelCtx.with_parent_context in each task — the same pattern already used by SpawnAgent.
execute_fan_out_branch ran the child node without creating a span, so individual branch executions were invisible to tracing. Now wraps each branch in a TOOL span with the child node name.
maybe_complete_fan_out in the workflow strategy transitioned to the next node without finishing the current node span. This left the fan-out node's span open, causing subsequent nodes to incorrectly nest under it instead of being siblings. Added finish_node_span before the transition.