In depth
YAML-first is the design choice that the agent's shape (tools, brains, prompts, triggers) lives in a config file the runtime reads, not in code you compile. The benefits compound: PRs are reviewable, prompts hot-reload in 200ms, non-engineers can edit safely, the shape travels as a file. The trade-off is less language flexibility for the rare edge cases where you genuinely need Python.
Related concepts
Hot reloadRe-applying config changes to a running agent in place, without restarting the process.ModuleA bundle of tools the agent can call (filesystem, web, shell, channels). Declared in YAML, loaded at boot.HooksDeclarative event handlers that fire at specific points in an agent's lifecycle (turn_start, tool_end, etc).
Read the deep dive
Why we chose YAML over Python for our agent runtime
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Engineering notes from the Digitorn team. No marketing, no launch announcements, no "10 prompts that will change your life". Just the things we write that we'd want to read.