theme.token source drift

theme.token-source-drift

Rule ID: theme.token-source-drift Severity: ERROR Category: theme Target Standards: W3C Design Tokens Community Group (DTCG), Single Source of Truth (SSOT) Architecture

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1. Overview & Core Invariant

Detects hardcoded color values bypassing the single source of truth design token pipeline

Core Invariant:

"Custom properties representing theme tokens must not be assigned raw color literals in component scopes; they must resolve to SSOT token references."

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2. Technical Grounding & Engine Realities

Assigning raw hex/rgb color values directly to theme custom properties inside components or local stylesheets fractures the design token pipeline.

When developers write style="--primary: #2563eb" or declare local --color-brand: #3b82f6:

1. Drift from Global SSOT: The component diverges from centralized theme tokens (global.css), creating fragmented brand colors.
2. Theme Switching Failure: Dynamic theme changes (e.g. high-contrast, dark mode, multi-tenant branding) cannot override local hardcoded values.
3. Design System Audit Blind Spot: Design linters fail to track where rogue colors enter the application.

Charites enforces binding theme variables to global design tokens via var(--...) instead of raw literals.

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3. Vulnerability & Risk Taxonomy

Risk Vector	Severity	Impact
Token SSOT Incoherence	HIGH	Hardcoded local variable assignments decouple components from global design system updates.
Theme Switch Blind Spot	HIGH	Local variable assignments prevent dynamic color schemes and tenant styling from cascading.

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4. Non-Compliant Code Patterns (Bad Examples)

ASTRO (Hardcoded hex assigned to theme token in inline style):

<div style="--primary: #2563eb; --background: #ffffff;">Drifting Tokens</div>

TSX (Hardcoded rgb assigned to custom property in JSX style):

export function Header() {
  return <header style={{ '--color-brand': 'rgb(37, 99, 235)' }}>Drifted Header</header>;
}

ASTRO (Raw color assigned to theme custom property in style tag):

<style>
  .card {
    --card-bg: #1e293b;
  }
</style>

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5. Compliant Implementation Patterns (Good Examples)

ASTRO (Theme token mapped via SSOT variable reference):

<div style="--primary: var(--color-blue-600);">SSOT Aligned</div>

TSX (Non-color numeric custom property):

export function Tabs() {
  return <div style={{ '--tab-index': '2' }}>Safe Property</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.token-source-drift 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.token-source-drift.
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.token-source-drift/:

flowchart TD
    subgraph GoldenCorpus ["1-SSOT Tri-Corpus Test Matrix for theme.token-source-drift"]
        subgraph P ["Positive Corpus (tests/correctness/theme.token-source-drift/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.token-source-drift/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.token-source-drift/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.token-source-drift intentional exception -->

// charites:ignore theme.token-source-drift intentional exception

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9. Configuration Reference (charites.yaml)

rules:
  theme.token-source-drift:
    severity: error # error | warn | info | off