feat: restore git-backed review modes (#20845)

23 files changed, 1102 insertions, 247 deletions

diff --git a/packages/app/src/context/global-sync/bootstrap.ts b/packages/app/src/context/global-sync/bootstrap.ts
index cf104ad97..7edd5a1ce 100644
--- a/packages/app/src/context/global-sync/bootstrap.ts
+++ b/packages/app/src/context/global-sync/bootstrap.ts
@@ -248,7 +248,7 @@ export async function bootstrapDirectory(input: {
         input.sdk.vcs.get().then((x) => {
           const next = x.data ?? input.store.vcs
           input.setStore("vcs", next)
-          if (next?.branch) input.vcsCache.setStore("value", next)
+          if (next) input.vcsCache.setStore("value", next)
         }),
       ),
     () => retry(() => input.sdk.command.list().then((x) => input.setStore("command", x.data ?? []))),
diff --git a/packages/app/src/context/global-sync/event-reducer.test.ts b/packages/app/src/context/global-sync/event-reducer.test.ts
index cf2da135c..892129788 100644
--- a/packages/app/src/context/global-sync/event-reducer.test.ts
+++ b/packages/app/src/context/global-sync/event-reducer.test.ts
@@ -494,8 +494,10 @@ describe("applyDirectoryEvent", () => {
   })
 
   test("updates vcs branch in store and cache", () => {
-    const [store, setStore] = createStore(baseState())
-    const [cacheStore, setCacheStore] = createStore({ value: undefined as State["vcs"] })
+    const [store, setStore] = createStore(baseState({ vcs: { branch: "main", default_branch: "main" } }))
+    const [cacheStore, setCacheStore] = createStore({
+      value: { branch: "main", default_branch: "main" } as State["vcs"],
+    })
 
     applyDirectoryEvent({
       event: { type: "vcs.branch.updated", properties: { branch: "feature/test" } },
@@ -511,8 +513,8 @@ describe("applyDirectoryEvent", () => {
       },
     })
 
-    expect(store.vcs).toEqual({ branch: "feature/test" })
-    expect(cacheStore.value).toEqual({ branch: "feature/test" })
+    expect(store.vcs).toEqual({ branch: "feature/test", default_branch: "main" })
+    expect(cacheStore.value).toEqual({ branch: "feature/test", default_branch: "main" })
   })
 
   test("routes disposal and lsp events to side-effect handlers", () => {
diff --git a/packages/app/src/context/global-sync/event-reducer.ts b/packages/app/src/context/global-sync/event-reducer.ts
index 5d8b7c4e3..4af636553 100644
--- a/packages/app/src/context/global-sync/event-reducer.ts
+++ b/packages/app/src/context/global-sync/event-reducer.ts
@@ -271,9 +271,9 @@ export function applyDirectoryEvent(input: {
       break
     }
     case "vcs.branch.updated": {
-      const props = event.properties as { branch: string }
+      const props = event.properties as { branch?: string }
       if (input.store.vcs?.branch === props.branch) break
-      const next = { branch: props.branch }
+      const next = { ...input.store.vcs, branch: props.branch }
       input.setStore("vcs", next)
       if (input.vcsCache) input.vcsCache.setStore("value", next)
       break
diff --git a/packages/app/src/i18n/en.ts b/packages/app/src/i18n/en.ts
index 39317b8d6..ace0efeb8 100644
--- a/packages/app/src/i18n/en.ts
+++ b/packages/app/src/i18n/en.ts
@@ -535,6 +535,8 @@ export const dict = {
   "session.review.noVcs.createGit.action": "Create Git repository",
   "session.review.noSnapshot": "Snapshot tracking is disabled in config, so session changes are unavailable",
   "session.review.noChanges": "No changes",
+  "session.review.noUncommittedChanges": "No uncommitted changes yet",
+  "session.review.noBranchChanges": "No branch changes yet",
 
   "session.files.selectToOpen": "Select a file to open",
   "session.files.all": "All files",
diff --git a/packages/app/src/pages/session.tsx b/packages/app/src/pages/session.tsx
index ae895adbe..a81df9dd2 100644
--- a/packages/app/src/pages/session.tsx
+++ b/packages/app/src/pages/session.tsx
@@ -1,4 +1,4 @@
-import type { Project, UserMessage } from "@opencode-ai/sdk/v2"
+import type { FileDiff, Project, UserMessage } from "@opencode-ai/sdk/v2"
 import { useDialog } from "@opencode-ai/ui/context/dialog"
 import { useMutation } from "@tanstack/solid-query"
 import {
@@ -68,6 +68,9 @@ type FollowupItem = FollowupDraft & { id: string }
 type FollowupEdit = Pick<FollowupItem, "id" | "prompt" | "context">
 const emptyFollowups: FollowupItem[] = []
 
+type ChangeMode = "git" | "branch" | "session" | "turn"
+type VcsMode = "git" | "branch"
+
 type SessionHistoryWindowInput = {
   sessionID: () => string | undefined
   messagesReady: () => boolean
@@ -427,15 +430,16 @@ export default function Page() {
 
   const info = createMemo(() => (params.id ? sync.session.get(params.id) : undefined))
   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)
+  const sessionCount = createMemo(() => Math.max(info()?.summary?.files ?? 0, diffs().length))
+  const hasSessionReview = createMemo(() => sessionCount() > 0)
+  const canReview = createMemo(() => !!sync.project)
   const reviewTab = createMemo(() => isDesktop())
   const tabState = createSessionTabs({
     tabs,
     pathFromTab: file.pathFromTab,
     normalizeTab,
     review: reviewTab,
-    hasReview,
+    hasReview: canReview,
   })
   const contextOpen = tabState.contextOpen
   const openedTabs = tabState.openedTabs
@@ -458,6 +462,12 @@ export default function Page() {
     if (!id) return false
     return sync.session.history.loading(id)
   })
+  const diffsReady = createMemo(() => {
+    const id = params.id
+    if (!id) return true
+    if (!hasSessionReview()) return true
+    return sync.data.session_diff[id] !== undefined
+  })
 
   const userMessages = createMemo(
     () => messages().filter((m) => m.role === "user") as UserMessage[],
@@ -511,11 +521,22 @@ export default function Page() {
   const [store, setStore] = createStore({
     messageId: undefined as string | undefined,
     mobileTab: "session" as "session" | "changes",
-    changes: "session" as "session" | "turn",
+    changes: "git" as ChangeMode,
     newSessionWorktree: "main",
     deferRender: false,
   })
 
+  const [vcs, setVcs] = createStore({
+    diff: {
+      git: [] as FileDiff[],
+      branch: [] as FileDiff[],
+    },
+    ready: {
+      git: false,
+      branch: false,
+    },
+  })
+
   const [followup, setFollowup] = persisted(
     Persist.workspace(sdk.directory, "followup", ["followup.v1"]),
     createStore<{
@@ -549,6 +570,68 @@ export default function Page() {
   let todoTimer: number | undefined
   let diffFrame: number | undefined
   let diffTimer: number | undefined
+  const vcsTask = new Map<VcsMode, Promise<void>>()
+  const vcsRun = new Map<VcsMode, number>()
+
+  const bumpVcs = (mode: VcsMode) => {
+    const next = (vcsRun.get(mode) ?? 0) + 1
+    vcsRun.set(mode, next)
+    return next
+  }
+
+  const resetVcs = (mode?: VcsMode) => {
+    const list = mode ? [mode] : (["git", "branch"] as const)
+    list.forEach((item) => {
+      bumpVcs(item)
+      vcsTask.delete(item)
+      setVcs("diff", item, [])
+      setVcs("ready", item, false)
+    })
+  }
+
+  const loadVcs = (mode: VcsMode, force = false) => {
+    if (sync.project?.vcs !== "git") return Promise.resolve()
+    if (!force && vcs.ready[mode]) return Promise.resolve()
+
+    if (force) {
+      if (vcsTask.has(mode)) bumpVcs(mode)
+      vcsTask.delete(mode)
+      setVcs("ready", mode, false)
+    }
+
+    const current = vcsTask.get(mode)
+    if (current) return current
+
+    const run = bumpVcs(mode)
+
+    const task = sdk.client.vcs
+      .diff({ mode })
+      .then((result) => {
+        if (vcsRun.get(mode) !== run) return
+        setVcs("diff", mode, result.data ?? [])
+        setVcs("ready", mode, true)
+      })
+      .catch((error) => {
+        if (vcsRun.get(mode) !== run) return
+        console.debug("[session-review] failed to load vcs diff", { mode, error })
+        setVcs("diff", mode, [])
+        setVcs("ready", mode, true)
+      })
+      .finally(() => {
+        if (vcsTask.get(mode) === task) vcsTask.delete(mode)
+      })
+
+    vcsTask.set(mode, task)
+    return task
+  }
+
+  const refreshVcs = () => {
+    resetVcs()
+    const mode = untrack(vcsMode)
+    if (!mode) return
+    if (!untrack(wantsReview)) return
+    void loadVcs(mode, true)
+  }
 
   createComputed((prev) => {
     const open = desktopReviewOpen()
@@ -564,7 +647,42 @@ export default function Page() {
   }, desktopReviewOpen())
 
   const turnDiffs = createMemo(() => lastUserMessage()?.summary?.diffs ?? [])
-  const reviewDiffs = createMemo(() => (store.changes === "session" ? diffs() : turnDiffs()))
+  const changesOptions = createMemo<ChangeMode[]>(() => {
+    const list: ChangeMode[] = []
+    if (sync.project?.vcs === "git") list.push("git")
+    if (
+      sync.project?.vcs === "git" &&
+      sync.data.vcs?.branch &&
+      sync.data.vcs?.default_branch &&
+      sync.data.vcs.branch !== sync.data.vcs.default_branch
+    ) {
+      list.push("branch")
+    }
+    list.push("session", "turn")
+    return list
+  })
+  const vcsMode = createMemo<VcsMode | undefined>(() => {
+    if (store.changes === "git" || store.changes === "branch") return store.changes
+  })
+  const reviewDiffs = createMemo(() => {
+    if (store.changes === "git") return vcs.diff.git
+    if (store.changes === "branch") return vcs.diff.branch
+    if (store.changes === "session") return diffs()
+    return turnDiffs()
+  })
+  const reviewCount = createMemo(() => {
+    if (store.changes === "git") return vcs.diff.git.length
+    if (store.changes === "branch") return vcs.diff.branch.length
+    if (store.changes === "session") return sessionCount()
+    return turnDiffs().length
+  })
+  const hasReview = createMemo(() => reviewCount() > 0)
+  const reviewReady = createMemo(() => {
+    if (store.changes === "git") return vcs.ready.git
+    if (store.changes === "branch") return vcs.ready.branch
+    if (store.changes === "session") return !hasSessionReview() || diffsReady()
+    return true
+  })
 
   const newSessionWorktree = createMemo(() => {
     if (store.newSessionWorktree === "create") return "create"
@@ -630,13 +748,7 @@ export default function Page() {
     scrollToMessage(msgs[targetIndex], "auto")
   }
 
-  const diffsReady = createMemo(() => {
-    const id = params.id
-    if (!id) return true
-    if (!hasReview()) return true
-    return sync.data.session_diff[id] !== undefined
-  })
-  const reviewEmptyKey = createMemo(() => {
+  const sessionEmptyKey = createMemo(() => {
     const project = sync.project
     if (project && !project.vcs) return "session.review.noVcs"
     if (sync.data.config.snapshot === false) return "session.review.noSnapshot"
@@ -790,7 +902,7 @@ export default function Page() {
       sessionKey,
       () => {
         setStore("messageId", undefined)
-        setStore("changes", "session")
+        setStore("changes", "git")
         setUi("pendingMessage", undefined)
       },
       { defer: true },
@@ -799,6 +911,39 @@ export default function Page() {
 
   createEffect(
     on(
+      () => sdk.directory,
+      () => {
+        resetVcs()
+      },
+      { defer: true },
+    ),
+  )
+
+  createEffect(
+    on(
+      () => [sync.data.vcs?.branch, sync.data.vcs?.default_branch] as const,
+      (next, prev) => {
+        if (prev === undefined || same(next, prev)) return
+        refreshVcs()
+      },
+      { defer: true },
+    ),
+  )
+
+  const stopVcs = sdk.event.listen((evt) => {
+    if (evt.details.type !== "file.watcher.updated") return
+    const props =
+      typeof evt.details.properties === "object" && evt.details.properties
+        ? (evt.details.properties as Record<string, unknown>)
+        : undefined
+    const file = typeof props?.file === "string" ? props.file : undefined
+    if (!file || file.startsWith(".git/")) return
+    refreshVcs()
+  })
+  onCleanup(stopVcs)
+
+  createEffect(
+    on(
       () => params.dir,
       (dir) => {
         if (!dir) return
@@ -919,6 +1064,40 @@ export default function Page() {
   }
 
   const mobileChanges = createMemo(() => !isDesktop() && store.mobileTab === "changes")
+  const wantsReview = createMemo(() =>
+    isDesktop()
+      ? desktopFileTreeOpen() || (desktopReviewOpen() && activeTab() === "review")
+      : store.mobileTab === "changes",
+  )
+
+  createEffect(() => {
+    const list = changesOptions()
+    if (list.includes(store.changes)) return
+    const next = list[0]
+    if (!next) return
+    setStore("changes", next)
+  })
+
+  createEffect(() => {
+    const mode = vcsMode()
+    if (!mode) return
+    if (!wantsReview()) return
+    void loadVcs(mode)
+  })
+
+  createEffect(
+    on(
+      () => sync.data.session_status[params.id ?? ""]?.type,
+      (next, prev) => {
+        const mode = vcsMode()
+        if (!mode) return
+        if (!wantsReview()) return
+        if (next !== "idle" || prev === undefined || prev === "idle") return
+        void loadVcs(mode, true)
+      },
+      { defer: true },
+    ),
+  )
 
   const fileTreeTab = () => layout.fileTree.tab()
   const setFileTreeTab = (value: "changes" | "all") => layout.fileTree.setTab(value)
@@ -965,21 +1144,23 @@ export default function Page() {
     loadFile: file.load,
   })
 
-  const changesOptions = ["session", "turn"] as const
-  const changesOptionsList = [...changesOptions]
-
   const changesTitle = () => {
-    if (!hasReview()) {
+    if (!canReview()) {
       return null
     }
 
+    const label = (option: ChangeMode) => {
+      if (option === "git") return language.t("ui.sessionReview.title.git")
+      if (option === "branch") return language.t("ui.sessionReview.title.branch")
+      if (option === "session") return language.t("ui.sessionReview.title")
+      return language.t("ui.sessionReview.title.lastTurn")
+    }
+
     return (
       <Select
-        options={changesOptionsList}
+        options={changesOptions()}
         current={store.changes}
-        label={(option) =>
-          option === "session" ? language.t("ui.sessionReview.title") : language.t("ui.sessionReview.title.lastTurn")
-        }
+        label={label}
         onSelect={(option) => option && setStore("changes", option)}
         variant="ghost"
         size="small"
@@ -988,20 +1169,34 @@ export default function Page() {
     )
   }
 
-  const emptyTurn = () => (
+  const empty = (text: string) => (
     <div class="h-full pb-64 -mt-4 flex flex-col items-center justify-center text-center gap-6">
-      <div class="text-14-regular text-text-weak max-w-56">{language.t("session.review.noChanges")}</div>
+      <div class="text-14-regular text-text-weak max-w-56">{text}</div>
     </div>
   )
 
+  const reviewEmptyText = createMemo(() => {
+    if (store.changes === "git") return language.t("session.review.noUncommittedChanges")
+    if (store.changes === "branch") return language.t("session.review.noBranchChanges")
+    if (store.changes === "turn") return language.t("session.review.noChanges")
+    return language.t(sessionEmptyKey())
+  })
+
   const reviewEmpty = (input: { loadingClass: string; emptyClass: string }) => {
-    if (store.changes === "turn") return emptyTurn()
+    if (store.changes === "git" || store.changes === "branch") {
+      if (!reviewReady()) return <div class={input.loadingClass}>{language.t("session.review.loadingChanges")}</div>
+      return empty(reviewEmptyText())
+    }
 
-    if (hasReview() && !diffsReady()) {
+    if (store.changes === "turn") {
+      return empty(reviewEmptyText())
+    }
+
+    if (hasSessionReview() && !diffsReady()) {
       return <div class={input.loadingClass}>{language.t("session.review.loadingChanges")}</div>
     }
 
-    if (reviewEmptyKey() === "session.review.noVcs") {
+    if (sessionEmptyKey() === "session.review.noVcs") {
       return (
         <div class={input.emptyClass}>
           <div class="flex flex-col gap-3">
@@ -1021,7 +1216,7 @@ export default function Page() {
 
     return (
       <div class={input.emptyClass}>
-        <div class="text-14-regular text-text-weak max-w-56">{language.t(reviewEmptyKey())}</div>
+        <div class="text-14-regular text-text-weak max-w-56">{reviewEmptyText()}</div>
       </div>
     )
   }
@@ -1128,7 +1323,7 @@ export default function Page() {
     const pending = tree.pendingDiff
     if (!pending) return
     if (!tree.reviewScroll) return
-    if (!diffsReady()) return
+    if (!reviewReady()) return
 
     const attempt = (count: number) => {
       if (tree.pendingDiff !== pending) return
@@ -1169,10 +1364,7 @@ export default function Page() {
     const id = params.id
     if (!id) return
 
-    const wants = isDesktop()
-      ? desktopFileTreeOpen() || (desktopReviewOpen() && activeTab() === "review")
-      : store.mobileTab === "changes"
-    if (!wants) return
+    if (!wantsReview()) return
     if (sync.data.session_diff[id] !== undefined) return
     if (sync.status === "loading") return
 
@@ -1181,13 +1373,7 @@ export default function Page() {
 
   createEffect(
     on(
-      () =>
-        [
-          sessionKey(),
-          isDesktop()
-            ? desktopFileTreeOpen() || (desktopReviewOpen() && activeTab() === "review")
-            : store.mobileTab === "changes",
-        ] as const,
+      () => [sessionKey(), wantsReview()] as const,
       ([key, wants]) => {
         if (diffFrame !== undefined) cancelAnimationFrame(diffFrame)
         if (diffTimer !== undefined) window.clearTimeout(diffTimer)
@@ -1867,6 +2053,12 @@ export default function Page() {
         </div>
 
         <SessionSidePanel
+          canReview={canReview}
+          diffs={reviewDiffs}
+          diffsReady={reviewReady}
+          empty={reviewEmptyText}
+          hasReview={hasReview}
+          reviewCount={reviewCount}
           reviewPanel={reviewPanel}
           activeDiff={tree.activeDiff}
           focusReviewDiff={focusReviewDiff}
diff --git a/packages/app/src/pages/session/session-side-panel.tsx b/packages/app/src/pages/session/session-side-panel.tsx
index c07942627..86f932ea2 100644
--- a/packages/app/src/pages/session/session-side-panel.tsx
+++ b/packages/app/src/pages/session/session-side-panel.tsx
@@ -8,6 +8,7 @@ import { ResizeHandle } from "@opencode-ai/ui/resize-handle"
 import { Mark } from "@opencode-ai/ui/logo"
 import { DragDropProvider, DragDropSensors, DragOverlay, SortableProvider, closestCenter } from "@thisbeyond/solid-dnd"
 import type { DragEvent } from "@thisbeyond/solid-dnd"
+import type { FileDiff } from "@opencode-ai/sdk/v2"
 import { ConstrainDragYAxis, getDraggableId } from "@/utils/solid-dnd"
 import { useDialog } from "@opencode-ai/ui/context/dialog"
 
@@ -18,7 +19,6 @@ import { useCommand } from "@/context/command"
 import { useFile, type SelectedLineRange } from "@/context/file"
 import { useLanguage } from "@/context/language"
 import { useLayout } from "@/context/layout"
-import { useSync } from "@/context/sync"
 import { createFileTabListSync } from "@/pages/session/file-tab-scroll"
 import { FileTabContent } from "@/pages/session/file-tabs"
 import { createOpenSessionFileTab, createSessionTabs, getTabReorderIndex, type Sizing } from "@/pages/session/helpers"
@@ -26,6 +26,12 @@ import { setSessionHandoff } from "@/pages/session/handoff"
 import { useSessionLayout } from "@/pages/session/session-layout"
 
 export function SessionSidePanel(props: {
+  canReview: () => boolean
+  diffs: () => FileDiff[]
+  diffsReady: () => boolean
+  empty: () => string
+  hasReview: () => boolean
+  reviewCount: () => number
   reviewPanel: () => JSX.Element
   activeDiff?: string
   focusReviewDiff: (path: string) => void
@@ -33,12 +39,11 @@ export function SessionSidePanel(props: {
   size: Sizing
 }) {
   const layout = useLayout()
-  const sync = useSync()
   const file = useFile()
   const language = useLanguage()
   const command = useCommand()
   const dialog = useDialog()
-  const { params, sessionKey, tabs, view } = useSessionLayout()
+  const { sessionKey, tabs, view } = useSessionLayout()
 
   const isDesktop = createMediaQuery("(min-width: 768px)")
 
@@ -53,24 +58,7 @@ export function SessionSidePanel(props: {
   })
   const treeWidth = createMemo(() => (fileOpen() ? `${layout.fileTree.width()}px` : "0px"))
 
-  const info = createMemo(() => (params.id ? sync.session.get(params.id) : undefined))
-  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)
-  const diffsReady = createMemo(() => {
-    const id = params.id
-    if (!id) return true
-    if (!hasReview()) return true
-    return sync.data.session_diff[id] !== undefined
-  })
-
-  const reviewEmptyKey = createMemo(() => {
-    if (sync.project && !sync.project.vcs) return "session.review.noVcs"
-    if (sync.data.config.snapshot === false) return "session.review.noSnapshot"
-    return "session.review.noChanges"
-  })
-
-  const diffFiles = createMemo(() => diffs().map((d) => d.file))
+  const diffFiles = createMemo(() => props.diffs().map((d) => d.file))
   const kinds = createMemo(() => {
     const merge = (a: "add" | "del" | "mix" | undefined, b: "add" | "del" | "mix") => {
       if (!a) return b
@@ -81,7 +69,7 @@ export function SessionSidePanel(props: {
     const normalize = (p: string) => p.replaceAll("\\\\", "/").replace(/\/+$/, "")
 
     const out = new Map<string, "add" | "del" | "mix">()
-    for (const diff of diffs()) {
+    for (const diff of props.diffs()) {
       const file = normalize(diff.file)
       const kind = diff.status === "added" ? "add" : diff.status === "deleted" ? "del" : "mix"
 
@@ -135,7 +123,7 @@ export function SessionSidePanel(props: {
     pathFromTab: file.pathFromTab,
     normalizeTab,
     review: reviewTab,
-    hasReview,
+    hasReview: props.canReview,
   })
   const contextOpen = tabState.contextOpen
   const openedTabs = tabState.openedTabs
@@ -240,12 +228,12 @@ export function SessionSidePanel(props: {
                         onCleanup(stop)
                       }}
                     >
-                      <Show when={reviewTab()}>
+                      <Show when={reviewTab() && props.canReview()}>
                         <Tabs.Trigger value="review">
                           <div class="flex items-center gap-1.5">
                             <div>{language.t("session.tab.review")}</div>
-                            <Show when={hasReview()}>
-                              <div>{reviewCount()}</div>
+                            <Show when={props.hasReview()}>
+                              <div>{props.reviewCount()}</div>
                             </Show>
                           </div>
                         </Tabs.Trigger>
@@ -304,7 +292,7 @@ export function SessionSidePanel(props: {
                     </Tabs.List>
                   </div>
 
-                  <Show when={reviewTab()}>
+                  <Show when={reviewTab() && props.canReview()}>
                     <Tabs.Content value="review" class="flex flex-col h-full overflow-hidden contain-strict">
                       <Show when={activeTab() === "review"}>{props.reviewPanel()}</Show>
                     </Tabs.Content>
@@ -378,8 +366,10 @@ export function SessionSidePanel(props: {
               >
                 <Tabs.List>
                   <Tabs.Trigger value="changes" class="flex-1" classes={{ button: "w-full" }}>
-                    {reviewCount()}{" "}
-                    {language.t(reviewCount() === 1 ? "session.review.change.one" : "session.review.change.other")}
+                    {props.reviewCount()}{" "}
+                    {language.t(
+                      props.reviewCount() === 1 ? "session.review.change.one" : "session.review.change.other",
+                    )}
                   </Tabs.Trigger>
                   <Tabs.Trigger value="all" class="flex-1" classes={{ button: "w-full" }}>
                     {language.t("session.files.all")}
@@ -387,9 +377,9 @@ export function SessionSidePanel(props: {
                 </Tabs.List>
                 <Tabs.Content value="changes" class="bg-background-stronger px-3 py-0">
                   <Switch>
-                    <Match when={hasReview()}>
+                    <Match when={props.hasReview() || !props.diffsReady()}>
                       <Show
-                        when={diffsReady()}
+                        when={props.diffsReady()}
                         fallback={
                           <div class="px-2 py-2 text-12-regular text-text-weak">
                             {language.t("common.loading")}
@@ -408,11 +398,7 @@ export function SessionSidePanel(props: {
                         />
                       </Show>
                     </Match>
-                    <Match when={true}>
-                      {empty(
-                        language.t(sync.project && !sync.project.vcs ? "session.review.noChanges" : reviewEmptyKey()),
-                      )}
-                    </Match>
+                    <Match when={true}>{empty(props.empty())}</Match>
                   </Switch>
                 </Tabs.Content>
                 <Tabs.Content value="all" class="bg-background-stronger px-3 py-0">
diff --git a/packages/app/src/pages/session/use-session-commands.tsx b/packages/app/src/pages/session/use-session-commands.tsx
index 430fd46f8..239795373 100644
--- a/packages/app/src/pages/session/use-session-commands.tsx
+++ b/packages/app/src/pages/session/use-session-commands.tsx
@@ -52,11 +52,7 @@ export const useSessionCommands = (actions: SessionCommandContext) => {
     if (!id) return
     return sync.session.get(id)
   }
-  const hasReview = () => {
-    const id = params.id
-    if (!id) return false
-    return Math.max(info()?.summary?.files ?? 0, (sync.data.session_diff[id] ?? []).length) > 0
-  }
+  const hasReview = () => !!params.id
   const normalizeTab = (tab: string) => {
     if (!tab.startsWith("file://")) return tab
     return file.tab(tab)
diff --git a/packages/opencode/src/cli/cmd/github.ts b/packages/opencode/src/cli/cmd/github.ts
index 6353ca79a..e8f3e6a11 100644
--- a/packages/opencode/src/cli/cmd/github.ts
+++ b/packages/opencode/src/cli/cmd/github.ts
@@ -28,9 +28,9 @@ import { Provider } from "../../provider/provider"
 import { Bus } from "../../bus"
 import { MessageV2 } from "../../session/message-v2"
 import { SessionPrompt } from "@/session/prompt"
+import { Git } from "@/git"
 import { setTimeout as sleep } from "node:timers/promises"
 import { Process } from "@/util/process"
-import { git } from "@/util/git"
 
 type GitHubAuthor = {
   login: string
@@ -257,7 +257,7 @@ export const GithubInstallCommand = cmd({
             }
 
             // Get repo info
-            const info = (await git(["remote", "get-url", "origin"], { cwd: Instance.worktree })).text().trim()
+            const info = (await Git.run(["remote", "get-url", "origin"], { cwd: Instance.worktree })).text().trim()
             const parsed = parseGitHubRemote(info)
             if (!parsed) {
               prompts.log.error(`Could not find git repository. Please run this command from a git repository.`)
@@ -496,20 +496,20 @@ export const GithubRunCommand = cmd({
           : "issue"
         : undefined
       const gitText = async (args: string[]) => {
-        const result = await git(args, { cwd: Instance.worktree })
+        const result = await Git.run(args, { cwd: Instance.worktree })
         if (result.exitCode !== 0) {
           throw new Process.RunFailedError(["git", ...args], result.exitCode, result.stdout, result.stderr)
         }
         return result.text().trim()
       }
       const gitRun = async (args: string[]) => {
-        const result = await git(args, { cwd: Instance.worktree })
+        const result = await Git.run(args, { cwd: Instance.worktree })
         if (result.exitCode !== 0) {
           throw new Process.RunFailedError(["git", ...args], result.exitCode, result.stdout, result.stderr)
         }
         return result
       }
-      const gitStatus = (args: string[]) => git(args, { cwd: Instance.worktree })
+      const gitStatus = (args: string[]) => Git.run(args, { cwd: Instance.worktree })
       const commitChanges = async (summary: string, actor?: string) => {
         const args = ["commit", "-m", summary]
         if (actor) args.push("-m", `Co-authored-by: ${actor} <${actor}@users.noreply.github.com>`)
diff --git a/packages/opencode/src/cli/cmd/pr.ts b/packages/opencode/src/cli/cmd/pr.ts
index 8826fe343..58d42c6ef 100644
--- a/packages/opencode/src/cli/cmd/pr.ts
+++ b/packages/opencode/src/cli/cmd/pr.ts
@@ -1,8 +1,8 @@
 import { UI } from "../ui"
 import { cmd } from "./cmd"
+import { Git } from "@/git"
 import { Instance } from "@/project/instance"
 import { Process } from "@/util/process"
-import { git } from "@/util/git"
 
 export const PrCommand = cmd({
   command: "pr <number>",
@@ -67,9 +67,9 @@ export const PrCommand = cmd({
               const remoteName = forkOwner
 
               // Check if remote already exists
-              const remotes = (await git(["remote"], { cwd: Instance.worktree })).text().trim()
+              const remotes = (await Git.run(["remote"], { cwd: Instance.worktree })).text().trim()
               if (!remotes.split("\n").includes(remoteName)) {
-                await git(["remote", "add", remoteName, `https://github.com/${forkOwner}/${forkName}.git`], {
+                await Git.run(["remote", "add", remoteName, `https://github.com/${forkOwner}/${forkName}.git`], {
                   cwd: Instance.worktree,
                 })
                 UI.println(`Added fork remote: ${remoteName}`)
@@ -77,7 +77,7 @@ export const PrCommand = cmd({
 
               // Set upstream to the fork so pushes go there
               const headRefName = prInfo.headRefName
-              await git(["branch", `--set-upstream-to=${remoteName}/${headRefName}`, localBranchName], {
+              await Git.run(["branch", `--set-upstream-to=${remoteName}/${headRefName}`, localBranchName], {
                 cwd: Instance.worktree,
               })
             }
diff --git a/packages/opencode/src/file/index.ts b/packages/opencode/src/file/index.ts
index 353f02c31..cdcf80a99 100644
--- a/packages/opencode/src/file/index.ts
+++ b/packages/opencode/src/file/index.ts
@@ -2,7 +2,7 @@ import { BusEvent } from "@/bus/bus-event"
 import { InstanceState } from "@/effect/instance-state"
 import { makeRuntime } from "@/effect/run-service"
 import { AppFileSystem } from "@/filesystem"
-import { git } from "@/util/git"
+import { Git } from "@/git"
 import { Effect, Layer, ServiceMap } from "effect"
 import { formatPatch, structuredPatch } from "diff"
 import fuzzysort from "fuzzysort"
@@ -419,7 +419,7 @@ export namespace File {
 
         return yield* Effect.promise(async () => {
           const diffOutput = (
-            await git(["-c", "core.fsmonitor=false", "-c", "core.quotepath=false", "diff", "--numstat", "HEAD"], {
+            await Git.run(["-c", "core.fsmonitor=false", "-c", "core.quotepath=false", "diff", "--numstat", "HEAD"], {
               cwd: Instance.directory,
             })
           ).text()
@@ -439,7 +439,7 @@ export namespace File {
           }
 
           const untrackedOutput = (
-            await git(
+            await Git.run(
               [
                 "-c",
                 "core.fsmonitor=false",
@@ -472,7 +472,7 @@ export namespace File {
           }
 
           const deletedOutput = (
-            await git(
+            await Git.run(
               [
                 "-c",
                 "core.fsmonitor=false",
@@ -560,17 +560,17 @@ export namespace File {
         if (Instance.project.vcs === "git") {
           return yield* Effect.promise(async (): Promise<File.Content> => {
             let diff = (
-              await git(["-c", "core.fsmonitor=false", "diff", "--", file], { cwd: Instance.directory })
+              await Git.run(["-c", "core.fsmonitor=false", "diff", "--", file], { cwd: Instance.directory })
             ).text()
             if (!diff.trim()) {
               diff = (
-                await git(["-c", "core.fsmonitor=false", "diff", "--staged", "--", file], {
+                await Git.run(["-c", "core.fsmonitor=false", "diff", "--staged", "--", file], {
                   cwd: Instance.directory,
                 })
               ).text()
             }
             if (diff.trim()) {
-              const original = (await git(["show", `HEAD:${file}`], { cwd: Instance.directory })).text()
+              const original = (await Git.run(["show", `HEAD:${file}`], { cwd: Instance.directory })).text()
               const patch = structuredPatch(file, file, original, content, "old", "new", {
                 context: Infinity,
                 ignoreWhitespace: true,
diff --git a/packages/opencode/src/file/watcher.ts b/packages/opencode/src/file/watcher.ts
index 73c40e133..b78b3a33a 100644
--- a/packages/opencode/src/file/watcher.ts
+++ b/packages/opencode/src/file/watcher.ts
@@ -10,8 +10,8 @@ import { BusEvent } from "@/bus/bus-event"
 import { InstanceState } from "@/effect/instance-state"
 import { makeRuntime } from "@/effect/run-service"
 import { Flag } from "@/flag/flag"
+import { Git } from "@/git"
 import { Instance } from "@/project/instance"
-import { git } from "@/util/git"
 import { lazy } from "@/util/lazy"
 import { Config } from "../config/config"
 import { FileIgnore } from "./ignore"
@@ -132,7 +132,7 @@ export namespace FileWatcher {
 
             if (Instance.project.vcs === "git") {
               const result = yield* Effect.promise(() =>
-                git(["rev-parse", "--git-dir"], {
+                Git.run(["rev-parse", "--git-dir"], {
                   cwd: Instance.project.worktree,
                 }),
               )
diff --git a/packages/opencode/src/git/index.ts b/packages/opencode/src/git/index.ts
new file mode 100644
index 000000000..2b3a8a9b0
--- /dev/null
+++ b/packages/opencode/src/git/index.ts
@@ -0,0 +1,303 @@
+import * as CrossSpawnSpawner from "@/effect/cross-spawn-spawner"
+import { Effect, Layer, ServiceMap, Stream } from "effect"
+import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process"
+import { makeRuntime } from "@/effect/run-service"
+
+export namespace Git {
+  const cfg = [
+    "--no-optional-locks",
+    "-c",
+    "core.autocrlf=false",
+    "-c",
+    "core.fsmonitor=false",
+    "-c",
+    "core.longpaths=true",
+    "-c",
+    "core.symlinks=true",
+    "-c",
+    "core.quotepath=false",
+  ] as const
+
+  const out = (result: { text(): string }) => result.text().trim()
+  const nuls = (text: string) => text.split("\0").filter(Boolean)
+  const fail = (err: unknown) =>
+    ({
+      exitCode: 1,
+      text: () => "",
+      stdout: Buffer.alloc(0),
+      stderr: Buffer.from(err instanceof Error ? err.message : String(err)),
+    }) satisfies Result
+
+  export type Kind = "added" | "deleted" | "modified"
+
+  export type Base = {
+    readonly name: string
+    readonly ref: string
+  }
+
+  export type Item = {
+    readonly file: string
+    readonly code: string
+    readonly status: Kind
+  }
+
+  export type Stat = {
+    readonly file: string
+    readonly additions: number
+    readonly deletions: number
+  }
+
+  export interface Result {
+    readonly exitCode: number
+    readonly text: () => string
+    readonly stdout: Buffer
+    readonly stderr: Buffer
+  }
+
+  export interface Options {
+    readonly cwd: string
+    readonly env?: Record<string, string>
+  }
+
+  export interface Interface {
+    readonly run: (args: string[], opts: Options) => Effect.Effect<Result>
+    readonly branch: (cwd: string) => Effect.Effect<string | undefined>
+    readonly prefix: (cwd: string) => Effect.Effect<string>
+    readonly defaultBranch: (cwd: string) => Effect.Effect<Base | undefined>
+    readonly hasHead: (cwd: string) => Effect.Effect<boolean>
+    readonly mergeBase: (cwd: string, base: string, head?: string) => Effect.Effect<string | undefined>
+    readonly show: (cwd: string, ref: string, file: string, prefix?: string) => Effect.Effect<string>
+    readonly status: (cwd: string) => Effect.Effect<Item[]>
+    readonly diff: (cwd: string, ref: string) => Effect.Effect<Item[]>
+    readonly stats: (cwd: string, ref: string) => Effect.Effect<Stat[]>
+  }
+
+  const kind = (code: string): Kind => {
+    if (code === "??") return "added"
+    if (code.includes("U")) return "modified"
+    if (code.includes("A") && !code.includes("D")) return "added"
+    if (code.includes("D") && !code.includes("A")) return "deleted"
+    return "modified"
+  }
+
+  export class Service extends ServiceMap.Service<Service, Interface>()("@opencode/Git") {}
+
+  export const layer = Layer.effect(
+    Service,
+    Effect.gen(function* () {
+      const spawner = yield* ChildProcessSpawner.ChildProcessSpawner
+
+      const run = Effect.fn("Git.run")(
+        function* (args: string[], opts: Options) {
+          const proc = ChildProcess.make("git", [...cfg, ...args], {
+            cwd: opts.cwd,
+            env: opts.env,
+            extendEnv: true,
+            stdin: "ignore",
+            stdout: "pipe",
+            stderr: "pipe",
+          })
+          const handle = yield* spawner.spawn(proc)
+          const [stdout, stderr] = yield* Effect.all(
+            [Stream.mkString(Stream.decodeText(handle.stdout)), Stream.mkString(Stream.decodeText(handle.stderr))],
+            { concurrency: 2 },
+          )
+          return {
+            exitCode: yield* handle.exitCode,
+            text: () => stdout,
+            stdout: Buffer.from(stdout),
+            stderr: Buffer.from(stderr),
+          } satisfies Result
+        },
+        Effect.scoped,
+        Effect.catch((err) => Effect.succeed(fail(err))),
+      )
+
+      const text = Effect.fn("Git.text")(function* (args: string[], opts: Options) {
+        return (yield* run(args, opts)).text()
+      })
+
+      const lines = Effect.fn("Git.lines")(function* (args: string[], opts: Options) {
+        return (yield* text(args, opts))
+          .split(/\r?\n/)
+          .map((item) => item.trim())
+          .filter(Boolean)
+      })
+
+      const refs = Effect.fnUntraced(function* (cwd: string) {
+        return yield* lines(["for-each-ref", "--format=%(refname:short)", "refs/heads"], { cwd })
+      })
+
+      const configured = Effect.fnUntraced(function* (cwd: string, list: string[]) {
+        const result = yield* run(["config", "init.defaultBranch"], { cwd })
+        const name = out(result)
+        if (!name || !list.includes(name)) return
+        return { name, ref: name } satisfies Base
+      })
+
+      const primary = Effect.fnUntraced(function* (cwd: string) {
+        const list = yield* lines(["remote"], { cwd })
+        if (list.includes("origin")) return "origin"
+        if (list.length === 1) return list[0]
+        if (list.includes("upstream")) return "upstream"
+        return list[0]
+      })
+
+      const branch = Effect.fn("Git.branch")(function* (cwd: string) {
+        const result = yield* run(["symbolic-ref", "--quiet", "--short", "HEAD"], { cwd })
+        if (result.exitCode !== 0) return
+        const text = out(result)
+        return text || undefined
+      })
+
+      const prefix = Effect.fn("Git.prefix")(function* (cwd: string) {
+        const result = yield* run(["rev-parse", "--show-prefix"], { cwd })
+        if (result.exitCode !== 0) return ""
+        return out(result)
+      })
+
+      const defaultBranch = Effect.fn("Git.defaultBranch")(function* (cwd: string) {
+        const remote = yield* primary(cwd)
+        if (remote) {
+          const head = yield* run(["symbolic-ref", `refs/remotes/${remote}/HEAD`], { cwd })
+          if (head.exitCode === 0) {
+            const ref = out(head).replace(/^refs\/remotes\//, "")
+            const name = ref.startsWith(`${remote}/`) ? ref.slice(`${remote}/`.length) : ""
+            if (name) return { name, ref } satisfies Base
+          }
+        }
+
+        const list = yield* refs(cwd)
+        const next = yield* configured(cwd, list)
+        if (next) return next
+        if (list.includes("main")) return { name: "main", ref: "main" } satisfies Base
+        if (list.includes("master")) return { name: "master", ref: "master" } satisfies Base
+      })
+
+      const hasHead = Effect.fn("Git.hasHead")(function* (cwd: string) {
+        const result = yield* run(["rev-parse", "--verify", "HEAD"], { cwd })
+        return result.exitCode === 0
+      })
+
+      const mergeBase = Effect.fn("Git.mergeBase")(function* (cwd: string, base: string, head = "HEAD") {
+        const result = yield* run(["merge-base", base, head], { cwd })
+        if (result.exitCode !== 0) return
+        const text = out(result)
+        return text || undefined
+      })
+
+      const show = Effect.fn("Git.show")(function* (cwd: string, ref: string, file: string, prefix = "") {
+        const target = prefix ? `${prefix}${file}` : file
+        const result = yield* run(["show", `${ref}:${target}`], { cwd })
+        if (result.exitCode !== 0) return ""
+        if (result.stdout.includes(0)) return ""
+        return result.text()
+      })
+
+      const status = Effect.fn("Git.status")(function* (cwd: string) {
+        return nuls(
+          yield* text(["status", "--porcelain=v1", "--untracked-files=all", "--no-renames", "-z", "--", "."], {
+            cwd,
+          }),
+        ).flatMap((item) => {
+          const file = item.slice(3)
+          if (!file) return []
+          const code = item.slice(0, 2)
+          return [{ file, code, status: kind(code) } satisfies Item]
+        })
+      })
+
+      const diff = Effect.fn("Git.diff")(function* (cwd: string, ref: string) {
+        const list = nuls(
+          yield* text(["diff", "--no-ext-diff", "--no-renames", "--name-status", "-z", ref, "--", "."], { cwd }),
+        )
+        return list.flatMap((code, idx) => {
+          if (idx % 2 !== 0) return []
+          const file = list[idx + 1]
+          if (!code || !file) return []
+          return [{ file, code, status: kind(code) } satisfies Item]
+        })
+      })
+
+      const stats = Effect.fn("Git.stats")(function* (cwd: string, ref: string) {
+        return nuls(
+          yield* text(["diff", "--no-ext-diff", "--no-renames", "--numstat", "-z", ref, "--", "."], { cwd }),
+        ).flatMap((item) => {
+          const a = item.indexOf("\t")
+          const b = item.indexOf("\t", a + 1)
+          if (a === -1 || b === -1) return []
+          const file = item.slice(b + 1)
+          if (!file) return []
+          const adds = item.slice(0, a)
+          const dels = item.slice(a + 1, b)
+          const additions = adds === "-" ? 0 : Number.parseInt(adds || "0", 10)
+          const deletions = dels === "-" ? 0 : Number.parseInt(dels || "0", 10)
+          return [
+            {
+              file,
+              additions: Number.isFinite(additions) ? additions : 0,
+              deletions: Number.isFinite(deletions) ? deletions : 0,
+            } satisfies Stat,
+          ]
+        })
+      })
+
+      return Service.of({
+        run,
+        branch,
+        prefix,
+        defaultBranch,
+        hasHead,
+        mergeBase,
+        show,
+        status,
+        diff,
+        stats,
+      })
+    }),
+  )
+
+  export const defaultLayer = layer.pipe(Layer.provide(CrossSpawnSpawner.defaultLayer))
+
+  const { runPromise } = makeRuntime(Service, defaultLayer)
+
+  export async function run(args: string[], opts: Options) {
+    return runPromise((git) => git.run(args, opts))
+  }
+
+  export async function branch(cwd: string) {
+    return runPromise((git) => git.branch(cwd))
+  }
+
+  export async function prefix(cwd: string) {
+    return runPromise((git) => git.prefix(cwd))
+  }
+
+  export async function defaultBranch(cwd: string) {
+    return runPromise((git) => git.defaultBranch(cwd))
+  }
+
+  export async function hasHead(cwd: string) {
+    return runPromise((git) => git.hasHead(cwd))
+  }
+
+  export async function mergeBase(cwd: string, base: string, head?: string) {
+    return runPromise((git) => git.mergeBase(cwd, base, head))
+  }
+
+  export async function show(cwd: string, ref: string, file: string, prefix?: string) {
+    return runPromise((git) => git.show(cwd, ref, file, prefix))
+  }
+
+  export async function status(cwd: string) {
+    return runPromise((git) => git.status(cwd))
+  }
+
+  export async function diff(cwd: string, ref: string) {
+    return runPromise((git) => git.diff(cwd, ref))
+  }
+
+  export async function stats(cwd: string, ref: string) {
+    return runPromise((git) => git.stats(cwd, ref))
+  }
+}
diff --git a/packages/opencode/src/project/vcs.ts b/packages/opencode/src/project/vcs.ts
index 25f172b8a..5142079b1 100644
--- a/packages/opencode/src/project/vcs.ts
+++ b/packages/opencode/src/project/vcs.ts
@@ -1,17 +1,111 @@
 import { Effect, Layer, ServiceMap, Stream } from "effect"
-import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process"
+import path from "path"
 import { Bus } from "@/bus"
 import { BusEvent } from "@/bus/bus-event"
-import * as CrossSpawnSpawner from "@/effect/cross-spawn-spawner"
 import { InstanceState } from "@/effect/instance-state"
 import { makeRuntime } from "@/effect/run-service"
+import { AppFileSystem } from "@/filesystem"
 import { FileWatcher } from "@/file/watcher"
+import { Git } from "@/git"
+import { Snapshot } from "@/snapshot"
 import { Log } from "@/util/log"
+import { Instance } from "./instance"
 import z from "zod"
 
 export namespace Vcs {
   const log = Log.create({ service: "vcs" })
 
+  const count = (text: string) => {
+    if (!text) return 0
+    if (!text.endsWith("\n")) return text.split("\n").length
+    return text.slice(0, -1).split("\n").length
+  }
+
+  const work = Effect.fnUntraced(function* (fs: AppFileSystem.Interface, cwd: string, file: string) {
+    const full = path.join(cwd, file)
+    if (!(yield* fs.exists(full).pipe(Effect.orDie))) return ""
+    const buf = yield* fs.readFile(full).pipe(Effect.catch(() => Effect.succeed(new Uint8Array())))
+    if (Buffer.from(buf).includes(0)) return ""
+    return Buffer.from(buf).toString("utf8")
+  })
+
+  const nums = (list: Git.Stat[]) =>
+    new Map(list.map((item) => [item.file, { additions: item.additions, deletions: item.deletions }] as const))
+
+  const merge = (...lists: Git.Item[][]) => {
+    const out = new Map<string, Git.Item>()
+    lists.flat().forEach((item) => {
+      if (!out.has(item.file)) out.set(item.file, item)
+    })
+    return [...out.values()]
+  }
+
+  const files = Effect.fnUntraced(function* (
+    fs: AppFileSystem.Interface,
+    git: Git.Interface,
+    cwd: string,
+    ref: string | undefined,
+    list: Git.Item[],
+    map: Map<string, { additions: number; deletions: number }>,
+  ) {
+    const base = ref ? yield* git.prefix(cwd) : ""
+    const next = yield* Effect.forEach(
+      list,
+      (item) =>
+        Effect.gen(function* () {
+          const before = item.status === "added" || !ref ? "" : yield* git.show(cwd, ref, item.file, base)
+          const after = item.status === "deleted" ? "" : yield* work(fs, cwd, item.file)
+          const stat = map.get(item.file)
+          return {
+            file: item.file,
+            before,
+            after,
+            additions: stat?.additions ?? (item.status === "added" ? count(after) : 0),
+            deletions: stat?.deletions ?? (item.status === "deleted" ? count(before) : 0),
+            status: item.status,
+          } satisfies Snapshot.FileDiff
+        }),
+      { concurrency: 8 },
+    )
+    return next.toSorted((a, b) => a.file.localeCompare(b.file))
+  })
+
+  const track = Effect.fnUntraced(function* (
+    fs: AppFileSystem.Interface,
+    git: Git.Interface,
+    cwd: string,
+    ref: string | undefined,
+  ) {
+    if (!ref) return yield* files(fs, git, cwd, ref, yield* git.status(cwd), new Map())
+    const [list, stats] = yield* Effect.all([git.status(cwd), git.stats(cwd, ref)], { concurrency: 2 })
+    return yield* files(fs, git, cwd, ref, list, nums(stats))
+  })
+
+  const compare = Effect.fnUntraced(function* (
+    fs: AppFileSystem.Interface,
+    git: Git.Interface,
+    cwd: string,
+    ref: string,
+  ) {
+    const [list, stats, extra] = yield* Effect.all([git.diff(cwd, ref), git.stats(cwd, ref), git.status(cwd)], {
+      concurrency: 3,
+    })
+    return yield* files(
+      fs,
+      git,
+      cwd,
+      ref,
+      merge(
+        list,
+        extra.filter((item) => item.code === "??"),
+      ),
+      nums(stats),
+    )
+  })
+
+  export const Mode = z.enum(["git", "branch"])
+  export type Mode = z.infer<typeof Mode>
+
   export const Event = {
     BranchUpdated: BusEvent.define(
       "vcs.branch.updated",
@@ -24,6 +118,7 @@ export namespace Vcs {
   export const Info = z
     .object({
       branch: z.string().optional(),
+      default_branch: z.string().optional(),
     })
     .meta({
       ref: "VcsInfo",
@@ -33,57 +128,45 @@ export namespace Vcs {
   export interface Interface {
     readonly init: () => Effect.Effect<void>
     readonly branch: () => Effect.Effect<string | undefined>
+    readonly defaultBranch: () => Effect.Effect<string | undefined>
+    readonly diff: (mode: Mode) => Effect.Effect<Snapshot.FileDiff[]>
   }
 
   interface State {
     current: string | undefined
+    root: Git.Base | undefined
   }
 
   export class Service extends ServiceMap.Service<Service, Interface>()("@opencode/Vcs") {}
 
-  export const layer: Layer.Layer<Service, never, Bus.Service | ChildProcessSpawner.ChildProcessSpawner> = Layer.effect(
+  export const layer: Layer.Layer<Service, never, AppFileSystem.Service | Git.Service | Bus.Service> = Layer.effect(
     Service,
     Effect.gen(function* () {
+      const fs = yield* AppFileSystem.Service
+      const git = yield* Git.Service
       const bus = yield* Bus.Service
-      const spawner = yield* ChildProcessSpawner.ChildProcessSpawner
-
-      const git = Effect.fnUntraced(
-        function* (args: string[], opts: { cwd: string }) {
-          const handle = yield* spawner.spawn(
-            ChildProcess.make("git", args, { cwd: opts.cwd, extendEnv: true, stdin: "ignore" }),
-          )
-          const text = yield* Stream.mkString(Stream.decodeText(handle.stdout))
-          const code = yield* handle.exitCode
-          return { code, text }
-        },
-        Effect.scoped,
-        Effect.catch(() => Effect.succeed({ code: ChildProcessSpawner.ExitCode(1), text: "" })),
-      )
 
       const state = yield* InstanceState.make<State>(
         Effect.fn("Vcs.state")((ctx) =>
           Effect.gen(function* () {
             if (ctx.project.vcs !== "git") {
-              return { current: undefined }
+              return { current: undefined, root: undefined }
             }
 
-            const getBranch = Effect.fnUntraced(function* () {
-              const result = yield* git(["rev-parse", "--abbrev-ref", "HEAD"], { cwd: ctx.worktree })
-              if (result.code !== 0) return undefined
-              const text = result.text.trim()
-              return text || undefined
+            const get = Effect.fnUntraced(function* () {
+              return yield* git.branch(ctx.directory)
             })
-
-            const value = {
-              current: yield* getBranch(),
-            }
-            log.info("initialized", { branch: value.current })
+            const [current, root] = yield* Effect.all([git.branch(ctx.directory), git.defaultBranch(ctx.directory)], {
+              concurrency: 2,
+            })
+            const value = { current, root }
+            log.info("initialized", { branch: value.current, default_branch: value.root?.name })
 
             yield* bus.subscribe(FileWatcher.Event.Updated).pipe(
               Stream.filter((evt) => evt.properties.file.endsWith("HEAD")),
-              Stream.runForEach(() =>
+              Stream.runForEach((_evt) =>
                 Effect.gen(function* () {
-                  const next = yield* getBranch()
+                  const next = yield* get()
                   if (next !== value.current) {
                     log.info("branch changed", { from: value.current, to: next })
                     value.current = next
@@ -106,19 +189,52 @@ export namespace Vcs {
         branch: Effect.fn("Vcs.branch")(function* () {
           return yield* InstanceState.use(state, (x) => x.current)
         }),
+        defaultBranch: Effect.fn("Vcs.defaultBranch")(function* () {
+          return yield* InstanceState.use(state, (x) => x.root?.name)
+        }),
+        diff: Effect.fn("Vcs.diff")(function* (mode: Mode) {
+          const value = yield* InstanceState.get(state)
+          if (Instance.project.vcs !== "git") return []
+          if (mode === "git") {
+            return yield* track(
+              fs,
+              git,
+              Instance.directory,
+              (yield* git.hasHead(Instance.directory)) ? "HEAD" : undefined,
+            )
+          }
+
+          if (!value.root) return []
+          if (value.current && value.current === value.root.name) return []
+          const ref = yield* git.mergeBase(Instance.directory, value.root.ref)
+          if (!ref) return []
+          return yield* compare(fs, git, Instance.directory, ref)
+        }),
       })
     }),
   )
 
-  export const defaultLayer = layer.pipe(Layer.provide(Bus.layer), Layer.provide(CrossSpawnSpawner.defaultLayer))
+  const defaultLayer = layer.pipe(
+    Layer.provide(Git.defaultLayer),
+    Layer.provide(AppFileSystem.defaultLayer),
+    Layer.provide(Bus.layer),
+  )
 
   const { runPromise } = makeRuntime(Service, defaultLayer)
 
-  export function init() {
+  export async function init() {
     return runPromise((svc) => svc.init())
   }
 
-  export function branch() {
+  export async function branch() {
     return runPromise((svc) => svc.branch())
   }
+
+  export async function defaultBranch() {
+    return runPromise((svc) => svc.defaultBranch())
+  }
+
+  export async function diff(mode: Mode) {
+    return runPromise((svc) => svc.diff(mode))
+  }
 }
diff --git a/packages/opencode/src/server/instance.ts b/packages/opencode/src/server/instance.ts
index 4bb6efaf9..0186bf467 100644
--- a/packages/opencode/src/server/instance.ts
+++ b/packages/opencode/src/server/instance.ts
@@ -1,4 +1,4 @@
-import { describeRoute, resolver } from "hono-openapi"
+import { describeRoute, resolver, validator } from "hono-openapi"
 import { Hono } from "hono"
 import { proxy } from "hono/proxy"
 import z from "zod"
@@ -16,6 +16,7 @@ import { Command } from "../command"
 import { Flag } from "../flag/flag"
 import { QuestionRoutes } from "./routes/question"
 import { PermissionRoutes } from "./routes/permission"
+import { Snapshot } from "@/snapshot"
 import { ProjectRoutes } from "./routes/project"
 import { SessionRoutes } from "./routes/session"
 import { PtyRoutes } from "./routes/pty"
@@ -134,13 +135,41 @@ export const InstanceRoutes = (app?: Hono) =>
         },
       }),
       async (c) => {
-        const branch = await Vcs.branch()
+        const [branch, default_branch] = await Promise.all([Vcs.branch(), Vcs.defaultBranch()])
         return c.json({
           branch,
+          default_branch,
         })
       },
     )
     .get(
+      "/vcs/diff",
+      describeRoute({
+        summary: "Get VCS diff",
+        description: "Retrieve the current git diff for the working tree or against the default branch.",
+        operationId: "vcs.diff",
+        responses: {
+          200: {
+            description: "VCS diff",
+            content: {
+              "application/json": {
+                schema: resolver(Snapshot.FileDiff.array()),
+              },
+            },
+          },
+        },
+      }),
+      validator(
+        "query",
+        z.object({
+          mode: Vcs.Mode,
+        }),
+      ),
+      async (c) => {
+        return c.json(await Vcs.diff(c.req.valid("query").mode))
+      },
+    )
+    .get(
       "/command",
       describeRoute({
         summary: "List commands",
diff --git a/packages/opencode/src/storage/storage.ts b/packages/opencode/src/storage/storage.ts
index 268b18f68..0d0dce726 100644
--- a/packages/opencode/src/storage/storage.ts
+++ b/packages/opencode/src/storage/storage.ts
@@ -3,10 +3,10 @@ import path from "path"
 import { Global } from "../global"
 import { NamedError } from "@opencode-ai/util/error"
 import z from "zod"
-import { git } from "@/util/git"
 import { AppFileSystem } from "@/filesystem"
 import { makeRuntime } from "@/effect/run-service"
 import { Effect, Exit, Layer, Option, RcMap, Schema, ServiceMap, TxReentrantLock } from "effect"
+import { Git } from "@/git"
 
 export namespace Storage {
   const log = Log.create({ service: "storage" })
@@ -111,7 +111,7 @@ export namespace Storage {
           if (!worktree) continue
           if (!(yield* fs.isDir(worktree))) continue
           const result = yield* Effect.promise(() =>
-            git(["rev-list", "--max-parents=0", "--all"], {
+            Git.run(["rev-list", "--max-parents=0", "--all"], {
               cwd: worktree,
             }),
           )
diff --git a/packages/opencode/src/util/git.ts b/packages/opencode/src/util/git.ts
deleted file mode 100644
index 731131357..000000000
--- a/packages/opencode/src/util/git.ts
+++ /dev/null
@@ -1,35 +0,0 @@
-import { Process } from "./process"
-
-export interface GitResult {
-  exitCode: number
-  text(): string
-  stdout: Buffer
-  stderr: Buffer
-}
-
-/**
- * Run a git command.
- *
- * Uses Process helpers with stdin ignored to avoid protocol pipe inheritance
- * issues in embedded/client environments.
- */
-export async function git(args: string[], opts: { cwd: string; env?: Record<string, string> }): Promise<GitResult> {
-  return Process.run(["git", ...args], {
-    cwd: opts.cwd,
-    env: opts.env,
-    stdin: "ignore",
-    nothrow: true,
-  })
-    .then((result) => ({
-      exitCode: result.code,
-      text: () => result.stdout.toString(),
-      stdout: result.stdout,
-      stderr: result.stderr,
-    }))
-    .catch((error) => ({
-      exitCode: 1,
-      text: () => "",
-      stdout: Buffer.alloc(0),
-      stderr: Buffer.from(error instanceof Error ? error.message : String(error)),
-    }))
-}
diff --git a/packages/opencode/src/worktree/index.ts b/packages/opencode/src/worktree/index.ts
index da20a5d6d..b34364ccd 100644
--- a/packages/opencode/src/worktree/index.ts
+++ b/packages/opencode/src/worktree/index.ts
@@ -12,6 +12,7 @@ import { Slug } from "@opencode-ai/util/slug"
 import { errorMessage } from "../util/error"
 import { BusEvent } from "@/bus/bus-event"
 import { GlobalBus } from "@/bus/global"
+import { Git } from "@/git"
 import { Effect, Layer, Path, Scope, ServiceMap, Stream } from "effect"
 import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process"
 import { NodePath } from "@effect/platform-node"
@@ -515,56 +516,24 @@ export namespace Worktree {
 
         const worktreePath = entry.path
 
-        const remoteList = yield* git(["remote"], { cwd: Instance.worktree })
-        if (remoteList.code !== 0) {
-          throw new ResetFailedError({ message: remoteList.stderr || remoteList.text || "Failed to list git remotes" })
-        }
-
-        const remotes = remoteList.text
-          .split("\n")
-          .map((l) => l.trim())
-          .filter(Boolean)
-        const remote = remotes.includes("origin")
-          ? "origin"
-          : remotes.length === 1
-            ? remotes[0]
-            : remotes.includes("upstream")
-              ? "upstream"
-              : ""
-
-        const remoteHead = remote
-          ? yield* git(["symbolic-ref", `refs/remotes/${remote}/HEAD`], { cwd: Instance.worktree })
-          : { code: 1, text: "", stderr: "" }
-
-        const remoteRef = remoteHead.code === 0 ? remoteHead.text.trim() : ""
-        const remoteTarget = remoteRef ? remoteRef.replace(/^refs\/remotes\//, "") : ""
-        const remoteBranch =
-          remote && remoteTarget.startsWith(`${remote}/`) ? remoteTarget.slice(`${remote}/`.length) : ""
-
-        const [mainCheck, masterCheck] = yield* Effect.all(
-          [
-            git(["show-ref", "--verify", "--quiet", "refs/heads/main"], { cwd: Instance.worktree }),
-            git(["show-ref", "--verify", "--quiet", "refs/heads/master"], { cwd: Instance.worktree }),
-          ],
-          { concurrency: 2 },
-        )
-        const localBranch = mainCheck.code === 0 ? "main" : masterCheck.code === 0 ? "master" : ""
-
-        const target = remoteBranch ? `${remote}/${remoteBranch}` : localBranch
-        if (!target) {
+        const base = yield* Effect.promise(() => Git.defaultBranch(Instance.worktree))
+        if (!base) {
           throw new ResetFailedError({ message: "Default branch not found" })
         }
 
-        if (remoteBranch) {
+        const sep = base.ref.indexOf("/")
+        if (base.ref !== base.name && sep > 0) {
+          const remote = base.ref.slice(0, sep)
+          const branch = base.ref.slice(sep + 1)
           yield* gitExpect(
-            ["fetch", remote, remoteBranch],
+            ["fetch", remote, branch],
             { cwd: Instance.worktree },
-            (r) => new ResetFailedError({ message: r.stderr || r.text || `Failed to fetch ${target}` }),
+            (r) => new ResetFailedError({ message: r.stderr || r.text || `Failed to fetch ${base.ref}` }),
           )
         }
 
         yield* gitExpect(
-          ["reset", "--hard", target],
+          ["reset", "--hard", base.ref],
           { cwd: worktreePath },
           (r) => new ResetFailedError({ message: r.stderr || r.text || "Failed to reset worktree to target" }),
         )
diff --git a/packages/opencode/test/git/git.test.ts b/packages/opencode/test/git/git.test.ts
new file mode 100644
index 000000000..a897a38e6
--- /dev/null
+++ b/packages/opencode/test/git/git.test.ts
@@ -0,0 +1,128 @@
+import { $ } from "bun"
+import { describe, expect, test } from "bun:test"
+import fs from "fs/promises"
+import path from "path"
+import { ManagedRuntime } from "effect"
+import { Git } from "../../src/git"
+import { tmpdir } from "../fixture/fixture"
+
+const weird = process.platform === "win32" ? "space file.txt" : "tab\tfile.txt"
+
+async function withGit<T>(body: (rt: ManagedRuntime.ManagedRuntime<Git.Service, never>) => Promise<T>) {
+  const rt = ManagedRuntime.make(Git.defaultLayer)
+  try {
+    return await body(rt)
+  } finally {
+    await rt.dispose()
+  }
+}
+
+describe("Git", () => {
+  test("branch() returns current branch name", async () => {
+    await using tmp = await tmpdir({ git: true })
+
+    await withGit(async (rt) => {
+      const branch = await rt.runPromise(Git.Service.use((git) => git.branch(tmp.path)))
+      expect(branch).toBeDefined()
+      expect(typeof branch).toBe("string")
+    })
+  })
+
+  test("branch() returns undefined for non-git directories", async () => {
+    await using tmp = await tmpdir()
+
+    await withGit(async (rt) => {
+      const branch = await rt.runPromise(Git.Service.use((git) => git.branch(tmp.path)))
+      expect(branch).toBeUndefined()
+    })
+  })
+
+  test("branch() returns undefined for detached HEAD", async () => {
+    await using tmp = await tmpdir({ git: true })
+    const hash = (await $`git rev-parse HEAD`.cwd(tmp.path).quiet().text()).trim()
+    await $`git checkout --detach ${hash}`.cwd(tmp.path).quiet()
+
+    await withGit(async (rt) => {
+      const branch = await rt.runPromise(Git.Service.use((git) => git.branch(tmp.path)))
+      expect(branch).toBeUndefined()
+    })
+  })
+
+  test("defaultBranch() uses init.defaultBranch when available", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await $`git branch -M trunk`.cwd(tmp.path).quiet()
+    await $`git config init.defaultBranch trunk`.cwd(tmp.path).quiet()
+
+    await withGit(async (rt) => {
+      const branch = await rt.runPromise(Git.Service.use((git) => git.defaultBranch(tmp.path)))
+      expect(branch?.name).toBe("trunk")
+      expect(branch?.ref).toBe("trunk")
+    })
+  })
+
+  test("status() handles special filenames", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await fs.writeFile(path.join(tmp.path, weird), "hello\n", "utf-8")
+
+    await withGit(async (rt) => {
+      const status = await rt.runPromise(Git.Service.use((git) => git.status(tmp.path)))
+      expect(status).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({
+            file: weird,
+            status: "added",
+          }),
+        ]),
+      )
+    })
+  })
+
+  test("diff(), stats(), and mergeBase() parse tracked changes", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await $`git branch -M main`.cwd(tmp.path).quiet()
+    await fs.writeFile(path.join(tmp.path, weird), "before\n", "utf-8")
+    await $`git add .`.cwd(tmp.path).quiet()
+    await $`git commit --no-gpg-sign -m "add file"`.cwd(tmp.path).quiet()
+    await $`git checkout -b feature/test`.cwd(tmp.path).quiet()
+    await fs.writeFile(path.join(tmp.path, weird), "after\n", "utf-8")
+
+    await withGit(async (rt) => {
+      const [base, diff, stats] = await Promise.all([
+        rt.runPromise(Git.Service.use((git) => git.mergeBase(tmp.path, "main"))),
+        rt.runPromise(Git.Service.use((git) => git.diff(tmp.path, "HEAD"))),
+        rt.runPromise(Git.Service.use((git) => git.stats(tmp.path, "HEAD"))),
+      ])
+
+      expect(base).toBeTruthy()
+      expect(diff).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({
+            file: weird,
+            status: "modified",
+          }),
+        ]),
+      )
+      expect(stats).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({
+            file: weird,
+            additions: 1,
+            deletions: 1,
+          }),
+        ]),
+      )
+    })
+  })
+
+  test("show() returns empty text for binary blobs", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await fs.writeFile(path.join(tmp.path, "bin.dat"), new Uint8Array([0, 1, 2, 3]))
+    await $`git add .`.cwd(tmp.path).quiet()
+    await $`git commit --no-gpg-sign -m "add binary"`.cwd(tmp.path).quiet()
+
+    await withGit(async (rt) => {
+      const text = await rt.runPromise(Git.Service.use((git) => git.show(tmp.path, "HEAD", "bin.dat")))
+      expect(text).toBe("")
+    })
+  })
+})
diff --git a/packages/opencode/test/project/vcs.test.ts b/packages/opencode/test/project/vcs.test.ts
index 346f55039..a327f65fa 100644
--- a/packages/opencode/test/project/vcs.test.ts
+++ b/packages/opencode/test/project/vcs.test.ts
@@ -8,8 +8,13 @@ import { Instance } from "../../src/project/instance"
 import { GlobalBus } from "../../src/bus/global"
 import { Vcs } from "../../src/project/vcs"
 
+// Skip in CI — native @parcel/watcher binding needed
 const describeVcs = FileWatcher.hasNativeBinding() && !process.env.CI ? describe : describe.skip
 
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
 async function withVcs(directory: string, body: () => Promise<void>) {
   return Instance.provide({
     directory,
@@ -22,8 +27,20 @@ async function withVcs(directory: string, body: () => Promise<void>) {
   })
 }
 
+function withVcsOnly(directory: string, body: () => Promise<void>) {
+  return Instance.provide({
+    directory,
+    fn: async () => {
+      Vcs.init()
+      await body()
+    },
+  })
+}
+
 type BranchEvent = { directory?: string; payload: { type: string; properties: { branch?: string } } }
+const weird = process.platform === "win32" ? "space file.txt" : "tab\tfile.txt"
 
+/** Wait for a Vcs.Event.BranchUpdated event on GlobalBus, with retry polling as fallback */
 function nextBranchUpdate(directory: string, timeout = 10_000) {
   return new Promise<string | undefined>((resolve, reject) => {
     let settled = false
@@ -49,6 +66,10 @@ function nextBranchUpdate(directory: string, timeout = 10_000) {
   })
 }
 
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
 describeVcs("Vcs", () => {
   afterEach(async () => {
     await Instance.disposeAll()
@@ -82,11 +103,7 @@ describeVcs("Vcs", () => {
       const pending = nextBranchUpdate(tmp.path)
 
       const head = path.join(tmp.path, ".git", "HEAD")
-      await fs.writeFile(
-        head,
-        `ref: refs/heads/${branch}
-`,
-      )
+      await fs.writeFile(head, `ref: refs/heads/${branch}\n`)
 
       const updated = await pending
       expect(updated).toBe(branch)
@@ -102,11 +119,7 @@ describeVcs("Vcs", () => {
       const pending = nextBranchUpdate(tmp.path)
 
       const head = path.join(tmp.path, ".git", "HEAD")
-      await fs.writeFile(
-        head,
-        `ref: refs/heads/${branch}
-`,
-      )
+      await fs.writeFile(head, `ref: refs/heads/${branch}\n`)
 
       await pending
       const current = await Vcs.branch()
@@ -114,3 +127,102 @@ describeVcs("Vcs", () => {
     })
   })
 })
+
+describe("Vcs diff", () => {
+  afterEach(async () => {
+    await Instance.disposeAll()
+  })
+
+  test("defaultBranch() falls back to main", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await $`git branch -M main`.cwd(tmp.path).quiet()
+
+    await withVcsOnly(tmp.path, async () => {
+      const branch = await Vcs.defaultBranch()
+      expect(branch).toBe("main")
+    })
+  })
+
+  test("defaultBranch() uses init.defaultBranch when available", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await $`git branch -M trunk`.cwd(tmp.path).quiet()
+    await $`git config init.defaultBranch trunk`.cwd(tmp.path).quiet()
+
+    await withVcsOnly(tmp.path, async () => {
+      const branch = await Vcs.defaultBranch()
+      expect(branch).toBe("trunk")
+    })
+  })
+
+  test("detects current branch from the active worktree", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await using wt = await tmpdir()
+    await $`git branch -M main`.cwd(tmp.path).quiet()
+    const dir = path.join(wt.path, "feature")
+    await $`git worktree add -b feature/test ${dir} HEAD`.cwd(tmp.path).quiet()
+
+    await withVcsOnly(dir, async () => {
+      const [branch, base] = await Promise.all([Vcs.branch(), Vcs.defaultBranch()])
+      expect(branch).toBe("feature/test")
+      expect(base).toBe("main")
+    })
+  })
+
+  test("diff('git') returns uncommitted changes", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await fs.writeFile(path.join(tmp.path, "file.txt"), "original\n", "utf-8")
+    await $`git add .`.cwd(tmp.path).quiet()
+    await $`git commit --no-gpg-sign -m "add file"`.cwd(tmp.path).quiet()
+    await fs.writeFile(path.join(tmp.path, "file.txt"), "changed\n", "utf-8")
+
+    await withVcsOnly(tmp.path, async () => {
+      const diff = await Vcs.diff("git")
+      expect(diff).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({
+            file: "file.txt",
+            status: "modified",
+          }),
+        ]),
+      )
+    })
+  })
+
+  test("diff('git') handles special filenames", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await fs.writeFile(path.join(tmp.path, weird), "hello\n", "utf-8")
+
+    await withVcsOnly(tmp.path, async () => {
+      const diff = await Vcs.diff("git")
+      expect(diff).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({
+            file: weird,
+            status: "added",
+          }),
+        ]),
+      )
+    })
+  })
+
+  test("diff('branch') returns changes against default branch", async () => {
+    await using tmp = await tmpdir({ git: true })
+    await $`git branch -M main`.cwd(tmp.path).quiet()
+    await $`git checkout -b feature/test`.cwd(tmp.path).quiet()
+    await fs.writeFile(path.join(tmp.path, "branch.txt"), "hello\n", "utf-8")
+    await $`git add .`.cwd(tmp.path).quiet()
+    await $`git commit --no-gpg-sign -m "branch file"`.cwd(tmp.path).quiet()
+
+    await withVcsOnly(tmp.path, async () => {
+      const diff = await Vcs.diff("branch")
+      expect(diff).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({
+            file: "branch.txt",
+            status: "added",
+          }),
+        ]),
+      )
+    })
+  })
+})
diff --git a/packages/sdk/js/src/v2/gen/sdk.gen.ts b/packages/sdk/js/src/v2/gen/sdk.gen.ts
index 113b3ed0f..3a780e234 100644
--- a/packages/sdk/js/src/v2/gen/sdk.gen.ts
+++ b/packages/sdk/js/src/v2/gen/sdk.gen.ts
@@ -175,6 +175,7 @@ import type {
   TuiSelectSessionResponses,
   TuiShowToastResponses,
   TuiSubmitPromptResponses,
+  VcsDiffResponses,
   VcsGetResponses,
   WorktreeCreateErrors,
   WorktreeCreateInput,
@@ -3848,6 +3849,38 @@ export class Vcs extends HeyApiClient {
       ...params,
     })
   }
+
+  /**
+   * Get VCS diff
+   *
+   * Retrieve the current git diff for the working tree or against the default branch.
+   */
+  public diff<ThrowOnError extends boolean = false>(
+    parameters: {
+      directory?: string
+      workspace?: string
+      mode: "git" | "branch"
+    },
+    options?: Options<never, ThrowOnError>,
+  ) {
+    const params = buildClientParams(
+      [parameters],
+      [
+        {
+          args: [
+            { in: "query", key: "directory" },
+            { in: "query", key: "workspace" },
+            { in: "query", key: "mode" },
+          ],
+        },
+      ],
+    )
+    return (options?.client ?? this.client).get<VcsDiffResponses, unknown, ThrowOnError>({
+      url: "/vcs/diff",
+      ...options,
+      ...params,
+    })
+  }
 }
 
 export class Command extends HeyApiClient {
diff --git a/packages/sdk/js/src/v2/gen/types.gen.ts b/packages/sdk/js/src/v2/gen/types.gen.ts
index 2f8e99cfe..d517abf2c 100644
--- a/packages/sdk/js/src/v2/gen/types.gen.ts
+++ b/packages/sdk/js/src/v2/gen/types.gen.ts
@@ -2003,6 +2003,7 @@ export type Path = {
 
 export type VcsInfo = {
   branch?: string
+  default_branch?: string
 }
 
 export type Command = {
@@ -5065,6 +5066,26 @@ export type VcsGetResponses = {
 
 export type VcsGetResponse = VcsGetResponses[keyof VcsGetResponses]
 
+export type VcsDiffData = {
+  body?: never
+  path?: never
+  query: {
+    directory?: string
+    workspace?: string
+    mode: "git" | "branch"
+  }
+  url: "/vcs/diff"
+}
+
+export type VcsDiffResponses = {
+  /**
+   * VCS diff
+   */
+  200: Array<FileDiff>
+}
+
+export type VcsDiffResponse = VcsDiffResponses[keyof VcsDiffResponses]
+
 export type CommandListData = {
   body?: never
   path?: never
diff --git a/packages/ui/src/components/session-review.tsx b/packages/ui/src/components/session-review.tsx
index 1040aa292..3b582d66f 100644
--- a/packages/ui/src/components/session-review.tsx
+++ b/packages/ui/src/components/session-review.tsx
@@ -359,11 +359,10 @@ export const SessionReview = (props: SessionReviewProps) => {
           <Show when={hasDiffs()} fallback={props.empty}>
             <div class="pb-6">
               <Accordion multiple value={open()} onChange={handleChange}>
-                <For each={files()}>
-                  {(file) => {
+                <For each={props.diffs}>
+                  {(diff) => {
                     let wrapper: HTMLDivElement | undefined
-
-                    const item = createMemo(() => diffs().get(file)!)
+                    const file = diff.file
 
                     const expanded = createMemo(() => open().includes(file))
                     const mounted = createMemo(() => expanded() && (!!store.visible[file] || pinned(file)))
@@ -372,9 +371,9 @@ export const SessionReview = (props: SessionReviewProps) => {
                     const comments = createMemo(() => grouped().get(file) ?? [])
                     const commentedLines = createMemo(() => comments().map((c) => c.selection))
 
-                    const beforeText = () => (typeof item().before === "string" ? item().before : "")
-                    const afterText = () => (typeof item().after === "string" ? item().after : "")
-                    const changedLines = () => item().additions + item().deletions
+                    const beforeText = () => (typeof diff.before === "string" ? diff.before : "")
+                    const afterText = () => (typeof diff.after === "string" ? diff.after : "")
+                    const changedLines = () => diff.additions + diff.deletions
                     const mediaKind = createMemo(() => mediaKindFromPath(file))
 
                     const tooLarge = createMemo(() => {
@@ -385,9 +384,9 @@ export const SessionReview = (props: SessionReviewProps) => {
                     })
 
                     const isAdded = () =>
-                      item().status === "added" || (beforeText().length === 0 && afterText().length > 0)
+                      diff.status === "added" || (beforeText().length === 0 && afterText().length > 0)
                     const isDeleted = () =>
-                      item().status === "deleted" || (afterText().length === 0 && beforeText().length > 0)
+                      diff.status === "deleted" || (afterText().length === 0 && beforeText().length > 0)
 
                     const selectedLines = createMemo(() => {
                       const current = selection()
@@ -425,7 +424,7 @@ export const SessionReview = (props: SessionReviewProps) => {
                           file,
                           selection,
                           comment,
-                          preview: selectionPreview(item(), selection),
+                          preview: selectionPreview(diff, selection),
                         })
                       },
                       onUpdate: ({ id, comment, selection }) => {
@@ -434,7 +433,7 @@ export const SessionReview = (props: SessionReviewProps) => {
                           file,
                           selection,
                           comment,
-                          preview: selectionPreview(item(), selection),
+                          preview: selectionPreview(diff, selection),
                         })
                       },
                       onDelete: (comment) => {
@@ -513,7 +512,7 @@ export const SessionReview = (props: SessionReviewProps) => {
                                       <span data-slot="session-review-change" data-type="added">
                                         {i18n.t("ui.sessionReview.change.added")}
                                       </span>
-                                      <DiffChanges changes={item()} />
+                                      <DiffChanges changes={diff} />
                                     </div>
                                   </Match>
                                   <Match when={isDeleted()}>
@@ -527,7 +526,7 @@ export const SessionReview = (props: SessionReviewProps) => {
                                     </span>
                                   </Match>
                                   <Match when={true}>
-                                    <DiffChanges changes={item()} />
+                                    <DiffChanges changes={diff} />
                                   </Match>
                                 </Switch>
                                 <span data-slot="session-review-diff-chevron">
@@ -582,7 +581,7 @@ export const SessionReview = (props: SessionReviewProps) => {
                                   <Dynamic
                                     component={fileComponent}
                                     mode="diff"
-                                    preloadedDiff={item().preloaded}
+                                    preloadedDiff={diff.preloaded}
                                     diffStyle={diffStyle()}
                                     onRendered={() => {
                                       props.onDiffRendered?.()
@@ -599,17 +598,17 @@ export const SessionReview = (props: SessionReviewProps) => {
                                     commentedLines={commentedLines()}
                                     before={{
                                       name: file,
-                                      contents: typeof item().before === "string" ? item().before : "",
+                                      contents: typeof diff.before === "string" ? diff.before : "",
                                     }}
                                     after={{
                                       name: file,
-                                      contents: typeof item().after === "string" ? item().after : "",
+                                      contents: typeof diff.after === "string" ? diff.after : "",
                                     }}
                                     media={{
                                       mode: "auto",
                                       path: file,
-                                      before: item().before,
-                                      after: item().after,
+                                      before: diff.before,
+                                      after: diff.after,
                                       readFile: props.readFile,
                                     }}
                                   />
diff --git a/packages/ui/src/i18n/en.ts b/packages/ui/src/i18n/en.ts
index e66b55092..837fd5afc 100644
--- a/packages/ui/src/i18n/en.ts
+++ b/packages/ui/src/i18n/en.ts
@@ -1,5 +1,7 @@
 export const dict: Record<string, string> = {
   "ui.sessionReview.title": "Session changes",
+  "ui.sessionReview.title.git": "Git changes",
+  "ui.sessionReview.title.branch": "Branch changes",
   "ui.sessionReview.title.lastTurn": "Last turn changes",
   "ui.sessionReview.diffStyle.unified": "Unified",
   "ui.sessionReview.diffStyle.split": "Split",