mfe-boundary-review

mfe-boundary-review is a cursor rule for Cursor from lucamezzalira/mfe-skills. It costs 185 tokens per session (3,154 once invoked), scanned A, original, MIT.

A rule set for reviewing and generating micro-frontend code, where separately deployed parts of a web application work together. It checks business ownership, interface size, isolation, communication, deployment independence, failure handling, and nesting.

In plain words
What is it for?
Use it to review shell code and micro-frontends, assess whether a boundary is valid, and check fallback behavior, imports, props, events, deployment setup, and nesting.
Why use it?
It identifies boundary problems that can create tight coupling, shared-state risks, fragile deployments, or failures that spread between parts of the application.

Cursor rule for Cursor

Written for Cursor: installed under .cursor/.

Good fit Use it to review shell code and micro-frontends, assess whether a boundary is valid, and check fallback behavior, imports, props, events, deployment setup, and nesting.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/lucamezzalira/mfe-skills/mfe-boundary-review
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.

agentmods badge for mfe-boundary-review

README.md
[![agentmods](https://agentmods.dev/badge/rules/lucamezzalira/mfe-skills/mfe-boundary-review/github.svg)](https://agentmods.dev/rules/lucamezzalira/mfe-skills/mfe-boundary-review)
Your own site
<a href="https://agentmods.dev/rules/lucamezzalira/mfe-skills/mfe-boundary-review"><img src="https://agentmods.dev/badge/rules/lucamezzalira/mfe-skills/mfe-boundary-review/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.

agentmods 80×15 button for mfe-boundary-review

Your own site · 80×15
<a href="https://agentmods.dev/rules/lucamezzalira/mfe-skills/mfe-boundary-review"><img src="https://agentmods.dev/badge/rules/lucamezzalira/mfe-skills/mfe-boundary-review.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 185 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,154 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00185 $0.03154
Opus 5 $0.00093 $0.01577
Sonnet 5 $0.00037 $0.00631
Haiku 4.5 $0.00018 $0.00315

Measured 12d ago against content hash 23a171d3b8b7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

mfe-boundary-review 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 12d 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-boundary-review.mdc · 263 lines

How it starts

The opening of the file, as written. The whole thing — 263 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MFE boundary health

Reviews and generates micro-frontend code against the eight boundary rules from Building Micro-Frontends (O'Reilly). All rules are tool-agnostic. Full rule definitions, violation signals, and code-checkable patterns are in references/rules-core.md — load it when you need the detail for a specific rule.

On every activation, apply this summary table directly — no file load needed:

Rule What to check in code Severity
1 — Business subdomain Name reflects a business capability, not a UI element High
2 — Minimal API surface Fewer than 5 props; no full domain objects passed Critical
3 — Hide implementation details No direct imports from another MFE's internals Critical
4 — Events not shared state No shared store; shell handles shell:* only; domain events peer-to-peer or URL Critical
5 — Independent deployment No versioned URLs in shell config; no build-time MFE imports; no CI pipeline coupling High
6 — Isolate failure Every remote mount has a fallback in the shell High
7 — Coarse-grained Nesting depth > 1 (MFE inside MFE); more than 3 MFEs per view High
8 — Single-team ownership One team in CODEOWNERS; no cross-team sign-off on internals High

For full rule definitions and violation signals: load references/rules-core.md. For framework-specific patterns (MF v2, Angular/Native Federation, Single SPA): load references/rules-toolchain.md. For URL routing ownership (shell first segment, MFE deeper paths): load references/routing-ownership.md. For fix patterns and step-by-step remediation: load references/remediation.md when the user asks how to fix a violation or requests a migration plan.


Cold start: new project

If no boundaries exist yet, ask about the highest-priority unknown first — one question per turn. Do not generate implementation code until each check is resolved.

Check 1 — Team ownership Ask: "Which team will own this micro-frontend end-to-end — design, development, deployment, and operations?" If unresolved: do not generate implementation code. Ask the user to install the micro-frontend-canvas skill and complete a canvas iteration (see https://github.com/lucamezzalira/mfe-canvas).

Read the full file on GitHub · 263 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.

  1. 12d ago First seen · 263 lines · 185 tokens per session scan A 23a171d3b8b7

Subscribe to this mod's changes

mfe-boundary-review is a cursor rule published in the GitHub repository lucamezzalira/mfe-skills (51 stars, last pushed 17d ago), licensed MIT. It adds 185 tokens to every session and 3,154 once invoked, about $0.0009 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.