fix(server): serve HttpApi OpenAPI document (#26438)

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 { FetchHttpClient, HttpClient, HttpMiddleware, HttpRouter, HttpServer } from "effect/unstable/http"
+import { HttpApiBuilder, OpenApi } from "effect/unstable/httpapi"
+import { FetchHttpClient, HttpClient, HttpMiddleware, HttpRouter, HttpServer, HttpServerResponse } from "effect/unstable/http"
 import * as Socket from "effect/unstable/socket/Socket"
 import { AppFileSystem } from "@opencode-ai/core/filesystem"
 import { Account } from "@/account/account"
@@ -49,6 +49,7 @@ import { CorsConfig, isAllowedCorsOrigin, type CorsOptions } from "@/server/cors
 import { serveUIEffect } from "@/server/shared/ui"
 import { ServerAuth } from "@/server/auth"
 import { InstanceHttpApi, RootHttpApi } from "./api"
+import { PublicApi } from "./public"
 import { authorizationLayer, authorizationRouterMiddleware } from "./middleware/authorization"
 import { EventApi, eventHandlers } from "./event"
 import { configHandlers } from "./handlers/config"
@@ -144,6 +145,17 @@ const instanceRoutes = Layer.mergeAll(rawInstanceRoutes, instanceApiRoutes).pipe
   ]),
 )
 
+const openApiDocument = OpenApi.fromApi(PublicApi)
+const openApiDocumentJson = JSON.stringify(openApiDocument)
+
+const docRoute = HttpRouter.use((router) =>
+  router.add(
+    "GET",
+    "/doc",
+    () => Effect.succeed(HttpServerResponse.text(openApiDocumentJson, { headers: { "content-type": "application/json" } })),
+  ),
+).pipe(Layer.provide(authOnlyRouterLayer))
+
 const uiRoute = HttpRouter.use((router) =>
   Effect.gen(function* () {
     const fs = yield* AppFileSystem.Service
@@ -153,7 +165,7 @@ const uiRoute = HttpRouter.use((router) =>
 ).pipe(Layer.provide(authOnlyRouterLayer))
 
 export function createRoutes(corsOptions?: CorsOptions) {
-  return Layer.mergeAll(rootApiRoutes, eventApiRoutes, instanceRoutes, uiRoute).pipe(
+  return Layer.mergeAll(rootApiRoutes, eventApiRoutes, instanceRoutes, docRoute, uiRoute).pipe(
     Layer.provide([
       errorLayer,
       cors(corsOptions),