theme.dual strategy collision

theme.dual-strategy-collision

Rule ID: theme.dual-strategy-collision Severity: WARN Category: theme Target Standards: W3C CSS Cascading and Inheritance Level 5, Design System Theming Strategy Alignment, Tailwind CSS Dark Mode Strategy Selector vs Media

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1. Overview & Core Invariant

Detects conflicting dark mode strategies (@media vs .dark/[data-theme]) in the same style scope

Core Invariant:

"Stylesheets must adhere to a single unified dark mode strategy (either media query or selector-based), avoiding contradictory cascade conflicts."

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2. Technical Grounding & Engine Realities

When developers mix @media (prefers-color-scheme: dark) with class (.dark) or attribute ([data-theme="dark"]) selectors within the same scope:

1. Frankenstein Interface: System dark mode triggers media queries while manual theme toggles toggle classes, producing a fractured, half-dark layout.
2. Specificity Inversion: Class selectors have higher specificity than unnested media query elements, creating unpredictable styling overrides.
3. State Desynchronization: Manual UI theme switches fail to override hardcoded @media rules.

Charites enforces choosing a single, coherent dark mode switching strategy across each style scope.

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3. Vulnerability & Risk Taxonomy

Risk Vector	Severity	Impact
Frankenstein UI Collision	HIGH	System dark mode and application theme toggles conflict, resulting in partially inverted and illegible components.
Cascade Specificity Wars	MEDIUM	Rules under @media cannot be overridden by user-selected theme classes without high-specificity hacks.

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4. Non-Compliant Code Patterns (Bad Examples)

ASTRO (Mixing prefers-color-scheme media query with .dark class selector):

<style>
  @media (prefers-color-scheme: dark) {
    body {
      background: #121212;
    }
  }
  .dark {
    --bg-main: #000000;
  }
</style>

TSX (Mixing media query with data-theme attribute in TSX style):

<style>{`
  @media (prefers-color-scheme: dark) {
    :root { --card: #18181b; }
  }
  [data-theme="dark"] {
    --card: #09090b;
  }
`}</style>

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5. Compliant Implementation Patterns (Good Examples)

ASTRO (Single coherent class-based strategy):

<style>
  :root {
    --bg-main: #ffffff;
  }
  .dark {
    color-scheme: dark;
    --bg-main: #09090b;
  }
</style>

TSX (Single coherent media-query-based strategy):

<style>{`
  :root {
    --bg-main: #ffffff;
  }
  @media (prefers-color-scheme: dark) {
    :root {
      color-scheme: dark;
      --bg-main: #09090b;
    }
  }
`}</style>

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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.dual-strategy-collision 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.dual-strategy-collision.
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.dual-strategy-collision/:

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

// charites:ignore theme.dual-strategy-collision intentional exception

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9. Configuration Reference (charites.yaml)

rules:
  theme.dual-strategy-collision:
    severity: warn # error | warn | info | off