---
title: Bootstrap binary StepSettings from defaults, config, registries, and profile
description: Applications now bootstrap StepSettings from defaults/config/env/flags only; profiles no longer patch them.
doc_version: 1
last_updated: 2026-07-02
---


# Bootstrap binary StepSettings from defaults, config, registries, and profile

This playbook changed with the StepSettingsPatch hard cut.

Current rule:

1. Build `StepSettings` from schema defaults, config files, env, and flags.
2. Resolve profile registries separately for runtime metadata (`system_prompt`, `tools`, `middlewares`).
3. Build engines from the app-owned final `StepSettings`.

Profiles no longer produce final `StepSettings`, and `ResolveEffectiveProfile` no longer returns `effectiveStepSettings`.