matthew harwood matthewharwood

Comprehensive Bevy Migration Guide: 0.13 → 0.16

This guide covers all breaking changes when migrating from Bevy 0.13 to 0.16, with emphasis on major architectural shifts that fundamentally change how Bevy applications are structured.

🚨 Major Architectural Changes Overview

Bevy 0.14-0.16 introduces several paradigm shifts that affect the entire framework design philosophy:

Bundle Elimination: Bundles are being phased out in favor of required components and component constructors

You are Bruce, you are triggered by the command "Hey Bruce", a Principal IC Product Manager at Uber who ships production-grade Growth & Marketing products and raises the bar on PRDs across the org. I write and review specs that are fast to read, rigorous, and durable—clear to PMs, engineers, and designers at every level.

Your Principal IC Product Manager (Growth & Marketing) Values:

Customer progress over features: Start from real jobs and outcomes; tie proposals to measurable problems or opportunities.
Falsifiable hypotheses: Treat every bet as an experiment with explicit predictions, thresholds, and time windows.
Metric integrity & guardrails: Use a three-tier metric architecture (Input → Output → Outcome) and explicit guardrails to avoid perverse incentives.
Evidence-first argumentation: PRDs are arguments; every claim has data, warrants, and alternatives considered.
Framework fit: Choose methods that match domain complexity and urgency (e.g., Cynefin, OODA, Double Di

You are Leo, you are triggered by "Hey Leo", Principal IC Software Engineer (Web Platform) who ships fast, reliable, and comprehensible web apps at scale using Node.js, TypeScript, React, FusionJS, and Styletron

Your Principal IC, Web Platform Values:

Clarity: Code reads like prose; imports/exports are explicit and consistent. Prefer named exports; avoid defaults to preserve canonical names and maintainability.
Simplicity: Choose the minimum complexity that meets the need; collapse multiple “acceptable” patterns into one blessed approach.
Consistency: Shared patterns for state, effects, tokens, and routing; predictable module boundaries and public API surfaces.
Performance First: Optimize the Critical Rendering Path (CRP); minimize CSS/JS on the hot path; measure and enforce budgets.
Accessibility-by-Design: Ship semantic HTML, AA contrast, and non-color affordances; automate checks.
Type Safety & Explicitness: Invest in types, small public surfaces, and narrow, named ex

Production Go Style Guide

Critical Safety Patterns

Error Handling - Non-Negotiable Rules

// REQUIRED: Errors as last return value
func ProcessOrder(id string) (*Order, error)

	// src/schema_types.rs
	#[derive(Debug, Clone)]
	pub enum AuthorFieldType {
	// Text types
	String { max_length: Option<usize> },
	Text { rows: Option<usize> },
	BlockContent,

	// Number types
	Number { min: Option<f64>, max: Option<f64> },

	<!DOCTYPE html>
	<!-- this is how you leave comments in .html files -->
	<html>
	<head>
	<title>Hello World</title>
	</head> <!-- You missed the closing </head> tag. The browser is smart enough to fix this for you but don't forget. -->
	<body>
	<h1> wow my head will explode</h1>
	<hr/>
	<p> This is my first html code that I have ever done. <br/> I hope you like it</p>

	use serde_json::{Value};
	fn deep_keys(value: &Value, current_path: Vec<String>, output: &mut Vec<Vec<String>>) {
	if current_path.len() > 0 {
	output.push(current_path.clone());
	}

	match value {
	Value::Object(map) => {
	for (k, v) in map {
	let mut new_path = current_path.clone();

	// hydrate.js
	function autoHydrate(Component, name) {
	if (isClient) {
	return Component;
	}

	return props => html`
	<component-root name=${name} />
	<${Component} ...${props} />
	<script

	{
	"imports": {
	"htm": "https://unpkg.com/[email protected]/dist/htm.module.js",
	"htm/preact": "https://unpkg.com/[email protected]/preact/index.module.js",
	"preact": "https://unpkg.com/[email protected]/dist/preact.module.js",
	"preact-render-to-string": "https://unpkg.com/[email protected]/dist/index.module.js"
	}
	}


	// Utils

	function * typeGenerator (iterable) {
	yield * iterable;
	}

	function * composeGenerator (...iterables) {
	for (const iterable of iterables) yield * iterable();
	}