fix(session): restore busy route handling and add regression coverage (#20125)

packages/opencode/src/server/middleware.ts

@@ -1,6 +1,7 @@
 import { Provider } from "../provider/provider"
 import { NamedError } from "@opencode-ai/util/error"
 import { NotFoundError } from "../storage/db"
+import { Session } from "../session"
 import type { ContentfulStatusCode } from "hono/utils/http-status"
 import type { ErrorHandler } from "hono"
 import { HTTPException } from "hono/http-exception"
@@ -20,6 +21,9 @@ export function errorHandler(log: Log.Logger): ErrorHandler {
       else status = 500
       return c.json(err.toObject(), { status })
     }
+    if (err instanceof Session.BusyError) {
+      return c.json(new NamedError.Unknown({ message: err.message }).toObject(), { status: 400 })
+    }
     if (err instanceof HTTPException) return err.getResponse()
     const message = err instanceof Error && err.stack ? err.stack : err.toString()
     return c.json(new NamedError.Unknown({ message }).toObject(), {

packages/opencode/src/session/index.ts

@@ -849,7 +849,8 @@ export namespace Session {
   export const children = fn(SessionID.zod, (id) => runPromise((svc) => svc.children(id)))
   export const remove = fn(SessionID.zod, (id) => runPromise((svc) => svc.remove(id)))
   export async function updateMessage<T extends MessageV2.Info>(msg: T): Promise<T> {
-    return runPromise((svc) => svc.updateMessage(MessageV2.Info.parse(msg) as T))
+    MessageV2.Info.parse(msg)
+    return runPromise((svc) => svc.updateMessage(msg))
   }
 
   export const removeMessage = fn(z.object({ sessionID: SessionID.zod, messageID: MessageID.zod }), (input) =>
@@ -862,7 +863,8 @@ export namespace Session {
   )
 
   export async function updatePart<T extends MessageV2.Part>(part: T): Promise<T> {
-    return runPromise((svc) => svc.updatePart(MessageV2.Part.parse(part) as T))
+    MessageV2.Part.parse(part)
+    return runPromise((svc) => svc.updatePart(part))
   }
 
   export const updatePartDelta = fn(

packages/opencode/src/session/revert.ts

@@ -92,12 +92,10 @@ export namespace SessionRevert {
     const sessionID = session.id
     const msgs = await Session.messages({ sessionID })
     const messageID = session.revert.messageID
-    const preserve = [] as MessageV2.WithParts[]
     const remove = [] as MessageV2.WithParts[]
     let target: MessageV2.WithParts | undefined
     for (const msg of msgs) {
       if (msg.info.id < messageID) {
-        preserve.push(msg)
         continue
       }
       if (msg.info.id > messageID) {
@@ -105,7 +103,6 @@ export namespace SessionRevert {
         continue
       }
       if (session.revert.partID) {
-        preserve.push(msg)
         target = msg
         continue
       }