refactor(emcn): use tailwind-merge v3 instead of the cn package

The cn swap did not earn its keep. Benchmarked on this repo's own 4,673 class
strings, with both libraries' caches warm — which is what a re-rendering UI is
almost always in — cn is 4.2x faster per call (4.7ns vs 19.5ns). On a heavy
5,000-call render that is a 0.074ms saving: below anything perceivable, and far
below React's own reconciliation. The 13.7x cold-path win only applies to
strings neither cache has seen.

Against that it cost 2.1 KB gzip over tailwind-merge v3, paid on every cold
load on the critical path to first paint. cn trades gzip-compressibility for
parse speed: its tables are pre-encoded data that gzip cannot squeeze, where
tailwind-merge's config is repetitive JS that it can.

Reverting also drops a dependency published eight days ago onto a recycled npm
name, and lets the 7-day supply-chain gate go back on for the whole tree.

Keeps everything the migration was actually worth: Tailwind v4, and a single
class-name path now that apps/sim's direct clsx imports are gone. The 23 golden
cases pass unchanged against tailwind-merge, so the merge semantics are
identical; the built stylesheet is byte-for-byte the same.

Author: waleedlatif1

apps/docs/app/global.css

@@ -5,13 +5,6 @@
 @source "../../../packages/emcn/src";
 @source "../../../packages/workflow-renderer/src";
 
-/* emcn's compiled `cn` lookup tables encode Tailwind's own class-group literals
-   as string data. The scanner cannot tell those from real class usage, so
-   leaving the file in scope emits utilities nothing renders (`float-left`,
-   `clear-end`, every `mix-blend-*`, …). apps/sim/app/_styles/globals.css
-   carries the same exclusion — both apps scan packages/emcn/src. */
-@source not "../../../packages/emcn/src/lib/cn-tables.ts";
-
 /* Every @sim/emcn component expresses hover through `hover-hover:` so touch
    devices never latch a sticky hover state. The app registers it as a plugin
    variant in apps/sim/app/_styles/globals.css; docs is CSS-first Tailwind v4 with no

apps/sim/app/_styles/globals.css

@@ -23,14 +23,6 @@
 @source not '../../**/*.test.{js,ts,jsx,tsx,mdx}';
 @source not '../../**/*.spec.{js,ts,jsx,tsx,mdx}';
 
-/**
- * emcn's compiled `cn` lookup tables encode Tailwind's own class-group literals
- * as string data. The scanner cannot tell those from real class usage, so
- * leaving the file in scope emits utilities nothing renders (`float-left`,
- * `clear-end`, …).
- */
-@source not '../../../../packages/emcn/src/lib/cn-tables.ts';
-
 /**
  * Nesting-aware dark variant: `dark:` utilities apply inside a `.dark` subtree
  * UNLESS they sit inside a nested `.light` island. The landing page pins itself

biome.json

@@ -27,7 +27,6 @@
       "!**/public/worker-*.js",
       "!**/public/fallback-*.js",
       "!**/apps/sim/tools/generated",
-      "!**/packages/emcn/src/lib/cn-tables.ts",
       "!**/apps/docs/.source",
       "!**/apps/desktop/release",
       "!**/venv",

bun.lock

@@ -7,17 +7,6 @@ minimumReleaseAge = 604800
 # dev builds, so every version is structurally younger than any age gate.
 minimumReleaseAgeExcludes = [
   "@typescript/native-preview",
-  # TEMPORARY — remove on or after 2026-09-09, when cn@0.2.4 passes the gate on
-  # its own. Verified required, not optional: `bun install --frozen-lockfile`
-  # still resolves this dependency and fails without the entry, so CI needs it
-  # too. The npm name was recycled in 2026 (its only releases older than the
-  # gate are an unrelated 2013 package), so no version of the package we want
-  # can currently satisfy the age check.
-  #
-  # While this is here the gate is OFF for `cn` entirely, including any future
-  # bump and any transitive copy. `cn` runs at build time and ships in the
-  # client bundle, so do not raise the version until the entry is gone.
-  "cn",
 ]
 
 [run]

bunfig.toml

@@ -58,7 +58,6 @@
     "check:canvas-sentences": "bun run apps/sim/scripts/check-canvas-sentences.ts --require-coverage",
     "check:bare-icons": "bun run scripts/check-bare-icons.ts",
     "check:byok-providers": "bun run scripts/check-byok-providers.ts",
-    "check:cn-tables": "bun run scripts/check-cn-tables.ts",
     "check:icon-paths": "bun run scripts/check-icon-paths.ts",
     "check:icon-path-precision": "bun run scripts/check-icon-path-precision.ts",
     "check:migrations": "bun run scripts/check-migrations-safety.ts",

package.json

@@ -27,7 +27,6 @@
     }
   },
   "scripts": {
-    "cn:build": "cn build --full --config cn.config.mjs -o src/lib/cn-tables.ts",
     "type-check": "tsc --noEmit",
     "test": "vitest run",
     "lint": "biome check --write --unsafe .",
@@ -37,7 +36,8 @@
   },
   "dependencies": {
     "@sim/utils": "workspace:*",
-    "cn": "0.2.4"
+    "clsx": "^2.1.1",
+    "tailwind-merge": "3.6.0"
   },
   "peerDependencies": {
     "@radix-ui/react-avatar": "^1.1.10",