fix(attributes): limit insensitive comparisons to ASCII

[xiehuanyi]

[data-foo="ä" i] currently matches data-foo="Ä". The same non-ASCII folding affects all insensitive comparison operators and attributes whose default comparison is insensitive. Selectors require ASCII case-insensitive comparison, so these distinct non-ASCII characters must remain distinct.

Restrict folding to A–Z in string comparisons. Build explicit ASCII character pairs for regex-based comparisons instead of using JavaScript's Unicode-aware i flag. Regex metacharacters remain escaped. Existing ASCII-insensitive behavior is retained.

Validation: eight new cases fail before the fix. npm test passes 226 tests with one existing skipped test, including ESLint, TypeScript and Biome. Tests cover all operators, implicit HTML attribute comparison, exact non-ASCII matches, and literal regex characters. npm run build and git diff --check pass.

Prepared and tested with OpenAI Codex assistance.

Summary by CodeRabbit

• Bug Fixes
  • Case-insensitive attribute selectors now match ASCII letters without treating non-ASCII uppercase and lowercase characters as equivalent. This applies across equality, prefix, suffix, substring, word, and hyphen-prefix matching, including negated equality and implicit type matching.
  • Attribute values containing regex metacharacters are now matched literally by substring and word selectors. Case-sensitive matching remains unchanged.

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-12T19:15:24.664871Z	258df45	PR opened

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Organization UI
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• Plan: Advanced
• Run ID: 1d772c49-a57a-42d6-8239-f2ea1cea47cb

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📥 Commits

Reviewing files that changed from the base of the PR and between 94edb4b and 258df45.

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📒 Files selected for processing (2)

• src/attributes.ts
• test/attributes.ts

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Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 2 remain after this review.

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📝 Walkthrough

Walkthrough

Case-insensitive attribute selector matching now folds ASCII uppercase letters only. Equality, hyphen, word, prefix, suffix, substring, and negated-equality selectors use this behavior. Tests cover non-ASCII distinctions, implicit type matching, and literal regex characters.

Changes

Attribute selector matching

Layer / File(s)	Summary
ASCII case-insensitive matching src/attributes.ts, test/attributes.ts	Case-insensitive selectors now fold ASCII letters only. Word and substring selectors use escaped patterns with explicit ASCII case alternatives. Tests check non-ASCII distinctions, implicit type matching, and literal regex characters.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

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Merge Risk: ⚪ Minimal · up to 258df

The change aims to preserve ASCII-insensitive matching while distinguishing non-ASCII attribute values. No concrete merge-blocking risk is established by the available evidence.

Pre-merge checks | 4 | 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: limiting case-insensitive attribute comparisons to ASCII.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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_{A rabbit checks each letter’s case
And keeps non-ASCII in its place
Escaped stars stay literal
Tests make the rules clear
Then hops away with ears held high}

_{Comment @coderabbitai help to get the list of available commands.}

[cubic-dev-ai]

No issues found across 2 files

_{View guided diff | Re-trigger cubic}

[greptile-apps]

Confidence Score: 5/5

[Medium impact] This PR appears safe to merge.

Summary

Restricts insensitive attribute comparisons to ASCII letters.

• Insensitive attribute selectors now fold only ASCII letters.

_{Reviews (1) · Last reviewed commit: "fix(attributes): limit insensitive compa..." · Reviewed by Greptile}