fix(cordis): make config reload transactional

vendor/loader/src/config/tree.ts

@@ -39,12 +39,27 @@ export abstract class EntryTree {
       .filter(isNonNullable)
   }
 
-  /** Wait until this tree has no pending import or lifecycle tasks. */
+  /**
+   * Wait until this tree has no active import or lifecycle tasks.
+   * @throws a settled fiber failure, or an aggregate when several fibers failed.
+   */
   async await() {
     while (true) {
       const tasks = this.getTasks()
-      if (!tasks.length) return
-      await Promise.allSettled(tasks)
+      if (tasks.length) {
+        await Promise.allSettled(tasks)
+        continue
+      }
+      const outcomes = await Promise.allSettled(
+        [...this.entries()].map(entry => entry.fiber?.await()),
+      )
+      const failures = outcomes
+        .filter((outcome): outcome is PromiseRejectedResult => outcome.status === 'rejected')
+        .map(outcome => outcome.reason)
+      if (failures.length === 1) throw failures[0]
+      if (failures.length > 1) throw new AggregateError(failures, 'loader fibers failed')
+      this.ctx.reflect.notify(['loader'])
+      if (!this.getTasks().length) return
     }
   }
 
@@ -81,15 +96,17 @@ export abstract class EntryTree {
   /** Create an entry in the root group or a nested group. */
   async create(options: Omit<EntryOptions, 'id'>, parent: string | null = null, position = Infinity) {
     const group = this.resolveGroup(parent)
-    group.data.splice(position, 0, options as EntryOptions)
+    const id = await group.create(options)
+    const entry = this.resolve(id)
+    group.data.splice(position, 0, entry.options)
     group.tree.write()
-    return group.create(options)
+    return id
   }
 
   /** Stop and remove an entry from its parent group. */
-  remove(id: string) {
+  async remove(id: string) {
     const entry = this.resolve(id)
-    entry.parent.remove(id)
+    await entry.parent.remove(id)
     entry.parent.tree.write()
   }
 
@@ -97,15 +114,31 @@ export abstract class EntryTree {
   async update(id: string, options: Omit<EntryOptions, 'id' | 'name'>, parent?: string | null, position?: number) {
     const entry = this.resolve(id)
     const source = entry.parent
+    const sourceIndex = source.data.indexOf(entry.options)
+    let target = source
     if (parent !== undefined) {
-      const target = this.resolveGroup(parent)
+      target = this.resolveGroup(parent)
       source.unlink(entry.options)
       target.data.splice(position ?? Infinity, 0, entry.options)
-      target.tree.write()
       entry.parent = target
     }
+    try {
+      await entry.update(options, false, true)
+    } catch (error) {
+      if (parent !== undefined) {
+        target.unlink(entry.options)
+        source.data.splice(sourceIndex < 0 ? source.data.length : sourceIndex, 0, entry.options)
+        entry.parent = source
+        try {
+          await entry.update({}, false, true)
+        } catch (rollbackError) {
+          throw new AggregateError([error, rollbackError], `failed to roll back loader entry move ${id}`)
+        }
+      }
+      throw error
+    }
     source.tree.write()
-    return entry.update(options, false, true)
+    if (target !== source) target.tree.write()
   }
 
   /** Import a plugin module from a specifier or `cordis:` builtin. */