FN-6351: add plugin scaffold dev toolchain dependencies

Ensure standalone plugin scaffolds declare the tools required by their generated config and scripts.

- Add @types/node, TypeScript, and Vitest dev dependencies to generated standalone plugin package manifests.
- Cover scaffold dependency ranges, script/tool alignment, scoped plugin names, and tsconfig types in plugin scaffold tests.
- Add a patch changeset documenting the scaffold dependency fix.

Files changed:
 .changeset/FN-6351-plugin-scaffold-devdeps.md      | 16 +++++++++++++++
 packages/cli/src/__tests__/plugin-scaffold.test.ts | 24 ++++++++++++++++++++--
 packages/cli/src/commands/plugin-scaffold.ts       |  6 ++++++
 3 files changed, 44 insertions(+), 2 deletions(-)

Fusion-Task-Id: FN-6351

Fusion-Task-Lineage: 4134d7cb-b493-49a7-abe1-154a875aec0e

.changeset/FN-6351-plugin-scaffold-devdeps.md

@@ -0,0 +1,16 @@
+---
+"@runfusion/fusion": patch
+---
+
+Standalone plugin scaffolds now declare the dev toolchain they generate scripts and config for: `@types/node`, `vitest`, and `typescript`. This lets projects created with `fn plugin new` install, build, test, and load through `fn plugin dev . --once` via the documented external-author path without relying on transitive or hoisted dependencies.
+
+Manual spot-check for release validation:
+
+```sh
+npx @runfusion/fusion@latest plugin new proof-point-plugin
+cd proof-point-plugin
+pnpm install
+pnpm build
+pnpm test
+fn plugin dev . --once
+```

packages/cli/src/__tests__/plugin-scaffold.test.ts

@@ -8,6 +8,13 @@ import { runPluginCreate, runPluginNew } from "../commands/plugin-scaffold.js";
 
 describe("plugin-scaffold", () => {
   const tmpBase = join(tmpdir(), `fn-scaffold-${Date.now()}-${Math.random().toString(36).slice(2)}`);
+  const standaloneDevDependencyKeys = [
+    "@runfusion/fusion",
+    "@types/node",
+    "typescript",
+    "vitest",
+  ];
+  const caretRangePattern = /^\^\d+\.\d+\.\d+$/;
 
   beforeEach(() => {
     mkdirSync(tmpBase, { recursive: true });
@@ -64,6 +71,7 @@ describe("plugin-scaffold", () => {
         private?: boolean;
         keywords: string[];
         exports: { ".": { types: string; import: string } };
+        scripts: { build: string; test: string };
         devDependencies: Record<string, string>;
       };
 
@@ -72,8 +80,10 @@ describe("plugin-scaffold", () => {
       expect(packageJson.private).toBeUndefined();
       expect(packageJson.exports["."].types).toBe("./dist/index.d.ts");
       expect(packageJson.exports["."].import).toBe("./dist/index.js");
-      expect(Object.keys(packageJson.devDependencies)).toEqual(["@runfusion/fusion"]);
+      expect(Object.keys(packageJson.devDependencies)).toEqual(standaloneDevDependencyKeys);
-      expect(packageJson.devDependencies["@runfusion/fusion"]).toMatch(/^\^\d+\.\d+\.\d+$/);
+      for (const dependencyName of standaloneDevDependencyKeys) {
+        expect(packageJson.devDependencies[dependencyName]).toMatch(caretRangePattern);
+      }
 
       const packageContents = readFileSync(join(outputDir, "package.json"), "utf-8");
       const indexContents = readFileSync(join(outputDir, "src/index.ts"), "utf-8");
@@ -87,8 +97,16 @@ describe("plugin-scaffold", () => {
 
       const tsconfig = JSON.parse(readFileSync(join(outputDir, "tsconfig.json"), "utf-8")) as {
         extends?: string;
+        compilerOptions: { types?: string[] };
       };
       expect(tsconfig.extends).toBeUndefined();
+      for (const typeName of tsconfig.compilerOptions.types ?? []) {
+        expect(packageJson.devDependencies[`@types/${typeName}`]).toBeDefined();
+      }
+      expect(packageJson.scripts.test.split(/\s+/)[0]).toBe("vitest");
+      expect(packageJson.devDependencies.vitest).toBeDefined();
+      expect(packageJson.scripts.build.split(/\s+/)[0]).toBe("tsc");
+      expect(packageJson.devDependencies.typescript).toBeDefined();
     });
 
     it("supports scoped package names", async () => {
@@ -96,8 +114,10 @@ describe("plugin-scaffold", () => {
       await runPluginNew("scoped-plugin", { output: outputDir, scope: "acme" });
       const packageJson = JSON.parse(readFileSync(join(outputDir, "package.json"), "utf-8")) as {
         name: string;
+        devDependencies: Record<string, string>;
       };
       expect(packageJson.name).toBe("@acme/fusion-plugin-scoped-plugin");
+      expect(Object.keys(packageJson.devDependencies)).toEqual(standaloneDevDependencyKeys);
     });
 
     it("rejects invalid plugin names", async () => {

packages/cli/src/commands/plugin-scaffold.ts

@@ -12,6 +12,9 @@ import { fileURLToPath } from "node:url";
 // Valid plugin name pattern: kebab-case
 const PLUGIN_NAME_REGEX = /^[a-z0-9][a-z0-9-]*[a-z0-9]$/;
 const DEFAULT_RUNFUSION_VERSION = "0.39.0";
+const SCAFFOLD_TYPES_NODE_VERSION = "^22.0.0";
+const SCAFFOLD_VITEST_VERSION = "^4.1.0";
+const SCAFFOLD_TYPESCRIPT_VERSION = "^5.7.0";
 
 /**
  * Convert a kebab-case string to Title Case
@@ -167,6 +170,9 @@ function generateStandalonePackageJson(name: string, scope?: string): string {
       },
       devDependencies: {
         "@runfusion/fusion": resolveFusionCaretVersion(),
+        "@types/node": SCAFFOLD_TYPES_NODE_VERSION,
+        typescript: SCAFFOLD_TYPESCRIPT_VERSION,
+        vitest: SCAFFOLD_VITEST_VERSION,
       },
     },
     null,