feat: add experimental background subagents (#27084)

packages/opencode/src/session/run-state.ts

@@ -1,5 +1,6 @@
 import { InstanceState } from "@/effect/instance-state"
 import { Runner } from "@/effect/runner"
+import { BackgroundJob } from "@/background/job"
 import { Effect, Latch, Layer, Scope, Context } from "effect"
 import * as Session from "./session"
 import { MessageV2 } from "./message-v2"
@@ -27,6 +28,7 @@ export class Service extends Context.Service<Service, Interface>()("@opencode/Se
 export const layer = Layer.effect(
   Service,
   Effect.gen(function* () {
+    const background = yield* BackgroundJob.Service
     const status = yield* SessionStatus.Service
 
     const state = yield* InstanceState.make(
@@ -72,6 +74,7 @@ export const layer = Layer.effect(
     })
 
     const cancel = Effect.fn("SessionRunState.cancel")(function* (sessionID: SessionID) {
+      yield* cancelBackgroundJobs(background, sessionID)
       const data = yield* InstanceState.get(state)
       const existing = data.runners.get(sessionID)
       if (!existing || !existing.busy) {
@@ -104,7 +107,41 @@ export const layer = Layer.effect(
   }),
 )
 
-export const defaultLayer = layer.pipe(Layer.provide(SessionStatus.defaultLayer))
+export const defaultLayer = layer.pipe(Layer.provide(BackgroundJob.defaultLayer), Layer.provide(SessionStatus.defaultLayer))
+
+const cancelBackgroundJobs = Effect.fn("SessionRunState.cancelBackgroundJobs")(function* (
+  background: BackgroundJob.Interface,
+  sessionID: SessionID,
+) {
+  const jobs = yield* background.list()
+  const pending = new Set<string>([sessionID])
+  const cancelled = new Set<string>()
+  const matches = (job: BackgroundJob.Info) => {
+    if (job.status !== "running") return false
+    if (cancelled.has(job.id)) return false
+    if (pending.has(job.id)) return true
+    if (typeof job.metadata?.sessionId === "string" && pending.has(job.metadata.sessionId)) return true
+    return typeof job.metadata?.parentSessionId === "string" && pending.has(job.metadata.parentSessionId)
+  }
+  let batch = jobs.filter(matches)
+  while (batch.length > 0) {
+    yield* Effect.forEach(
+      batch,
+      (job) =>
+        background.cancel(job.id).pipe(
+          Effect.tap(() =>
+            Effect.sync(() => {
+              cancelled.add(job.id)
+              pending.add(job.id)
+              if (typeof job.metadata?.sessionId === "string") pending.add(job.metadata.sessionId)
+            }),
+          ),
+        ),
+      { concurrency: "unbounded", discard: true },
+    )
+    batch = jobs.filter(matches)
+  }
+})
 
 function busyError(sessionID: SessionID) {
   return new Session.BusyError({ sessionID })