ux.missing autofill

ux.missing-autofill

Rule ID: ux.missing-autofill Severity: WARN Category: ux Target Standards: HTML Living Standard Section 4.10.18.7 (Autofill / The autocomplete attribute), WCAG 2.2 Success Criterion 3.3.7 (Redundant Entry - Level A), Tesler's Law of Conservation of Complexity

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1. Overview & Core Invariant

Enforces W3C Living Standard autocomplete attributes on personal identity, credential, and payment form inputs (Tesler's Law)

Core Invariant:

"Form controls collecting Personally Identifiable Information (PII), authentication credentials, or financial payment details must declare valid HTML autocomplete attributes and never disable autofill on sensitive fields."

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2. Technical Grounding & Engine Realities

According to Tesler's Law, every application has an inherent amount of irreducible complexity. The design decision is whether the software absorbs this complexity or forces it upon the human user.

Entering email addresses, physical street addresses, telephone numbers, and generated complex passwords manually on every single website forces extreme cognitive friction and typing typos upon users. Modern browsers, OS keychains, and third-party password managers rely on standardized W3C 'autocomplete' tokens (e.g. 'current-password', 'new-password', 'email', 'tel', 'cc-number') to securely fill verified data.

Explicitly setting 'autocomplete="off"' on password or credit card fields is a severe antipattern that breaks password generation, encourages weak password reuse, and degrades account security.

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3. Vulnerability & Risk Taxonomy

Risk Vector	Severity	Impact
Weak Password Reuse & Credential Hijacking	HIGH	Blocking or omitting password autofill forces users to type passwords manually, leading to short, memorable, and easily cracked credentials.
Form Abandonment & Redundant Data Entry Friction	MEDIUM	Users abandon multi-field checkout and registration flows when forced to re-type address and phone details manually.

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4. Non-Compliant Code Patterns (Bad Examples)

TSX (Password input lacking autocomplete attribute):

<input
  type="password"
  name="password"
  placeholder="Masukkan kata sandi..."
  className="border rounded px-3 py-2"
/>

ASTRO (Payment input explicitly disabling autocomplete):

<input
  type="text"
  name="cc-number"
  autocomplete="off"
  placeholder="Nomor Kartu Kredit"
  class="border rounded px-3 py-2"
/>

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5. Compliant Implementation Patterns (Good Examples)

TSX (Explicit current-password token assisting password managers):

<input
  type="password"
  name="password"
  autoComplete="current-password"
  placeholder="Masukkan kata sandi..."
  className="border rounded px-3 py-2"
/>

ASTRO (Compliant contact field with valid email autocomplete token):

<input
  type="email"
  name="user_email"
  autocomplete="email"
  placeholder="name@example.com"
  class="border rounded px-3 py-2"
/>

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

This rule evaluates source code through the standard AST inspection pipeline:

flowchart TD
    Node["AST Node (Astro / TSX element)"] --> Inspect["1. Inspect Element & Attributes"]
    Inspect --> Invariant{"2. Evaluate Rule Invariant"}
    Invariant -- "Compliant" --> Safe["Pass"]
    Invariant -- "Non-Compliant" --> IgnoreCheck{"3. Check charites:ignore directive"}
    IgnoreCheck -- "Ignored" --> Safe
    IgnoreCheck -- "Not Ignored" --> Diag["4. Emit Diagnostic: ux.missing-autofill"]

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Step-by-Step Evaluation:

1. AST Traversal: Visits normalized ir.Node structures during AST streaming.
2. Invariant Check: Compares node attributes against rule invariants.
3. Directive Suppression Check: Honors inline charites:ignore ux.missing-autofill directives.
4. Diagnostic Emission: Emits compiler-grade diagnostic on invariant violation.

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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/ux.missing-autofill/:

flowchart TD
    subgraph GoldenCorpus ["1-SSOT Tri-Corpus Test Matrix for ux.missing-autofill"]
        subgraph P ["Positive Corpus (tests/correctness/ux.missing-autofill/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/ux.missing-autofill/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/ux.missing-autofill/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 ux.missing-autofill intentional exception -->

// charites:ignore ux.missing-autofill intentional exception

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9. Configuration Reference (charites.yaml)

rules:
  ux.missing-autofill:
    severity: warn # error | warn | info | off