fix(invariants): assert runtime relationships, not API shapes

packages/core/system-prompt/tests/invariant.spec.ts

@@ -0,0 +1,44 @@
+import { describe, expect, it } from 'vitest'
+import { Context } from 'cordis'
+import type { PromptAssembly } from '@deepseek-ai/dsh-system-prompt'
+import * as SystemPromptInvariant from '@deepseek-ai/dsh-system-prompt/invariant'
+import InvariantService from '@deepseek-ai/dsh-invariants'
+
+async function setup(): Promise<Context> {
+  const ctx = new Context()
+  await ctx.plugin(InvariantService)
+  await ctx.plugin(SystemPromptInvariant)
+  return ctx
+}
+
+const valid = (): PromptAssembly => ({
+  sections: [{ name: 'identity', text: 'prompt' }],
+  tools: [{ name: 'echo', description: 'Echo', parameters: {} }],
+  variables: { cwd: '/repo', optional: undefined },
+})
+
+async function assemble(ctx: Context, result: PromptAssembly): Promise<PromptAssembly> {
+  return ctx.waterfall(
+    ctx as never, 'system-prompt/assemble', valid(), {},
+    () => Promise.resolve(result),
+  )
+}
+
+describe('system-prompt invariants', () => {
+  it('accepts a well-formed authoritative assembly', async () => {
+    const ctx = await setup()
+    await expect(assemble(ctx, valid())).resolves.toEqual(valid())
+  })
+
+  it.each([
+    [{ ...valid(), sections: [{ name: '', text: 'x' }] }, /section names must be non-empty/],
+    [{ ...valid(), sections: [{ name: 'x', text: 'a' }, { name: 'x', text: 'b' }] }, /section name "x" is duplicated/],
+    [{ ...valid(), sections: [{ name: 'x', text: 1 as never }] }, /section "x" text must be a string/],
+    [{ ...valid(), tools: [{ name: '', description: 'x', parameters: {} }] }, /tool names must be non-empty/],
+    [{ ...valid(), variables: { Bad: 'x' } }, /variable name "Bad" is invalid/],
+    [{ ...valid(), variables: { value: 1 as never } }, /variable "value" must be a string or undefined/],
+  ])('rejects malformed authoritative assembly %#', async (assembly, message) => {
+    const ctx = await setup()
+    await expect(assemble(ctx, assembly)).rejects.toThrow(message)
+  })
+})