diff --git a/packages/app/e2e/browser/changes-pane.spec.ts b/packages/app/e2e/browser/changes-pane.spec.ts
index a233567b5f..24b45a706d 100644
--- a/packages/app/e2e/browser/changes-pane.spec.ts
+++ b/packages/app/e2e/browser/changes-pane.spec.ts
@@ -262,6 +262,93 @@ test.afterEach(async () => {
   }
 });
 
+test("streamed Changes shows the tree before completion and applies a one-file refresh", async ({
+  page,
+}, testInfo) => {
+  test.setTimeout(120_000);
+  const workspace = await createLargeStreamedWorkspace();
+  const stream = await holdDiffCompletion(page);
+  await openWorkspaceChangesSurface(page, workspace, 90_000);
+  await expectAnnouncedTreeAndLoader(page);
+  await page.screenshot({ path: testInfo.outputPath("tree-loading.png") });
+  stream.finish();
+  await expect.poll(() => stream.completed, { timeout: 60_000 }).toBeGreaterThan(0);
+  await expect(page.getByRole("progressbar", { name: "Loading..." })).toHaveCount(0);
+  const connections = stream.connections;
+  const panel = page.getByTestId("working-diff-panel").filter({ visible: true });
+  await expect(panel.getByTestId("diff-file-0")).toHaveAccessibleName("src/file-0000.ts, +90, -1");
+  await addOneLineToFirstFile(workspace);
+  await expect.poll(() => stream.changedBodies.at(-1), { timeout: 30_000 }).toBe(1);
+  await expect(panel.getByTestId("diff-file-0")).toHaveAccessibleName("src/file-0000.ts, +91, -1");
+  await expect(page.getByRole("progressbar", { name: "Loading..." })).toHaveCount(0);
+  expect(stream.connections).toBe(connections);
+  await page.screenshot({ path: testInfo.outputPath("refreshed.png") });
+});
+
+async function createLargeStreamedWorkspace(): Promise<DirtyWorkspace> {
+  const workspace = await createWorkspaceWithManyTinyDiffs(252);
+  await Promise.all(
+    Array.from({ length: 252 }, (_, file) =>
+      writeFile(
+        path.join(workspace.repoPath, `src/file-${String(file).padStart(4, "0")}.ts`),
+        Array.from(
+          { length: 90 },
+          (_unused, line) =>
+            `export const fn${line} = (param: string) => ({ key: param, value: ${file} });`,
+        ).join("\n") + "\n",
+      ),
+    ),
+  );
+  return workspace;
+}
+async function addOneLineToFirstFile(workspace: DirtyWorkspace): Promise<void> {
+  const file = path.join(workspace.repoPath, "src/file-0000.ts");
+  await writeFile(file, (await readFile(file, "utf8")) + "export const refreshed = true;\n");
+}
+async function holdDiffCompletion(page: Page) {
+  const { decodeDiffFrame, DiffOpcode } = await import("@getpaseo/protocol/binary-frames/index");
+  let holding = true;
+  let connections = 0;
+  let completed = 0;
+  const completions: Array<() => void> = [];
+  const changedBodies: number[] = [];
+  await page.routeWebSocket(daemonWsRoutePattern(), (browserSocket) => {
+    connections++;
+    const serverSocket = browserSocket.connectToServer();
+    browserSocket.onMessage((message) => serverSocket.send(message));
+    serverSocket.onMessage((message) => {
+      if (typeof message !== "string" && message[0] === DiffOpcode.Begin) {
+        const frame = decodeDiffFrame(message);
+        if (frame.opcode === DiffOpcode.Begin)
+          changedBodies.push(frame.entries.filter((entry) => entry.body).length);
+      }
+      if (typeof message !== "string" && message[0] === DiffOpcode.End) completed++;
+      if (holding && typeof message !== "string" && message[0] === DiffOpcode.End) {
+        completions.push(() => browserSocket.send(message));
+        return;
+      }
+      browserSocket.send(message);
+    });
+  });
+  return {
+    changedBodies,
+    get connections() {
+      return connections;
+    },
+    get completed() {
+      return completed;
+    },
+    finish: () => {
+      holding = false;
+      completions.splice(0).forEach((send) => send());
+    },
+  };
+}
+async function expectAnnouncedTreeAndLoader(page: Page): Promise<void> {
+  await expect(changesTree(page).first()).toBeVisible();
+  await expect(page.getByRole("progressbar", { name: "Loading..." }).first()).toBeVisible();
+}
+
 test("Changes opens All changes for a clean checkout", async ({ page }) => {
   const workspace = await createWorkspaceWithCommittedDiff();
 
@@ -490,6 +577,35 @@ test("an empty Changes comparison links to the populated comparison", async ({ p
   await expect(panel.getByTestId("diff-file-0")).toHaveAccessibleName("committed-only.ts, +1, -0");
 });
 
+test("legacy diff hosts keep All, Committed and Uncommitted comparisons", async ({ page }) => {
+  await useLegacyDiffHost(page);
+  const workspace = await createWorkspaceWithScrollableComparisons();
+  await openWorkspaceChangesSurface(page, workspace);
+  await expect(changesTree(page).getByText("committed", { exact: true })).toBeVisible();
+  await expect(changesTree(page).getByText("uncommitted", { exact: true })).toBeVisible();
+  await selectChangesComparison(page, "Committed");
+  await expectWorkingComparisonFiles(page, "committed");
+  await selectChangesComparison(page, "Uncommitted");
+  await expectWorkingComparisonFiles(page, "uncommitted");
+});
+async function useLegacyDiffHost(page: Page): Promise<void> {
+  await page.routeWebSocket(daemonWsRoutePattern(), (browserSocket) => {
+    const serverSocket = browserSocket.connectToServer();
+    browserSocket.onMessage((message) => serverSocket.send(message));
+    serverSocket.onMessage((message) => {
+      if (typeof message === "string") {
+        const envelope = JSON.parse(message);
+        if (envelope.message?.payload?.status === "server_info") {
+          delete envelope.message.payload.features.diffSubscription;
+          browserSocket.send(JSON.stringify(envelope));
+          return;
+        }
+      }
+      browserSocket.send(message);
+    });
+  });
+}
+
 test("Changes comparison controls the working diff and tree selection focuses its file", async ({
   page,
 }) => {
diff --git a/packages/app/src/data/push-router.test.ts b/packages/app/src/data/push-router.test.ts
index 6599c28467..432d8b8224 100644
--- a/packages/app/src/data/push-router.test.ts
+++ b/packages/app/src/data/push-router.test.ts
@@ -1,4 +1,4 @@
-import type { OwnedSubscription, SubscriptionObserver } from "@getpaseo/client";
+import type { DiffState, OwnedSubscription, SubscriptionObserver } from "@getpaseo/client";
 import { QueryClient, QueryObserver, skipToken } from "@tanstack/react-query";
 import { describe, expect, it } from "vitest";
 import type { MutableDaemonConfig, SessionOutboundMessage } from "@getpaseo/protocol/messages";
@@ -144,10 +144,21 @@ function createFakeClient(config: { rejectCheckoutDiffSubscribe?: boolean } = {}
           ["status", "providers_snapshot_update"],
           () => {},
         ),
-      observeCheckoutDiff(cwd, compare) {
+      observeDiff(input) {
+        const cwd = input.cwd;
+        let mode: "uncommitted" | "base" | "all" = "uncommitted";
+        if (input.head.kind === "rev") mode = "base";
+        else if (input.mergeBase) mode = "all";
+        const compare = {
+          mode,
+          ...(input.base.kind === "rev" && input.base.rev !== "HEAD"
+            ? { baseRef: input.base.rev }
+            : {}),
+          ignoreWhitespace: input.ignoreWhitespace,
+        };
         const subscriptionId = `server-diff-${subscribeCheckoutDiffCalls.length + 1}`;
         subscribeCheckoutDiffCalls.push({ cwd, compare, subscriptionId });
-        const handle = observe(
+        const handle = observe<SubscribeCheckoutDiffResponseMessage["payload"]>(
           { subscriptionId, cwd, files: [], error: null, requestId: "subscribe-checkout-diff" },
           ["checkout_diff_update", "subscribe_checkout_diff_response"],
           () => unsubscribeCheckoutDiffCalls.push(subscriptionId),
@@ -155,9 +166,43 @@ function createFakeClient(config: { rejectCheckoutDiffSubscribe?: boolean } = {}
             "subscriptionId" in message.payload &&
             message.payload.subscriptionId === subscriptionId,
         );
-        if (!config.rejectCheckoutDiffSubscribe) return handle;
-        return {
+        const modern: OwnedSubscription<DiffState> = {
           ...handle,
+          ready: Promise.resolve({
+            phase: "ready",
+            revision: 1,
+            resolved: { baseSha: "", headSha: "", mergeBaseSha: "" },
+            files: [],
+            diffTooLarge: false,
+            subscriptionId,
+          }),
+          subscribe: (observer) =>
+            handle.subscribe({
+              snapshot: (payload) =>
+                observer.snapshot({
+                  phase: "ready",
+                  revision: 1,
+                  resolved: { baseSha: "", headSha: "", mergeBaseSha: "" },
+                  files: payload.files,
+                  diffTooLarge: payload.diffTooLarge === true,
+                  subscriptionId,
+                }),
+              update: (message) => {
+                if (message.type === "checkout_diff_update")
+                  observer.snapshot({
+                    phase: "ready",
+                    revision: 2,
+                    resolved: { baseSha: "", headSha: "", mergeBaseSha: "" },
+                    files: message.payload.files,
+                    diffTooLarge: message.payload.diffTooLarge === true,
+                    subscriptionId,
+                  });
+              },
+            }),
+        };
+        if (!config.rejectCheckoutDiffSubscribe) return modern;
+        return {
+          ...modern,
           subscribe: (observer) => {
             queueMicrotask(() => observer.error?.(new Error("subscribe failed")));
             return () => {};
@@ -328,7 +373,7 @@ describe("server data push router", () => {
       const first = publish(files, "first");
       const same = publish(structuredClone(files), "reopen");
       expect(same.files).toBe(first.files);
-      expect(same.requestId).toBe("reopen");
+      expect(same.requestId).toBe("diff:1:ready");
       const changed = structuredClone(files);
       changed[0]!.hunks[0]!.lines[0]!.tokens![0]!.style = "variable";
       const next = publish(changed, "edit");
@@ -430,7 +475,7 @@ describe("server data push router", () => {
       files: [],
       error: null,
       diffTooLarge: true,
-      requestId: "diff-1",
+      requestId: "diff:1:ready",
     });
 
     fake.emit({
@@ -449,7 +494,7 @@ describe("server data push router", () => {
       files: [],
       error: null,
       diffTooLarge: true,
-      requestId: `subscription:${serverSubscriptionId}`,
+      requestId: "diff:2:ready",
     });
 
     unsubscribeObserver();
diff --git a/packages/app/src/data/push-router.ts b/packages/app/src/data/push-router.ts
index cc32f8f8e3..5e51ded0d4 100644
--- a/packages/app/src/data/push-router.ts
+++ b/packages/app/src/data/push-router.ts
@@ -1,3 +1,5 @@
+import { checkoutDiffSnapshot, type CheckoutDiffSnapshot } from "@/git/diff-snapshot";
+import type { DiffState } from "@getpaseo/client";
 import type { OwnedSubscription } from "@getpaseo/client";
 import type { ProviderSnapshotEntry } from "@getpaseo/protocol/agent-types";
 import type { Query, QueryCacheNotifyEvent, QueryClient, QueryKey } from "@tanstack/react-query";
@@ -23,14 +25,9 @@ type ProvidersSnapshotUpdateMessage = Extract<
   SessionOutboundMessage,
   { type: "providers_snapshot_update" }
 >;
-type SubscribeCheckoutDiffResponseMessage = Extract<
-  SessionOutboundMessage,
-  { type: "subscribe_checkout_diff_response" }
->;
 type StatusMessage = Extract<SessionOutboundMessage, { type: "status" }>;
 type TerminalsChangedMessage = Extract<SessionOutboundMessage, { type: "terminals_changed" }>;
-type CheckoutDiffResponsePayload = SubscribeCheckoutDiffResponseMessage["payload"];
-type CheckoutDiffCachePayload = Omit<CheckoutDiffResponsePayload, "subscriptionId">;
+type CheckoutDiffCachePayload = CheckoutDiffSnapshot;
 type ListTerminalsPayload = ListTerminalsResponse["payload"];
 
 interface CheckoutDiffCompare {
@@ -49,7 +46,7 @@ interface CheckoutDiffRoute {
 }
 
 interface CheckoutDiffRegistration extends CheckoutDiffRoute {
-  subscription: OwnedSubscription<CheckoutDiffResponsePayload>;
+  subscription: OwnedSubscription<DiffState>;
 }
 
 interface WorkspaceTerminalsRoute {
@@ -75,7 +72,7 @@ export type ProvidersSnapshotUpdate = ProvidersSnapshotUpdateMessage;
 interface ServerDataPushClient {
   getProvidersSnapshot: import("@getpaseo/client/internal/daemon-client").DaemonClient["getProvidersSnapshot"];
   observeEvents: import("@getpaseo/client/internal/daemon-client").DaemonClient["observeEvents"];
-  observeCheckoutDiff: import("@getpaseo/client/internal/daemon-client").DaemonClient["observeCheckoutDiff"];
+  observeDiff: import("@getpaseo/client/internal/daemon-client").DaemonClient["observeDiff"];
   observeTerminals: import("@getpaseo/client/internal/daemon-client").DaemonClient["observeTerminals"];
 }
 
@@ -339,34 +336,34 @@ function reconcileCheckoutDiffSubscriptions(input: {
   }
   for (const [key, desired] of input.desired) {
     if (input.active.has(key)) continue;
-    const subscription = input.client.observeCheckoutDiff(desired.cwd, desired.compare);
+    const { mode, baseRef, ignoreWhitespace } = desired.compare;
+    const revision = mode === "uncommitted" ? "HEAD" : baseRef;
+    if (!revision) continue;
+    const subscription = input.client.observeDiff({
+      cwd: desired.cwd,
+      base: { kind: "rev", rev: revision },
+      head: mode === "base" ? { kind: "rev", rev: "HEAD" } : { kind: "worktree" },
+      mergeBase: mode !== "uncommitted",
+      ignoreWhitespace,
+    });
     const registration = { ...desired, subscription };
     input.active.set(key, registration);
-    const apply = (
-      payload: Omit<CheckoutDiffResponsePayload, "requestId"> & { requestId?: string },
-    ) => {
-      if (input.active.get(key) !== registration) return;
-      const { subscriptionId, ...snapshot } = payload;
-      setCheckoutDiffPayload({
-        activeCheckoutDiffSubscriptions: input.active,
-        queryClient: input.queryClient,
-        serverId: input.serverId,
-        subscriptionId: key,
-        payload: {
-          ...snapshot,
-          files: orderCheckoutDiffFiles(payload.files),
-          requestId: payload.requestId ?? `subscription:${subscriptionId}`,
-        },
-      });
-    };
     subscription.subscribe({
-      snapshot: apply,
-      update: (message) => {
-        if (message.type === "checkout_diff_update") apply(message.payload);
+      snapshot: (state) => {
+        if (input.active.get(key) !== registration) return;
+        const snapshot = checkoutDiffSnapshot(desired.cwd, state);
+        setCheckoutDiffPayload({
+          activeCheckoutDiffSubscriptions: input.active,
+          queryClient: input.queryClient,
+          serverId: input.serverId,
+          subscriptionId: key,
+          payload: { ...snapshot, files: orderCheckoutDiffFiles(snapshot.files) },
+        });
       },
+      update: () => {},
       error: (error) => {
         if (input.active.get(key) === registration) input.active.delete(key);
-        console.error("[server-data] observeCheckoutDiff failed", {
+        console.error("[server-data] observeDiff failed", {
           serverId: input.serverId,
           cwd: desired.cwd,
           error,
diff --git a/packages/app/src/git/changed-files-tree.tsx b/packages/app/src/git/changed-files-tree.tsx
index 0b88d33e96..f020cfa101 100644
--- a/packages/app/src/git/changed-files-tree.tsx
+++ b/packages/app/src/git/changed-files-tree.tsx
@@ -13,10 +13,10 @@ import {
   type DiffTreeRow,
 } from "@/git/diff-tree";
 import { FileHeader } from "@/git/file-header";
-import type { ParsedDiffFile } from "@/git/use-diff-query";
+import type { DiffFileHeader } from "@/git/diff-snapshot";
 
 export interface ChangedFilesTreeProps {
-  files: ParsedDiffFile[];
+  files: DiffFileHeader[];
   mode: WorkingDiffMode;
   onSelectFile: (path: string) => void;
   collapsedFolderPaths: string[];
diff --git a/packages/app/src/git/diff-order.ts b/packages/app/src/git/diff-order.ts
index d57bb0ef29..0ad572866f 100644
--- a/packages/app/src/git/diff-order.ts
+++ b/packages/app/src/git/diff-order.ts
@@ -13,6 +13,6 @@ export function orderCheckoutDiffFiles(files: ParsedDiffFile[]): ParsedDiffFile[
   // chains, so it is skipped; the collapsed set is empty because the flat list
   // always carries every file, whatever the rail has collapsed.
   return flattenDiffTree(buildDiffTree(files), new Set()).flatMap((row) =>
-    row.kind === "file" ? [row.file] : [],
+    row.kind === "file" ? [files[row.fileIndex]] : [],
   );
 }
diff --git a/packages/app/src/git/diff-pane.tsx b/packages/app/src/git/diff-pane.tsx
index d4a7d43ea8..8fe6a909e8 100644
--- a/packages/app/src/git/diff-pane.tsx
+++ b/packages/app/src/git/diff-pane.tsx
@@ -1,3 +1,4 @@
+import type { DiffFileHeader } from "@/git/diff-snapshot";
 import { useSafeAreaInsets } from "react-native-safe-area-context";
 import { floatingActionsClearance } from "@/components/ui/floating-action-button";
 import { useState, useCallback, useMemo, type ReactElement, type ReactNode } from "react";
@@ -1095,6 +1096,7 @@ interface DiffBodyContentProps {
   emptyMessage: string;
   emptyAction: ChangesEmptyAction | null;
   children: ReactElement;
+  loadingLabel: string;
   checkingRepositoryLabel: string;
   notRepositoryLabel: string;
 }
@@ -1111,11 +1113,16 @@ function DiffBodyContent({
   emptyAction,
   children,
   checkingRepositoryLabel,
+  loadingLabel,
   notRepositoryLabel,
 }: DiffBodyContentProps) {
   if (isStatusLoading) {
     return (
-      <View style={styles.loadingContainer}>
+      <View
+        style={styles.loadingContainer}
+        accessibilityRole="progressbar"
+        accessibilityLabel={loadingLabel}
+      >
         <ThemedLoadingSpinner size="large" uniProps={foregroundMutedIconColorMapping} />
         <Text style={styles.loadingText}>{checkingRepositoryLabel}</Text>
       </View>
@@ -1137,7 +1144,11 @@ function DiffBodyContent({
   }
   if (isDiffLoading) {
     return (
-      <View style={styles.loadingContainer}>
+      <View
+        style={styles.loadingContainer}
+        accessibilityRole="progressbar"
+        accessibilityLabel={loadingLabel}
+      >
         <ThemedLoadingSpinner size="large" uniProps={foregroundMutedIconColorMapping} />
       </View>
     );
@@ -1321,7 +1332,7 @@ function ChangesTreeRail({
 }: {
   shown: boolean;
   children: ReactElement;
-  files: ParsedDiffFile[];
+  files: DiffFileHeader[];
   mode: WorkingDiffMode;
   onSelectFile: (path: string) => void;
   treeWidth?: number;
@@ -1361,7 +1372,7 @@ function ChangesBody({
   children: ReactElement;
   desktopTreeVisible: boolean;
   isMobile: boolean;
-  files: ParsedDiffFile[];
+  files: DiffFileHeader[];
   mode: WorkingDiffMode;
   onSelectFile: (path: string) => void;
   treeWidth?: number;
@@ -1586,6 +1597,7 @@ export function ChangesSurface({
     selectBase: handleSelectBase,
     selectAll: handleSelectAll,
     files,
+    treeFiles,
     diffPayloadError,
     diffTooLarge,
     isDiffLoading,
@@ -1835,6 +1847,7 @@ export function ChangesSurface({
         hasChanges={hasChanges}
         emptyMessage={emptyMessage}
         emptyAction={emptyAction}
+        loadingLabel={t("common.loading")}
         checkingRepositoryLabel={t("workspace.git.diff.checkingRepository")}
         notRepositoryLabel={t("workspace.git.diff.notRepository")}
       >
@@ -1865,7 +1878,7 @@ export function ChangesSurface({
       presentation={presentation}
       desktopTreeVisible={desktopTreeVisible}
       isMobile={isMobile}
-      files={files}
+      files={treeFiles}
       mode={workingMode}
       onSelectFile={handleSelectTreeFile}
       treeWidth={instanceState.treeWidth}
diff --git a/packages/app/src/git/diff-sharing.ts b/packages/app/src/git/diff-sharing.ts
index 6bdac10ddf..d426960d9f 100644
--- a/packages/app/src/git/diff-sharing.ts
+++ b/packages/app/src/git/diff-sharing.ts
@@ -1,7 +1,8 @@
 import { replaceEqualDeep } from "@tanstack/react-query";
-import type { ParsedDiffFile, SubscribeCheckoutDiffResponse } from "@getpaseo/protocol/messages";
+import type { CheckoutDiffSnapshot } from "./diff-snapshot";
+import type { ParsedDiffFile } from "@getpaseo/protocol/messages";
 
-type DiffPayload = Omit<SubscribeCheckoutDiffResponse["payload"], "subscriptionId">;
+type DiffPayload = CheckoutDiffSnapshot;
 
 /** File identity owns text-model reuse. Never reconstruct the hunk/token graph. */
 export function retainDiffFiles(
@@ -30,6 +31,7 @@ export function shareCheckoutDiff(previous: unknown, incoming: unknown): DiffPay
     error === old.error &&
     old.cwd === next.cwd &&
     old.requestId === next.requestId &&
+    old.entries === next.entries &&
     old.diffTooLarge === next.diffTooLarge
     ? old
     : { ...next, files, error };
diff --git a/packages/app/src/git/diff-snapshot.ts b/packages/app/src/git/diff-snapshot.ts
new file mode 100644
index 0000000000..25f073b4ef
--- /dev/null
+++ b/packages/app/src/git/diff-snapshot.ts
@@ -0,0 +1,60 @@
+import type { DiffState, DiffEntry } from "@getpaseo/client";
+import type { DiffError, ParsedDiffFile } from "@getpaseo/protocol/messages";
+export type DiffFileHeader = Omit<ParsedDiffFile, "hunks">;
+export interface CheckoutDiffSnapshot {
+  requestId: string;
+  cwd: string;
+  files: ParsedDiffFile[];
+  entries?: DiffEntry[];
+  error: DiffError | null;
+  diffTooLarge?: boolean;
+}
+export function checkoutDiffSnapshot(cwd: string, state: DiffState): CheckoutDiffSnapshot {
+  const common = { cwd, requestId: `diff:${state.revision}:${state.phase}` };
+  if (state.phase === "loading")
+    return { ...common, files: [], entries: state.entries, error: null };
+  if (state.phase === "error") return { ...common, files: [], error: state.error };
+  return { ...common, files: state.files, error: null, diffTooLarge: state.diffTooLarge };
+}
+export function diffEntryHeaders(entries: DiffEntry[]): DiffFileHeader[] {
+  return entries.map((entry) => ({
+    path: entry.path,
+    ...(entry.oldPath === null ? {} : { oldPath: entry.oldPath }),
+    isNew: entry.change === "added",
+    isDeleted: entry.change === "deleted",
+    additions: entry.additions,
+    deletions: entry.deletions,
+    status: entry.content === "binary" ? "binary" : "ok",
+  }));
+}
+export interface CheckoutDiffResult {
+  files: ParsedDiffFile[];
+  entries: DiffEntry[] | null;
+  payloadError: CheckoutDiffSnapshot["error"];
+  diffTooLarge: boolean;
+  isLoading: boolean;
+  isFetching: boolean;
+  isError: boolean;
+  error: null;
+}
+
+/**
+ * The result derives from the payload alone. Until a payload arrives there is no
+ * diff to describe, so the boundary reports loading rather than an empty diff —
+ * whether the query is idle (an inactive retained panel), in flight, or the host
+ * is disconnected. Reporting `files: []` as settled made callers render "+0 -0"
+ * and "No changes" for a diff nobody has fetched yet.
+ */
+export function deriveCheckoutDiffResult(payload: CheckoutDiffSnapshot | null): CheckoutDiffResult {
+  const payloadError = payload?.error ?? null;
+  return {
+    files: payload?.files ?? [],
+    entries: payload?.entries ?? null,
+    payloadError,
+    diffTooLarge: payload?.diffTooLarge === true,
+    isLoading: payload === null || payload.entries !== undefined,
+    isFetching: false,
+    isError: Boolean(payloadError),
+    error: null,
+  };
+}
diff --git a/packages/app/src/git/diff-tree.ts b/packages/app/src/git/diff-tree.ts
index 49709cd5e2..c3130b1cae 100644
--- a/packages/app/src/git/diff-tree.ts
+++ b/packages/app/src/git/diff-tree.ts
@@ -1,6 +1,6 @@
-import type { ParsedDiffFile } from "@/git/use-diff-query";
+import type { DiffFileHeader } from "@/git/diff-snapshot";
 
-// Builds a directory hierarchy from the `ParsedDiffFile[]` the Changes view
+// Builds a directory hierarchy from the `DiffFileHeader[]` the Changes view
 // renders. The tree renders on every form factor, consistent with the Files
 // explorer.
 //
@@ -17,7 +17,7 @@ import type { ParsedDiffFile } from "@/git/use-diff-query";
 
 export interface DiffTreeFileNode {
   kind: "file";
-  file: ParsedDiffFile;
+  file: DiffFileHeader;
   fileIndex: number;
   /** basename, e.g. "diff-pane.tsx" */
   name: string;
@@ -47,7 +47,7 @@ export interface DiffTreeFolderRow {
 
 export interface DiffTreeFileRow {
   kind: "file";
-  file: ParsedDiffFile;
+  file: DiffFileHeader;
   fileIndex: number;
   depth: number;
 }
@@ -73,7 +73,7 @@ function sortTree(node: DiffTreeDirNode): void {
 }
 
 /** Build the (uncompressed) directory tree. Returns the virtual root (dirPath ""). */
-export function buildDiffTree(files: ParsedDiffFile[]): DiffTreeDirNode {
+export function buildDiffTree(files: DiffFileHeader[]): DiffTreeDirNode {
   const root: DiffTreeDirNode = { kind: "dir", dirPath: "", name: "", children: [] };
   const dirByPath = new Map<string, DiffTreeDirNode>([["", root]]);
 
diff --git a/packages/app/src/git/file-header.tsx b/packages/app/src/git/file-header.tsx
index d19d58cbf2..39427a612b 100644
--- a/packages/app/src/git/file-header.tsx
+++ b/packages/app/src/git/file-header.tsx
@@ -28,11 +28,11 @@ import {
   fileNameForPath,
   formatDiffCount,
 } from "@/git/file-header-presentation";
-import type { ParsedDiffFile } from "@/git/use-diff-query";
+import type { DiffFileHeader } from "@/git/diff-snapshot";
 import { inlineUnistylesStyle } from "@/styles/unistyles-inline-style";
 
 export interface FileHeaderProps {
-  file: ParsedDiffFile;
+  file: DiffFileHeader;
   workspaceFileDragScope?: { serverId: string; workspaceId: string };
   bodyVisible: boolean;
   showsBodyState?: boolean;
@@ -73,7 +73,7 @@ function expandedAriaValue(showsBodyState: boolean, bodyVisible: boolean): boole
   return showsBodyState ? bodyVisible : undefined;
 }
 
-function fileHeaderAccessibilityLabel(canvasRendered: boolean, file: ParsedDiffFile) {
+function fileHeaderAccessibilityLabel(canvasRendered: boolean, file: DiffFileHeader) {
   if (!canvasRendered) return undefined;
   return `${file.path}, +${formatDiffCount(file.additions)}, -${formatDiffCount(file.deletions)}`;
 }
@@ -130,7 +130,7 @@ function fileHeaderNameStyle(showsBodyState: boolean, isHovered: boolean) {
   ];
 }
 
-function fileChange(file: ParsedDiffFile): "added" | "deleted" | "modified" {
+function fileChange(file: DiffFileHeader): "added" | "deleted" | "modified" {
   return diffFileChangeKind(file);
 }
 
diff --git a/packages/app/src/git/use-diff-query.test.ts b/packages/app/src/git/use-diff-query.test.ts
index 94b18a7d16..1d5f644a12 100644
--- a/packages/app/src/git/use-diff-query.test.ts
+++ b/packages/app/src/git/use-diff-query.test.ts
@@ -1,6 +1,6 @@
 import { describe, expect, it } from "vitest";
 import type { ParsedDiffFile } from "@getpaseo/protocol/messages";
-import { deriveCheckoutDiffResult } from "./use-diff-query";
+import { deriveCheckoutDiffResult } from "./diff-snapshot";
 
 function createParsedDiffFile(path: string): ParsedDiffFile {
   return {
@@ -59,6 +59,7 @@ describe("deriveCheckoutDiffResult", () => {
 
     expect(result).toEqual({
       files: [],
+      entries: null,
       payloadError: error,
       diffTooLarge: true,
       isLoading: false,
@@ -68,3 +69,20 @@ describe("deriveCheckoutDiffResult", () => {
     });
   });
 });
+
+it("shows the announced tree while file bodies are still loading", () => {
+  const entries = [
+    {
+      path: "src/app.ts",
+      oldPath: null,
+      change: "modified",
+      content: "text",
+      additions: 3,
+      deletions: 1,
+    },
+  ] as const;
+  const result = deriveCheckoutDiffResult({ ...createPayload([]), entries: [...entries] });
+  expect(result.isLoading).toBe(true);
+  expect(result.entries).toEqual(entries);
+  expect(result.files).toEqual([]);
+});
diff --git a/packages/app/src/git/use-diff-query.ts b/packages/app/src/git/use-diff-query.ts
index ebfcd4c354..7f1d3ab521 100644
--- a/packages/app/src/git/use-diff-query.ts
+++ b/packages/app/src/git/use-diff-query.ts
@@ -5,7 +5,9 @@ import { useRetainedPanelActive } from "@/components/retained-panel";
 import { useReplicaQuery } from "@/data/query";
 import { checkoutDiffPushRoute } from "@/data/push-router";
 import { useHostRuntimeIsConnected } from "@/runtime/host-runtime";
-import type { ParsedDiffFile, SubscribeCheckoutDiffResponse } from "@getpaseo/protocol/messages";
+import { deriveCheckoutDiffResult, type CheckoutDiffSnapshot } from "./diff-snapshot";
+export { deriveCheckoutDiffResult } from "./diff-snapshot";
+import type { ParsedDiffFile } from "@getpaseo/protocol/messages";
 import { checkoutDiffQueryKey } from "@/git/query-keys";
 
 interface UseCheckoutDiffQueryOptions {
@@ -18,7 +20,7 @@ interface UseCheckoutDiffQueryOptions {
   queryScope?: string;
 }
 
-type CheckoutDiffQueryPayload = Omit<SubscribeCheckoutDiffResponse["payload"], "subscriptionId">;
+type CheckoutDiffQueryPayload = CheckoutDiffSnapshot;
 
 // Re-export the canonical protocol type so all consumers share one definition.
 export type { ParsedDiffFile };
@@ -108,35 +110,3 @@ export function useCheckoutDiffQuery({
       : (query.data ?? null),
   );
 }
-
-export interface CheckoutDiffResult {
-  files: ParsedDiffFile[];
-  payloadError: CheckoutDiffQueryPayload["error"];
-  diffTooLarge: boolean;
-  isLoading: boolean;
-  isFetching: boolean;
-  isError: boolean;
-  error: null;
-}
-
-/**
- * The result derives from the payload alone. Until a payload arrives there is no
- * diff to describe, so the boundary reports loading rather than an empty diff —
- * whether the query is idle (an inactive retained panel), in flight, or the host
- * is disconnected. Reporting `files: []` as settled made callers render "+0 -0"
- * and "No changes" for a diff nobody has fetched yet.
- */
-export function deriveCheckoutDiffResult(
-  payload: CheckoutDiffQueryPayload | null,
-): CheckoutDiffResult {
-  const payloadError = payload?.error ?? null;
-  return {
-    files: payload?.files ?? [],
-    payloadError,
-    diffTooLarge: payload?.diffTooLarge === true,
-    isLoading: payload === null,
-    isFetching: false,
-    isError: Boolean(payloadError),
-    error: null,
-  };
-}
diff --git a/packages/app/src/git/use-working-diff.ts b/packages/app/src/git/use-working-diff.ts
index f835d44f53..9f32ce8819 100644
--- a/packages/app/src/git/use-working-diff.ts
+++ b/packages/app/src/git/use-working-diff.ts
@@ -9,6 +9,8 @@ import {
   useReviewAttachmentSnapshot,
   useReviewFeedback,
 } from "@/review";
+import { useSessionStore } from "@/stores/session-store";
+import { diffEntryHeaders } from "./diff-snapshot";
 import { useCheckoutDiffQuery } from "@/git/use-diff-query";
 import { useCheckoutStatusQuery } from "@/git/use-status-query";
 import { useWorkingDiffComparison } from "@/git/working-diff-comparison";
@@ -44,7 +46,11 @@ export function useWorkingDiff({
   const statusErrorMessage =
     status?.error?.message ??
     (isStatusError && statusError instanceof Error ? statusError.message : null);
-  const baseRef = gitStatus?.baseRef ?? undefined;
+  const modernDiff = useSessionStore(
+    (state) => state.sessions[serverId]?.serverInfo?.features?.diffSubscription === true,
+  );
+  // COMPAT(diffSubscription): added in v0.15.0, remove after 2027-05-06.
+  const baseRef = (modernDiff ? gitStatus?.comparisonBaseRef : gitStatus?.baseRef) ?? undefined;
   const currentBranchName =
     gitStatus?.currentBranch && gitStatus.currentBranch !== "HEAD" ? gitStatus.currentBranch : null;
 
@@ -59,6 +65,7 @@ export function useWorkingDiff({
 
   const {
     files,
+    entries,
     payloadError: diffPayloadError,
     diffTooLarge,
     isLoading: isDiffLoading,
@@ -71,6 +78,7 @@ export function useWorkingDiff({
     enabled: enabled && isGit,
     queryScope,
   });
+  const treeFiles = useMemo(() => (entries ? diffEntryHeaders(entries) : files), [entries, files]);
   const reviewDraftKey = useMemo(
     () =>
       buildReviewDraftKey({
@@ -112,6 +120,7 @@ export function useWorkingDiff({
     selectBase,
     selectAll,
     files,
+    treeFiles,
     diffPayloadError,
     diffTooLarge,
     isDiffLoading,
diff --git a/packages/server/src/utils/checkout-git.commits.test.ts b/packages/server/src/utils/checkout-git.commits.test.ts
index 1f82fe73b0..dc57333cee 100644
--- a/packages/server/src/utils/checkout-git.commits.test.ts
+++ b/packages/server/src/utils/checkout-git.commits.test.ts
@@ -424,3 +424,17 @@ it("compares tag-based worktrees in status, history and legacy diff modes", asyn
   const all = await getCheckoutDiff(repoDir, { mode: "all", baseRef: "refs/tags/v1" });
   expect(all.diff).toContain("+edited");
 });
+
+it("announces a usable comparison base while checked out on the base branch", async () => {
+  const cwd = makeTempDir();
+  git(["init", "-b", "main"], cwd);
+  writeFileSync(join(cwd, "a.txt"), "before\n");
+  git(["add", "."], cwd);
+  commit(cwd, "base");
+  writeFileSync(join(cwd, "a.txt"), "after\n");
+  const status = await getCheckoutStatus(cwd);
+  expect(status).toMatchObject({ isGit: true, comparisonBaseRef: "refs/heads/main" });
+  if (!status.isGit || !status.comparisonBaseRef) throw new Error("Missing comparison base");
+  const all = await getCheckoutDiff(cwd, { mode: "all", baseRef: status.comparisonBaseRef });
+  expect(all.diff).toContain("+after");
+});
diff --git a/packages/server/src/utils/checkout-git.ts b/packages/server/src/utils/checkout-git.ts
index 50d312a757..a9109ba6d1 100644
--- a/packages/server/src/utils/checkout-git.ts
+++ b/packages/server/src/utils/checkout-git.ts
@@ -1786,6 +1786,16 @@ async function resolveBestComparisonBaseRef(
   return resolveCommitComparisonRef(cwd, baseRef, context);
 }
 
+async function resolveQualifiedComparisonBaseRef(
+  cwd: string,
+  baseRef: string,
+  context: CheckoutContext,
+): Promise<string> {
+  const comparison = context.facts?.isGit ? context.facts.comparisonBaseRef : null;
+  const ref = comparison ?? (await resolveBestComparisonBaseRef(cwd, baseRef, context));
+  return resolveCommitComparisonRef(cwd, ref, context);
+}
+
 async function resolveMostAheadBaseRef(cwd: string, baseRef: string): Promise<string> {
   if (isQualifiedBranchRef(baseRef)) {
     if (await doesGitRefExist(cwd, baseRef)) {
@@ -2404,6 +2414,10 @@ export async function getCheckoutStatus(
   const baseRef = facts.resolvedBaseRef;
   const mainRepoRoot = facts.mainRepoRoot;
   const factsContext = { ...context, facts };
+  // Ref-derived counts skip the current base branch; the diff consumer still needs its ref.
+  const comparisonBaseRef = baseRef
+    ? await resolveQualifiedComparisonBaseRef(cwd, baseRef, factsContext).catch(() => null)
+    : null;
   const aheadBehind =
     baseRef && currentBranch
       ? await getAheadBehind(cwd, baseRef, currentBranch, factsContext)
@@ -2426,7 +2440,7 @@ export async function getCheckoutStatus(
       isDirty,
       baseRef: displayBaseRef ?? baseRef,
       baseRefExact: baseRef,
-      comparisonBaseRef: facts.comparisonBaseRef,
+      comparisonBaseRef,
       aheadBehind,
       upstreamRef,
       aheadOfOrigin,
@@ -2446,7 +2460,7 @@ export async function getCheckoutStatus(
     isDirty,
     baseRef: displayBaseRef,
     baseRefExact: baseRef,
-    comparisonBaseRef: facts.comparisonBaseRef,
+    comparisonBaseRef,
     aheadBehind,
     upstreamRef,
     aheadOfOrigin,