fix: default edit-tool diff to side-by-side (split) view

Add an explicit initialDiffStyle field to the openDiffVirtual message flow so each caller declares the desired diff style up front while having `unified` diff as default to prevent regressions.

.changeset/edit-tool-diff-split-view.md

@@ -0,0 +1,5 @@
+---
+"kilo-code": patch
+---
+
+Open edit-tool diffs in side-by-side (split) mode by default; permission-dock expand stays unified.

packages/kilo-vscode/src/DiffVirtualProvider.ts

@@ -8,6 +8,7 @@ export interface DiffVirtualFile {
   after: string
   additions: number
   deletions: number
+  initialDiffStyle: "unified" | "split"
 }
 
 /**
@@ -83,7 +84,7 @@ export class DiffVirtualProvider implements vscode.Disposable {
 
   private pushData(): void {
     if (!this.pending) return
-    this.post({ type: "diffVirtual.data", diff: this.pending })
+    this.post({ type: "diffVirtual.data", diff: this.pending, initialDiffStyle: this.pending.initialDiffStyle })
   }
 
   private post(message: Record<string, unknown>): void {

packages/kilo-vscode/src/KiloProvider.ts

@@ -729,7 +729,7 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
           vscode.commands.executeCommand("kilo-code.new.marketplaceButtonClicked", this.projectDirectory)
           break
         case "openDiffVirtual":
-          this.openDiffVirtual(message.diff)
+          this.openDiffVirtual(message.diff, message.initialDiffStyle)
           break
         case "forkSession":
           handleForkSession(this.forkCtx, message.sessionId, message.messageId).catch((e) =>
@@ -1073,9 +1073,11 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
     void vscode.env.openExternal(vscode.Uri.parse(url))
   }
 
-  private openDiffVirtual(diff: unknown): void {
+  private openDiffVirtual(diff: unknown, initialDiffStyle?: unknown): void {
     if (!this.diffVirtualProvider || !diff) return
-    this.diffVirtualProvider.open(diff as import("./DiffVirtualProvider").DiffVirtualFile)
+    const d = diff as import("./DiffVirtualProvider").DiffVirtualFile
+    d.initialDiffStyle = initialDiffStyle === "split" ? "split" : "unified"
+    this.diffVirtualProvider.open(d)
   }
 
   /**

packages/kilo-vscode/tests/unit/databridge-shape.test.ts

@@ -68,7 +68,9 @@ describe("DataBridge openDiff wiring (regression guard)", () => {
   }
 
   it("wires openDiff to the openDiffVirtual webview message", () => {
-    expect(openDiffBlock()).toMatch(/postMessage\(\{\s*type:\s*["']openDiffVirtual["']\s*,\s*diff\s*\}\)/)
+    expect(openDiffBlock()).toMatch(
+      /postMessage\(\{\s*type:\s*["']openDiffVirtual["']\s*,\s*diff\s*,\s*initialDiffStyle:\s*["']split["']\s*\}\)/,
+    )
     expect(src).toContain("onOpenDiff={openDiff}")
   })
 })

packages/kilo-vscode/webview-ui/diff-virtual/DiffVirtualApp.tsx

@@ -32,9 +32,10 @@ const DiffVirtualContent: Component = () => {
   const [style, setStyle] = createSignal<DiffStyle>("unified")
 
   const handler = (event: MessageEvent) => {
-    const msg = event.data as { type: string; diff?: DiffVirtualFile }
+    const msg = event.data as { type: string; diff?: DiffVirtualFile; initialDiffStyle?: DiffStyle }
     if (msg?.type === "diffVirtual.data" && msg.diff) {
       setDiff(msg.diff)
+      setStyle(msg.initialDiffStyle ?? "unified")
     }
   }
 

packages/kilo-vscode/webview-ui/src/App.tsx

@@ -134,7 +134,7 @@ export const DataBridge: Component<{ children: any }> = (props) => {
   }
 
   const openDiff = (diff: { file: string; before: string; after: string; additions: number; deletions: number }) => {
-    vscode.postMessage({ type: "openDiffVirtual", diff })
+    vscode.postMessage({ type: "openDiffVirtual", diff, initialDiffStyle: "split" })
   }
 
   const openUrl = (url: string) => {

packages/kilo-vscode/webview-ui/src/components/chat/PermissionDiff.tsx

@@ -39,6 +39,7 @@ export const PermissionDiff: Component<PermissionDiffProps> = (props) => {
     vscode.postMessage({
       type: "openDiffVirtual",
       diff: { ...props.filediff, before, after },
+      initialDiffStyle: "unified",
     })
   }
 

packages/kilo-vscode/webview-ui/src/types/messages/webview-messages.ts

@@ -731,6 +731,7 @@ export interface OpenChangesRequest {
 export interface OpenDiffVirtualRequest {
   type: "openDiffVirtual"
   diff: PermissionFileDiff
+  initialDiffStyle: "unified" | "split"
 }
 
 export interface RetryConnectionRequest {