fix: prevent infinite loop in base URL with a relative base

[cossssmin]

Problem

Setting a relative url.base (e.g. /images/) hangs the build / dev server — the process spins at 100% CPU and memory climbs unbounded — whenever the document contains a url() in a <style> block or inline style attribute.

Minimal repro:

import { base } from '@maizzle/framework'
base('<style>a{background-image:url(x.jpg)}</style>', '/images/') // hangs forever
base('<style>a{background-image:url(x.jpg)}</style>', 'https://cdn/') // fine

Cause

postcssBaseUrl rewrites url() from a PostCSS Declaration visitor. PostCSS 8 re-visits a declaration whose value a visitor mutates (so other plugins can react). The plugin prepends the base only when isAbsoluteUrl(value) is false — but with a relative base the result (/images/x.jpg) is still not absolute, so on the re-visit the guard is false again and it prepends once more: /images//images/x.jpg → /images//images//images/…, forever.

Absolute bases become absolute after the first prepend, so the guard trips and the loop terminates — which is why it only surfaced with relative bases (common in dev, where the CDN isn't wanted).

Fix

Rewrite declarations in a single OnceExit pass via root.walkDecls, which visits each declaration exactly once and is not subject to the visitor re-run semantics. Attribute/VML/MSO handling is unchanged.

Tests

Added regression tests for a relative base with url() in a <style> tag and in an inline style — each asserts the base is prepended exactly once (url(/images/bg.jpg), never /images//images/). Full base.test.ts suite green (79 tests), lint clean.

Summary by CodeRabbit

• Bug Fixes
  • Fixed CSS URL rewriting to prevent base paths from being added more than once.
  • Improved handling of relative base URLs in both <style> blocks and inline styles.
  • Ensured image and other asset paths retain the correct URL structure.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 395e293c-b063-4726-8d12-5fafe7417008

📥 Commits

Reviewing files that changed from the base of the PR and between 551a17c and 470954d.

📒 Files selected for processing (2)

• src/tests/transformers/base.test.ts
• src/transformers/base.ts

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📝 Walkthrough

Walkthrough

The base-URL transformer now rewrites CSS declarations in a single traversal. Regression tests verify that relative base paths apply once in style tags and inline styles.

Changes

Base-URL rewriting

Layer / File(s)	Summary
Single-pass declaration rewriting src/transformers/base.ts, src/tests/transformers/base.test.ts	The transformer uses a reusable declaration helper and one OnceExit pass. Tests verify that relative CSS URLs do not receive repeated base-path prefixes.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the main fix: preventing an infinite loop when the base URL is relative.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/baseurl-relative-infinite-loop

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