fix(app): better optimistic prompt submit (#17337)

2 files changed, 171 insertions, 3 deletions

diff --git a/packages/app/src/context/sync-optimistic.test.ts b/packages/app/src/context/sync-optimistic.test.ts
index 7deeddd6e..94324f8a0 100644
--- a/packages/app/src/context/sync-optimistic.test.ts
+++ b/packages/app/src/context/sync-optimistic.test.ts
@@ -1,6 +1,8 @@
 import { describe, expect, test } from "bun:test"
 import type { Message, Part } from "@opencode-ai/sdk/v2/client"
-import { applyOptimisticAdd, applyOptimisticRemove } from "./sync"
+import { applyOptimisticAdd, applyOptimisticRemove, mergeOptimisticPage } from "./sync"
+
+type Text = Extract<Part, { type: "text" }>
 
 const userMessage = (id: string, sessionID: string): Message => ({
   id,
@@ -11,7 +13,7 @@ const userMessage = (id: string, sessionID: string): Message => ({
   model: { providerID: "openai", modelID: "gpt" },
 })
 
-const textPart = (id: string, sessionID: string, messageID: string): Part => ({
+const textPart = (id: string, sessionID: string, messageID: string): Text => ({
   id,
   sessionID,
   messageID,
@@ -53,4 +55,69 @@ describe("sync optimistic reducers", () => {
     expect(draft.part.msg_1).toBeUndefined()
     expect(draft.part.msg_2).toHaveLength(1)
   })
+
+  test("mergeOptimisticPage keeps pending messages in fetched timelines", () => {
+    const sessionID = "ses_1"
+    const page = mergeOptimisticPage(
+      {
+        session: [userMessage("msg_1", sessionID)],
+        part: [{ id: "msg_1", part: [textPart("prt_1", sessionID, "msg_1")] }],
+        complete: true,
+      },
+      [{ message: userMessage("msg_2", sessionID), parts: [textPart("prt_2", sessionID, "msg_2")] }],
+    )
+
+    expect(page.session.map((x) => x.id)).toEqual(["msg_1", "msg_2"])
+    expect(page.part.find((x) => x.id === "msg_2")?.part.map((x) => x.id)).toEqual(["prt_2"])
+    expect(page.confirmed).toEqual([])
+    expect(page.complete).toBe(true)
+  })
+
+  test("mergeOptimisticPage keeps missing optimistic parts until the server has them", () => {
+    const sessionID = "ses_1"
+    const page = mergeOptimisticPage(
+      {
+        session: [userMessage("msg_2", sessionID)],
+        part: [{ id: "msg_2", part: [textPart("prt_2", sessionID, "msg_2")] }],
+        complete: true,
+      },
+      [
+        {
+          message: userMessage("msg_2", sessionID),
+          parts: [textPart("prt_1", sessionID, "msg_2"), textPart("prt_2", sessionID, "msg_2")],
+        },
+      ],
+    )
+
+    expect(page.part.find((x) => x.id === "msg_2")?.part.map((x) => x.id)).toEqual(["prt_1", "prt_2"])
+    expect(page.confirmed).toEqual([])
+  })
+
+  test("mergeOptimisticPage confirms echoed messages once all parts arrive", () => {
+    const sessionID = "ses_1"
+    const page = mergeOptimisticPage(
+      {
+        session: [userMessage("msg_2", sessionID)],
+        part: [
+          {
+            id: "msg_2",
+            part: [{ ...textPart("prt_1", sessionID, "msg_2"), text: "server" }, textPart("prt_2", sessionID, "msg_2")],
+          },
+        ],
+        complete: true,
+      },
+      [
+        {
+          message: userMessage("msg_2", sessionID),
+          parts: [textPart("prt_1", sessionID, "msg_2"), textPart("prt_2", sessionID, "msg_2")],
+        },
+      ],
+    )
+
+    expect(page.confirmed).toEqual(["msg_2"])
+    expect(page.part.find((x) => x.id === "msg_2")?.part).toMatchObject([
+      { id: "prt_1", type: "text", text: "server" },
+      { id: "prt_2", type: "text", text: "prt_2" },
+    ])
+  })
 })
diff --git a/packages/app/src/context/sync.tsx b/packages/app/src/context/sync.tsx
index 9dc6623a7..0f2008723 100644
--- a/packages/app/src/context/sync.tsx
+++ b/packages/app/src/context/sync.tsx
@@ -54,6 +54,67 @@ type OptimisticRemoveInput = {
   messageID: string
 }
 
+type OptimisticItem = {
+  message: Message
+  parts: Part[]
+}
+
+type MessagePage = {
+  session: Message[]
+  part: { id: string; part: Part[] }[]
+  cursor?: string
+  complete: boolean
+}
+
+const hasParts = (parts: Part[] | undefined, want: Part[]) => {
+  if (!parts) return want.length === 0
+  return want.every((part) => Binary.search(parts, part.id, (item) => item.id).found)
+}
+
+const mergeParts = (parts: Part[] | undefined, want: Part[]) => {
+  if (!parts) return sortParts(want)
+  const next = [...parts]
+  let changed = false
+  for (const part of want) {
+    const result = Binary.search(next, part.id, (item) => item.id)
+    if (result.found) continue
+    next.splice(result.index, 0, part)
+    changed = true
+  }
+  if (!changed) return parts
+  return next
+}
+
+export function mergeOptimisticPage(page: MessagePage, items: OptimisticItem[]) {
+  if (items.length === 0) return { ...page, confirmed: [] as string[] }
+
+  const session = [...page.session]
+  const part = new Map(page.part.map((item) => [item.id, sortParts(item.part)]))
+  const confirmed: string[] = []
+
+  for (const item of items) {
+    const result = Binary.search(session, item.message.id, (message) => message.id)
+    const found = result.found
+    if (!found) session.splice(result.index, 0, item.message)
+
+    const current = part.get(item.message.id)
+    if (found && hasParts(current, item.parts)) {
+      confirmed.push(item.message.id)
+      continue
+    }
+
+    part.set(item.message.id, mergeParts(current, item.parts))
+  }
+
+  return {
+    cursor: page.cursor,
+    complete: page.complete,
+    session,
+    part: [...part.entries()].sort((a, b) => cmp(a[0], b[0])).map(([id, part]) => ({ id, part })),
+    confirmed,
+  }
+}
+
 export function applyOptimisticAdd(draft: OptimisticStore, input: OptimisticAddInput) {
   const messages = draft.message[input.sessionID]
   if (messages) {
@@ -121,6 +182,7 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
     const inflight = new Map<string, Promise<void>>()
     const inflightDiff = new Map<string, Promise<void>>()
     const inflightTodo = new Map<string, Promise<void>>()
+    const optimistic = new Map<string, Map<string, OptimisticItem>>()
     const maxDirs = 30
     const seen = new Map<string, Set<string>>()
     const [meta, setMeta] = createStore({
@@ -137,6 +199,33 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
       return undefined
     }
 
+    const setOptimistic = (directory: string, sessionID: string, item: OptimisticItem) => {
+      const key = keyFor(directory, sessionID)
+      const list = optimistic.get(key)
+      if (list) {
+        list.set(item.message.id, { message: item.message, parts: sortParts(item.parts) })
+        return
+      }
+      optimistic.set(key, new Map([[item.message.id, { message: item.message, parts: sortParts(item.parts) }]]))
+    }
+
+    const clearOptimistic = (directory: string, sessionID: string, messageID?: string) => {
+      const key = keyFor(directory, sessionID)
+      if (!messageID) {
+        optimistic.delete(key)
+        return
+      }
+
+      const list = optimistic.get(key)
+      if (!list) return
+      list.delete(messageID)
+      if (list.size === 0) optimistic.delete(key)
+    }
+
+    const getOptimistic = (directory: string, sessionID: string) => [
+      ...(optimistic.get(keyFor(directory, sessionID))?.values() ?? []),
+    ]
+
     const seenFor = (directory: string) => {
       const existing = seen.get(directory)
       if (existing) {
@@ -159,6 +248,9 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
 
     const clearMeta = (directory: string, sessionIDs: string[]) => {
       if (sessionIDs.length === 0) return
+      for (const sessionID of sessionIDs) {
+        clearOptimistic(directory, sessionID)
+      }
       setMeta(
         produce((draft) => {
           for (const sessionID of sessionIDs) {
@@ -232,8 +324,12 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
 
       setMeta("loading", key, true)
       await fetchMessages(input)
-        .then((next) => {
+        .then((page) => {
           if (!tracked(input.directory, input.sessionID)) return
+          const next = mergeOptimisticPage(page, getOptimistic(input.directory, input.sessionID))
+          for (const messageID of next.confirmed) {
+            clearOptimistic(input.directory, input.sessionID, messageID)
+          }
           const [store] = globalSync.child(input.directory, { bootstrap: false })
           const cached = input.mode === "prepend" ? (store.message[input.sessionID] ?? []) : []
           const message = input.mode === "prepend" ? merge(cached, next.session) : next.session
@@ -290,11 +386,15 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
         get: getSession,
         optimistic: {
           add(input: { directory?: string; sessionID: string; message: Message; parts: Part[] }) {
+            const directory = input.directory ?? sdk.directory
             const [, setStore] = target(input.directory)
+            setOptimistic(directory, input.sessionID, { message: input.message, parts: input.parts })
             setOptimisticAdd(setStore as (...args: unknown[]) => void, input)
           },
           remove(input: { directory?: string; sessionID: string; messageID: string }) {
+            const directory = input.directory ?? sdk.directory
             const [, setStore] = target(input.directory)
+            clearOptimistic(directory, input.sessionID, input.messageID)
             setOptimisticRemove(setStore as (...args: unknown[]) => void, input)
           },
         },
@@ -316,6 +416,7 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
             variant: input.variant,
           }
           const [, setStore] = target()
+          setOptimistic(sdk.directory, input.sessionID, { message, parts: input.parts })
           setOptimisticAdd(setStore as (...args: unknown[]) => void, {
             sessionID: input.sessionID,
             message,