Reworks Twoslasher instance creation

[Adammatthiesen]

This pull request addresses several improvements and bug fixes for the expressive-code-twoslash package, focusing on Twoslasher instance creation, dependency configuration, and memory management documentation. The most significant changes involve refactoring Twoslasher instance handling for better caching and reliability, updating dependency bundling configurations, and enhancing documentation for users encountering memory issues.

• Closes: Running large docs causing memory overload in latest version #99
• Closes: ESLint dependency is now required #100
• Closes: Chore: Tweak tsdown configs for changes in 0.21.0 #102

Twoslasher instance creation and caching improvements

• Refactored Twoslasher instance creation to use async thunks, enabling proper caching and lazy loading of Twoslash, Vue, and ESLint instances via dedicated helper functions (getBaseTwoslasher, getVueTwoslasher, getEslintTwoslasher). This fixes issues with Twoslasher instance creation and ensures robust error handling for missing dependencies. [1] [2] [3] [4] [5] [6]
• Updated the plugin to use a singleton TwoslasherMap for storing Twoslasher functions, improving instance reuse and performance. [1] [2]

Dependency bundling configuration

• Changed tsdown.config.ts files in @ec-ts/twoslash and css-js-gen packages to use deps.onlyAllowBundle for specifying bundled dependencies, replacing the previous inlineOnly approach. [1] [2]

Documentation and usability enhancements

• Added a section to the installation.mdx documentation explaining potential memory issues when using Astro, including recommendations for adjusting the lib option and increasing Node.js memory limits.

Plugin initialization and resource management

• Introduced singletons for tsLibDirectory, includesMap, and the Expressive Code Engine instance to ensure consistent resource usage across plugin invocations. [1] [2] [3]
• Simplified plugin code by removing redundant cache and file system map creation in the Twoslash preprocessing logic. [1] [2]

Type improvements

• Added and exported the new TwoslasherThunk type for improved type safety and clarity in Twoslasher function signatures. [1] [2]

These changes collectively improve reliability, maintainability, and user experience for the expressive-code-twoslash package.

[changeset-bot]

🦋 Changeset detected

Latest commit: 621ffaf

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
expressive-code-twoslash	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[htg-1-studiocms-cloud]

Dokploy Preview Deployment

Name	Status	Preview	Updated (UTC)
Expressive-Code-Twoslash Docs	✅ Done	Preview URL	2026-03-13T06:37:38.531Z

[pkg-pr-new]

npm i https://pkg.pr.new/expressive-code-twoslash@103

commit: f1d9e32

[apollo-git-bot]

Allure Report Summary

	Name	Duration	Stats	New	Flaky	Retry	Report
	css-js-gen Tests	23ms	37	94	0	0
	@ec-ts/twoslash Tests	29s 828ms	29	94	0	0
	@ec-ts/twoslash-vue Tests	6s 12ms	7	94	0	0
	@ec-ts/vfs Tests	9s 281ms	21	94	0	0