feat(sdk): add developer project tooling

docs(rfc): propose SDK developer project tooling

feat: rename / docs

ci: fix windows gates

docs: revert

packages/sdk/create-sdk/src/project-scaffolder.ts

@@ -0,0 +1,41 @@
+/**
+ * Project creation use case over the shared SDK aggregate and edit session.
+ *
+ * @module @deepseek-ai/create-sdk/project-scaffolder
+ */
+
+import { stat } from 'node:fs/promises'
+import {
+  SdkProject,
+  createBuiltinRegistry,
+  type ChangeSet,
+  type ProjectCreationRequest,
+} from '@deepseek-ai/dsh-helper'
+
+/** Result of writing one new SDK project. */
+export interface ScaffoldResult {
+  project: SdkProject
+  changes: ChangeSet
+}
+
+/** Create a project entirely in memory, then validate and commit it once. */
+export async function scaffoldProject(root: string, request: ProjectCreationRequest): Promise<ScaffoldResult> {
+  let targetExists = true
+  try {
+    await stat(root)
+  } catch (error) {
+    /* v8 ignore else -- the other arm requires a filesystem permission/IO fault from stat */
+    if ((error as NodeJS.ErrnoException).code === 'ENOENT') targetExists = false
+    /* v8 ignore next -- paired with the ignored defensive stat-error arm above */
+    else throw error
+  }
+  if (targetExists) throw new Error(`target already exists: ${root}`)
+  const project = SdkProject.create(root, request)
+  const registry = createBuiltinRegistry(project.profile)
+  const edit = project.edit(registry)
+  for (const selection of request.features) {
+    edit.installFeature(registry.get(selection.id), selection)
+  }
+  for (const plugin of request.localPlugins) edit.addPlugin(plugin)
+  return edit.commit()
+}