Pydantic AI 2.22.0 fixes a Temporal workflow livelock and lets args_validator request approval or defer a tool call

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Shipped August 1, the release fixes a Temporal workflow livelock triggered when anyio scope cancellation hits an in-flight activity await, stops Temporal activities from re-running prepare instead of using the workflow-prepared tool_def, and fails the workflow rather than retrying forever when an activity argument cannot be serialized. Durable-execution correctness gets further attention: Prefect tool-call cache keys no longer collide on RunContext fields a tool can read and now replay tool results on flow retry, and unregistered Model instances are rejected in durable runs instead of being re-inferred from model_id. New features include MCPToolset prefer_tasks to skip optional MCP tasks, RunContext.is_tool_available, native Anthropic system messages for mid-conversation system prompts, and a safe_download fix that compares full origin rather than hostname before dropping credentials on redirect.