v0.46.4: preserve child ToolArgs handoff contract
Summary
- preserve canonical parent tool payload bytes when populating child run ToolArgs for agent-as-tool handoff
- remove silent ToolArgs loss path caused by re-encoding raw payload bytes through typed payload codecs
- add runtime regression coverage to lock canonical ToolArgs propagation across parent->child boundaries
Highlights
This release fixes a contract regression where child runs could receive null ToolArgs even when the parent tool payload was present, causing prompt template rendering failures in nested planners.