lcp

Lcp Rules (lcp)

The lcp category contains static analysis rules for code quality, architectural constraints, and design system governance.

---

Category Rule Index

Rule ID	Severity	Summary	Full Specification	Status
lcp.blocked-critical-font	WARN	Custom '@font-face' declaration lacks 'font-display: swap' or 'font-display: optional', risking FOIT (Flash of Invisible Text) and delaying LCP text paint	lcp.blocked-critical-font	enabled
lcp.client-only-lcp-content	WARN	Above-the-fold hero island declared with 'client:only' without an SSR fallback slot, eliminating server HTML and delaying LCP until client-side bundle execution	lcp.client-only-lcp-content	enabled
lcp.critical-head-style-bloat	WARN	Inline '<style>' in '' contains non-critical CSS selectors (footer, modal, dialog), inflating initial HTML payload and delaying LCP paint	lcp.critical-head-style-bloat	enabled
lcp.external-font-discovery-delay	WARN	External font stylesheet loaded without '' hints, adding 200ms-400ms connection handshake latency to LCP font discovery	lcp.external-font-discovery-delay	enabled
lcp.heavy-raster-lcp-asset	WARN	LCP candidate image uses legacy uncompressed raster format (.png, .bmp, .tiff, .gif); modern formats like WebP or AVIF should be served to reduce transfer size	lcp.heavy-raster-lcp-asset	enabled
lcp.image-source-density-mismatch	INFO	Fixed-dimension LCP candidate image lacks aligned '1x, 2x' pixel density descriptors in 'srcset', risking blurry rendering or unoptimized asset delivery on high-DPI screens	lcp.image-source-density-mismatch	enabled
lcp.lazy-loaded-lcp-image	ERROR	Critical above-the-fold LCP candidate image has loading="lazy", delaying resource discovery and load initiation	lcp.lazy-loaded-lcp-image	enabled
lcp.lcp-content-visibility-suppression	ERROR	Above-the-fold hero container specifies 'content-visibility: auto' or 'content-auto', suppressing initial paint and severely inflating LCP	lcp.lcp-content-visibility-suppression	enabled
lcp.legacy-critical-font-resource	WARN	Custom '@font-face' declaration provides only legacy uncompressed font formats (.ttf, .otf, .eot) or deprioritizes WOFF2 in 'src:', inflating byte transfer payload	lcp.legacy-critical-font-resource	enabled
lcp.missing-critical-origin-hint	INFO	Critical LCP visual asset loaded from third-party CDN origin without '' connection hint in ''	lcp.missing-critical-origin-hint	enabled
lcp.missing-lcp-image-preload	INFO	Delayed-discovery LCP image lacks in document head to initiate early asset transfer	lcp.missing-lcp-image-preload	enabled
lcp.oversized-lcp-resource-selection	WARN	Fluid responsive LCP candidate image lacks responsive 'srcset' and 'sizes' attributes, forcing mobile viewports to download oversized desktop assets	lcp.oversized-lcp-resource-selection	enabled
lcp.preload-font-cors-mismatch	ERROR	Font preload '' lacks 'crossorigin' attribute, triggering browser cache discard and double network downloads	lcp.preload-font-cors-mismatch	enabled
lcp.render-blocking-head-script	WARN	External script in '' without 'defer', 'async', or 'type="module"' synchronously blocks HTML parser and delays LCP candidate paint	lcp.render-blocking-head-script	enabled
lcp.undiscoverable-lcp-image	WARN	Above-the-fold hero container loads primary image via CSS background without in document head	lcp.undiscoverable-lcp-image	enabled
lcp.unhinted-lcp-image-priority	WARN	Above-the-fold LCP candidate image lacks fetchpriority="high", delaying bandwidth allocation in early network stream	lcp.unhinted-lcp-image-priority	enabled

---

How the Lcp Analysis Pipeline Works

The lcp engine applies static analysis checks against component source code:

flowchart LR
    TargetFiles["Target Files (*.astro, *.tsx)"] --> Parser["Leaf IR AST Parser"]
    Parser --> Engine["Rule Evaluator Engine"]
    Engine --> Check{"Evaluate Invariant"}
    Check -- "Compliant" --> Safe["Pass"]
    Check -- "Violation" --> Diag["Diagnostic: lcp.*"]

Loading

Pipeline Flow:

1. AST Node Traversal: Scans target template files into normalized intermediate representation.
2. Invariant Assertion: Validates structural and semantic invariants.
3. Diagnostic Reporting: Emits structured diagnostics for non-compliant patterns.

---

How Lcp Tests Work (Verification Harness)

All rules in lcp are verified using the canonical 1-SSOT Tri-Corpus (tests/correctness/lcp.*/) encompassing Positive (P1-P5), Negative (N1-N5), and Adversarial (A1-A7) fixture matrices.