How Block orchestrates Claude Fable across thousands of pull requests

Block builds tools that help businesses and individuals participate in the economy, including Square for sellers and Cash App for consumers. Bradley Axen leads AI capabilities at Block, where his team builds end-to-end AI products, including Buzz, an open-source workspace for human-agent teams (opens in new tab), and partners with the Square and Cash App teams to build customer-facing AI features. Brad spoke with Anthropic about how frontier models like Claude Opus 5 and Claude Fable 5 have transformed what it means to be an engineer, how Block applies agent orchestration patterns with Fable, and the role of safeguards when…

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