fix(app): reconcile session pages with concurrent events (#34042)

packages/app/src/context/server-sdk.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, test } from "bun:test"
-import { coalesceServerEvents, resumeStreamAfterPageShow } from "./server-sdk"
+import { coalesceServerEvents, enqueueServerEvent, resumeStreamAfterPageShow } from "./server-sdk"
 import type { Event } from "@opencode-ai/sdk/v2/client"
 
 describe("resumeStreamAfterPageShow", () => {
@@ -15,19 +15,23 @@ describe("resumeStreamAfterPageShow", () => {
 })
 
 describe("coalesceServerEvents", () => {
-  const delta = (value: string, field = "text") => ({
+  const delta = (value: string, field = "text", partID = "part") => ({
     directory: "/repo",
     payload: {
       type: "message.part.delta",
-      properties: { messageID: "msg", partID: "part", field, delta: value },
+      properties: { messageID: "msg", partID, field, delta: value },
     } as Event,
   })
 
   test("merges adjacent deltas for the same field", () => {
-    const result = coalesceServerEvents([delta("hello "), delta("world")])
+    const first = delta("hello ")
+    const second = delta("world")
+    first.payload.id = "first"
+    second.payload.id = "second"
+    const result = coalesceServerEvents([first, second])
 
     expect(result).toHaveLength(1)
-    expect(result[0]?.payload).toMatchObject({ properties: { delta: "hello world" } })
+    expect(result[0]?.payload).toMatchObject({ id: "second", properties: { delta: "hello world" } })
   })
 
   test("preserves event boundaries and distinct fields", () => {
@@ -45,9 +49,113 @@ describe("coalesceServerEvents", () => {
     ])
   })
 
-  test("drops stale deltas", () => {
-    const result = coalesceServerEvents([delta("stale")], new Set(["/repo:msg:part"]))
+  test("preserves event ID order across interleaved deltas", () => {
+    const first = delta("a")
+    const other = delta("b", "text", "other")
+    const last = delta("c")
+    first.payload.id = "1"
+    other.payload.id = "2"
+    last.payload.id = "3"
 
-    expect(result).toEqual([])
+    const result = coalesceServerEvents([first, other, last])
+
+    expect(result.map((event) => event.payload.id)).toEqual(["1", "2", "3"])
+  })
+
+})
+
+describe("enqueueServerEvent", () => {
+  const partUpdated = (text: string) =>
+    ({
+      type: "message.part.updated",
+      properties: {
+        sessionID: "session",
+        part: { id: "part", sessionID: "session", messageID: "message", type: "text", text },
+      },
+    }) as Event
+
+  test("preserves part updates across message remove and re-add barriers", () => {
+    const events: Array<{ directory: string; payload: Event }> = []
+    const enqueue = (payload: Event) => enqueueServerEvent(events, { directory: "/repo", payload })
+
+    enqueue(partUpdated("old"))
+    enqueue({ type: "message.removed", properties: { sessionID: "session", messageID: "message" } } as Event)
+    enqueue({
+      type: "message.updated",
+      properties: {
+        sessionID: "session",
+        info: {
+          id: "message",
+          sessionID: "session",
+          role: "user",
+          time: { created: 1 },
+          agent: "build",
+          model: { providerID: "provider", modelID: "model" },
+        },
+      },
+    } as Event)
+    enqueue(partUpdated("new"))
+
+    expect(events.map((event) => event.payload.type)).toEqual([
+      "message.part.updated",
+      "message.removed",
+      "message.updated",
+      "message.part.updated",
+    ])
+  })
+
+  test("preserves deltas after a replacement snapshot", () => {
+    const events: Array<{ directory: string; payload: Event }> = []
+    const enqueue = (payload: Event) => enqueueServerEvent(events, { directory: "/repo", payload })
+
+    enqueue(partUpdated("a"))
+    enqueue(partUpdated("ab"))
+    enqueue({
+      type: "message.part.delta",
+      properties: { sessionID: "session", messageID: "message", partID: "part", field: "text", delta: "c" },
+    } as Event)
+
+    const result = coalesceServerEvents(events)
+    expect(result.map((event) => event.payload.type)).toEqual(["message.part.updated", "message.part.delta"])
+    expect(result[0]?.payload).toMatchObject({ properties: { part: { text: "ab" } } })
+    expect(result[1]?.payload).toMatchObject({ properties: { delta: "c" } })
+  })
+
+  test("preserves updates after session deletion", () => {
+    const events: Array<{ directory: string; payload: Event }> = []
+    const enqueue = (payload: Event) => enqueueServerEvent(events, { directory: "/repo", payload })
+
+    enqueue(partUpdated("old"))
+    enqueue({
+      type: "session.deleted",
+      properties: { sessionID: "session", info: { id: "session" } },
+    } as Event)
+    enqueue(partUpdated("new"))
+
+    expect(events.map((event) => event.payload.type)).toEqual([
+      "message.part.updated",
+      "session.deleted",
+      "message.part.updated",
+    ])
+  })
+
+  test("does not coalesce edge-triggered session statuses", () => {
+    const events: Array<{ directory: string; payload: Event }> = []
+    const enqueue = (status: "retry" | "busy") =>
+      enqueueServerEvent(events, {
+        directory: "/repo",
+        payload: {
+          type: "session.status",
+          properties: {
+            sessionID: "session",
+            status: status === "retry" ? { type: "retry", attempt: 1, message: "retry", next: 1 } : { type: "busy" },
+          },
+        } as Event,
+      })
+
+    enqueue("retry")
+    enqueue("busy")
+
+    expect(events).toHaveLength(2)
   })
 })