fix(invariants): replay histories and pack companions

packages/todo/tool-todo/src/invariant.ts

@@ -33,14 +33,24 @@ function validateTodos(value: unknown, fail: InvariantFailure): void {
   if (active > 1) fail(`todo/write contains ${active} in-progress entries; at most one is allowed`)
 }
 
-/** Install validation for durable whole-list todo snapshots. */
-const install: InvariantInstaller = (ctx, fail) => {
+/* jscpd:ignore-start -- package companions share replay and dispatch plumbing */
+/** Validate the package-owned event shape and ignore unrelated events. */
+function validateEvent(event: SessionEvent, fail: InvariantFailure): void {
+  if (event.type === 'todo/write') validateTodos(event.data.todos, fail)
+}
+
+/** Install validation for loaded and newly appended whole-list todo snapshots. */
+const install: InvariantInstaller = Object.assign((ctx: Context, fail: InvariantFailure) => {
+  for (const session of ctx.sessions.list()) {
+    for (const event of session.events) validateEvent(event, fail)
+  }
   ctx.on('internal/dispatch', (_mode, eventName, args) => {
     if (eventName !== 'session/event') return
     const event = (args as [Session, SessionEvent])[1]
-    if (event.type === 'todo/write') validateTodos(event.data.todos, fail)
+    validateEvent(event, fail)
   }, { global: true })
-}
+}, { inject: ['sessions'] })
+/* jscpd:ignore-end */
 
 /**
  * Register the todo invariant companion.

packages/todo/tool-todo/tests/invariant.spec.ts

@@ -1,12 +1,13 @@
 import { describe, expect, it } from 'vitest'
 import { Context } from 'cordis'
-import type { Session, SessionEvent } from '@deepseek-ai/dsh-session'
+import SessionStore, { type Session, type SessionEvent } from '@deepseek-ai/dsh-session'
 import * as TodoInvariant from '@deepseek-ai/dsh-tool-todo/invariant'
 import InvariantService from '@deepseek-ai/dsh-invariants'
 
 async function setup(): Promise<Context> {
   const ctx = new Context()
-  await ctx.plugin(InvariantService)
+  await ctx.plugin(SessionStore)
+  await ctx.plugin(InvariantService, { enabled: true })
   await ctx.plugin(TodoInvariant)
   return ctx
 }
@@ -50,4 +51,18 @@ describe('todo snapshot invariants', () => {
       })
     }).not.toThrow()
   })
+
+  it('rejects an invalid existing snapshot on late registration', async () => {
+    const ctx = new Context()
+    await ctx.plugin(SessionStore)
+    ctx.sessions.create().append('todo/write', {
+      todos: [
+        { content: 'duplicate', status: 'pending' },
+        { content: 'duplicate', status: 'completed' },
+      ],
+    })
+    await ctx.plugin(InvariantService, { enabled: true })
+
+    await expect(ctx.plugin(TodoInvariant).then(() => undefined)).rejects.toThrow(/repeats content "duplicate"/)
+  })
 })