build: replace cnfast with cn

[mattrothenberg]

Summary

• replace cnfast with cn@0.4.0
• keep Kumo's internal cn API unchanged
• update the styling vendor chunk match and add a patch changeset

Follow-up to #775.

Validation

• git diff --check

• dependency installation is expected to fail temporarily because cn@0.4.0 has not yet aged past the repository's minimum-release-age cutoff

• Reviews

• bonk has reviewed the change

• automated review not possible because: no automated review was available before opening the pull request

• Tests

• Tests included/updated

• Automated tests not possible - manual testing has been completed as follows: not applicable

• Additional testing not necessary because: the existing cn utility suite covers the unchanged class merging API and will run after the release-age gate passes

[pkg-pr-new]

npm i https://pkg.pr.new/@cloudflare/kumo@820

commit: 8963139

[ask-bonk]

LGTM!

Review notes

• Confirming the checked-out PR target and reviewing its diff, package guidance, dependency lockfile changes, and prior reviews before assessing behavior.
• PR build: replace cnfast with cn #820 is open at the requested head SHA 89631392d18bc60b85f4e3bac43b7e10e61d2896; no prior reviews exist. The local checkout lacks origin/main, so I will compare the single PR commit with its parent and validate the replacement package's exported behavior from the installed dependency.
• The one-commit diff cleanly replaces cnfast with cn@0.3.0, updates the bundle split matcher, lockfile, and patch changeset. The workspace toolchain is not installed (pnpm is unavailable), so I am inspecting the utility's existing compatibility tests and both package distributions directly rather than running them.
• The updated package exposes the same named cn export, is ESM/CJS-compatible, and requires Node 20+, which is within Kumo's Node 24+ policy. Existing tests cover the changed utility's documented class-merge cases, including conditional and nested inputs; next I am comparing both implementations against that suite in memory and checking package declarations/source for unsupported API differences.
• cnfast@0.0.8 passes all 13 existing utility cases when evaluated directly from its published distribution. The initial equivalent check for cn@0.3.0 could not run because its ESM entry has relative chunks and no local install; I am resolving those published chunks in memory, then will compare the public type contracts and Kumo call sites.
• The Kumo cn re-export is public from both the root package entry and @cloudflare/kumo/utils. The new package's declared cn function supports ordinary clsx-style values, while the prior dependency also exposed a tagged-template overload; I am verifying whether that supported form is documented or used and checking its runtime behavior before deciding whether it is a compatibility finding.
• Completed the compatibility check: the published cn@0.3.0 implementation passes all 13 existing cases, including nested conditional inputs, and produces the same tagged-template output as cnfast@0.0.8. No repository call sites use tagged templates. git diff --check passed; package unit tests could not run because this read-only checkout has no installed workspace dependencies or pnpm binary.

github run

[github-actions]

📐 Bundle Size

Consumer fixtures bundled against packages/kumo/dist (peers external, minified ESM).

Fixture	Raw	Gzip	Brotli
Button (root)	165.2 KB	50.5 KB	43.8 KB
Button (components/button)	165.1 KB	50.5 KB	43.8 KB
Button + Dialog + Select (root)	290.1 KB	86.4 KB	72.5 KB
Button + Dialog + Select (component subpaths)	290.0 KB	86.4 KB	72.6 KB
Chart (root)	237.7 KB	71.7 KB	61.5 KB
Chart (components/chart)	237.7 KB	71.7 KB	61.6 KB
Badge (components/badge)	35.4 KB	12.3 KB	10.8 KB
Flow (components/flow)	199.6 KB	58.9 KB	51.4 KB
Button (primitives/button)	12.2 KB	4.4 KB	3.9 KB
Primitives barrel	635.8 KB	176.9 KB	139.3 KB
Code highlighting (code)	2.07 MB	468.6 KB	349.9 KB

npm tarball: 544 files, 1.49 MB packed, 6.90 MB unpacked.

⚠️ 23 flagged files in tarball (tests / raw scripts)

• dist/blocks-source/resource-list/resource-list.test.tsx
• scripts/component-registry/cache.ts
• scripts/component-registry/discovery.ts
• scripts/component-registry/example-cleanup.ts
• scripts/component-registry/index.test.ts
• scripts/component-registry/index.ts
• scripts/component-registry/markdown-generator.ts
• scripts/component-registry/metadata.ts
• scripts/component-registry/props-filter.ts
• scripts/component-registry/schema-generator.ts
• scripts/component-registry/sub-components.ts
• scripts/component-registry/types.ts
• scripts/component-registry/utils.ts
• scripts/component-registry/variant-parser.ts
• scripts/css-build.ts
• scripts/generate-globe-land-mask.mjs
• scripts/generate-primitives.ts
• scripts/theme-generator/config.ts
• scripts/theme-generator/generate-css.test.ts
• scripts/theme-generator/generate-css.ts
• scripts/theme-generator/index.ts
• scripts/theme-generator/migrate.ts
• scripts/theme-generator/types.ts

Report-only: no size thresholds are enforced yet.

Commit: 89631392

[github-actions]

Visual contracts

Linux Chromium references exercised by the PR's visual-contracts job.

1 curated contract

truncating text trigger

[cloudflare-workers-and-pages]

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