core: add Bun runtime support for Hono server

Enables running the agent on Bun runtime in addition to Node.js by
abstracting server initialization into runtime-specific adapters. The
server will automatically use Bun's native APIs when available.

packages/opencode/package.json

@@ -39,6 +39,11 @@
       "bun": "./src/pty/pty.bun.ts",
       "node": "./src/pty/pty.node.ts",
       "default": "./src/pty/pty.bun.ts"
+    },
+    "#hono": {
+      "bun": "./src/server/adapter.bun.ts",
+      "node": "./src/server/adapter.node.ts",
+      "default": "./src/server/adapter.bun.ts"
     }
   },
   "devDependencies": {

packages/opencode/src/config/config.ts

@@ -4,7 +4,6 @@ import { pathToFileURL } from "url"
 import os from "os"
 import { Process } from "../util/process"
 import z from "zod"
-import { ModelsDev } from "../provider/models"
 import { mergeDeep, pipe, unique } from "remeda"
 import { Global } from "../global"
 import fsNode from "fs/promises"

packages/opencode/src/server/adapter.bun.ts

@@ -0,0 +1,40 @@
+import type { Hono } from "hono"
+import { createBunWebSocket } from "hono/bun"
+import type { Adapter } from "./adapter"
+
+export const adapter: Adapter = {
+  create(app: Hono) {
+    const ws = createBunWebSocket()
+    return {
+      upgradeWebSocket: ws.upgradeWebSocket,
+      async listen(opts) {
+        const args = {
+          fetch: app.fetch,
+          hostname: opts.hostname,
+          idleTimeout: 0,
+          websocket: ws.websocket,
+        } as const
+        const start = (port: number) => {
+          try {
+            return Bun.serve({ ...args, port })
+          } catch {
+            return
+          }
+        }
+        const server = opts.port === 0 ? (start(4096) ?? start(0)) : start(opts.port)
+        if (!server) {
+          throw new Error(`Failed to start server on port ${opts.port}`)
+        }
+        if (!server.port) {
+          throw new Error(`Failed to resolve server address for port ${opts.port}`)
+        }
+        return {
+          port: server.port,
+          stop(close?: boolean) {
+            return Promise.resolve(server.stop(close))
+          },
+        }
+      },
+    }
+  },
+}

packages/opencode/src/server/adapter.node.ts

@@ -0,0 +1,66 @@
+import { createAdaptorServer, type ServerType } from "@hono/node-server"
+import { createNodeWebSocket } from "@hono/node-ws"
+import type { Hono } from "hono"
+import type { Adapter } from "./adapter"
+
+export const adapter: Adapter = {
+  create(app: Hono) {
+    const ws = createNodeWebSocket({ app })
+    return {
+      upgradeWebSocket: ws.upgradeWebSocket,
+      async listen(opts) {
+        const start = (port: number) =>
+          new Promise<ServerType>((resolve, reject) => {
+            const server = createAdaptorServer({ fetch: app.fetch })
+            ws.injectWebSocket(server)
+            const fail = (err: Error) => {
+              cleanup()
+              reject(err)
+            }
+            const ready = () => {
+              cleanup()
+              resolve(server)
+            }
+            const cleanup = () => {
+              server.off("error", fail)
+              server.off("listening", ready)
+            }
+            server.once("error", fail)
+            server.once("listening", ready)
+            server.listen(port, opts.hostname)
+          })
+
+        const server = opts.port === 0 ? await start(4096).catch(() => start(0)) : await start(opts.port)
+        const addr = server.address()
+        if (!addr || typeof addr === "string") {
+          throw new Error(`Failed to resolve server address for port ${opts.port}`)
+        }
+
+        let closing: Promise<void> | undefined
+        return {
+          port: addr.port,
+          stop(close?: boolean) {
+            closing ??= new Promise((resolve, reject) => {
+              server.close((err) => {
+                if (err) {
+                  reject(err)
+                  return
+                }
+                resolve()
+              })
+              if (close) {
+                if ("closeAllConnections" in server && typeof server.closeAllConnections === "function") {
+                  server.closeAllConnections()
+                }
+                if ("closeIdleConnections" in server && typeof server.closeIdleConnections === "function") {
+                  server.closeIdleConnections()
+                }
+              }
+            })
+            return closing
+          },
+        }
+      },
+    }
+  },
+}

packages/opencode/src/server/adapter.ts

@@ -0,0 +1,21 @@
+import type { Hono } from "hono"
+import type { UpgradeWebSocket } from "hono/ws"
+
+export type Opts = {
+  port: number
+  hostname: string
+}
+
+export type Listener = {
+  port: number
+  stop: (close?: boolean) => Promise<void>
+}
+
+export interface Runtime {
+  upgradeWebSocket: UpgradeWebSocket
+  listen(opts: Opts): Promise<Listener>
+}
+
+export interface Adapter {
+  create(app: Hono): Runtime
+}

packages/opencode/src/server/server.ts

@@ -1,12 +1,11 @@
 import { generateSpecs } from "hono-openapi"
 import { Hono } from "hono"
-import { createNodeWebSocket } from "@hono/node-ws"
+import { adapter } from "#hono"
 import { MDNS } from "./mdns"
 import { lazy } from "@/util/lazy"
 import { AuthMiddleware, CompressionMiddleware, CorsMiddleware, ErrorMiddleware, LoggerMiddleware } from "./middleware"
 import { InstanceRoutes } from "./instance"
 import { initProjectors } from "./projectors"
-import { createAdaptorServer, type ServerType } from "@hono/node-server"
 import { Log } from "@/util/log"
 import { ControlPlaneRoutes } from "./control"
 import { UIRoutes } from "./ui"
@@ -30,7 +29,7 @@ export namespace Server {
 
   function create(opts: { cors?: string[] }) {
     const app = new Hono()
-    const ws = createNodeWebSocket({ app })
+    const runtime = adapter.create(app)
     return {
       app: app
         .onError(ErrorMiddleware)
@@ -39,9 +38,9 @@ export namespace Server {
         .use(CompressionMiddleware)
         .use(CorsMiddleware(opts))
         .route("/", ControlPlaneRoutes())
-        .route("/", InstanceRoutes(ws.upgradeWebSocket))
+        .route("/", InstanceRoutes(runtime.upgradeWebSocket))
         .route("/", UIRoutes()),
-      ws,
+      runtime,
     }
   }
 
@@ -74,46 +73,21 @@ export namespace Server {
     cors?: string[]
   }): Promise<Listener> {
     const built = create(opts)
-    const start = (port: number) =>
-      new Promise<ServerType>((resolve, reject) => {
-        const server = createAdaptorServer({ fetch: built.app.fetch })
-        built.ws.injectWebSocket(server)
-        const fail = (err: Error) => {
-          cleanup()
-          reject(err)
-        }
-        const ready = () => {
-          cleanup()
-          resolve(server)
-        }
-        const cleanup = () => {
-          server.off("error", fail)
-          server.off("listening", ready)
-        }
-        server.once("error", fail)
-        server.once("listening", ready)
-        server.listen(port, opts.hostname)
-      })
-
-    const server = opts.port === 0 ? await start(4096).catch(() => start(0)) : await start(opts.port)
-    const addr = server.address()
-    if (!addr || typeof addr === "string") {
-      throw new Error(`Failed to resolve server address for port ${opts.port}`)
-    }
+    const server = await built.runtime.listen(opts)
 
     const next = new URL("http://localhost")
     next.hostname = opts.hostname
-    next.port = String(addr.port)
+    next.port = String(server.port)
     url = next
 
     const mdns =
       opts.mdns &&
-      addr.port &&
+      server.port &&
       opts.hostname !== "127.0.0.1" &&
       opts.hostname !== "localhost" &&
       opts.hostname !== "::1"
     if (mdns) {
-      MDNS.publish(addr.port, opts.mdnsDomain)
+      MDNS.publish(server.port, opts.mdnsDomain)
     } else if (opts.mdns) {
       log.warn("mDNS enabled but hostname is loopback; skipping mDNS publish")
     }
@@ -121,27 +95,13 @@ export namespace Server {
     let closing: Promise<void> | undefined
     return {
       hostname: opts.hostname,
-      port: addr.port,
+      port: server.port,
       url: next,
       stop(close?: boolean) {
-        closing ??= new Promise((resolve, reject) => {
+        closing ??= (async () => {
           if (mdns) MDNS.unpublish()
-          server.close((err) => {
-            if (err) {
-              reject(err)
-              return
-            }
-            resolve()
-          })
-          if (close) {
-            if ("closeAllConnections" in server && typeof server.closeAllConnections === "function") {
-              server.closeAllConnections()
-            }
-            if ("closeIdleConnections" in server && typeof server.closeIdleConnections === "function") {
-              server.closeIdleConnections()
-            }
-          }
-        })
+          await server.stop(close)
+        })()
         return closing
       },
     }