feat(core): resume suspended sessions after service restart (#36105)

packages/core/src/session/execution/restart.ts

@@ -0,0 +1,51 @@
+export * as SessionRestart from "./restart"
+
+import { Context, Effect, Layer } from "effect"
+import { makeGlobalNode } from "../../effect/app-node"
+import { SessionExecution } from "../execution"
+import { SessionStore } from "../store"
+
+export interface Interface {
+  /**
+   * Marks every execution active in this process for resumption by the next server start.
+   * Call once new work has stopped arriving and before teardown interrupts the drains.
+   */
+  readonly suspendActiveSessions: Effect.Effect<void>
+  /** Resumes suspended Sessions. Each suspension is consumed atomically, so a Session resumes at most once. */
+  readonly resumeSuspendedSessions: Effect.Effect<void>
+}
+
+/**
+ * Restart continuity actions for the managed server. The service is inert until called: only the
+ * managed server invokes it, so default, embedded, and stdio servers never suspend or auto-resume.
+ */
+export class Service extends Context.Service<Service, Interface>()("@opencode/v2/SessionRestart") {}
+
+export const layer = Layer.effect(
+  Service,
+  Effect.gen(function* () {
+    const store = yield* SessionStore.Service
+    const execution = yield* SessionExecution.Service
+    return Service.of({
+      suspendActiveSessions: Effect.gen(function* () {
+        yield* store.suspend(yield* execution.active)
+      }),
+      resumeSuspendedSessions: Effect.gen(function* () {
+        const sessions = yield* store.listSuspended()
+        yield* Effect.forEach(
+          sessions,
+          (sessionID) =>
+            Effect.gen(function* () {
+              if (!(yield* store.consumeSuspended(sessionID))) return
+              // Drain failures are already logged and durably recorded by the execution layer.
+              yield* Effect.ignore(execution.resume(sessionID))
+            }),
+          // Each suspension is consumed atomically right before its drain; at most four drains run at once.
+          { concurrency: 4, discard: true },
+        )
+      }),
+    })
+  }),
+)
+
+export const node = makeGlobalNode({ service: Service, layer, deps: [SessionStore.node, SessionExecution.node] })