diff --git a/packages/cli/src/services/web-ui.ts b/packages/cli/src/services/web-ui.ts
index 368e6eb48e9..c7306a6bc2a 100644
--- a/packages/cli/src/services/web-ui.ts
+++ b/packages/cli/src/services/web-ui.ts
@@ -42,7 +42,9 @@ function serveUI(request: HttpServerRequest.HttpServerRequest, url: URL, assets:
     "x-content-type-options": "nosniff",
   }
   return Effect.succeed(
-    request.method === "HEAD" ? HttpServerResponse.empty({ headers }) : HttpServerResponse.raw(file, { headers }),
+    request.method === "HEAD"
+      ? HttpServerResponse.empty({ headers })
+      : HttpServerResponse.raw(file, { headers, contentType: headers["content-type"] }),
   )
 }
 
diff --git a/packages/cli/test/web-ui.test.ts b/packages/cli/test/web-ui.test.ts
index 1aab6239785..773d4fbb8e2 100644
--- a/packages/cli/test/web-ui.test.ts
+++ b/packages/cli/test/web-ui.test.ts
@@ -55,6 +55,7 @@ describe("web UI", () => {
 
           const script = yield* Effect.promise(() => fetch(`${origin}/app.js`))
           expect(yield* Effect.promise(() => script.text())).toBe("console.log('embedded')")
+          expect(script.headers.get("content-type")).toContain("javascript")
           expect(script.headers.get("cache-control")).toBe("public, max-age=31536000, immutable")
 
           const worker = yield* Effect.promise(() => fetch(`${origin}/sw.js`))
@@ -64,6 +65,7 @@ describe("web UI", () => {
           expect(registration.headers.get("cache-control")).toBe("no-cache")
 
           const font = yield* Effect.promise(() => fetch(`${origin}/font.woff2`))
+          expect(font.headers.get("content-type")).toBe("font/woff2")
           expect(new Uint8Array(yield* Effect.promise(() => font.arrayBuffer()))).toEqual(
             new Uint8Array([0, 1, 2, 255]),
           )
diff --git a/packages/server/src/process.ts b/packages/server/src/process.ts
index fd2f2a7549e..05814cfe7a9 100644
--- a/packages/server/src/process.ts
+++ b/packages/server/src/process.ts
@@ -4,7 +4,14 @@ import { NodeHttpServer } from "@effect/platform-node"
 import { SessionRestart } from "@opencode-ai/core/session/execution/restart"
 import { hasPtyConnectTicketURL } from "@opencode-ai/protocol/groups/pty"
 import { Cause, Context, Effect, Exit, Latch, Layer, Option, Ref, Scope } from "effect"
-import { HttpMiddleware, HttpRouter, HttpServer, HttpServerRequest, HttpServerResponse } from "effect/unstable/http"
+import {
+  HttpMiddleware,
+  HttpPlatform,
+  HttpRouter,
+  HttpServer,
+  HttpServerRequest,
+  HttpServerResponse,
+} from "effect/unstable/http"
 import { createServer } from "node:http"
 import { ServerAuth } from "./auth"
 import { isAllowedCorsOrigin } from "./cors"
@@ -90,7 +97,7 @@ export const start = Effect.fn("ServerProcess.start")(function* <E, R>(
           const host = address.family === "IPv6" ? `[${address.address}]` : address.address
           return ServerInfo.connectionURLs(`http://${host}:${address.port}`, hostname)
         },
-      ).pipe(Layer.provide(NodeHttpServer.layerHttpServices)),
+      ).pipe(Layer.provideMerge(NodeHttpServer.layerHttpServices)),
       applicationScope,
     )
     if (lifecycle) {
@@ -98,7 +105,12 @@ export const start = Effect.fn("ServerProcess.start")(function* <E, R>(
         Effect.provideService(Scope.Scope, applicationScope),
       )
     }
-    const app = Context.get(context, HttpRouter.HttpRouter).asHttpEffect()
+    const app = Context.get(context, HttpRouter.HttpRouter)
+      .asHttpEffect()
+      .pipe(
+        HttpMiddleware.compression(),
+        Effect.provideService(HttpPlatform.HttpPlatform, Context.get(context, HttpPlatform.HttpPlatform)),
+      )
     yield* Ref.set(application, Option.some(transform ? transform(app) : app))
     yield* status.ready
     return { address: bound.http.address, shutdown: shutdown.await }
diff --git a/packages/server/test/process.test.ts b/packages/server/test/process.test.ts
index 71125a1d998..9deabc24ea0 100644
--- a/packages/server/test/process.test.ts
+++ b/packages/server/test/process.test.ts
@@ -6,6 +6,7 @@ import { ServerProcess } from "../src/process"
 
 it.live("allows browser preflight requests without credentials", () =>
   Effect.gen(function* () {
+    const fallback = "fallback".repeat(256)
     const server = yield* ServerProcess.start<never, never>(
       {
         hostname: "127.0.0.1",
@@ -19,7 +20,7 @@ it.live("allows browser preflight requests without credentials", () =>
         api.pipe(
           Effect.catchIf(
             (error) => error instanceof HttpServerError.HttpServerError && error.reason._tag === "RouteNotFound",
-            () => Effect.succeed(HttpServerResponse.text("fallback")),
+            () => Effect.succeed(HttpServerResponse.raw(fallback, { contentType: "text/plain" })),
           ),
         ),
     )
@@ -51,12 +52,30 @@ it.live("allows browser preflight requests without credentials", () =>
     expect(health.headers.get("access-control-allow-origin")).toBe("http://localhost:3000")
     expect(yield* Effect.promise(() => health.json())).toMatchObject({ version: "test-version" })
 
+    const event = yield* Effect.promise(() =>
+      fetch(new URL("/api/event", HttpServer.formatAddress(server.address)), {
+        headers: {
+          "accept-encoding": "br",
+          authorization: `Basic ${btoa("opencode:secret")}`,
+        },
+      }),
+    )
+    expect(event.status).toBe(200)
+    expect(event.headers.get("content-encoding")).toBeNull()
+    yield* Effect.promise(() => event.body?.cancel() ?? Promise.resolve())
+
     const missing = yield* Effect.promise(() =>
       fetch(new URL("/missing", HttpServer.formatAddress(server.address)), {
-        headers: { authorization: `Basic ${btoa("opencode:secret")}` },
+        headers: {
+          "accept-encoding": "br",
+          authorization: `Basic ${btoa("opencode:secret")}`,
+        },
       }),
     )
     expect(missing.status).toBe(200)
-    expect(yield* Effect.promise(() => missing.text())).toBe("fallback")
+    expect(missing.headers.get("content-encoding")).toBe("br")
+    expect(missing.headers.get("content-type")).toBe("text/plain")
+    expect(missing.headers.get("vary")?.toLowerCase()).toContain("accept-encoding")
+    expect(yield* Effect.promise(() => missing.text())).toBe(fallback)
   }),
 )