diff --git a/scripts/install-global.mjs b/scripts/install-global.mjs
index 62bc38c..de81919 100644
--- a/scripts/install-global.mjs
+++ b/scripts/install-global.mjs
@@ -1,12 +1,11 @@
 #!/usr/bin/env node
-import { cp, mkdir, readFile, rename, stat, writeFile } from 'node:fs/promises'
+import { cp, mkdir, readFile, rm, stat, writeFile } from 'node:fs/promises'
 import { createHash } from 'node:crypto'
 import { homedir } from 'node:os'
-import { dirname, join, resolve } from 'node:path'
+import { join, resolve } from 'node:path'
 
 const root = resolve(new URL('..', import.meta.url).pathname)
 const destination = process.env.TOOLBOX_SKILLS_DIR ?? join(homedir(), '.agents', 'skills')
-const backupRoot = join(destination, '_agent', 'install-backups', `toolbox-${Date.now()}`)
 const retired = ['refine-agent-work']
 const registry = JSON.parse(await readFile(join(root, 'skills-lock.json'), 'utf8'))
 const managed = Object.keys(registry.skills ?? registry)
@@ -27,9 +26,7 @@ await mkdir(destination, { recursive: true })
 for (const slug of [...managed, ...retired]) {
   const target = join(destination, slug)
   if (!(await exists(target))) continue
-  const backup = join(backupRoot, slug)
-  await mkdir(dirname(backup), { recursive: true })
-  await rename(target, backup)
+  await rm(target, { recursive: true, force: true })
 }
 for (const slug of managed) {
   const source = join(root, slug)
@@ -48,16 +45,9 @@ await writeFile(
       installedAt: new Date().toISOString(),
       skills: installed,
       retired,
-      backups: (await exists(backupRoot)) ? backupRoot : null,
     },
     null,
     2,
   ) + '\n',
 )
-console.log(
-  JSON.stringify({
-    destination,
-    skills: managed.length,
-    backups: (await exists(backupRoot)) ? backupRoot : null,
-  }),
-)
+console.log(JSON.stringify({ destination, skills: managed.length }))
diff --git a/scripts/sync-claude-skills.mjs b/scripts/sync-claude-skills.mjs
index 8231905..c8697db 100644
--- a/scripts/sync-claude-skills.mjs
+++ b/scripts/sync-claude-skills.mjs
@@ -8,7 +8,7 @@
  *
  * Run via `npm run sync:skills` (Node strip-types for the shared slug list).
  */
-import { mkdir, rm, symlink, lstat, readlink, rename } from 'node:fs/promises'
+import { mkdir, rm, symlink, lstat, readlink } from 'node:fs/promises'
 import { dirname, join } from 'node:path'
 import { fileURLToPath } from 'node:url'
 import { EXPECTED_SKILLS } from '../src/expected-skills.ts'
@@ -32,11 +32,7 @@ for (const skillsRoot of MIRRORS) {
       (await readlink(retired)) === join(RELATIVE_TARGET, 'refine-agent-work')
     )
       await rm(retired)
-    else {
-      const backup = join(root, '_agent', 'install-backups')
-      await mkdir(backup, { recursive: true })
-      await rename(retired, join(backup, `refine-agent-work-${Date.now()}`))
-    }
+    else await rm(retired, { recursive: true, force: true })
   } catch (error) {
     if (error.code !== 'ENOENT') throw error
   }
diff --git a/tests/skills.test.js b/tests/skills.test.js
index eb2f842..0530d45 100644
--- a/tests/skills.test.js
+++ b/tests/skills.test.js
@@ -452,10 +452,13 @@ describe('toolbox skill SSOT', () => {
 
   it('sync:skills imports EXPECTED_SKILLS (no duplicated slug list)', () => {
     const sync = readFileSync(join(root, 'scripts/sync-claude-skills.mjs'), 'utf8')
+    const install = readFileSync(join(root, 'scripts/install-global.mjs'), 'utf8')
     const pkg = readFileSync(join(root, 'package.json'), 'utf8')
     expect(sync).toMatch(/from ['"]\.\.\/src\/expected-skills\.ts['"]/)
     expect(sync).toMatch(/EXPECTED_SKILLS/)
     expect(sync).not.toMatch(/const SKILL_SLUGS = \[\s*'subagents'/)
+    expect(sync).not.toMatch(/install-backups/)
+    expect(install).not.toMatch(/install-backups|backupRoot|backups:/)
     expect(pkg).toMatch(/sync:skills": "node --experimental-strip-types/)
   })