Simplify single-backend HttpApi exerciser (#26906)

packages/opencode/test/server/httpapi-exercise/backend.ts

@@ -2,7 +2,7 @@ import { ConfigProvider, Effect, Layer } from "effect"
 import { HttpRouter } from "effect/unstable/http"
 import { parse } from "./assertions"
 import { runtime, type Runtime } from "./runtime"
-import type { ActiveScenario, Backend, BackendApp, CallResult, CaptureMode, SeededContext } from "./types"
+import type { ActiveScenario, BackendApp, CallResult, CaptureMode, SeededContext } from "./types"
 
 type CallOptions = {
   auth?: {
@@ -11,27 +11,18 @@ type CallOptions = {
   }
 }
 
-export function call(
-  backend: Backend,
-  scenario: ActiveScenario,
-  ctx: SeededContext<unknown>,
-  options: CallOptions = {},
-) {
+export function call(scenario: ActiveScenario, ctx: SeededContext<unknown>, options: CallOptions = {}) {
   return Effect.promise(async () =>
-    capture(await app(await runtime(), backend, options).request(toRequest(scenario, ctx)), scenario.capture),
+    capture(await app(await runtime(), options).request(toRequest(scenario, ctx)), scenario.capture),
   )
 }
 
-export function callAuthProbe(
-  backend: Backend,
-  scenario: ActiveScenario,
-  credentials: "missing" | "valid" = "missing",
-) {
+export function callAuthProbe(scenario: ActiveScenario, credentials: "missing" | "valid" = "missing") {
   return Effect.promise(async () => {
     const controller = new AbortController()
     return Promise.race([
       Promise.resolve(
-        app(await runtime(), backend, { auth: { password: "secret" } }).request(
+        app(await runtime(), { auth: { password: "secret" } }).request(
           toAuthProbeRequest(scenario, credentials, controller.signal),
         ),
       ).then((response) => capture(response, scenario.capture)),
@@ -51,10 +42,10 @@ export function callAuthProbe(
 
 const appCache: Partial<Record<string, BackendApp>> = {}
 
-function app(modules: Runtime, backend: Backend, options: CallOptions) {
+function app(modules: Runtime, options: CallOptions) {
   const username = options.auth?.username
   const password = options.auth?.password
-  const cacheKey = `${backend}:${username ?? ""}:${password ?? ""}`
+  const cacheKey = `${username ?? ""}:${password ?? ""}`
   if (appCache[cacheKey]) return appCache[cacheKey]
 
   const handler = HttpRouter.toWebHandler(