Fix HttpApi web UI fallback (#25163)

packages/opencode/src/server/routes/instance/httpapi/server.ts

@@ -1,6 +1,6 @@
 import { Context, Effect, Layer } from "effect"
 import { HttpApiBuilder } from "effect/unstable/httpapi"
-import { HttpMiddleware, HttpRouter, HttpServer } from "effect/unstable/http"
+import { HttpMiddleware, HttpRouter, HttpServer, HttpServerResponse } from "effect/unstable/http"
 import * as Socket from "effect/unstable/socket/Socket"
 import { Account } from "@/account/account"
 import { Agent } from "@/agent/agent"
@@ -38,6 +38,7 @@ import { Vcs } from "@/project/vcs"
 import { Worktree } from "@/worktree"
 import { Workspace } from "@/control-plane/workspace"
 import { isAllowedCorsOrigin } from "@/server/cors"
+import { UIRoutes } from "@/server/routes/ui"
 import { InstanceHttpApi, RootHttpApi } from "./api"
 import { ServerAuthConfig, authorizationLayer, authorizationRouterMiddleware } from "./middleware/authorization"
 import { eventRoute } from "./event"
@@ -119,7 +120,21 @@ const instanceRoutes = Layer.mergeAll(rawInstanceRoutes, instanceApiRoutes).pipe
   ]),
 )
 
-export const routes = Layer.mergeAll(rootApiRoutes, instanceRoutes).pipe(
+const uiRoutes = lazy(() => UIRoutes())
+const uiRoute = HttpRouter.add("*", "/*", (request) =>
+  Effect.promise(async () =>
+    uiRoutes().fetch(
+      request.source instanceof Request
+        ? request.source
+        : new Request(new URL(request.originalUrl, "http://localhost"), {
+            method: request.method,
+            headers: request.headers,
+          }),
+    ),
+  ).pipe(Effect.map(HttpServerResponse.fromWeb)),
+)
+
+export const routes = Layer.mergeAll(rootApiRoutes, instanceRoutes, uiRoute).pipe(
   Layer.provide([
     cors,
     runtime,