feat(core): add embedded v2 session runtime and tool foundation (#30632)

packages/core/src/opencode.ts

@@ -0,0 +1,39 @@
+export * as OpenCode from "./opencode"
+
+import { Context, Effect, Layer } from "effect"
+import { Database } from "./database/database"
+import { EventV2 } from "./event"
+import { LocationServiceMap } from "./location-layer"
+import { ProjectV2 } from "./project"
+import { SessionV2 } from "./session"
+import { SessionProjector } from "./session/projector"
+import * as SessionExecutionLocal from "./session/execution/local"
+import { SessionStore } from "./session/store"
+
+export interface Interface {
+  readonly sessions: SessionV2.Interface
+}
+
+/** Public embedded OpenCode API for Effect-native applications. */
+export class Service extends Context.Service<Service, Interface>()("@opencode/OpenCode") {}
+
+const DefaultSessions = SessionV2.layer.pipe(
+  Layer.provide(SessionProjector.layer),
+  Layer.provide(SessionExecutionLocal.layer),
+  Layer.provide(LocationServiceMap.layer),
+  Layer.provide(SessionStore.layer),
+  Layer.provide(EventV2.layer),
+  Layer.provide(Database.defaultLayer),
+  Layer.provide(ProjectV2.defaultLayer),
+  Layer.orDie,
+)
+
+// TODO: Accept explicit storage so tests and embeddings can select disposable or application-owned persistence.
+export const layer = Layer.effect(
+    Service,
+    Effect.gen(function* () {
+      return Service.of({ sessions: yield* SessionV2.Service })
+    }),
+  ).pipe(Layer.provide(DefaultSessions))
+
+// TODO: Add OpenCode.create(...) as the Promise facade over the same embedded API semantics.