feat(repo): migrate to Yarn 4 with 7-day npm cooldown

.github/renovate.json

@@ -12,6 +12,12 @@
 		"enabled": true,
 		"automerge": true
 	},
+	"minimumReleaseAge": "7 days",
+	"internalChecksFilter": "strict",
+	"osvVulnerabilityAlerts": true,
+	"vulnerabilityAlerts": {
+		"minimumReleaseAge": null
+	},
 	"autoApprove": true,
 	"labels": ["Dependencies", "Renovate"],
 	"packageRules": [

.github/workflows/test.yml

@@ -15,6 +15,10 @@ jobs:
         uses: actions/setup-node@v6
         with:
           node-version: 24
+      - name: Enable Corepack and setup Yarn v4
+        run: |
+          corepack enable
+          yarn --version
       - name: Cache dependencies
         id: cache-depends
         uses: actions/cache@v5
@@ -23,7 +27,7 @@ jobs:
           key: depends-${{ hashFiles('yarn.lock') }}
       - name: Install dependencies
         if: steps.cache-depends.outputs.cache-hit != 'true'
-        run: yarn --frozen-lockfile --check-files
+        run: yarn install --immutable
       - name: Lint
         run: yarn lint
       - name: Build

.gitignore

@@ -60,6 +60,15 @@ typings/
 # Yarn Integrity file
 .yarn-integrity
 
+# Yarn Berry (v2+)
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/sdks
+!.yarn/versions
+.pnp.*
+
 # dotenv environment variables file
 .env
 

.yarnrc.yml

@@ -0,0 +1,4 @@
+nodeLinker: node-modules
+npmRegistryServer: 'https://registry.npmjs.org'
+enableGlobalCache: true
+npmMinimalAgeGate: 7d

package.json

@@ -11,10 +11,10 @@
 		"dev": "vitepress dev src",
 		"build": "vitepress build src",
 		"lint": "run-s lint:eslint lint:prettier lint:textlint lint:cspell",
-		"lint:cspell": "cspell --no-progress --show-suggestions \"{*,src/{**,.vitepress/**}/*}/\"",
-		"lint:eslint": "eslint --fix \"*.{js,cjs,mjs}\"",
-		"lint:prettier": "prettier --write \"{*,src/{**,.vitepress/**}/*}.{md,json,js,cjs,mjs,jsx,ts,cts,mts,tsx}\"",
-		"lint:textlint": "textlint --fix ./src/{**,.vitepress/**}/*.md; textlint ./src/{**,.vitepress/**}/*.md",
+		"lint:cspell": "npx cspell --no-progress --show-suggestions \"{*,src/{**,.vitepress/**}/*}/\"",
+		"lint:eslint": "npx eslint --fix \"*.{js,cjs,mjs}\"",
+		"lint:prettier": "npx prettier --write \"{*,src/{**,.vitepress/**}/*}.{md,json,js,cjs,mjs,jsx,ts,cts,mts,tsx}\"",
+		"lint:textlint": "npx textlint --fix ./src/{**,.vitepress/**}/*.md; npx textlint ./src/{**,.vitepress/**}/*.md",
 		"release:major": "npm version major",
 		"release:minor": "npm version minor",
 		"release:patch": "npm version patch",
@@ -33,8 +33,9 @@
 		"vitepress": "1.6.4",
 		"vitepress-plugin-mermaid": "2.0.17"
 	},
+	"packageManager": "yarn@4.12.0",
 	"volta": {
 		"node": "24.14.0",
-		"yarn": "1.22.22"
+		"yarn": "4.12.0"
 	}
 }