round 1: implement bracket-first manual compaction

packages/compact/command-compact/tests/invariant.spec.ts

@@ -0,0 +1,18 @@
+import { describe, expect, it, vi } from 'vitest'
+import * as invariant from '@deepseek-ai/dsh-command-compact/invariant'
+
+describe('command-compact invariant companion', () => {
+  it('registers the package-owned no-op installer', async () => {
+    const register = vi.fn().mockReturnValue(() => {})
+    const ctx = { invariants: { register } } as never
+    const dispose = await invariant.apply(ctx)
+    expect(invariant.name).toBe('command-compact-invariant')
+    expect(invariant.inject).toEqual(['invariants'])
+    expect(register).toHaveBeenCalledWith('@deepseek-ai/dsh-command-compact', expect.any(Function))
+    expect(() => {
+      const install = register.mock.calls[0]![1] as () => void
+      install()
+    }).not.toThrow()
+    expect(dispose).toBeTypeOf('function')
+  })
+})