refactor(core): make v2 session inputs event sourced (#30785)

packages/opencode/src/session/compaction.ts

@@ -12,7 +12,7 @@ import { Plugin } from "@/plugin"
 import { Config } from "@/config/config"
 import { NotFoundError } from "@/storage/storage"
 
-import { Effect, Layer, Context, Schema } from "effect"
+import { Effect, Layer, Context } from "effect"
 import * as DateTime from "effect/DateTime"
 import { InstanceState } from "@/effect/instance-state"
 import { isOverflow as overflow, usable } from "./overflow"
@@ -20,6 +20,7 @@ import { serviceUse } from "@opencode-ai/core/effect/service-use"
 import { RuntimeFlags } from "@/effect/runtime-flags"
 import { EventV2Bridge } from "@/event-v2-bridge"
 import { SessionEvent } from "@opencode-ai/core/session/event"
+import { SessionMessage } from "@opencode-ai/core/session/message"
 import { ProviderV2 } from "@opencode-ai/core/provider"
 import { ModelV2 } from "@opencode-ai/core/model"
 import { EventV2 } from "@opencode-ai/core/event"
@@ -609,6 +610,7 @@ export const layer = Layer.effect(
       if (flags.experimentalEventSystem) {
         yield* events.publish(SessionEvent.Compaction.Started, {
           sessionID: input.sessionID,
+          messageID: SessionMessage.ID.create(),
           timestamp: DateTime.makeUnsafe(Date.now()),
           reason: input.auto ? "auto" : "manual",
         })