BREAKING CHANGE: StepRecord now requires startedAtMs and completedAtMs fields.
StepEntry now requires durationMs field. Old CAS data without these fields is invalid.
- Add startedAtMs/completedAtMs to StepRecord and StepNodePayload
- Add durationMs to StepEntry (computed: completedAtMs - startedAtMs)
- Update STEP_NODE_SCHEMA to require timing fields as integers
- Record Date.now() before/after agent execution in createAgent
- Show duration in thread read headers (formatStepHeader)
- Update existing test fixtures with timing fields
xiaoju
45f479e60f