fix(vscode): validate webview files input and extract FileAttachment type

Address PR review remarks: sanitize runtime-untyped files from webview
with Array.isArray + field validation, and extract shared FileAttachment
type to reduce inline type repetition.

packages/kilo-vscode/src/KiloProvider.ts

@@ -719,7 +719,7 @@ export class KiloProvider implements vscode.WebviewViewProvider {
     providerID?: string,
     modelID?: string,
     agent?: string,
-    files?: Array<{ mime: string; url: string }>,
+    files?: unknown,
   ): Promise<void> {
     if (!this.httpClient) {
       this.postMessage({
@@ -748,6 +748,13 @@ export class KiloProvider implements vscode.WebviewViewProvider {
         throw new Error("No session available")
       }
 
+      // Sanitize files input from webview (runtime-untyped)
+      const sanitized = Array.isArray(files)
+        ? files.filter(
+            (f): f is { mime: string; url: string } => f && typeof f.mime === "string" && typeof f.url === "string",
+          )
+        : []
+
       // Build parts array with file context and user text
       const parts: Array<{ type: "text"; text: string } | { type: "file"; mime: string; url: string }> = []
 
@@ -755,17 +762,15 @@ export class KiloProvider implements vscode.WebviewViewProvider {
       const editor = vscode.window.activeTextEditor
       if (editor && editor.document.uri.scheme === "file") {
         const url = editor.document.uri.toString()
-        const already = files?.some((f) => f.url === url)
+        const already = sanitized.some((f) => f.url === url)
         if (!already) {
           parts.push({ type: "file", mime: "text/plain", url })
         }
       }
 
       // Add any explicitly attached files from the webview
-      if (files) {
-        for (const f of files) {
-          parts.push({ type: "file", mime: f.mime, url: f.url })
-        }
+      for (const f of sanitized) {
+        parts.push({ type: "file", mime: f.mime, url: f.url })
       }
 
       parts.push({ type: "text", text })

packages/kilo-vscode/webview-ui/src/context/session.tsx

@@ -33,6 +33,7 @@ import type {
   ContextUsage,
   AgentInfo,
   ExtensionMessage,
+  FileAttachment,
 } from "../types/messages"
 
 // Store structure for messages and parts
@@ -87,12 +88,7 @@ interface SessionContextValue {
   selectAgent: (name: string) => void
 
   // Actions
-  sendMessage: (
-    text: string,
-    providerID?: string,
-    modelID?: string,
-    files?: Array<{ mime: string; url: string }>,
-  ) => void
+  sendMessage: (text: string, providerID?: string, modelID?: string, files?: FileAttachment[]) => void
   abort: () => void
   compact: () => void
   respondToPermission: (permissionId: string, response: "once" | "always" | "reject") => void
@@ -496,12 +492,7 @@ export const SessionProvider: ParentComponent = (props) => {
     setSelectedAgentName(name)
   }
 
-  function sendMessage(
-    text: string,
-    providerID?: string,
-    modelID?: string,
-    files?: Array<{ mime: string; url: string }>,
-  ) {
+  function sendMessage(text: string, providerID?: string, modelID?: string, files?: FileAttachment[]) {
     if (!server.isConnected()) {
       console.warn("[Kilo New] Cannot send message: not connected")
       return

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

@@ -519,6 +519,11 @@ export type ExtensionMessage =
 // Messages FROM webview TO extension
 // ============================================
 
+export interface FileAttachment {
+  mime: string
+  url: string
+}
+
 export interface SendMessageRequest {
   type: "sendMessage"
   text: string
@@ -526,7 +531,7 @@ export interface SendMessageRequest {
   providerID?: string
   modelID?: string
   agent?: string
-  files?: Array<{ mime: string; url: string }>
+  files?: FileAttachment[]
 }
 
 export interface AbortRequest {