theme.image theme hardcode

theme.image-theme-hardcode

Rule ID: theme.image-theme-hardcode Severity: WARN Category: theme Target Standards: WCAG 2.2 Success Criterion 1.4.11 (Non-text Contrast), W3C Responsive Images & Art Direction Specification, Tailwind CSS Dark Mode Graphic Switching Guidelines

---

1. Overview & Core Invariant

Detects graphic assets and logos in img tags lacking dark mode theme adaptation

Core Invariant:

"Graphic assets, logos, and diagrams in img tags must provide theme-adaptive variants via picture, dark: utility classes, or invert filters."

---

2. Technical Grounding & Engine Realities

Embedding graphical assets (such as brand logos, SVG diagrams, and charts) via static tags without dark mode adaptation triggers severe visual breakage:

1. Asset Invisibility: A dark or black logo rendered against a dark mode background becomes completely invisible.
2. Inverted Eye-Strain: High-glare white background diagrams blast excessive light on dark UI themes.
3. Inflexible Art Direction: Projects without responsive image pairing cannot tailor vector artwork to dark contrast requirements.

Charites enforces theme-aware graphic handling using dark:hidden / dark:block class pairs, dark:invert filters, or responsive elements.

---

3. Vulnerability & Risk Taxonomy

Risk Vector	Severity	Impact
Asset Disappearance in Dark Themes	MEDIUM	Brand logos, technical diagrams, and icon artwork become illegible on dark surfaces.
Non-text Contrast Failure (WCAG 1.4.11)	MEDIUM	Visual cues necessary for interface understanding fail accessibility contrast requirements.

---

4. Non-Compliant Code Patterns (Bad Examples)

TSX (Static logo in img tag without dark mode variant in TSX):

<img src="/images/logo-black.svg" alt="Company Logo" />

ASTRO (Vector architecture diagram without theme switching in Astro):

<img src="/assets/diagram.svg" alt="Architecture Flow" />

---

5. Compliant Implementation Patterns (Good Examples)

TSX (Theme-paired image switching using Tailwind dark utilities):

<>
  <img src="/images/logo-light.svg" className="dark:hidden" alt="Logo" />
  <img src="/images/logo-dark.svg" className="hidden dark:block" alt="Logo" />
</>

ASTRO (Using dark:invert filter for vector diagrams):

<img src="/assets/diagram.svg" class="dark:invert" alt="Architecture Flow" />

---

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.image-theme-hardcode with Replacement Suggestion"]

Loading

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.image-theme-hardcode.
7. Diagnostic Emission: Produces a structured diagnostic with line number, column span, and actionable replacement suggestion.

---

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.image-theme-hardcode/:

flowchart TD
    subgraph GoldenCorpus ["1-SSOT Tri-Corpus Test Matrix for theme.image-theme-hardcode"]
        subgraph P ["Positive Corpus (tests/correctness/theme.image-theme-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.image-theme-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.image-theme-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"]

Loading

• 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.

---

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.image-theme-hardcode intentional exception -->

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

---

9. Configuration Reference (charites.yaml)

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