chore: establish YCode replication baseline and TODO

src/main/workspace-revert.ts

@@ -0,0 +1,35 @@
+import { promises as fs } from 'node:fs'
+import { dirname, isAbsolute, relative, resolve, sep, join } from 'node:path'
+import { randomUUID } from 'node:crypto'
+import type { RevertChange } from '@shared/revert'
+
+async function replaceFile(path: string, content: string | null): Promise<void> {
+  if (content === null) { await fs.unlink(path); return }
+  const temporary = join(dirname(path), `.ycode-restore-${randomUUID()}.tmp`)
+  try { await fs.writeFile(temporary, content, 'utf8'); await fs.rename(temporary, path) }
+  finally { await fs.unlink(temporary).catch(() => undefined) }
+}
+/** Validate every current file before applying any change; roll back if a write fails. */
+export async function restoreWorkspaceFiles(workspace: string, changes: RevertChange[]): Promise<() => Promise<void>> {
+  const root = await fs.realpath(workspace)
+  const validated: RevertChange[] = []
+  for (const change of changes) {
+    const path = await fs.realpath(resolve(change.path))
+    const rel = relative(root, path)
+    if (!rel || rel === '..' || rel.startsWith(`..${sep}`) || isAbsolute(rel)) throw new Error('恢复文件不在当前工作区内')
+    if (await fs.readFile(path, 'utf8') !== change.after) throw new Error(`文件已被外部修改，未执行恢复：${rel}`)
+    validated.push({ ...change, path })
+  }
+  const applied: RevertChange[] = []
+  const undo = async (): Promise<void> => {
+    for (const change of [...applied].reverse()) await replaceFile(change.path, change.after)
+  }
+  try {
+    for (const change of validated) {
+      if (await fs.readFile(change.path, 'utf8') !== change.after) throw new Error('文件在恢复前已变化')
+      await replaceFile(change.path, change.before)
+      applied.push(change)
+    }
+  } catch (error) { await undo(); throw error }
+  return undo
+}