feat(server): add HTTP API response compression (#26440)

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

@@ -0,0 +1,64 @@
+import { deflateSync, gzipSync } from "node:zlib"
+import { Effect } from "effect"
+import { HttpBody, HttpRouter, HttpServerRequest, HttpServerResponse } from "effect/unstable/http"
+
+// Mirror of Hono's compressible content-type set so wire behavior matches.
+const COMPRESSIBLE_CONTENT_TYPE_REGEX =
+  /^\s*(?:text\/(?!event-stream(?:[;\s]|$))[^;\s]+|application\/(?:javascript|json|xml|xml-dtd|ecmascript|dart|postscript|rtf|tar|toml|vnd\.dart|vnd\.ms-fontobject|vnd\.ms-opentype|wasm|x-httpd-php|x-javascript|x-ns-proxy-autoconfig|x-sh|x-tar|x-www-form-urlencoded)|font\/(?:otf|ttf)|image\/(?:bmp|vnd\.adobe\.photoshop|vnd\.microsoft\.icon|vnd\.ms-dds|x-icon|x-ms-bmp)|message\/rfc822|model\/gltf-binary|x-shader\/x-fragment|x-shader\/x-vertex|[^;\s]+?\+(?:json|text|xml|yaml))(?:[;\s]|$)/i
+
+const NO_TRANSFORM_REGEX = /(?:^|,)\s*?no-transform\s*?(?:,|$)/i
+
+const STREAMING_PATHS = new Set(["/event", "/global/event"])
+const STREAMING_POST_REGEX = /^\/session\/[^/]+\/(?:message|prompt_async)$/
+
+const THRESHOLD_BYTES = 1024
+
+type Encoding = "gzip" | "deflate"
+
+function pickEncoding(acceptEncoding: string | undefined): Encoding | undefined {
+  if (!acceptEncoding) return undefined
+  const lower = acceptEncoding.toLowerCase()
+  if (lower.includes("gzip")) return "gzip"
+  if (lower.includes("deflate")) return "deflate"
+  return undefined
+}
+
+function pathOf(url: string): string {
+  const queryIndex = url.indexOf("?")
+  return queryIndex === -1 ? url : url.slice(0, queryIndex)
+}
+
+export const compressionLayer = HttpRouter.middleware<{ handles: unknown }>()((effect) =>
+  Effect.gen(function* () {
+    const response = yield* effect
+    const request = yield* HttpServerRequest.HttpServerRequest
+
+    if (request.method === "HEAD") return response
+    if (response.headers["content-encoding"]) return response
+    if (response.headers["transfer-encoding"]) return response
+
+    const body = response.body
+    if (body._tag !== "Uint8Array") return response
+    if (body.body.byteLength < THRESHOLD_BYTES) return response
+
+    const cacheControl = response.headers["cache-control"]
+    if (cacheControl && NO_TRANSFORM_REGEX.test(cacheControl)) return response
+
+    const path = pathOf(request.url)
+    if (STREAMING_PATHS.has(path)) return response
+    if (request.method === "POST" && STREAMING_POST_REGEX.test(path)) return response
+
+    const contentType = body.contentType
+    if (!COMPRESSIBLE_CONTENT_TYPE_REGEX.test(contentType)) return response
+
+    const encoding = pickEncoding(request.headers["accept-encoding"])
+    if (!encoding) return response
+
+    const compressed = encoding === "gzip" ? gzipSync(body.body) : deflateSync(body.body)
+    return HttpServerResponse.setHeader(
+      HttpServerResponse.setBody(response, HttpBody.uint8Array(compressed, contentType)),
+      "content-encoding",
+      encoding,
+    )
+  }),
+).layer

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

@@ -81,6 +81,7 @@ import { workspaceRouterMiddleware, workspaceRoutingLayer } from "./middleware/w
 import { disposeMiddleware } from "./lifecycle"
 import { memoMap } from "@opencode-ai/core/effect/memo-map"
 import * as ServerBackend from "@/server/backend"
+import { compressionLayer } from "./middleware/compression"
 import { errorLayer } from "./middleware/error"
 import { fenceLayer } from "./middleware/fence"
 
@@ -174,6 +175,7 @@ export function createRoutes(corsOptions?: CorsOptions) {
   return Layer.mergeAll(rootApiRoutes, eventApiRoutes, instanceRoutes, docRoute, uiRoute).pipe(
     Layer.provide([
       errorLayer,
+      compressionLayer,
       fenceLayer,
       cors(corsOptions),
       runtime,