fix(server): stop form polling from booting idle locations (#59083)

Co-authored-by: Kit Langton <kit.langton@gmail.com>

packages/core/src/effect/app-node-builder.ts

@@ -2,7 +2,7 @@ import { buildLocationServiceMap } from "../location-services.js"
 import { LocationServiceMap } from "../location-service-map.js"
 import { LayerNode } from "@opencode/util/effect/layer-node"
 import { makeGlobalNode } from "@opencode/util/effect/app-node"
-import { Effect, Layer } from "effect"
+import { Effect, Layer, RcMap } from "effect"
 import { Instance } from "../instance/service.js"
 
 const instances = makeGlobalNode({
@@ -13,6 +13,7 @@ const instances = makeGlobalNode({
       const locations = yield* LocationServiceMap.Service
       return Instance.Service.of({
         provide: (session) => Effect.provide(locations.get(session.location)),
+        live: (session) => RcMap.has(locations.rcMap, LocationServiceMap.canonical(session.location)),
       })
     }),
   ),

packages/core/src/instance/service.ts

@@ -12,6 +12,8 @@ export interface Interface {
   readonly provide: (
     session: Session.Info,
   ) => <A, E, R>(effect: Effect.Effect<A, E, R>) => Effect.Effect<A, E | Error, Exclude<R, Services>>
+  /** Whether `provide` would reuse built or booting capabilities. Selectors without it are assumed live. */
+  readonly live?: (session: Session.Info) => Effect.Effect<boolean>
 }
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/Instance") {}

packages/sdk/src/internal/instances.ts

@@ -7,7 +7,7 @@ import type { InstancePlugins } from "@opencode/core/plugin/instance"
 import type { Session } from "@opencode/schema/session"
 import { makeGlobalNode } from "@opencode/util/effect/app-node"
 import type { LayerNode } from "@opencode/util/effect/layer-node"
-import { Context, Duration, Effect, Layer, LayerMap, Scope } from "effect"
+import { Context, Duration, Effect, Layer, LayerMap, RcMap, Scope } from "effect"
 
 export interface Configuration {
   readonly plugins: InstancePlugins.List
@@ -101,7 +101,7 @@ export function layer(options: Options, replacements: () => LayerNode.Replacemen
           ),
         { idleTimeToLive: Duration.infinity },
       )
-      return Instance.Service.of({ provide })
+      return Instance.Service.of({ provide, live: (session) => RcMap.has(instances.rcMap, key(session)) })
     }),
   )
 }

packages/server/src/middleware/form-location.ts

@@ -3,7 +3,7 @@ import { LocationServiceMap } from "@opencode/core/location-services"
 import { Session } from "@opencode/core/session"
 import { LocationNotFoundError, InvalidRequestError, SessionNotFoundError } from "@opencode/protocol/errors"
 import { Effect, Layer } from "effect"
-import { HttpRouter, HttpServerRequest } from "effect/http"
+import { HttpRouter, HttpServerRequest, HttpServerResponse } from "effect/http"
 import { HttpApiMiddleware } from "effect/http-api"
 import { locationErrors, requestRef, sessionInfo, type LocationServices } from "../location"
 
@@ -21,7 +21,7 @@ export const formLocationLayer = Layer.effect(
     const instances = yield* Instance.Service
     const locations = yield* LocationServiceMap.Service
 
-    return FormLocationMiddleware.of((effect) =>
+    return FormLocationMiddleware.of((effect, options) =>
       Effect.gen(function* () {
         const route = yield* HttpRouter.RouteContext
         if (route.params.sessionID === "global") {
@@ -33,6 +33,10 @@ export const formLocationLayer = Layer.effect(
         }
 
         const session = yield* sessionInfo(sessions, route.params.sessionID)
+        // Forms live in memory, so a Session without live capabilities has none pending. Listing must
+        // not boot its Location: clients poll whole subagent trees, including deleted worktrees.
+        if (options.endpoint.identifier === "session.form.list" && instances.live && !(yield* instances.live(session)))
+          return HttpServerResponse.jsonUnsafe({ data: [] })
         return yield* effect.pipe(instances.provide(session), locationErrors)
       }),
     )

packages/server/test/fetch.test.ts

@@ -42,7 +42,6 @@ it.live("returns LocationNotFoundError for a missing folder and recovers once it
       "/api/model",
       "/api/integration",
       `/api/session/${session.id}/permission`,
-      `/api/session/${session.id}/form`,
       "/api/session/global/form",
     ]
     for (const endpoint of endpoints) {

packages/server/test/session-form.test.ts

@@ -0,0 +1,50 @@
+import { expect } from "bun:test"
+import fs from "fs/promises"
+import { Effect } from "effect"
+import { tmpdirScoped } from "../../core/test/fixture/tmpdir"
+import { it } from "../../core/test/lib/effect"
+import { ServerFetch } from "../src/fetch"
+
+it.live("lists no forms for a Session whose Location is not live, and pending forms once it is", () =>
+  Effect.gen(function* () {
+    const handler = yield* ServerFetch.make({
+      app: { version: "test" },
+      database: { path: ":memory:" },
+      fs: { filewatcher: false },
+      models: { fetch: false },
+    })
+    const request = (path: string, body?: unknown) =>
+      Effect.promise(async () => {
+        const response = await handler(
+          new Request(`http://opencode.local${path}`, {
+            method: body === undefined ? "GET" : "POST",
+            headers: { "content-type": "application/json" },
+            body: body === undefined ? undefined : JSON.stringify(body),
+          }),
+        )
+        return { status: response.status, body: await response.json() }
+      })
+    const create = (directory: string) =>
+      request("/api/session", { location: { directory } }).pipe(
+        Effect.map((response) => (response.body as { data: { id: string } }).data.id),
+      )
+
+    // A subagent whose worktree was deleted must not boot or 404.
+    const deleted = yield* tmpdirScoped()
+    const orphan = yield* create(deleted.path)
+    yield* Effect.promise(() => fs.rm(deleted.path, { recursive: true, force: true }))
+    expect(yield* request(`/api/session/${orphan}/form`)).toEqual({ status: 200, body: { data: [] } })
+
+    const directory = yield* tmpdirScoped()
+    const live = yield* create(directory.path)
+    const created = yield* request(`/api/session/${live}/form`, {
+      title: "Pick one",
+      fields: [{ key: "answer", type: "string" }],
+    })
+    expect(created.status).toBe(200)
+    expect(yield* request(`/api/session/${live}/form`)).toEqual({
+      status: 200,
+      body: { data: [(created.body as { data: unknown }).data] },
+    })
+  }).pipe(Effect.scoped),
+)