feat(httpapi): bridge event stream (#24518)

5 files changed, 104 insertions, 2 deletions

diff --git a/packages/opencode/specs/effect/http-api.md b/packages/opencode/specs/effect/http-api.md
index 5f16ef197..6536ac947 100644
--- a/packages/opencode/specs/effect/http-api.md
+++ b/packages/opencode/specs/effect/http-api.md
@@ -184,7 +184,7 @@ Use raw Effect HTTP routes where `HttpApi` does not fit. The goal is deleting Ho
 | experimental JSON routes  | `bridged`         | console, tool, worktree list/mutations, global session list, resource list |
 | `session`                 | `bridged`         | read, lifecycle, prompt, message/part mutations, revert, permission reply  |
 | `sync`                    | `bridged`         | start/replay/history                                                       |
-| `event`                   | `special`         | SSE                                                                        |
+| `event`                   | `bridged`         | SSE via raw Effect HTTP                                                    |
 | `pty`                     | `special`         | websocket                                                                  |
 | `tui`                     | `special`         | UI bridge                                                                  |
 
@@ -316,7 +316,7 @@ This checklist tracks bridge parity only. Checked routes are available through t
 
 ### Event Routes
 
-- [ ] `GET /event` - SSE event stream; replace with raw Effect HTTP, not `HttpApi`.
+- [x] `GET /event` - SSE event stream via raw Effect HTTP.
 
 ### PTY Routes
 
diff --git a/packages/opencode/src/server/routes/instance/httpapi/event.ts b/packages/opencode/src/server/routes/instance/httpapi/event.ts
new file mode 100644
index 000000000..dc5fa9c53
--- /dev/null
+++ b/packages/opencode/src/server/routes/instance/httpapi/event.ts
@@ -0,0 +1,46 @@
+import { Bus } from "@/bus"
+import { Log } from "@/util"
+import { Effect } from "effect"
+import * as Stream from "effect/Stream"
+import { HttpRouter, HttpServerResponse } from "effect/unstable/http"
+
+const log = Log.create({ service: "server" })
+
+export const EventPaths = {
+  event: "/event",
+} as const
+
+function eventData(data: unknown) {
+  return `data: ${JSON.stringify(data)}\n\n`
+}
+
+export const eventRoute = HttpRouter.add(
+  "GET",
+  EventPaths.event,
+  Effect.gen(function* () {
+    const bus = yield* Bus.Service
+    const events = bus.subscribeAll().pipe(Stream.takeUntil((event) => event.type === Bus.InstanceDisposed.type))
+    const heartbeat = Stream.tick("10 seconds").pipe(
+      Stream.drop(1),
+      Stream.map(() => ({ type: "server.heartbeat", properties: {} })),
+    )
+
+    log.info("event connected")
+    return HttpServerResponse.stream(
+      Stream.make({ type: "server.connected", properties: {} }).pipe(
+        Stream.concat(events.pipe(Stream.merge(heartbeat, { haltStrategy: "left" }))),
+        Stream.map(eventData),
+        Stream.encodeText,
+        Stream.ensuring(Effect.sync(() => log.info("event disconnected"))),
+      ),
+      {
+        contentType: "text/event-stream",
+        headers: {
+          "Cache-Control": "no-cache, no-transform",
+          "X-Accel-Buffering": "no",
+          "X-Content-Type-Options": "nosniff",
+        },
+      },
+    )
+  }).pipe(Effect.provide(Bus.layer)),
+)
diff --git a/packages/opencode/src/server/routes/instance/httpapi/server.ts b/packages/opencode/src/server/routes/instance/httpapi/server.ts
index adc70a43b..1e8b23f55 100644
--- a/packages/opencode/src/server/routes/instance/httpapi/server.ts
+++ b/packages/opencode/src/server/routes/instance/httpapi/server.ts
@@ -10,6 +10,7 @@ import { lazy } from "@/util/lazy"
 import { Filesystem } from "@/util"
 import { authorizationLayer } from "./auth"
 import { ConfigApi, configHandlers } from "./config"
+import { eventRoute } from "./event"
 import { FileApi, fileHandlers } from "./file"
 import { ExperimentalApi, experimentalHandlers } from "./experimental"
 import { InstanceApi, instanceHandlers } from "./instance"
@@ -66,6 +67,7 @@ const instance = HttpRouter.middleware()(
 ).layer
 
 export const routes = Layer.mergeAll(
+  eventRoute,
   HttpApiBuilder.layer(ConfigApi).pipe(Layer.provide(configHandlers)),
   HttpApiBuilder.layer(ExperimentalApi).pipe(Layer.provide(experimentalHandlers)),
   HttpApiBuilder.layer(FileApi).pipe(Layer.provide(fileHandlers)),
diff --git a/packages/opencode/src/server/routes/instance/index.ts b/packages/opencode/src/server/routes/instance/index.ts
index 4c0503af5..c2e89c14e 100644
--- a/packages/opencode/src/server/routes/instance/index.ts
+++ b/packages/opencode/src/server/routes/instance/index.ts
@@ -16,6 +16,7 @@ import { QuestionRoutes } from "./question"
 import { PermissionRoutes } from "./permission"
 import { Flag } from "@opencode-ai/core/flag/flag"
 import { ExperimentalHttpApiServer } from "./httpapi/server"
+import { EventPaths } from "./httpapi/event"
 import { ExperimentalPaths } from "./httpapi/experimental"
 import { FilePaths } from "./httpapi/file"
 import { InstancePaths } from "./httpapi/instance"
@@ -41,6 +42,7 @@ export const InstanceRoutes = (upgrade: UpgradeWebSocket): Hono => {
   if (Flag.OPENCODE_EXPERIMENTAL_HTTPAPI) {
     const handler = ExperimentalHttpApiServer.webHandler().handler
     const context = Context.empty() as Context.Context<unknown>
+    app.get(EventPaths.event, (c) => handler(c.req.raw, context))
     app.get("/question", (c) => handler(c.req.raw, context))
     app.post("/question/:requestID/reply", (c) => handler(c.req.raw, context))
     app.post("/question/:requestID/reject", (c) => handler(c.req.raw, context))
diff --git a/packages/opencode/test/server/httpapi-event.test.ts b/packages/opencode/test/server/httpapi-event.test.ts
new file mode 100644
index 000000000..42d2f8036
--- /dev/null
+++ b/packages/opencode/test/server/httpapi-event.test.ts
@@ -0,0 +1,52 @@
+import { afterEach, describe, expect, test } from "bun:test"
+import type { UpgradeWebSocket } from "hono/ws"
+import { Flag } from "@opencode-ai/core/flag/flag"
+import { Instance } from "../../src/project/instance"
+import { InstanceRoutes } from "../../src/server/routes/instance"
+import { EventPaths } from "../../src/server/routes/instance/httpapi/event"
+import { Log } from "../../src/util"
+import { resetDatabase } from "../fixture/db"
+import { tmpdir } from "../fixture/fixture"
+
+void Log.init({ print: false })
+
+const original = Flag.OPENCODE_EXPERIMENTAL_HTTPAPI
+const websocket = (() => () => new Response(null, { status: 501 })) as unknown as UpgradeWebSocket
+
+function app() {
+  Flag.OPENCODE_EXPERIMENTAL_HTTPAPI = true
+  return InstanceRoutes(websocket)
+}
+
+async function readFirstChunk(response: Response) {
+  if (!response.body) throw new Error("missing response body")
+  const reader = response.body.getReader()
+  const result = await Promise.race([
+    reader.read(),
+    new Promise<never>((_, reject) => setTimeout(() => reject(new Error("timed out waiting for event")), 5_000)),
+  ])
+  await reader.cancel()
+  return new TextDecoder().decode(result.value)
+}
+
+afterEach(async () => {
+  Flag.OPENCODE_EXPERIMENTAL_HTTPAPI = original
+  await Instance.disposeAll()
+  await resetDatabase()
+})
+
+describe("event HttpApi bridge", () => {
+  test("serves event stream through experimental Effect route", async () => {
+    await using tmp = await tmpdir({ git: true, config: { formatter: false, lsp: false } })
+    const response = await app().request(EventPaths.event, { headers: { "x-opencode-directory": tmp.path } })
+
+    expect(response.status).toBe(200)
+    expect(response.headers.get("content-type")).toContain("text/event-stream")
+    expect(response.headers.get("cache-control")).toBe("no-cache, no-transform")
+    expect(response.headers.get("x-accel-buffering")).toBe("no")
+    expect(response.headers.get("x-content-type-options")).toBe("nosniff")
+    expect(await readFirstChunk(response)).toContain(
+      'data: {"type":"server.connected","properties":{}}\n\n',
+    )
+  })
+})