Add lint rule for child :global selectors

[melohagan]

Description

Adds a local ESLint rule that flags comma-separated selectors containing multiple child combinator :global(...) entries, preventing the CSS minification issue fixed in bb648c7.

Screenshots

Example errors

Launchcontrol

Prevents unsafe child :global selector lists by linting for multiple child combinator :global entries in a single rule.

[cubic-dev-ai]

1 issue found across 6 files

Confidence score: 4/5

• ESLint location reporting may be off because eslint-local-rules/index.js compares against the literal "\n" instead of a newline, which affects buildLineOffsets accuracy
• Severity is moderate and limited to developer tooling rather than runtime behavior, so risk is low overall
• Pay close attention to eslint-local-rules/index.js - fix newline comparison to ensure correct offset calculations.

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="eslint-local-rules/index.js">

<violation number="1" location="eslint-local-rules/index.js:27">
P2: The newline check in buildLineOffsets compares against a literal "\\n", so offsets never include actual line breaks and reported ESLint locations will be wrong. Compare to `"\n"` instead.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[PClmnt]

Does this have any performance overhead?

This is some quite complex code - in terms of what it is and how it has to do it over everything?

[melohagan]

almost definitely

[melohagan]

I'll do a performance test now

[melohagan]

It's not as bad as I thought it would be actually:

 - Before (rules off): 40.43s
  - After (rules on): 40.48s
  - Delta: +0.05s (~0.1%), effectively within run‑to‑run noise

Going to run some additional tests

[melohagan]

Hmm I think this run is probably more realistic:

 - Before (rules off): 22.66s real
  - After (rules on): 23.54s real
  - Delta: +0.88s (~3.9% of ESLint time)