v1.21.0

Highlights

StepResult pattern across Agent, Chat, ToolUse, and Collaboration with immutable steps and explicit continuation outcomes.
Continuation evaluation is unified around ContinuationEvaluation and ContinuationOutcome, with clearer stop reasons.
Retry policy handling is explicit for Inference and Embeddings (no more retryPolicy inside options).
Hub status persistence now tolerates malformed UTF-8 output instead of failing to write status data.

Continuation interfaces CanDecideToContinue, CanExplainContinuation, and CanProvideStopReason were removed. Custom criteria must implement CanEvaluateContinuation and return ContinuationEvaluation.
Error handling classes moved from Cognesy\Addons\StepByStep\Continuation to Cognesy\Addons\StepByStep\ErrorHandling.
retryPolicy is no longer accepted in options or LLMConfig options. Use explicit retry policy objects.
Continuation outcomes are no longer stored on step objects. Use StepResult or state accessors instead.

States now store StepResult collections and serialize them.
canContinue() reads from the last step result; mismatches between steps and step results now raise a logic error.
Message compilation supports summary and buffer sections for inference context.
Token usage is accumulated before continuation evaluation so usage limits are accurate.

ContinuationCriteria composes CanEvaluateContinuation criteria and exposes evaluateAll() with aggregated outcomes.
Criteria classes return richer ContinuationEvaluation objects with explicit decisions and stop reasons.
New outcome helpers provide derived decision, resolver, and stop reason from evaluations.

InferenceRequest and EmbeddingsRequest now carry retry policies explicitly.
InferenceRequestBuilder and request builder traits expose withRetryPolicy().
PendingInference and PendingEmbeddings pull retry policies from requests rather than options.

Status JSON encoding now substitutes invalid UTF-8 bytes to avoid failures when saving example output.

Update custom continuation criteria to implement CanEvaluateContinuation and return ContinuationEvaluation (replace CanDecideToContinue, CanExplainContinuation, CanProvideStopReason).
Update imports to the new error handling namespace: Cognesy\Addons\StepByStep\ErrorHandling\*.
Remove retryPolicy from LLM or request options. Use withRetryPolicy() on inference/embeddings builders or requests.
Replace any step-level continuation outcome access with state->continuationOutcome() or state->lastStepResult().