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 cf2da135cb..892129788e 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 b8eda0573f..0e243e95a3 100644
--- a/packages/app/src/context/global-sync/event-reducer.ts
+++ b/packages/app/src/context/global-sync/event-reducer.ts
@@ -268,9 +268,9 @@ 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/opencode/src/server/server.ts b/packages/opencode/src/server/server.ts
index 7ead4df8a3..c2f3e64516 100644
--- a/packages/opencode/src/server/server.ts
+++ b/packages/opencode/src/server/server.ts
@@ -38,6 +38,7 @@ import { websocket } from "hono/bun"
 import { HTTPException } from "hono/http-exception"
 import { errors } from "./error"
 import { Filesystem } from "@/util/filesystem"
+import { Snapshot } from "@/snapshot"
 import { QuestionRoutes } from "./routes/question"
 import { PermissionRoutes } from "./routes/permission"
 import { GlobalRoutes } from "./routes/global"
@@ -330,12 +331,39 @@ export namespace Server {
           },
         }),
         async (c) => {
-          const branch = await Vcs.branch()
           return c.json({
-            branch,
+            branch: await Vcs.branch(),
+            default_branch: await Vcs.defaultBranch(),
           })
         },
       )
+      .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({
diff --git a/packages/sdk/js/src/v2/gen/sdk.gen.ts b/packages/sdk/js/src/v2/gen/sdk.gen.ts
index 7a4f4e40cf..5d559804c6 100644
--- a/packages/sdk/js/src/v2/gen/sdk.gen.ts
+++ b/packages/sdk/js/src/v2/gen/sdk.gen.ts
@@ -174,6 +174,7 @@ import type {
   TuiSelectSessionResponses,
   TuiShowToastResponses,
   TuiSubmitPromptResponses,
+  VcsDiffResponses,
   VcsGetResponses,
   WorktreeCreateErrors,
   WorktreeCreateInput,
@@ -3719,6 +3720,38 @@ 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 86a0c7e425..6ee94ec4d9 100644
--- a/packages/sdk/js/src/v2/gen/types.gen.ts
+++ b/packages/sdk/js/src/v2/gen/types.gen.ts
@@ -1889,7 +1889,8 @@ export type Path = {
 }
 
 export type VcsInfo = {
-  branch: string
+  branch?: string
+  default_branch?: string
 }
 
 export type Command = {
@@ -4887,6 +4888,26 @@ 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