theme.gradient hardcode

theme.gradient-hardcode

Rule ID: theme.gradient-hardcode Severity: WARN Category: theme Target Standards: W3C Design Tokens Community Group (DTCG), Tailwind CSS Gradient Token Architecture

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1. Overview & Core Invariant

Detects hardcoded primitive, arbitrary hex, or monochrome colors in gradient stops

Core Invariant:

"Gradient color stops must use semantic tokens (from-primary, to-accent), never primitive palette or arbitrary hex stops."

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2. Technical Grounding & Engine Realities

Gradients often span large hero sections or callout backgrounds. When color stops use primitive or arbitrary values (e.g. from-[#3b82f6] to-blue-500):

1. Inverted Muddy Colors: Light mode gradients rendered in dark mode produce muddy, low-contrast, or unreadable backgrounds behind text.
2. Theme Decoupling: Rebranding or dynamic tenant themes cannot adjust the stops without manually updating every gradient class.
3. Accessibility Violations: Static gradient stops cannot guarantee compliance with WCAG 2.2 text contrast across all screen areas.

Charites enforces gradient stops constructed from semantic tokens (from-primary, to-secondary, via-accent, from-transparent).

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3. Vulnerability & Risk Taxonomy

Risk Vector	Severity	Impact
Dark Mode Breakage	HIGH	Hardcoded gradient stops destroy text legibility and brand alignment in dark themes.
Design Token Fragmentation	MEDIUM	Gradients drift out of sync with established design system tokens.

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4. Non-Compliant Code Patterns (Bad Examples)

ASTRO (Gradient stops using arbitrary hex and primitive colors):

<div class="bg-gradient-to-r from-[#3b82f6] to-blue-500">Banner</div>

TSX (Gradient stops using monochrome white and primitive red):

export function Hero() {
  return <div className="bg-gradient-to-b from-white via-rose-500 to-black">Hero</div>;
}

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5. Compliant Implementation Patterns (Good Examples)

ASTRO (Semantic tokens for gradient stops):

<div class="bg-gradient-to-r from-primary to-accent">Banner</div>

TSX (Semantic tokens adapting cleanly to dark mode):

export function Hero() {
  return <div className="bg-gradient-to-b from-card via-primary to-background">Hero</div>;
}

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6. Detection & Verification Pipeline (How The Rule Evaluates Code)

This theme rule evaluates source templates against the project's design token graph:

flowchart TD
    Node["AST Node (Astro / TSX element)"] --> Extract["1. Extract Class Names (e.g. 'hover:bg-primary/10')"]
    Extract --> Strip["2. Strip Variants (hover:, dark:, sm:) -> 'bg-primary/10'"]
    Strip --> Split["3. Split Opacity Modifier -> Utility: 'bg-primary', Opacity: '/10'"]
    Split --> Convention["4. Query TokenConvention (Candidate: '--color-primary-light')"]
    Convention --> GraphQuery{"5. Check Token Graph (Does token exist in active scope?)"}
    GraphQuery -- "No (Banana Test)" --> Safe["Pass (Valid Custom / Untokenized Color)"]
    GraphQuery -- "Yes (Official Token Exists)" --> IgnoreCheck{"6. Check charites:ignore directive"}
    IgnoreCheck -- "Ignored" --> Safe
    IgnoreCheck -- "Not Ignored" --> Diag["7. Emit Diagnostic: theme.gradient-hardcode with Replacement Suggestion"]

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Step-by-Step Evaluation:

1. AST Node Traversal: internal/analyzer streams JSX/Astro AST elements to the rule's Evaluate visitor.
2. Variant Normalization: Strips responsive (sm:, md:), interaction state (hover:, focus:), and theme (dark:) prefixes to isolate the core utility class.
3. Modifier Extraction: Parses utility segments and extracts slash opacity modifiers.
4. Token Convention Resolution: Consults the TokenConvention adapter to determine the official semantic design token replacement candidate.
5. Token Graph Verification (Banana Test): Queries token.Context to verify that the candidate token is declared in global.css or tokens.json within the element's scope. If not declared, the custom value is permitted without a false-positive diagnostic.
6. Directive Suppression Check: Inspects preceding AST comments for charites:ignore theme.gradient-hardcode.
7. Diagnostic Emission: Produces a structured diagnostic with line number, column span, and actionable replacement suggestion.

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7. Verification & Test Harness (How The Test Works: 1-SSOT Tri-Corpus)

This rule is rigorously tested and validated across the canonical 1-SSOT Tri-Corpus in tests/correctness/theme.gradient-hardcode/:

flowchart TD
    subgraph GoldenCorpus ["1-SSOT Tri-Corpus Test Matrix for theme.gradient-hardcode"]
        subgraph P ["Positive Corpus (tests/correctness/theme.gradient-hardcode/positive/)"]
            P1["P1: Obvious Direct Violation"]
            P2["P2: Indirect / Variant Concatenation"]
            P3["P3: Helper / clsx / cn Wrapper"]
            P4["P4: Deeply Nested Elements"]
            P5["P5: Aliased Imports / Re-exports"]
        end
        subgraph N ["Negative Corpus (tests/correctness/theme.gradient-hardcode/negative/)"]
            N1["N1: Valid Design Tokens"]
            N2["N2: Explicit charites:ignore Directive"]
            N3["N3: Third-Party / Vendor Components"]
            N4["N4: Clean Semantic HTML"]
            N5["N5: Untokenized Custom Values (Banana Test)"]
        end
        subgraph A ["Adversarial Corpus (tests/correctness/theme.gradient-hardcode/adversarial/)"]
            A1["A1: Template Literal Interpolations"]
            A2["A2: Ternary Conditional Expressions"]
            A3["A3: Spread Properties & Dynamic Overrides"]
            A4["A4: Dynamic Object Class Syntax"]
            A5["A5: Shadowed Variable Identifiers"]
            A6["A6: Nested Closures & HOC Wrappers"]
            A7["A7: Obfuscated Classes & Cyclic Tokens"]
        end
    end

    P --> TestRunner["Automated Runner (rule_test.go)"]
    N --> TestRunner
    A --> TestRunner
    TestRunner --> Gates["Quality Gates: Zero Panic, Zero False-Positive, Zero Bypass"]

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• Positive Fixtures (P1-P5): Verified to trigger diagnostics at exact lines and column spans.
• Negative Fixtures (N1-N5): Verified to produce zero diagnostics on valid tokens and legitimate exemptions.
• Adversarial Fixtures (A1-A7): Verified to prevent evasion across dynamic expressions, string interpolations, and cyclic references.

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8. How to Suppress (Ignore Directives)

If this pattern is required for an intentional exception, suppress the diagnostic using the canonical Charites Rule ID:

<!-- charites:ignore theme.gradient-hardcode intentional exception -->

// charites:ignore theme.gradient-hardcode intentional exception

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9. Configuration Reference (charites.yaml)

rules:
  theme.gradient-hardcode:
    severity: warn # error | warn | info | off