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

packages/core/src/session/runner/index.ts

@@ -0,0 +1,28 @@
+export * as SessionRunner from "./index"
+
+import type { LLMError } from "@opencode-ai/llm"
+import { Context, Effect, Schema } from "effect"
+import { SessionSchema } from "../schema"
+import type { MessageDecodeError } from "../error"
+import { SessionRunnerModel } from "./model"
+
+export class StepLimitExceededError extends Schema.TaggedErrorClass<StepLimitExceededError>()(
+  "SessionRunner.StepLimitExceededError",
+  {
+    sessionID: SessionSchema.ID,
+    limit: Schema.Int,
+  },
+) {}
+
+export type RunError = LLMError | SessionRunnerModel.Error | MessageDecodeError | StepLimitExceededError
+
+/** Runs one local continuation from already-recorded Session history. */
+export interface Interface {
+  /** Drains eligible durable work. Explicit runs perform one provider attempt even when no work is eligible. */
+  readonly run: (input: {
+    readonly sessionID: SessionSchema.ID
+    readonly force?: boolean
+  }) => Effect.Effect<void, RunError>
+}
+
+export class Service extends Context.Service<Service, Interface>()("@opencode/v2/SessionRunner") {}