P2-02: serialize persistence writes

tests/facade.test.ts

@@ -2,6 +2,7 @@ import { test } from 'node:test'
 import assert from 'node:assert/strict'
 import { createMockFacade } from '../src/facade/mockFacade'
 import { PROJECT_SCHEMA_MIGRATIONS, PROJECT_SCHEMA_SQL, PROJECT_SCHEMA_VERSION } from '../src/facade/projectSchema'
+import { PersistenceWriteQueue } from '../src/facade/projectStore'
 
 test('facade exposes a stable initial document projection', () => {
   const facade = createMockFacade()
@@ -19,6 +20,28 @@ test('project schema is versioned and covers the FreeCAD document graph', () =>
   assert.match(PROJECT_SCHEMA_SQL, /CREATE INDEX IF NOT EXISTS objects_document_ordinal/)
 })
 
+test('persistence writes are serialized and continue after a failed write', async () => {
+  const queue = new PersistenceWriteQueue()
+  let inFlight = 0
+  let maximumInFlight = 0
+  const order: string[] = []
+  const write = (id: string, shouldFail = false) => queue.run(async () => {
+    inFlight += 1
+    maximumInFlight = Math.max(maximumInFlight, inFlight)
+    await new Promise((resolve) => setTimeout(resolve, 2))
+    order.push(id)
+    inFlight -= 1
+    if (shouldFail) throw new Error('expected write failure')
+    return id
+  })
+  const results = await Promise.allSettled([write('one'), write('two', true), write('three')])
+  assert.equal(maximumInFlight, 1)
+  assert.deepEqual(order, ['one', 'two', 'three'])
+  assert.equal(results[0].status, 'fulfilled')
+  assert.equal(results[1].status, 'rejected')
+  assert.equal(results[2].status, 'fulfilled')
+})
+
 test('workbench and selection changes are event driven', () => {
   const facade = createMockFacade()
   const events: string[] = []