R1.7: LCP asset priority

Short answer: Priority/fetchpriority=high on hero LCP image, lazy below fold. The browser cannot know the hero image is the largest paint unless you say so.

Group: UI and mobile performance. Status: stable. Generated from the rule definitions; do not edit by hand.

Playground: https://brevio.pro/tools/agent-guard-playground?rule=R1.7

What it catches

LCP asset priority: priority/fetchpriority=high on hero LCP image, lazy below fold.

Why

The browser cannot know the hero image is the largest paint unless you say so.

A bad example

<img src="/hero.jpg" />

A good example

<Image src="/hero.jpg" priority alt="" width={1200} height={600} />

How it is checked

A one-line card in the prompt of a slice that touches matching files (dev_rules.slice_micro_rules).

How to silence it

A person can silence one finding with brevio-core: ignore R1.7 -- reason on the line or the line above. Without the reason it does not count. An agent cannot silence it: the agent hook and the MCP tools never honour the comment, and a pull request that adds one is reported until a reviewer allows it. Fixing the code is still the better answer.

To change what the rule flags, edit its definition in dev_rules.py or code_rules/__init__.py. That is a code change and is reviewed like one.

R1.8 Async polling hygiene
R1.1 Mobile GPU budget
R1.2 SSR visibility resilience
R1.3 Third-party script deferral
Every rule