fix(httpapi): return session busy error bodies (#28684)

packages/opencode/src/server/routes/instance/httpapi/handlers/session-errors.ts

@@ -1,7 +1,6 @@
 import type { NotFoundError as StorageNotFoundError } from "@/storage/storage"
 import type { Session } from "@/session/session"
 import { Effect } from "effect"
-import { HttpApiError } from "effect/unstable/httpapi"
 import * as ApiError from "../errors"
 
 export function mapStorageNotFound<A, R>(self: Effect.Effect<A, StorageNotFoundError, R>) {
@@ -9,5 +8,14 @@ export function mapStorageNotFound<A, R>(self: Effect.Effect<A, StorageNotFoundE
 }
 
 export function mapBusy<A, R>(self: Effect.Effect<A, Session.BusyError, R>) {
-  return self.pipe(Effect.catchTag("SessionBusyError", () => Effect.fail(new HttpApiError.BadRequest({}))))
+  return self.pipe(
+    Effect.catchTag("SessionBusyError", (error) =>
+      Effect.fail(
+        new ApiError.SessionBusyError({
+          sessionID: error.sessionID,
+          message: `Session is busy: ${error.sessionID}`,
+        }),
+      ),
+    ),
+  )
 }