From da19cb5dd15439c27d183f278eaafc103bdd59ed Mon Sep 17 00:00:00 2001
From: solimant <solimant@users.noreply.github.com>
Date: Thu, 23 Oct 2025 22:38:21 +0000
Subject: [PATCH] Fix package name plugin infix with yarn new

Signed-off-by: solimant <solimant@users.noreply.github.com>
---
 .changeset/funny-stars-open.md                |  5 +++
 .../loadPortableTemplateConfig.test.ts        |  6 ++--
 .../preparation/loadPortableTemplateConfig.ts | 35 ++++++++++++++-----
 3 files changed, 35 insertions(+), 11 deletions(-)
 create mode 100644 .changeset/funny-stars-open.md

diff --git a/.changeset/funny-stars-open.md b/.changeset/funny-stars-open.md
new file mode 100644
index 0000000000..336e68bac1
--- /dev/null
+++ b/.changeset/funny-stars-open.md
@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Fix inconsistent behavior in the `new` command for the `@internal` scope: it now consistently defaults to the `backstage-plugin-` infix whether the `--scope` option is not set or it's set to `internal`.
diff --git a/packages/cli/src/modules/new/lib/preparation/loadPortableTemplateConfig.test.ts b/packages/cli/src/modules/new/lib/preparation/loadPortableTemplateConfig.test.ts
index b8a7940bcf..f8167ef339 100644
--- a/packages/cli/src/modules/new/lib/preparation/loadPortableTemplateConfig.test.ts
+++ b/packages/cli/src/modules/new/lib/preparation/loadPortableTemplateConfig.test.ts
@@ -196,7 +196,7 @@ describe('loadPortableTemplateConfig', () => {
       private: true,
       version: '0.1.0',
       packageNamePrefix: '@internal/',
-      packageNamePluginInfix: 'plugin-',
+      packageNamePluginInfix: 'backstage-plugin-',
     });
   });
 
@@ -316,7 +316,7 @@ describe('loadPortableTemplateConfig', () => {
       version: '0.1.0',
       private: true,
       packageNamePrefix: '@internal/',
-      packageNamePluginInfix: 'plugin-',
+      packageNamePluginInfix: 'backstage-plugin-',
     });
 
     await expect(
@@ -333,7 +333,7 @@ describe('loadPortableTemplateConfig', () => {
       version: '0.1.0',
       private: true,
       packageNamePrefix: '@internal/',
-      packageNamePluginInfix: 'plugin-',
+      packageNamePluginInfix: 'backstage-plugin-',
     });
   });
 });
diff --git a/packages/cli/src/modules/new/lib/preparation/loadPortableTemplateConfig.ts b/packages/cli/src/modules/new/lib/preparation/loadPortableTemplateConfig.ts
index 5ef61bfb6b..2e736d9c29 100644
--- a/packages/cli/src/modules/new/lib/preparation/loadPortableTemplateConfig.ts
+++ b/packages/cli/src/modules/new/lib/preparation/loadPortableTemplateConfig.ts
@@ -70,6 +70,21 @@ type LoadConfigOptions = {
   overrides?: Partial<PortableTemplateConfig>;
 };
 
+function computePackageNamePluginInfix(
+  packageNamePrefix: string,
+  namePluginInfix?: string,
+) {
+  const packageNamePluginInfix =
+    namePluginInfix ??
+    (packageNamePrefix.includes('backstage')
+      ? defaults.packageNamePluginInfix
+      : 'backstage-plugin-');
+
+  return {
+    packageNamePluginInfix,
+  };
+}
+
 export async function loadPortableTemplateConfig(
   options: LoadConfigOptions = {},
 ): Promise<PortableTemplateConfig> {
@@ -116,6 +131,16 @@ export async function loadPortableTemplateConfig(
     templateNameConflicts.set(pointer.name, rawPointer);
   }
 
+  const packageNamePrefix =
+    overrides.packageNamePrefix ??
+    config?.globals?.namePrefix ??
+    defaults.packageNamePrefix;
+
+  const { packageNamePluginInfix } = computePackageNamePluginInfix(
+    packageNamePrefix,
+    overrides.packageNamePluginInfix ?? config?.globals?.namePluginInfix,
+  );
+
   return {
     isUsingDefaultTemplates: !config?.templates,
     templatePointers: templatePointerEntries.map(({ pointer }) => pointer),
@@ -126,14 +151,8 @@ export async function loadPortableTemplateConfig(
       overrides.publishRegistry ??
       config?.globals?.publishRegistry ??
       defaults.publishRegistry,
-    packageNamePrefix:
-      overrides.packageNamePrefix ??
-      config?.globals?.namePrefix ??
-      defaults.packageNamePrefix,
-    packageNamePluginInfix:
-      overrides.packageNamePluginInfix ??
-      config?.globals?.namePluginInfix ??
-      defaults.packageNamePluginInfix,
+    packageNamePrefix,
+    packageNamePluginInfix,
   };
 }