fix(httpapi): preserve event stream context (#27425)

Co-authored-by: Aiden Cline <aidenpcline@gmail.com>
Co-authored-by: James Long <longster@gmail.com>

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

@@ -40,30 +40,37 @@ function eventData(data: unknown): Sse.Event {
 }
 
 function eventResponse(bus: Bus.Interface) {
-  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(() => ({ id: Bus.createID(), type: "server.heartbeat", properties: {} })),
-  )
+  return Effect.gen(function* () {
+    const context = yield* Effect.context()
 
-  log.info("event connected")
-  return HttpServerResponse.stream(
-    Stream.make({ id: Bus.createID(), type: "server.connected", properties: {} }).pipe(
-      Stream.concat(events.pipe(Stream.merge(heartbeat, { haltStrategy: "left" }))),
-      Stream.map(eventData),
-      Stream.pipeThroughChannel(Sse.encode()),
-      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",
+    const events = bus.subscribeAll().pipe(
+      Stream.provideContext(context),
+      Stream.takeUntil((event) => event.type === Bus.InstanceDisposed.type),
+    )
+    const heartbeat = Stream.tick("10 seconds").pipe(
+      Stream.drop(1),
+      Stream.map(() => ({ id: Bus.createID(), type: "server.heartbeat", properties: {} })),
+    )
+
+    log.info("event connected")
+    return HttpServerResponse.stream(
+      Stream.make({ id: Bus.createID(), type: "server.connected", properties: {} }).pipe(
+        Stream.concat(events.pipe(Stream.merge(heartbeat, { haltStrategy: "left" }))),
+        Stream.map(eventData),
+        Stream.pipeThroughChannel(Sse.encode()),
+        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",
+        },
       },
-    },
-  )
+    )
+  })
 }
 
 export const eventHandlers = HttpApiBuilder.group(EventApi, "event", (handlers) =>
@@ -72,7 +79,7 @@ export const eventHandlers = HttpApiBuilder.group(EventApi, "event", (handlers)
     return handlers.handleRaw(
       "subscribe",
       Effect.fn("EventHttpApi.subscribe")(function* () {
-        return eventResponse(bus)
+        return yield* eventResponse(bus)
       }),
     )
   }),

packages/opencode/test/server/httpapi-event.test.ts

@@ -1,10 +1,13 @@
 import { afterEach, describe, expect, test } from "bun:test"
+import { Bus } from "../../src/bus"
 import { Instance } from "../../src/project/instance"
 import { Server } from "../../src/server/server"
 import { EventPaths } from "../../src/server/routes/instance/httpapi/event"
+import { Event as ServerEvent } from "../../src/server/event"
 import * as Log from "@opencode-ai/core/util/log"
+import { Schema } from "effect"
 import { resetDatabase } from "../fixture/db"
-import { disposeAllInstances, tmpdir } from "../fixture/fixture"
+import { disposeAllInstances, reloadTestInstance, tmpdir } from "../fixture/fixture"
 
 void Log.init({ print: false })
 
@@ -12,25 +15,42 @@ function app() {
   return Server.Default().app
 }
 
-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)
+const EventData = Schema.Struct({
+  id: Schema.optional(Schema.String),
+  type: Schema.String,
+  properties: Schema.Record(Schema.String, Schema.Any),
+})
+
+async function readChunk(reader: ReadableStreamDefaultReader<Uint8Array>) {
+  let timeout: ReturnType<typeof setTimeout> | undefined
+  try {
+    return await Promise.race([
+      reader.read(),
+      new Promise<never>((_, reject) => {
+        timeout = setTimeout(() => reject(new Error("timed out waiting for event")), 5_000)
+      }),
+    ])
+  } finally {
+    if (timeout) clearTimeout(timeout)
+  }
 }
 
 async function readFirstEvent(response: Response) {
-  return JSON.parse((await readFirstChunk(response)).replace(/^data: /, "")) as {
-    id?: string
-    type: string
-    properties: Record<string, unknown>
+  if (!response.body) throw new Error("missing response body")
+  const reader = response.body.getReader()
+  try {
+    return await readEvent(reader)
+  } finally {
+    await reader.cancel()
   }
 }
 
+async function readEvent(reader: ReadableStreamDefaultReader<Uint8Array>) {
+  const result = await readChunk(reader)
+  if (result.done || !result.value) throw new Error("event stream closed")
+  return Schema.decodeUnknownSync(EventData)(JSON.parse(new TextDecoder().decode(result.value).replace(/^data: /, "")))
+}
+
 afterEach(async () => {
   await disposeAllInstances()
   await resetDatabase()
@@ -56,4 +76,42 @@ describe("event HttpApi", () => {
 
     expect(await readFirstEvent(response)).toMatchObject({ type: "server.connected", properties: {} })
   })
+
+  test("keeps the event stream open after the initial event", 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 } })
+    if (!response.body) throw new Error("missing response body")
+
+    const reader = response.body.getReader()
+    try {
+      expect(await readEvent(reader)).toMatchObject({ type: "server.connected", properties: {} })
+      const next = await Promise.race([
+        reader.read().then((result) => (result.done ? "closed" : "event")),
+        new Promise<"open">((resolve) => setTimeout(() => resolve("open"), 250)),
+      ])
+
+      expect(next).toBe("open")
+    } finally {
+      await reader.cancel()
+    }
+  })
+
+  test("delivers instance bus events after the initial event", 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 } })
+    if (!response.body) throw new Error("missing response body")
+
+    const reader = response.body.getReader()
+    try {
+      expect(await readEvent(reader)).toMatchObject({ type: "server.connected", properties: {} })
+
+      const next = readEvent(reader)
+      const ctx = await reloadTestInstance({ directory: tmp.path })
+      await Instance.restore(ctx, () => Bus.publish(ServerEvent.Connected, {}))
+
+      expect(await next).toMatchObject({ type: "server.connected", properties: {} })
+    } finally {
+      await reader.cancel()
+    }
+  })
 })