feat(session): add fork/edit and revert actions with reliable revert diffs

packages/app/src/context/sync.tsx

@@ -108,6 +108,7 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
     const messagePageSize = 400
     const inflight = new Map<string, Promise<void>>()
     const inflightDiff = new Map<string, Promise<void>>()
+    const inflightDiffVersion = new Map<string, number>()
     const inflightTodo = new Map<string, Promise<void>>()
     const [meta, setMeta] = createStore({
       limit: {} as Record<string, number>,
@@ -272,18 +273,25 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
 
           return runInflight(inflight, key, () => Promise.all([sessionReq, messagesReq]).then(() => {}))
         },
-        async diff(sessionID: string) {
+        async diff(sessionID: string, input?: { refresh?: boolean }) {
           const directory = sdk.directory
           const client = sdk.client
           const [store, setStore] = globalSync.child(directory)
-          if (store.session_diff[sessionID] !== undefined) return
+          if (!input?.refresh && store.session_diff[sessionID] !== undefined) return
 
           const key = keyFor(directory, sessionID)
-          return runInflight(inflightDiff, key, () =>
+          const version = (inflightDiffVersion.get(key) ?? 0) + 1
+          inflightDiffVersion.set(key, version)
+
+          const fetch = () =>
             retry(() => client.session.diff({ sessionID })).then((diff) => {
+              if (inflightDiffVersion.get(key) !== version) return
               setStore("session_diff", sessionID, reconcile(diff.data ?? [], { key: "file" }))
-            }),
-          )
+            })
+
+          if (input?.refresh) return fetch()
+
+          return runInflight(inflightDiff, key, fetch)
         },
         async todo(sessionID: string) {
           const directory = sdk.directory

packages/app/src/pages/session.tsx

@@ -8,6 +8,7 @@ import { ResizeHandle } from "@opencode-ai/ui/resize-handle"
 import { Select } from "@opencode-ai/ui/select"
 import { createAutoScroll } from "@opencode-ai/ui/hooks"
 import { Mark } from "@opencode-ai/ui/logo"
+import { showToast } from "@opencode-ai/ui/toast"
 
 import { useSync } from "@/context/sync"
 import { useLayout } from "@/context/layout"
@@ -31,6 +32,7 @@ import { SessionComposerRegion, createSessionComposerState } from "@/pages/sessi
 import { SessionMobileTabs } from "@/pages/session/session-mobile-tabs"
 import { SessionSidePanel } from "@/pages/session/session-side-panel"
 import { useSessionHashScroll } from "@/pages/session/use-session-hash-scroll"
+import { extractPromptFromParts } from "@/utils/prompt"
 
 export default function Page() {
   const layout = useLayout()
@@ -157,6 +159,8 @@ export default function Page() {
   })
 
   const info = createMemo(() => (params.id ? sync.session.get(params.id) : undefined))
+  const idle = { type: "idle" as const }
+  const status = createMemo(() => sync.data.session_status[params.id ?? ""] ?? idle)
   const diffs = createMemo(() => (params.id ? (sync.data.session_diff[params.id] ?? []) : []))
   const reviewCount = createMemo(() => Math.max(info()?.summary?.files ?? 0, diffs().length))
   const hasReview = createMemo(() => reviewCount() > 0)
@@ -187,8 +191,11 @@ export default function Page() {
   const visibleUserMessages = createMemo(
     () => {
       const revert = revertMessageID()
-      if (!revert) return userMessages()
-      return userMessages().filter((m) => m.id < revert)
+      const messages = userMessages()
+      if (!revert) return messages
+      const index = messages.findIndex((message) => message.id === revert)
+      if (index < 0) return messages
+      return messages.slice(0, index)
     },
     emptyUserMessages,
     {
@@ -497,6 +504,59 @@ export default function Page() {
     focusInput,
   })
 
+  const restore = (messageID: string) =>
+    extractPromptFromParts(sync.data.part[messageID] ?? [], {
+      directory: sdk.directory,
+      attachmentName: language.t("common.attachment"),
+    })
+
+  const fail = (error: unknown) => {
+    const message = error instanceof Error ? error.message : String(error)
+    showToast({ title: language.t("common.requestFailed"), description: message })
+  }
+
+  const onForkFromMessage = async (messageID: string) => {
+    const sessionID = params.id
+    if (!sessionID) return
+
+    const restored = restore(messageID)
+    const forked = await sdk.client.session
+      .fork({ sessionID, messageID })
+      .then((result) => result.data)
+      .catch((error: unknown) => {
+        fail(error)
+        return
+      })
+    if (!forked) return
+
+    navigate(`/${base64Encode(sdk.directory)}/session/${forked.id}`)
+    requestAnimationFrame(() => prompt.set(restored))
+  }
+
+  const onRevertToMessage = async (messageID: string) => {
+    const sessionID = params.id
+    if (!sessionID) return
+
+    if (status().type !== "idle") await sdk.client.session.abort({ sessionID }).catch(() => {})
+
+    const restored = restore(messageID)
+    const done = await sdk.client.session
+      .revert({ sessionID, messageID })
+      .then(() => true)
+      .catch((error: unknown) => {
+        fail(error)
+        return false
+      })
+    if (!done) return
+
+    void sync.session.diff(sessionID, { refresh: true })
+
+    prompt.set(restored)
+    const messages = userMessages()
+    const index = messages.findIndex((message) => message.id === messageID)
+    setActiveMessage(index > 0 ? messages[index - 1] : undefined)
+  }
+
   const openReviewFile = createOpenReviewFile({
     showAllFiles,
     tabForPath: file.tab,
@@ -1100,6 +1160,8 @@ export default function Page() {
                     onRegisterMessage={scrollSpy.register}
                     onUnregisterMessage={scrollSpy.unregister}
                     lastUserMessageID={lastUserMessage()?.id}
+                    onForkFromMessage={onForkFromMessage}
+                    onRevertToMessage={onRevertToMessage}
                   />
                 </Show>
               </Match>

packages/app/src/pages/session/message-timeline.tsx

@@ -106,6 +106,8 @@ export function MessageTimeline(props: {
   onRegisterMessage: (el: HTMLDivElement, id: string) => void
   onUnregisterMessage: (id: string) => void
   lastUserMessageID?: string
+  onForkFromMessage: (messageID: string) => void
+  onRevertToMessage: (messageID: string) => void
 }) {
   let touchGesture: number | undefined
 
@@ -602,6 +604,8 @@ export function MessageTimeline(props: {
                       sessionID={sessionID() ?? ""}
                       messageID={message.id}
                       lastUserMessageID={props.lastUserMessageID}
+                      onForkFromMessage={props.onForkFromMessage}
+                      onRevertToMessage={props.onRevertToMessage}
                       showReasoningSummaries={settings.general.showReasoningSummaries()}
                       shellToolDefaultOpen={settings.general.shellToolPartsExpanded()}
                       editToolDefaultOpen={settings.general.editToolPartsExpanded()}

packages/opencode/src/pty/index.ts

@@ -23,6 +23,11 @@ export namespace Pty {
     close: (code?: number, reason?: string) => void
   }
 
+  type Subscriber = {
+    ws: Socket
+    send: (data: string | Uint8Array | ArrayBuffer) => void
+  }
+
   // WebSocket control frame: 0x00 + UTF-8 JSON.
   const meta = (cursor: number) => {
     const json = JSON.stringify({ cursor })
@@ -87,7 +92,7 @@ export namespace Pty {
     buffer: string
     bufferCursor: number
     cursor: number
-    subscribers: Map<unknown, Socket>
+    subscribers: Map<unknown, Subscriber>
   }
 
   const state = Instance.state(
@@ -97,7 +102,8 @@ export namespace Pty {
         try {
           session.process.kill()
         } catch {}
-        for (const [key, ws] of session.subscribers.entries()) {
+        for (const [key, sub] of session.subscribers.entries()) {
+          const ws = sub.ws
           try {
             if (ws.data === key) ws.close()
           } catch {
@@ -170,7 +176,8 @@ export namespace Pty {
     ptyProcess.onData((chunk) => {
       session.cursor += chunk.length
 
-      for (const [key, ws] of session.subscribers.entries()) {
+      for (const [key, sub] of session.subscribers.entries()) {
+        const ws = sub.ws
         if (ws.readyState !== 1) {
           session.subscribers.delete(key)
           continue
@@ -182,7 +189,7 @@ export namespace Pty {
         }
 
         try {
-          ws.send(chunk)
+          sub.send(chunk)
         } catch {
           session.subscribers.delete(key)
         }
@@ -197,7 +204,8 @@ export namespace Pty {
     ptyProcess.onExit(({ exitCode }) => {
       log.info("session exited", { id, exitCode })
       session.info.status = "exited"
-      for (const [key, ws] of session.subscribers.entries()) {
+      for (const [key, sub] of session.subscribers.entries()) {
+        const ws = sub.ws
         try {
           if (ws.data === key) ws.close()
         } catch {
@@ -232,7 +240,8 @@ export namespace Pty {
     try {
       session.process.kill()
     } catch {}
-    for (const [key, ws] of session.subscribers.entries()) {
+    for (const [key, sub] of session.subscribers.entries()) {
+      const ws = sub.ws
       try {
         if (ws.data === key) ws.close()
       } catch {
@@ -272,7 +281,7 @@ export namespace Pty {
 
     // Optionally cleanup if the key somehow exists
     session.subscribers.delete(connectionKey)
-    session.subscribers.set(connectionKey, ws)
+    session.subscribers.set(connectionKey, { ws, send: ws.send.bind(ws) })
 
     const cleanup = () => {
       session.subscribers.delete(connectionKey)

packages/opencode/src/session/index.ts

@@ -244,7 +244,7 @@ export namespace Session {
       const idMap = new Map<string, string>()
 
       for (const msg of msgs) {
-        if (input.messageID && msg.info.id >= input.messageID) break
+        if (input.messageID && msg.info.id === input.messageID) break
         const newID = Identifier.ascending("message")
         idMap.set(msg.info.id, newID)
 

packages/opencode/src/session/message-v2.ts

@@ -722,7 +722,7 @@ export namespace MessageV2 {
           .select()
           .from(MessageTable)
           .where(eq(MessageTable.session_id, sessionID))
-          .orderBy(desc(MessageTable.time_created))
+          .orderBy(desc(MessageTable.time_created), desc(MessageTable.id))
           .limit(size)
           .offset(offset)
           .all(),

packages/opencode/src/session/revert.ts

@@ -55,12 +55,21 @@ export namespace SessionRevert {
     }
 
     if (revert) {
-      const session = await Session.get(input.sessionID)
       revert.snapshot = session.revert?.snapshot ?? (await Snapshot.track())
       await Snapshot.revert(patches)
       if (revert.snapshot) revert.diff = await Snapshot.diff(revert.snapshot)
-      const rangeMessages = all.filter((msg) => msg.info.id >= revert!.messageID)
-      const diffs = await SessionSummary.computeDiff({ messages: rangeMessages })
+      const pivot = all.findIndex((msg) => msg.info.id === revert.messageID)
+      const preserved = all.flatMap((msg, index) => {
+        if (pivot < 0) return [msg]
+        if (index < pivot) return [msg]
+        if (index > pivot) return []
+        if (!revert.partID) return []
+
+        const part = msg.parts.findIndex((item) => item.id === revert.partID)
+        if (part < 0) return [msg]
+        return [{ ...msg, parts: msg.parts.slice(0, part) }]
+      })
+      const diffs = await SessionSummary.computeDiff({ messages: preserved })
       await Storage.write(["session_diff", input.sessionID], diffs)
       Bus.publish(Session.Event.Diff, {
         sessionID: input.sessionID,
@@ -93,20 +102,22 @@ export namespace SessionRevert {
     const sessionID = session.id
     const msgs = await Session.messages({ sessionID })
     const messageID = session.revert.messageID
-    const preserve = [] as MessageV2.WithParts[]
+    const pivot = msgs.findIndex((msg) => msg.info.id === messageID)
+    if (pivot < 0) {
+      await Session.clearRevert(sessionID)
+      return
+    }
     const remove = [] as MessageV2.WithParts[]
     let target: MessageV2.WithParts | undefined
-    for (const msg of msgs) {
-      if (msg.info.id < messageID) {
-        preserve.push(msg)
+    for (const [index, msg] of msgs.entries()) {
+      if (index < pivot) {
         continue
       }
-      if (msg.info.id > messageID) {
+      if (index > pivot) {
         remove.push(msg)
         continue
       }
       if (session.revert.partID) {
-        preserve.push(msg)
         target = msg
         continue
       }

packages/opencode/src/tool/bash.ts

@@ -207,6 +207,7 @@ export const BashTool = Tool.define("bash", async () => {
       let timedOut = false
       let aborted = false
       let exited = false
+      let exit: number | null = null
 
       const kill = () => Shell.killTree(proc, { exited: () => exited })
 
@@ -233,8 +234,9 @@ export const BashTool = Tool.define("bash", async () => {
           ctx.abort.removeEventListener("abort", abortHandler)
         }
 
-        proc.once("exit", () => {
+        proc.once("exit", (code) => {
           exited = true
+          exit = code
           cleanup()
           resolve()
         })
@@ -264,7 +266,7 @@ export const BashTool = Tool.define("bash", async () => {
         title: params.description,
         metadata: {
           output: output.length > MAX_METADATA_LENGTH ? output.slice(0, MAX_METADATA_LENGTH) + "\n\n..." : output,
-          exit: proc.exitCode,
+          exit: exit ?? proc.exitCode,
           description: params.description,
         },
         output,