feat(core): replace instruction checkpoints with value-delta sync (#36254)

packages/core/src/event.ts

@@ -137,7 +137,8 @@ export interface Interface {
   ) => Effect.Effect<Payload<D>>
   readonly subscribe: Subscribe
   /**
-   * Durable, ordered, gap-free per-aggregate log read. `follow: false`
+   * Durable, ordered per-aggregate log read. Forked aggregates may reserve an
+   * inherited prefix before their first child-authored event. `follow: false`
    * completes at the end of the log; `follow: true` replays then transitions
    * to live. Both modes emit one `Synced` marker at the captured replay
    * watermark.
@@ -203,7 +204,6 @@ export const layerWith = (options?: LayerOptions) =>
         typed: new Map<string, PubSub.PubSub<Payload>>(),
       }
       const projectors = new Map<string, Subscriber[]>()
-      // TODO: Bind durable projectors to exact type+version before supporting incompatible historical payloads.
       const listeners = new Array<Subscriber>()
       const { db } = yield* Database.Service
       const logReadPageSize = options?.logReadPageSize ?? 512
@@ -260,7 +260,7 @@ export const layerWith = (options?: LayerOptions) =>
                   }),
                 )
               }
-              const list = projectors.get(event.type) ?? []
+              const list = projectors.get(versionedType(definition.type, durable.version)) ?? []
               return yield* Effect.uninterruptible(
                 Effect.gen(function* () {
                   const committed = yield* db
@@ -515,18 +515,6 @@ export const layerWith = (options?: LayerOptions) =>
               }),
             )
           }
-          const start = events[0]?.seq ?? 0
-          for (const [index, event] of events.entries()) {
-            const seq = start + index
-            if (event.seq !== seq) {
-              yield* Effect.die(
-                new InvalidDurableEventError({
-                  type: event.type,
-                  message: `Replay sequence mismatch at index ${index}: expected ${seq}, got ${event.seq}`,
-                }),
-              )
-            }
-          }
           for (const event of events) {
             yield* replay(event, options)
           }
@@ -727,9 +715,10 @@ export const layerWith = (options?: LayerOptions) =>
 
       const project = <D extends Definition>(definition: D, projector: Subscriber<D>): Effect.Effect<void> =>
         Effect.sync(() => {
-          const list = projectors.get(definition.type) ?? []
+          const key = definition.durable ? versionedType(definition.type, definition.durable.version) : definition.type
+          const list = projectors.get(key) ?? []
           list.push((event) => projector(event as Payload<D>))
-          projectors.set(definition.type, list)
+          projectors.set(key, list)
         })
 
       return Service.of({