fix(agent): tolerate explicit null outputs in streamed conversation events - #572
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…vents
`WorkflowFinishedPayload.outputs`, `NodeToolUseFinishedPayload.outputs`,
and `SubagentFinishedPayload.outputs` were `#[serde(default)]`, which only
applies to a missing key — not an explicit `null`. A `workflow_finished`
(or node/subagent finished) event carrying `"outputs": null`, which the
server can send on resumed/continued conversations, failed to deserialize
and aborted the whole event stream:
invalid type: null, expected struct WorkflowOutputs
Deserialize these fields through `null_as_default` so `null` maps to the
type's default, matching how the sibling `null` lists are already handled.
hogan-yuan
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Aug 14, 2026
…#573) Follow-up to the `null` `outputs` fix (#572), same class of bug. Several list-typed fields on the streamed AI Agent conversation event payloads were `#[serde(default)]`, which only fills a **missing** key — it does not accept an explicit `null`. An event carrying e.g. `"tip_chips": null` failed to deserialize and aborted the whole event stream: ``` invalid type: null, expected a sequence ``` Fixed by deserializing these through `serde_utils::null_as_default` so `null` maps to an empty list: - `tip_chips` — on the node / subagent / agent-tool `*_started` payloads - `WorkflowFinishedPayload.process_data` - `SubagentStartedPayload.tools` Added a unit test covering `null` for each.
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Problem
A streamed AI Agent conversation aborts mid-run with:
when the server sends an explicit
"outputs": nullon aworkflow_finishedevent (observed on resumed/continued conversations).Root cause:
WorkflowFinishedPayload.outputs(and the siblingNodeToolUseFinishedPayload.outputs,SubagentFinishedPayload.outputs) were annotated#[serde(default)].serde'sdefaultonly fills a missing key — it does not accept an explicitnull, sonullfails to deserialize into the struct and the whole event stream errors out.Fix
Deserialize these three fields through the existing
serde_utils::null_as_default, mappingnullto the type'sDefault. This mirrors how siblingnulllists (e.g.Interrupt.questions/interactions) are already handled.Added a unit test covering both
"outputs": nulland a missingoutputskey.