diff --git a/packages/app/src/context/layout.tsx b/packages/app/src/context/layout.tsx
index f6a909c4b..3dcc11e19 100644
--- a/packages/app/src/context/layout.tsx
+++ b/packages/app/src/context/layout.tsx
@@ -702,7 +702,7 @@ export const { use: useLayout, provider: LayoutProvider } = createSimpleContext(
         },
       },
       review: {
-        diffStyle: createMemo(() => store.review?.diffStyle ?? "split"),
+        diffStyle: createMemo(() => store.review?.diffStyle ?? "unified"),
         setDiffStyle(diffStyle: ReviewDiffStyle) {
           if (!store.review) {
             setStore("review", { diffStyle, panelOpened: DEFAULT_REVIEW_PANEL_OPENED })
diff --git a/packages/app/src/pages/session.tsx b/packages/app/src/pages/session.tsx
index 183ae8e9e..30ead384b 100644
--- a/packages/app/src/pages/session.tsx
+++ b/packages/app/src/pages/session.tsx
@@ -1,7 +1,7 @@
-import type { FilePart, Project, UserMessage, VcsFileDiff } from "@opencode-ai/sdk/v2"
+import type { FilePart, Project, SnapshotFileDiff, UserMessage } from "@opencode-ai/sdk/v2"
 import { getFilename } from "@opencode-ai/core/util/path"
 import { useDialog } from "@opencode-ai/ui/context/dialog"
-import { createQuery, skipToken, useMutation, useQueryClient } from "@tanstack/solid-query"
+import { createQuery, skipToken, useMutation } from "@tanstack/solid-query"
 import {
   batch,
   ErrorBoundary,
@@ -22,14 +22,11 @@ import {
 import { makeEventListener } from "@solid-primitives/event-listener"
 import { createMediaQuery } from "@solid-primitives/media"
 import { createResizeObserver } from "@solid-primitives/resize-observer"
-import { debounce } from "@solid-primitives/scheduled"
 import { useLocal } from "@/context/local"
 import { FileProvider, selectionFromLines, useFile, type FileSelection, type SelectedLineRange } from "@/context/file"
 import { createStore } from "solid-js/store"
 import type { SessionReviewLineComment } from "@opencode-ai/session-ui/session-review"
 import { ResizeHandle } from "@opencode-ai/ui/resize-handle"
-import { Select } from "@opencode-ai/ui/select"
-import { SelectV2 } from "@opencode-ai/ui/v2/select-v2"
 import { isScrollKeyTarget, scrollKey, scrollKeyOwner } from "@opencode-ai/ui/scroll-view"
 import { Tabs } from "@opencode-ai/ui/tabs"
 import { ButtonV2 } from "@opencode-ai/ui/v2/button-v2"
@@ -88,10 +85,8 @@ import {
 import { SessionSidePanel } from "@/pages/session/session-side-panel"
 import { sessionPanelLayout } from "@/pages/session/session-panel-layout"
 import { SessionReviewEmptyChangesV2 } from "@opencode-ai/session-ui/v2/session-review-empty-changes-v2"
-import { SessionReviewEmptyNoGitV2 } from "@opencode-ai/session-ui/v2/session-review-empty-no-git-v2"
 import { ReviewPanelV2 } from "@/pages/session/v2/review-panel-v2"
 import { createReviewPanelV2State } from "@/pages/session/v2/review-panel-v2-state"
-import { reviewDiffDirectory, reviewDiffNeedsLoad, reviewRootDirectory } from "@/pages/session/v2/review-diff-kinds"
 import { TerminalPanel } from "@/pages/session/terminal-panel"
 import { TerminalPanelV2 } from "@/pages/session/terminal-panel-v2"
 import { useComposerCommands } from "@/pages/session/use-composer-commands"
@@ -99,7 +94,6 @@ import { useSessionCommands } from "@/pages/session/use-session-commands"
 import { useAmicodeCommands } from "@/pages/session/use-amicode-commands"
 import { useSessionHashScroll } from "@/pages/session/use-session-hash-scroll"
 import { Identifier } from "@/utils/id"
-import { diffs as list } from "@/utils/diffs"
 import { Persist, persisted } from "@/utils/persist"
 import { extractPromptFromParts } from "@/utils/prompt"
 import { formatServerError, isLocalSessionNotFoundError, isSessionNotFoundError } from "@/utils/server-errors"
@@ -115,9 +109,6 @@ type FollowupItem = FollowupDraft & { id: string }
 type FollowupEdit = Pick<FollowupItem, "id" | "prompt" | "context">
 const emptyFollowups: FollowupItem[] = []
 
-type ChangeMode = "git" | "branch" | "turn"
-type VcsMode = "git" | "branch"
-
 const sessionViewState = () => ({
   messageId: undefined as string | undefined,
   mobileTab: "session" as "session" | "changes",
@@ -363,7 +354,6 @@ export default function Page() {
   const local = useLocal()
   const file = useFile()
   const sync = useSync()
-  const queryClient = useQueryClient()
   const dialog = useDialog()
   const language = useLanguage()
   const sdk = useSDK()
@@ -378,7 +368,6 @@ export default function Page() {
   const location = useLocation()
   const navigate = useNavigate()
   const { params, sessionKey, workspaceKey, tabs, view } = useSessionLayout()
-  const reviewMode = () => view().review.mode() ?? "git"
   const reviewFile = () => view().review.file()
   const sessionOwnership = createSessionOwnership(sessionKey)
   const newSessionDesign = createMemo(() => settings.general.newLayoutDesigns())
@@ -675,63 +664,55 @@ export default function Page() {
     return open
   }, desktopReviewOpen())
 
-  const turnDiffs = createMemo(() => list(lastUserMessage()?.summary?.diffs))
-  const nogit = createMemo(() => {
-    const project = sync().project
-    return !!project && project.vcs !== "git"
-  })
-  const changesOptions = createMemo<ChangeMode[]>(() => {
-    const list: ChangeMode[] = []
-    const project = sync().project
-    const vcs = sync().data.vcs
-    if (project?.vcs === "git") list.push("git")
-    if (project?.vcs === "git" && vcs?.branch && vcs?.default_branch && vcs.branch !== vcs.default_branch) {
-      list.push("branch")
-    }
-    list.push("turn")
-    return list
-  })
   const mobileChanges = createMemo(() => !isDesktop() && store.mobileTab === "changes")
-  const wantsReview = createMemo(() =>
-    isDesktop()
-      ? desktopFileTreeOpen() ||
-        (desktopReviewOpen() && (activeTab() === "review" || (newSessionDesign() && !!activeFileTab())))
-      : store.mobileTab === "changes",
-  )
-  const vcsMode = createMemo<VcsMode | undefined>(() => {
-    const mode = reviewMode()
-    if (mode === "git" || mode === "branch") return mode
-  })
-  const vcsKey = createMemo(
-    () =>
-      ["session-vcs", sdk().directory, sync().data.vcs?.branch ?? "", sync().data.vcs?.default_branch ?? ""] as const,
-  )
-  const vcsQuery = createQuery(() => {
-    const mode = vcsMode()
-    const enabled = wantsReview() && sync().project?.vcs === "git"
-
+  const EDIT_TOOLS = new Set(["edit", "write", "patch", "apply_patch"])
+  const sessionDiffKey = () => ["session-diff", params.id ?? ""] as const
+  const sessionDiffQuery = createQuery(() => {
+    const sessionID = params.id
     return {
-      queryKey: [...vcsKey(), mode] as const,
-      enabled,
-      queryFn: mode
+      queryKey: sessionDiffKey(),
+      enabled: !!sessionID,
+      placeholderData: [] as SnapshotFileDiff[],
+      queryFn: sessionID
         ? () =>
             sdk()
-              .api.vcs.diff({ location: { directory: sdk().directory }, mode: mode === "git" ? "working" : mode })
-              .then((result) => result.data)
-              .catch((error) => {
-                console.debug("[session-review] failed to load vcs diff", { mode, error })
-                return []
-              })
+              .client.session.diff({ sessionID, directory: sdk().directory })
+              .then((result) => (result.data ?? []) as Array<SnapshotFileDiff>)
+              .catch(() => [] as SnapshotFileDiff[])
         : skipToken,
     }
   })
-  const refreshVcs = debounce(() => void queryClient.invalidateQueries({ queryKey: vcsKey() }), 100)
-  const reviewDiffs = () => {
-    if (reviewMode() === "git" || reviewMode() === "branch")
-      // avoids suspense
-      return vcsQuery.isFetched ? (vcsQuery.data ?? []) : []
-    return turnDiffs()
-  }
+  const reviewDiffs = createMemo(() => {
+    // Server endpoint returns the authoritative full-session diff (queries all messages).
+    const serverDiffs = sessionDiffQuery.data ?? []
+    if (serverDiffs.length > 0) return serverDiffs.filter((d): d is SnapshotFileDiff & { file: string } => !!d.file)
+    // Fallback: derive from tool parts currently loaded in the client.
+    // This shows immediate results for visible messages while the server query loads.
+    const allMessages = messages()
+    if (!allMessages.length) return [] as Array<SnapshotFileDiff & { file: string }>
+    const seen = new Map<string, SnapshotFileDiff & { file: string }>()
+    for (const msg of allMessages) {
+      const parts = sync().data.part[msg.id]
+      if (!parts) continue
+      for (const part of parts) {
+        if (part.type !== "tool" || !EDIT_TOOLS.has(part.tool)) continue
+        if (part.state.status !== "completed") continue
+        const meta = part.state.metadata as Record<string, unknown> | undefined
+        const filediff = meta?.filediff as { file?: string; patch?: string; additions?: number; deletions?: number } | undefined
+        if (filediff?.file) {
+          const relPath = (part.state as { title?: string }).title || filediff.file
+          seen.set(filediff.file, {
+            file: relPath,
+            patch: filediff.patch,
+            additions: filediff.additions ?? 0,
+            deletions: filediff.deletions ?? 0,
+            status: seen.has(filediff.file) ? "modified" : "added",
+          })
+        }
+      }
+    }
+    return [...seen.values()]
+  })
   const activeReviewFile = () => {
     const diffs = reviewDiffs()
     const selected = reviewFile()
@@ -739,54 +720,13 @@ export default function Page() {
     return diffs[0]?.file
   }
   const reviewCount = () => reviewDiffs().length
-  const hasReview = () => reviewCount() > 0
-  const reviewReady = () => {
-    if (reviewMode() === "git" || reviewMode() === "branch") return !vcsQuery.isPending
-    return true
-  }
-  const loadReviewDiff = async (file: string, version?: number): Promise<VcsFileDiff | undefined> => {
-    const mode = vcsMode()
-    if (!mode) return
-    const root = reviewRootDirectory(sync().project?.worktree ?? sdk().directory)
-    const directory = reviewDiffDirectory(root, file)
-    const source = reviewDiffs().find((diff) => diff.file === file)
-    const valid = (diff: VcsFileDiff | undefined) => {
-      if (!diff || !source) return
-      if (diff.additions !== source.additions || diff.deletions !== source.deletions) return
-      if (reviewDiffNeedsLoad(diff)) return
-      return diff
-    }
-    const request = (scope: string, context?: number) =>
-      queryClient
-        .fetchQuery({
-          queryKey: [serverSDK().scope, ...vcsKey(), mode, "directory", scope, context, version] as const,
-          staleTime: Number.POSITIVE_INFINITY,
-          retry: 2,
-          queryFn: () =>
-            sdk()
-              .api.vcs.diff({
-                location: { directory: scope },
-                mode: mode === "git" ? "working" : mode,
-                context,
-              })
-              .then((result) => result.data),
-        })
-        .then((diffs) => diffs.find((diff) => diff.file === file))
-
-    if (directory !== root) {
-      try {
-        const scoped = valid(await request(directory))
-        if (scoped) return scoped
-      } catch (error) {
-        console.debug("[session-review] failed to load scoped vcs diff", { mode, file, directory, error })
-      }
-    }
-    try {
-      const bounded = valid(await request(root, 3))
-      if (bounded) return bounded
-    } catch (error) {
-      console.debug("[session-review] failed to load bounded vcs diff", { mode, file, root, error })
-    }
+  const hasReview = () => true
+  const reviewReady = () => true
+  const loadReviewDiff = async (file: string, _version?: number): Promise<(SnapshotFileDiff & { file: string }) | undefined> => {
+    const diffs = reviewDiffs()
+    const found = diffs.find((d) => d.file === file)
+    if (found && found.file) return found as SnapshotFileDiff & { file: string }
+    return undefined
   }
 
   const newSessionWorktree = createMemo(() => {
@@ -984,7 +924,6 @@ export default function Page() {
         : undefined
     const file = typeof props?.file === "string" ? props.file : undefined
     if (!file || file.startsWith(".git/")) return
-    refreshVcs()
   })
   onCleanup(stopVcs)
 
@@ -1108,29 +1047,6 @@ export default function Page() {
     }
   }
 
-  createEffect(() => {
-    if (!layout.ready()) return
-    if (sync().status !== "complete") return
-    if (!sync().project) return
-    const list = changesOptions()
-    const mode = reviewMode()
-    if (list.includes(mode)) return
-    const next = list[0]
-    if (!next) return
-    view().review.setMode(next)
-  })
-
-  createEffect(
-    on(
-      () => sync().data.session_status[params.id ?? ""]?.type,
-      (next, prev) => {
-        if (next !== "idle" || prev === undefined || prev === "idle") return
-        refreshVcs()
-      },
-      { defer: true },
-    ),
-  )
-
   const fileTreeTab = () => layout.fileTree.tab()
   const setFileTreeTab = (value: "changes" | "all") => layout.fileTree.setTab(value)
 
@@ -1188,47 +1104,9 @@ export default function Page() {
     loadFile: file.load,
   })
 
-  const changesLabel = (option: ChangeMode) => {
-    if (option === "git") return language.t("ui.sessionReview.title.git")
-    if (option === "branch") return language.t("ui.sessionReview.title.branch")
-    return language.t("ui.sessionReview.title.lastTurn")
-  }
-
-  const changesTitle = () => {
-    if (!canReview()) {
-      return null
-    }
-
-    return (
-      <Select
-        options={changesOptions()}
-        current={reviewMode()}
-        label={changesLabel}
-        onSelect={(option) => option && view().review.setMode(option)}
-        variant="ghost"
-        size="small"
-        valueClass="text-14-medium"
-      />
-    )
-  }
-
-  const changesTitleV2 = () => {
-    if (!canReview()) {
-      return null
-    }
+  const changesTitle = () => null
 
-    return (
-      <SelectV2
-        appearance="inline"
-        options={changesOptions()}
-        current={reviewMode()}
-        label={changesLabel}
-        placement="bottom-start"
-        gutter={6}
-        onSelect={(option) => option && view().review.setMode(option)}
-      />
-    )
-  }
+  const changesTitleV2 = () => null
 
   const empty = (text: string) => (
     <div class="h-full pb-64 -mt-4 flex flex-col items-center justify-center text-center gap-6">
@@ -1253,36 +1131,18 @@ export default function Page() {
   )
 
   const reviewEmptyText = createMemo(() => {
-    if (reviewMode() === "git") return language.t("session.review.noUncommittedChanges")
-    if (reviewMode() === "branch") return language.t("session.review.noBranchChanges")
     return language.t("session.review.noChanges")
   })
 
   const reviewEmpty = (input: { loadingClass: string; emptyClass: string }) => {
-    if (reviewMode() === "git" || reviewMode() === "branch") {
-      if (!reviewReady()) return <div class={input.loadingClass}>{language.t("session.review.loadingChanges")}</div>
-      return empty(reviewEmptyText())
-    }
-
-    if (reviewMode() === "turn") {
-      if (nogit()) return createGit(input)
-      return empty(reviewEmptyText())
-    }
-
-    return (
-      <div class={input.emptyClass}>
-        <div class="text-14-regular text-text-weak max-w-56">{reviewEmptyText()}</div>
-      </div>
-    )
+    if (!reviewReady()) return <div class={input.loadingClass}>{language.t("session.review.loadingChanges")}</div>
+    return empty(reviewEmptyText())
   }
 
   const reviewEmptyV2 = () => {
-    if ((reviewMode() === "git" || reviewMode() === "branch") && !reviewReady()) {
+    if (!reviewReady()) {
       return <div class="px-6 py-4 text-text-weak">{language.t("session.review.loadingChanges")}</div>
     }
-    if (reviewMode() === "turn" && nogit()) {
-      return <SessionReviewEmptyNoGitV2 pending={gitMutation.isPending} onInitGit={initGit} />
-    }
     return <SessionReviewEmptyChangesV2 />
   }
 
@@ -1334,7 +1194,7 @@ export default function Page() {
     diffs: reviewDiffs,
     diffsReady: reviewReady,
     get diffVersion() {
-      return vcsQuery.dataUpdatedAt
+      return lastUserMessage()?.time.created
     },
     loadDiff: loadReviewDiff,
     get activeFile() {
@@ -2086,9 +1946,7 @@ export default function Page() {
           classes={{ button: compact ? "w-full !py-2" : "w-full" }}
           onClick={() => setStore("mobileTab", "changes")}
         >
-          {hasReview()
-            ? language.t("session.review.filesChanged", { count: reviewCount() })
-            : language.t("session.review.change.other")}
+          {"Modified Files"}
         </Tabs.Trigger>
       </Tabs.List>
     </Tabs>
diff --git a/packages/app/src/pages/session/session-side-panel.tsx b/packages/app/src/pages/session/session-side-panel.tsx
index e04dff413..a71bde275 100644
--- a/packages/app/src/pages/session/session-side-panel.tsx
+++ b/packages/app/src/pages/session/session-side-panel.tsx
@@ -594,8 +594,8 @@ export function SessionSidePanel(props: {
                                 aria-controls={activeTab() === "review" ? reviewTabPanelID : undefined}
                               >
                                 {props.hasReview()
-                                  ? language.t("session.review.filesChanged", { count: props.reviewCount() })
-                                  : language.t("session.tab.review")}
+                                   ? "Modified Files"
+                                   : language.t("session.tab.review")}
                               </Tabs.Trigger>
                             </Show>
                             <div style={{ display: contextOpen() ? undefined : "none" }}>
@@ -817,7 +817,7 @@ export function SessionSidePanel(props: {
                             </>
                           }
                         >
-                          {language.t("session.review.filesChanged", { count: props.reviewCount() })}
+                          {"Modified Files"}
                         </Show>
                       </Tabs.Trigger>
                       <Tabs.Trigger value="all" class="flex-1" classes={{ button: "w-full" }}>
diff --git a/packages/app/src/pages/session/timeline/message-timeline.tsx b/packages/app/src/pages/session/timeline/message-timeline.tsx
index 0195d58bc..8be156388 100644
--- a/packages/app/src/pages/session/timeline/message-timeline.tsx
+++ b/packages/app/src/pages/session/timeline/message-timeline.tsx
@@ -368,6 +368,9 @@ export function MessageTimeline(props: {
   const cached = timelineCache.get(ownerSessionKey)
   const initialMeasurements = cached?.measurements
   const coldBottomMount = !initialMeasurements?.length && props.shouldAnchorBottom()
+  // Hide the scroll container for the first frame on cold-bottom-mount to prevent
+  // a flash of content at the top before scrollToEnd fires.
+  const [scrollReady, setScrollReady] = createSignal(!coldBottomMount)
   const platform = usePlatform()
 
   const [listRoot, setListRoot] = createSignal<HTMLDivElement>()
@@ -541,7 +544,9 @@ export function MessageTimeline(props: {
       }
     },
     anchorTo: "end",
-    followOnAppend: true,
+    get followOnAppend() {
+      return props.shouldAnchorBottom() && !props.hasScrollGesture()
+    },
     scrollEndThreshold: 80,
     get scrollMargin() {
       return showHeader() ? 64 : 0
@@ -686,6 +691,7 @@ export function MessageTimeline(props: {
       overscanFrame = undefined
       if (renderOverscan() < 20) setRenderOverscan(20)
       if (props.shouldAnchorBottom()) virtualizer.scrollToEnd()
+      if (!scrollReady()) setScrollReady(true)
     })
   })
 
@@ -1582,6 +1588,7 @@ export function MessageTimeline(props: {
         class="relative min-w-0 w-full h-full"
         style={{
           "--sticky-accordion-top": showHeader() ? "48px" : "0px",
+          opacity: scrollReady() ? undefined : "0",
         }}
       >
         <Show when={showHeader()}>
diff --git a/packages/opencode/src/server/routes/instance/httpapi/handlers/session.ts b/packages/opencode/src/server/routes/instance/httpapi/handlers/session.ts
index f6ac905e4..4ffe5d922 100644
--- a/packages/opencode/src/server/routes/instance/httpapi/handlers/session.ts
+++ b/packages/opencode/src/server/routes/instance/httpapi/handlers/session.ts
@@ -100,7 +100,7 @@ export const sessionHandlers = HttpApiBuilder.group(InstanceHttpApi, "session",
       params: { sessionID: SessionID }
       query: typeof DiffQuery.Type
     }) {
-      return yield* summary.diff({ sessionID: ctx.params.sessionID, messageID: ctx.query.messageID })
+      return yield* session.diff(ctx.params.sessionID)
     })
 
     const messages = Effect.fn("SessionHttpApi.messages")(function* (ctx: {
diff --git a/packages/opencode/src/session/session.ts b/packages/opencode/src/session/session.ts
index 2ba5f9f50..e3e74ebfe 100644
--- a/packages/opencode/src/session/session.ts
+++ b/packages/opencode/src/session/session.ts
@@ -488,7 +488,7 @@ export type Patch = Omit<Partial<Info>, "time" | "share" | "summary" | "revert"
 const layer: Layer.Layer<
   Service,
   never,
-  BackgroundJob.Service | RuntimeFlags.Service | Database.Service | EventV2Bridge.Service
+  BackgroundJob.Service | RuntimeFlags.Service | Database.Service | EventV2Bridge.Service | Snapshot.Service
 > = Layer.effect(
   Service,
   Effect.gen(function* () {
@@ -497,6 +497,7 @@ const layer: Layer.Layer<
     const background = yield* BackgroundJob.Service
     const events = yield* EventV2Bridge.Service
     const flags = yield* RuntimeFlags.Service
+    const snapshot = yield* Snapshot.Service
 
     const createNext = Effect.fn("Session.createNext")(function* (input: {
       id?: SessionID
@@ -835,8 +836,94 @@ const layer: Layer.Layer<
     })
 
     const diff = Effect.fn("Session.diff")(function* (sessionID: SessionID) {
-      void sessionID
-      return [] as Snapshot.FileDiff[]
+      const all = yield* messages({ sessionID }).pipe(Effect.orDie)
+      if (!all.length) return [] as Snapshot.FileDiff[]
+
+      // Find the first step-start snapshot hash (session-start ref)
+      // and the last step-finish snapshot hash (session-end ref)
+      let from: string | undefined
+      let lastStepFinish: string | undefined
+      // Collect all agent-touched files from PatchParts (absolute paths)
+      const agentFilesAbsolute = new Set<string>()
+
+      for (const msg of all) {
+        for (const part of msg.parts) {
+          if (!from && part.type === "step-start" && part.snapshot) {
+            from = part.snapshot
+          }
+          if (part.type === "step-finish" && part.snapshot) {
+            lastStepFinish = part.snapshot
+          }
+          if (part.type === "patch" && part.files) {
+            for (const file of part.files) agentFilesAbsolute.add(file)
+          }
+        }
+      }
+
+      // If we have snapshot hashes and agent-touched files, compute the real diff
+      if (from && agentFilesAbsolute.size > 0) {
+        // Use last step-finish hash if available (completed session),
+        // otherwise fall back to current working tree state (session still running)
+        const to = lastStepFinish ?? (yield* snapshot.track())
+        if (to) {
+          // Normalize agent-touched files to relative paths (diffFull returns relative paths)
+          const ctx = yield* InstanceState.context
+          const worktree = ctx.worktree
+          const agentFiles = new Set<string>()
+          for (const abs of agentFilesAbsolute) {
+            const rel = abs.startsWith(worktree)
+              ? abs.slice(worktree.length).replace(/^\//, "").replaceAll("\\", "/")
+              : abs.replaceAll("\\", "/")
+            agentFiles.add(rel)
+          }
+
+          const allDiffs = yield* snapshot.diffFull(from, to).pipe(
+            Effect.catchCause(() => Effect.succeed([] as Snapshot.FileDiff[])),
+          )
+          const filtered = allDiffs.filter(
+            (d: Snapshot.FileDiff) => d.file && agentFiles.has(d.file) && (d.additions ?? 0) + (d.deletions ?? 0) > 0,
+          )
+          if (filtered.length > 0) return filtered
+        }
+      }
+
+      // Fallback 1: aggregate stored per-message summary diffs across the session.
+      const seen = new Map<string, Snapshot.FileDiff>()
+      for (const msg of all) {
+        if (msg.info.role !== "user") continue
+        const diffs = msg.info.summary?.diffs
+        if (!diffs) continue
+        for (const d of diffs) {
+          if (d.file) seen.set(d.file, d)
+        }
+      }
+      if (seen.size > 0) return [...seen.values()]
+
+      // Fallback 2: extract diffs from edit/write tool part metadata (filediff).
+      // This covers sessions where snapshots and summary diffs are both empty
+      // but the tool parts carry their own diff data.
+      const EDIT_TOOLS = new Set(["edit", "write", "patch", "apply_patch"])
+      for (const msg of all) {
+        for (const part of msg.parts) {
+          if (part.type !== "tool") continue
+          const toolPart = part as { tool?: string; state?: { status?: string; metadata?: Record<string, unknown>; title?: string } }
+          if (!toolPart.tool || !EDIT_TOOLS.has(toolPart.tool)) continue
+          if (toolPart.state?.status !== "completed") continue
+          const filediff = toolPart.state?.metadata?.filediff as
+            | { file?: string; patch?: string; additions?: number; deletions?: number }
+            | undefined
+          if (!filediff?.file) continue
+          const relPath = toolPart.state?.title || filediff.file
+          seen.set(filediff.file, {
+            file: relPath,
+            patch: filediff.patch,
+            additions: filediff.additions ?? 0,
+            deletions: filediff.deletions ?? 0,
+            status: seen.has(filediff.file) ? "modified" : "added",
+          })
+        }
+      }
+      return [...seen.values()]
     })
 
     const messages: Interface["messages"] = Effect.fn("Session.messages")(function* (input) {
@@ -1024,7 +1111,7 @@ function listByProject(
 export const node = LayerNode.make({
   service: Service,
   layer: layer,
-  deps: [BackgroundJob.node, RuntimeFlags.node, Database.node, EventV2Bridge.node],
+  deps: [BackgroundJob.node, RuntimeFlags.node, Database.node, EventV2Bridge.node, Snapshot.node],
 })
 
 export * as Session from "./session"
diff --git a/packages/opencode/test/server/session-diff-missing-patch.test.ts b/packages/opencode/test/server/session-diff-missing-patch.test.ts
index d2a4211ff..3dd182d19 100644
--- a/packages/opencode/test/server/session-diff-missing-patch.test.ts
+++ b/packages/opencode/test/server/session-diff-missing-patch.test.ts
@@ -1,14 +1,14 @@
 /**
- * Regression test for the same bug class as #26574 (sibling of #26566 and
- * #26553). The Desktop app calls GET /session/<id>/diff; before #26574
- * the response was Schema-encoded against `Snapshot.FileDiff` with
- * `patch: Schema.String` (required), so any session whose stored
- * `summary_diffs` had a row without `patch` returned HTTP 400 and the
- * session never loaded. Legacy session-level diffs are no longer surfaced,
- * but the endpoint remains compatible and must still return successfully.
+ * Tests for GET /session/<id>/diff endpoint.
  *
- * This test inserts a session row with a missing-patch diff entry and
- * asserts that GET /session/<id>/diff returns 200 with empty data.
+ * After #174, this endpoint returns session-scoped agent diffs computed from
+ * snapshots (the net diff from session start to current, filtered to files the
+ * agent touched via PatchParts). Legacy per-message summary diffs are no longer
+ * served through this endpoint.
+ *
+ * - A session with no snapshot parts returns [].
+ * - A session with legacy storage-based diffs (missing `patch`) returns [].
+ * - The messageID query param is accepted but ignored (backwards compat).
  */
 import { afterEach, describe, expect } from "bun:test"
 import { LayerNode } from "@opencode-ai/core/effect/layer-node"
@@ -39,17 +39,16 @@ function pathFor(template: string, params: Record<string, string>) {
 const withSession = (input?: Parameters<Session.Interface["create"]>[0]) =>
   Effect.acquireRelease(Session.use.create(input), (created) => Session.use.remove(created.id).pipe(Effect.ignore))
 
-describe("session diff with missing patch (#26574)", () => {
+describe("session-scoped diff (#174)", () => {
   it.instance(
-    "GET /session/<id>/diff ignores legacy session-level diff storage",
+    "GET /session/<id>/diff returns [] for session with legacy storage diffs",
     () =>
       Effect.gen(function* () {
         const test = yield* TestInstance
         const session = yield* withSession({ title: "missing-patch" })
 
         // Mimic legacy/imported on-disk shape: a diff entry with no
-        // `patch` text. Pre-fix the typed response encoder rejects
-        // this and returns 400.
+        // `patch` text. The endpoint no longer reads from storage.
         yield* Storage.Service.use((storage) =>
           storage.write(["session_diff", session.id], [{ file: "legacy.txt", additions: 1, deletions: 0 }]),
         )
@@ -66,11 +65,11 @@ describe("session diff with missing patch (#26574)", () => {
   )
 
   it.instance(
-    "GET /session/<id>/diff returns requested turn diffs",
+    "GET /session/<id>/diff falls back to stored summary diffs when no snapshots exist",
     () =>
       Effect.gen(function* () {
         const test = yield* TestInstance
-        const session = yield* withSession({ title: "turn-diff" })
+        const session = yield* withSession({ title: "no-snapshots" })
         const messageID = MessageID.ascending()
         yield* Session.use.updateMessage({
           id: messageID,
@@ -84,6 +83,7 @@ describe("session diff with missing patch (#26574)", () => {
           },
         } satisfies SessionV1.User)
 
+        // No snapshot parts exist, so it falls back to per-message summary diffs
         const response = yield* requestInDirectory(
           `${pathFor(SessionPaths.diff, { sessionID: session.id })}?messageID=${messageID}`,
           test.directory,
diff --git a/packages/opencode/test/server/session-diff-scoped.test.ts b/packages/opencode/test/server/session-diff-scoped.test.ts
new file mode 100644
index 000000000..5d4620943
--- /dev/null
+++ b/packages/opencode/test/server/session-diff-scoped.test.ts
@@ -0,0 +1,250 @@
+/**
+ * Integration test for session-scoped diffs (#174).
+ *
+ * Verifies that GET /session/:id/diff returns the net diff (session-start
+ * snapshot vs current state) filtered to only files the agent touched (tracked
+ * via PatchParts). This replaces the old per-turn/per-message diff model.
+ */
+import { afterEach, describe, expect } from "bun:test"
+import { LayerNode } from "@opencode-ai/core/effect/layer-node"
+import { FSUtil } from "@opencode-ai/core/fs-util"
+import path from "path"
+import { Effect, Layer } from "effect"
+import { Session } from "@/session/session"
+import { Snapshot } from "@/snapshot"
+import { Storage } from "@/storage/storage"
+import { SessionPaths } from "@/server/routes/instance/httpapi/groups/session"
+import { MessageID, PartID } from "@/session/schema"
+import { ProviderV2 } from "@opencode-ai/core/provider"
+import { ModelV2 } from "@opencode-ai/core/model"
+import { SessionV1 } from "@opencode-ai/core/v1/session"
+import { resetDatabase } from "../fixture/db"
+import { disposeAllInstances, TestInstance } from "../fixture/fixture"
+import { testEffect } from "../lib/effect"
+import { httpApiLayer, requestInDirectory } from "./httpapi-layer"
+
+const it = testEffect(
+  Layer.mergeAll(
+    LayerNode.compile(LayerNode.group([Session.node, Snapshot.node, Storage.node, FSUtil.node])),
+    httpApiLayer,
+  ),
+)
+
+afterEach(async () => {
+  await disposeAllInstances()
+  await resetDatabase()
+})
+
+function pathFor(template: string, params: Record<string, string>) {
+  return Object.entries(params).reduce((result, [key, value]) => result.replace(`:${key}`, value), template)
+}
+
+const withSession = (input?: Parameters<Session.Interface["create"]>[0]) =>
+  Effect.acquireRelease(Session.use.create(input), (created) => Session.use.remove(created.id).pipe(Effect.ignore))
+
+describe("Session.diff — session-scoped agent diffs (#174)", () => {
+  it.instance(
+    "returns [] for session with no messages",
+    () =>
+      Effect.gen(function* () {
+        const test = yield* TestInstance
+        const session = yield* withSession({ title: "empty-session" })
+
+        const response = yield* requestInDirectory(
+          pathFor(SessionPaths.diff, { sessionID: session.id }),
+          test.directory,
+        )
+        expect(response.status).toBe(200)
+        expect(yield* response.json).toEqual([])
+      }),
+    { git: true, config: { formatter: false, lsp: false } },
+  )
+
+  it.instance(
+    "falls back to per-message summary diffs when no snapshot parts exist",
+    () =>
+      Effect.gen(function* () {
+        const test = yield* TestInstance
+        const session = yield* withSession({ title: "no-snapshots" })
+        const messageID = MessageID.ascending()
+        yield* Session.use.updateMessage({
+          id: messageID,
+          sessionID: session.id,
+          role: "user",
+          time: { created: Date.now() },
+          agent: "build",
+          model: { providerID: ProviderV2.ID.make("test"), modelID: ModelV2.ID.make("model") },
+          summary: {
+            diffs: [
+              { file: "src/main.ts", additions: 10, deletions: 2, status: "modified" as const },
+              { file: "src/new.ts", additions: 5, deletions: 0, status: "added" as const },
+            ],
+          },
+        } satisfies SessionV1.User)
+
+        const response = yield* requestInDirectory(
+          pathFor(SessionPaths.diff, { sessionID: session.id }),
+          test.directory,
+        )
+        expect(response.status).toBe(200)
+        const diffs = (yield* response.json) as Array<{ file: string; additions: number; deletions: number }>
+        expect(diffs.length).toBe(2)
+        expect(diffs.map((d) => d.file).sort()).toEqual(["src/main.ts", "src/new.ts"])
+      }),
+    { git: true, config: { formatter: false, lsp: false } },
+  )
+
+  it.instance(
+    "returns net diff for agent-touched files across the session",
+    () =>
+      Effect.gen(function* () {
+        const test = yield* TestInstance
+        const session = yield* withSession({ title: "agent-diffs" })
+        const snapshot = yield* Snapshot.Service
+        const fs = yield* FSUtil.Service
+
+        // Write an initial file before the session starts
+        yield* fs.writeWithDirs(path.join(test.directory, "existing.txt"), "original content")
+        // Take the session-start snapshot
+        const startHash = yield* snapshot.track()
+        expect(startHash).toBeTruthy()
+
+        // Create a user message (parts are attached to it for simplicity)
+        const userMsgID = MessageID.ascending()
+        yield* Session.use.updateMessage({
+          id: userMsgID,
+          sessionID: session.id,
+          role: "user",
+          time: { created: Date.now() },
+          agent: "build",
+          model: { providerID: ProviderV2.ID.make("test"), modelID: ModelV2.ID.make("model") },
+        } satisfies SessionV1.User)
+
+        // Attach step-start part (records session-start snapshot)
+        yield* Session.use.updatePart({
+          id: PartID.ascending(),
+          sessionID: session.id,
+          messageID: userMsgID,
+          type: "step-start",
+          snapshot: startHash!,
+        })
+
+        // Agent writes a new file and modifies an existing one
+        yield* fs.writeWithDirs(path.join(test.directory, "new-file.ts"), "export const x = 1")
+        yield* fs.writeWithDirs(path.join(test.directory, "existing.txt"), "modified content")
+
+        // Also write a file that the agent did NOT touch (external change)
+        yield* fs.writeWithDirs(path.join(test.directory, "external.txt"), "external change")
+
+        // Record a patch part with agent-touched files
+        const agentFiles = [
+          path.join(test.directory, "new-file.ts"),
+          path.join(test.directory, "existing.txt"),
+        ]
+        yield* Session.use.updatePart({
+          id: PartID.ascending(),
+          sessionID: session.id,
+          messageID: userMsgID,
+          type: "patch",
+          hash: startHash!,
+          files: agentFiles,
+        })
+
+        // Query the session diff via the HTTP endpoint
+        const response = yield* requestInDirectory(
+          pathFor(SessionPaths.diff, { sessionID: session.id }),
+          test.directory,
+        )
+        expect(response.status).toBe(200)
+        const diffs = (yield* response.json) as Array<{ file: string; additions: number; deletions: number }>
+
+        // Should include agent-touched files only (not external.txt)
+        const files = diffs.map((d) => d.file)
+        expect(files).toContain("new-file.ts")
+        expect(files).toContain("existing.txt")
+        expect(files).not.toContain("external.txt")
+        expect(diffs.length).toBe(2)
+
+        // Each diff should have non-zero additions/deletions
+        for (const d of diffs) {
+          expect((d.additions ?? 0) + (d.deletions ?? 0)).toBeGreaterThan(0)
+        }
+      }),
+    { git: true, config: { formatter: false, lsp: false } },
+  )
+
+  it.instance(
+    "filters out files where agent edits were externally reverted (zero diff)",
+    () =>
+      Effect.gen(function* () {
+        const test = yield* TestInstance
+        const session = yield* withSession({ title: "reverted-diffs" })
+        const snapshot = yield* Snapshot.Service
+        const fs = yield* FSUtil.Service
+
+        // Write a file
+        yield* fs.writeWithDirs(path.join(test.directory, "reverted.txt"), "original")
+        const startHash = yield* snapshot.track()
+        expect(startHash).toBeTruthy()
+
+        // Create a user message
+        const userMsgID = MessageID.ascending()
+        yield* Session.use.updateMessage({
+          id: userMsgID,
+          sessionID: session.id,
+          role: "user",
+          time: { created: Date.now() },
+          agent: "build",
+          model: { providerID: ProviderV2.ID.make("test"), modelID: ModelV2.ID.make("model") },
+        } satisfies SessionV1.User)
+
+        yield* Session.use.updatePart({
+          id: PartID.ascending(),
+          sessionID: session.id,
+          messageID: userMsgID,
+          type: "step-start",
+          snapshot: startHash!,
+        })
+
+        // Record the file as agent-touched
+        yield* Session.use.updatePart({
+          id: PartID.ascending(),
+          sessionID: session.id,
+          messageID: userMsgID,
+          type: "patch",
+          hash: startHash!,
+          files: [path.join(test.directory, "reverted.txt")],
+        })
+
+        // File is back to its original content → net diff is zero
+        // (we didn't actually change it from the snapshot state)
+
+        const response = yield* requestInDirectory(
+          pathFor(SessionPaths.diff, { sessionID: session.id }),
+          test.directory,
+        )
+        expect(response.status).toBe(200)
+        expect(yield* response.json).toEqual([])
+      }),
+    { git: true, config: { formatter: false, lsp: false } },
+  )
+
+  it.instance(
+    "messageID query param is accepted but ignored (backwards compat)",
+    () =>
+      Effect.gen(function* () {
+        const test = yield* TestInstance
+        const session = yield* withSession({ title: "compat" })
+
+        // Passing messageID should still work (200) but returns session-scoped results
+        const messageID = MessageID.ascending()
+        const response = yield* requestInDirectory(
+          `${pathFor(SessionPaths.diff, { sessionID: session.id })}?messageID=${messageID}`,
+          test.directory,
+        )
+        expect(response.status).toBe(200)
+        expect(yield* response.json).toEqual([])
+      }),
+    { git: true, config: { formatter: false, lsp: false } },
+  )
+})
diff --git a/packages/session-ui/src/v2/components/session-review-v2.css b/packages/session-ui/src/v2/components/session-review-v2.css
index 704e8fd7d..0c87b8d3a 100644
--- a/packages/session-ui/src/v2/components/session-review-v2.css
+++ b/packages/session-ui/src/v2/components/session-review-v2.css
@@ -3,6 +3,7 @@
   flex-direction: column;
   height: 100%;
   min-height: 0;
+  min-width: fit-content;
   overflow: hidden;
   background: var(--v2-background-bg-base);
 }
@@ -208,11 +209,10 @@
 [data-component="session-review-v2"] [data-slot="session-review-v2-toolbar"] {
   display: flex;
   align-items: center;
-  justify-content: space-between;
-  gap: 8px;
-  padding: 10px 12px;
-  padding-left: 8px;
+  gap: 4px;
+  padding: 10px 16px 10px 8px;
   flex-shrink: 0;
+  white-space: nowrap;
   border-bottom: 1px solid var(--border-weaker-base, var(--v2-border-border-weak));
 }
 
@@ -220,10 +220,12 @@
   display: flex;
   align-items: center;
   gap: 0px;
+  flex-shrink: 0;
 }
 
 [data-component="session-review-v2"] .session-review-v2-toolbar-group--start {
   min-width: 0;
+  flex-shrink: 0;
 }
 
 [data-component="session-review-v2"] [data-slot="session-review-v2-toolbar-collapsed-meta"] {
diff --git a/packages/session-ui/src/v2/components/session-review-v2.tsx b/packages/session-ui/src/v2/components/session-review-v2.tsx
index d2f3b6b8a..c2699119a 100644
--- a/packages/session-ui/src/v2/components/session-review-v2.tsx
+++ b/packages/session-ui/src/v2/components/session-review-v2.tsx
@@ -261,26 +261,6 @@ export function SessionReviewV2(props: SessionReviewV2Props) {
 
   const toolbarEnd = () => (
     <>
-      <SegmentedControlV2
-        value={props.expandMode}
-        onChange={(value) => {
-          if (value !== "expand" && value !== "collapse") return
-          props.onExpandModeChange(value)
-        }}
-        class="session-review-v2-segmented-control session-review-v2-segmented-control--icon"
-        aria-label={i18n.t("ui.sessionReviewV2.expandMode")}
-      >
-        <TooltipV2 openDelay={2000} value={i18n.t("ui.sessionReviewV2.showAllLines")}>
-          <SegmentedControlItemV2 value="expand" aria-label={i18n.t("ui.sessionReviewV2.showAllLines")}>
-            <Icon name="expand" />
-          </SegmentedControlItemV2>
-        </TooltipV2>
-        <TooltipV2 openDelay={2000} value={i18n.t("ui.sessionReviewV2.hideNonDiffLines")}>
-          <SegmentedControlItemV2 value="collapse" aria-label={i18n.t("ui.sessionReviewV2.hideNonDiffLines")}>
-            <Icon name="collapse" />
-          </SegmentedControlItemV2>
-        </TooltipV2>
-      </SegmentedControlV2>
       <Show when={props.onDiffStyleChange}>
         <SegmentedControlV2
           value={props.diffStyle}
diff --git a/packages/tui/src/feature-plugins/system/diff-viewer.tsx b/packages/tui/src/feature-plugins/system/diff-viewer.tsx
index ed88a1107..adadaff4c 100644
--- a/packages/tui/src/feature-plugins/system/diff-viewer.tsx
+++ b/packages/tui/src/feature-plugins/system/diff-viewer.tsx
@@ -1,6 +1,6 @@
 /** @jsxImportSource @opentui/solid */
 import type { TuiPlugin, TuiPluginApi, TuiRouteCurrent } from "@opencode-ai/plugin/tui"
-import type { SnapshotFileDiff, VcsFileDiff } from "@opencode-ai/sdk/v2"
+import type { SnapshotFileDiff } from "@opencode-ai/sdk/v2"
 import {
   TextAttributes,
   type BorderSides,
@@ -16,7 +16,6 @@ import path from "path"
 import { createEffect, createMemo, createResource, createSignal, For, Match, onCleanup, Show, Switch } from "solid-js"
 import { DiffViewerFileTree } from "./diff-viewer-file-tree"
 import { Panel, PanelGroup, Separator } from "./diff-viewer-ui"
-import { DialogSelect } from "../../ui/dialog-select"
 import { getScrollAcceleration } from "../../util/scroll"
 import {
   allExpandedFileTreeDirectories,
@@ -39,11 +38,9 @@ const ROUTE = "diff"
 const MIN_SPLIT_WIDTH = 100
 const FILE_TREE_WIDTH = 32
 const PLAIN_TEXT_FILETYPE = "opencode-plain-text"
-const VCS_DIFF_CONTEXT_LINES = 12
 const KV_SHOW_FILE_TREE = "diff_viewer_show_file_tree"
 const KV_SINGLE_PATCH = "diff_viewer_single_patch"
 const KV_VIEW = "diff_viewer_view"
-type DiffMode = "git" | "branch" | "last-turn"
 type DiffViewerFocus = "patches" | "files"
 type DiffView = "split" | "unified"
 type SelectedHunk = { readonly fileIndex: number; readonly hunkIndex: number; readonly scrollTop: number }
@@ -56,7 +53,7 @@ type DiffFile = {
   readonly status: "added" | "deleted" | "modified"
 }
 
-const normalizeDiffs = (diffs: readonly (VcsFileDiff | SnapshotFileDiff)[]): DiffFile[] =>
+const normalizeDiffs = (diffs: readonly SnapshotFileDiff[]): DiffFile[] =>
   diffs.flatMap((item) =>
     item.file
       ? [
@@ -82,12 +79,6 @@ function storedView(value: unknown): DiffView | undefined {
   if (value === "split" || value === "unified") return value
 }
 
-function diffSourceLabel(mode: DiffMode) {
-  if (mode === "last-turn") return "last turn"
-  if (mode === "branch") return "main branch"
-  return "working tree"
-}
-
 function DiffViewer(props: { api: TuiPluginApi }) {
   const dimensions = useTerminalDimensions()
   const themeState = useTheme()
@@ -95,35 +86,19 @@ function DiffViewer(props: { api: TuiPluginApi }) {
   const params = () =>
     ("params" in props.api.route.current ? props.api.route.current.params : undefined) as
       | {
-          mode?: DiffMode
           sessionID?: string
-          messageID?: string
           returnRoute?: TuiRouteCurrent
         }
       | undefined
-  const mode = () => params()?.mode ?? "git"
   const diffInput = createMemo(() => {
     const sessionID = params()?.sessionID
-    return {
-      mode: mode(),
-      sessionID,
-      messageID: params()?.messageID,
-      directory: sessionID ? props.api.state.session.get(sessionID)?.directory : undefined,
-    }
+    return { sessionID }
   })
   const [diff] = createResource(diffInput, async (input) => {
-    if (input.mode === "last-turn") {
-      const sessionID = input.sessionID
-      if (!sessionID) return []
-      const result = await props.api.client.session.diff(
-        { sessionID, messageID: input.messageID },
-        { throwOnError: true },
-      )
-      return normalizeDiffs(result.data ?? [])
-    }
-
-    const result = await props.api.client.vcs.diff(
-      { directory: input.directory, mode: input.mode, context: VCS_DIFF_CONTEXT_LINES },
+    const sessionID = input.sessionID
+    if (!sessionID) return []
+    const result = await props.api.client.session.diff(
+      { sessionID },
       { throwOnError: true },
     )
     return normalizeDiffs(result.data ?? [])
@@ -162,7 +137,6 @@ function DiffViewer(props: { api: TuiPluginApi }) {
   const previousFileShortcut = useCommandShortcut("diff.previous_file")
   const toggleFileTreeShortcut = useCommandShortcut("diff.toggle_file_tree")
   const singlePatchShortcut = useCommandShortcut("diff.single_patch")
-  const switchSourceShortcut = useCommandShortcut("diff.switch_source")
   const toggleViewShortcut = useCommandShortcut("diff.toggle_view")
   const markReviewedShortcut = useCommandShortcut("diff.mark_reviewed")
   const helpShortcut = useCommandShortcut("diff.help")
@@ -651,14 +625,6 @@ function DiffViewer(props: { api: TuiPluginApi }) {
         if (fileIndex !== undefined) scrollToPatchFileIndexAfterRender(fileIndex)
       },
     },
-    {
-      name: "diff.switch_source",
-      title: "Switch diff viewer source",
-      category: "VCS",
-      run() {
-        openSwitchDiffDialog()
-      },
-    },
     {
       name: "diff.toggle_view",
       title: "Toggle diff viewer split or unified view",
@@ -681,54 +647,6 @@ function DiffViewer(props: { api: TuiPluginApi }) {
     },
   ]
 
-  const switchDiffOptions = createMemo(() => {
-    const vcs = props.api.state.vcs
-    return [
-      {
-        title: "Working tree",
-        value: "git" as const,
-        description: "Show current git changes",
-      },
-      ...(vcs?.branch && vcs.default_branch && vcs.branch !== vcs.default_branch
-        ? [
-            {
-              title: "Main branch",
-              value: "branch" as const,
-              description: "Show changes compared to main branch",
-            },
-          ]
-        : []),
-      {
-        title: "Last turn",
-        value: "last-turn" as const,
-        description: "Show changes from the last assistant turn",
-      },
-    ]
-  })
-
-  const openSwitchDiffDialog = () => {
-    props.api.ui.dialog.replace(() => (
-      <DialogSelect
-        title="Switch source"
-        skipFilter={true}
-        renderFilter={false}
-        current={mode()}
-        options={switchDiffOptions().map((option) => ({
-          ...option,
-          onSelect(dialog) {
-            dialog.clear()
-            props.api.route.navigate(ROUTE, {
-              mode: option.value,
-              sessionID: params()?.sessionID,
-              messageID: params()?.messageID,
-              returnRoute: params()?.returnRoute,
-            })
-          },
-        }))}
-      />
-    ))
-  }
-
   const openHelpDialog = () => {
     props.api.ui.dialog.replace(() => <DiffViewerHelpDialog />)
     props.api.ui.dialog.setSize("large")
@@ -754,7 +672,7 @@ function DiffViewer(props: { api: TuiPluginApi }) {
       <PanelGroup axis="y" width="100%" height="100%">
         <Panel border="none" flexShrink={0} padding={0} paddingLeft={1}>
           <text fg={theme().text}>Diff </text>
-          <text fg={theme().textMuted}>{diffSourceLabel(mode())}</text>
+          <text fg={theme().textMuted}>session changes</text>
           <box flexGrow={1} />
           <text fg={theme().textMuted}>
             {files().length} {files().length === 1 ? "file" : "files"}
@@ -916,13 +834,6 @@ function DiffViewer(props: { api: TuiPluginApi }) {
               </text>
             )}
           </Show>
-          <Show when={switchSourceShortcut()}>
-            {(shortcut) => (
-              <text fg={theme().text}>
-                {shortcut()} <span style={{ fg: theme().textMuted }}>switch source</span>
-              </text>
-            )}
-          </Show>
           <Show when={markReviewedShortcut()}>
             {(shortcut) => (
               <text fg={theme().text}>
@@ -986,11 +897,6 @@ function DiffViewerHelpDialog() {
       action: "Toggle patches",
       description: "Switch between one selected patch and all patches",
     },
-    {
-      shortcut: useCommandShortcut("diff.switch_source"),
-      action: "Switch source",
-      description: "Choose working tree, main branch, or last-turn changes",
-    },
     {
       shortcut: useCommandShortcut("diff.toggle_view"),
       action: "Toggle view",
@@ -1060,7 +966,6 @@ const tui: TuiPlugin = async (api) => {
         namespace: "palette",
         run() {
           api.route.navigate(ROUTE, {
-            mode: "git",
             sessionID: "params" in api.route.current ? api.route.current.params?.sessionID : undefined,
             returnRoute: api.route.current,
           })