feat(config): support --registry=default shorthand

tap-snapshots/test/lib/docs.js.test.cjs

@@ -1794,10 +1794,14 @@ Rebuild bundled dependencies after installation.
 #### \`registry\`
 
 * Default: "https://registry.npmjs.org/"
-* Type: URL
+* Type: URL or "default"
 
 The base URL of the npm registry.
 
+Can be set to \`"default"\` to use the default npm registry
+(\`https://registry.npmjs.org/\`), which is useful when you have a custom
+registry configured globally but want to temporarily use the default one.
+
 
 
 #### \`replace-registry-host\`

workspaces/config/lib/definitions/definitions.js

@@ -2048,11 +2048,21 @@ const definitions = {
   }),
   registry: new Definition('registry', {
     default: 'https://registry.npmjs.org/',
-    type: url,
+    type: [url, 'default'],
     description: `
       The base URL of the npm registry.
+
+      Can be set to \`"default"\` to use the default npm registry
+      (\`https://registry.npmjs.org/\`), which is useful when you have
+      a custom registry configured globally but want to temporarily
+      use the default one.
     `,
-    flatten,
+    flatten (key, obj, flatOptions) {
+      const val = obj[key]
+      flatOptions.registry = /^default$/i.test(val)
+        ? 'https://registry.npmjs.org/'
+        : val
+    },
   }),
   'replace-registry-host': new Definition('replace-registry-host', {
     default: 'npmjs',

workspaces/config/tap-snapshots/test/type-description.js.test.cjs

@@ -539,6 +539,7 @@ Object {
   ],
   "registry": Array [
     "full url with \\"http://\\"",
+    "default",
   ],
   "replace-registry-host": Array [
     "npmjs",

workspaces/config/test/definitions/definitions.js

@@ -592,6 +592,28 @@ t.test('scope', t => {
   t.end()
 })
 
+t.test('registry - "default" maps to default registry URL', t => {
+  const defs = mockDefs()
+
+  const flat1 = {}
+  defs.registry.flatten('registry', { registry: 'default' }, flat1)
+  t.equal(flat1.registry, 'https://registry.npmjs.org/', 'lowercase default')
+
+  const flat2 = {}
+  defs.registry.flatten('registry', { registry: 'DEFAULT' }, flat2)
+  t.equal(flat2.registry, 'https://registry.npmjs.org/', 'uppercase DEFAULT')
+
+  const flat3 = {}
+  defs.registry.flatten('registry', { registry: 'Default' }, flat3)
+  t.equal(flat3.registry, 'https://registry.npmjs.org/', 'mixed case Default')
+
+  const flat4 = {}
+  defs.registry.flatten('registry', { registry: 'https://custom.registry.com/' }, flat4)
+  t.equal(flat4.registry, 'https://custom.registry.com/', 'custom URL passes through')
+
+  t.end()
+})
+
 t.test('strictSSL', t => {
   const obj = { 'strict-ssl': false }
   const flat = {}