What is mfe-architecture-decisions?

A decision framework for designing micro-frontends, which are independently built parts of a web application. It covers how to split them, combine them, route between them, and let them communicate.

Use it when planning a micro-frontend system, especially when choosing between business-area or page splits, browser or server composition, routing methods, and communication methods.

It makes related architecture choices explicit because one choice can limit the others. This helps teams avoid incompatible designs and excessive coordination.

mfe-architecture-decisions — Cursor rule for Cursor by lucamezzalira

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo

git clone --depth 1 https://github.com/lucamezzalira/mfe-skills

Made for: Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/rules/lucamezzalira/mfe-skills/mfe-architecture-decisions/github.svg)](https://agentmods.dev/rules/lucamezzalira/mfe-skills/mfe-architecture-decisions)

Your own site

<a href="https://agentmods.dev/rules/lucamezzalira/mfe-skills/mfe-architecture-decisions"><img src="https://agentmods.dev/badge/rules/lucamezzalira/mfe-skills/mfe-architecture-decisions/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/rules/lucamezzalira/mfe-skills/mfe-architecture-decisions"><img src="https://agentmods.dev/badge/rules/lucamezzalira/mfe-skills/mfe-architecture-decisions.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 25 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 2,091 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00025	$0.02091
Opus 5	$0.00013	$0.01045
Sonnet 5	$0.00005	$0.00418
Haiku 4.5	$0.00003	$0.00209

Measured 11d ago against content hash 3fb8286c26d7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

mfe-architecture-decisions scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/mfe-architecture-decisions.mdc · 180 lines

How it starts

The opening of the file, as written. The whole thing — 180 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Micro-frontends decisions framework

Version: 1.2 | Skill: understanding-mfe-architecture | Source: Building Micro-Frontends (O'Reilly)

The decisions framework is composed of four areas that must be resolved upfront because each one constrains the next:

Define — horizontal or vertical split?
Compose — client-side or server-side?
Route — client-side or server-side?
Communicate — event emitter, custom events, web storage, query strings?

These decisions are not independent — composition constrains routing, and split strategy constrains communication. The table at the end of this file shows the valid combinations.

Decision 1 — Define: horizontal or vertical split?

Vertical split: one micro-frontend per view or group of views. Each team owns a complete business domain end-to-end — authentication, catalog, checkout. The micro-frontend owns all the routes under its domain.

Closer to a traditional SPA or server-side rendering approach
Each team has full autonomy — fewer cross-team coordination points
Better fit for teams new to micro-frontends
Recommended as the starting point for most organisations

Horizontal split: multiple micro-frontends composing the same view. Multiple teams share responsibility for parts of the same page.

Requires more discipline and governance — without it, proliferation of micro-frontends creates a distributed monolith
Higher granularity → higher coupling → context leakage risk
Requires upfront investment in a solid development experience (local composition, testing across teams)
Better fit for teams experienced with micro-frontends and with strong automation

Both are valid and not mutually exclusive. Some parts of an application may suit a vertical split, others a horizontal split. Start with vertical where possible and introduce horizontal where domain ownership genuinely requires it.

The granularity warning: resist the instinct to split finely. A large number of micro-frontends composing a single view is a warning sign — each additional micro-frontend increases the coordination surface in the container and risks pushing domain logic into the shell.

Read the full file on GitHub · 180 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

11d ago First seen · 180 lines · 2,091 tokens per session scan A 3fb8286c26d7

Subscribe to this mod's changes

mfe-architecture-decisions is a cursor rule published in the GitHub repository lucamezzalira/mfe-skills (51 stars, last pushed 16d ago), licensed MIT. It adds 25 tokens to every session and 2,091 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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