fix: allow arbitrary workspace file delivery

hub/src/feishu/fileDelivery.ts

@@ -1,4 +1,4 @@
-import { extname, isAbsolute, join } from "node:path";
+import { isAbsolute, join, relative, resolve, sep } from "node:path";
 import {
   WorkspaceFileBoundaryError,
   readWorkspaceFileNoFollow,
@@ -10,39 +10,21 @@ export interface DeliverableFile {
   readonly data: Buffer;
 }
 
-const DELIVERABLE_EXTENSIONS = new Set([
-  ".csv",
-  ".doc",
-  ".docx",
-  ".gif",
-  ".jpeg",
-  ".jpg",
-  ".md",
-  ".pdf",
-  ".png",
-  ".ppt",
-  ".pptx",
-  ".svg",
-  ".txt",
-  ".typ",
-  ".xls",
-  ".xlsx",
-  ".zip",
-]);
+const DELIVERABLE_CPH_DIRECTORY = "inbox";
 
 export async function resolveDeliverableFile(
   requestedPath: string,
   workspaceRoot: string,
   workspaceDir: string,
+  maxBytes?: number,
 ): Promise<DeliverableFile | null> {
   const token = requestedPath.trim();
-  if (token === "" || !DELIVERABLE_EXTENSIONS.has(extname(token).toLowerCase())) {
-    return null;
-  }
+  if (token === "") return null;
 
   for (const candidate of candidatePaths(token)) {
+    assertNotPlatformRuntimePath(candidate, workspaceDir);
     try {
-      return await readWorkspaceFileNoFollow(workspaceRoot, workspaceDir, candidate);
+      return await readWorkspaceFileNoFollow(workspaceRoot, workspaceDir, candidate, maxBytes);
     } catch (error) {
       if (!(error instanceof WorkspaceFileBoundaryError) || error.reason !== "not_found") {
         throw error;
@@ -54,6 +36,20 @@ export async function resolveDeliverableFile(
   return null;
 }
 
+function assertNotPlatformRuntimePath(candidate: string, workspaceDir: string): void {
+  const workspace = resolve(workspaceDir);
+  const target = isAbsolute(candidate) ? resolve(candidate) : resolve(workspace, candidate);
+  const rel = relative(workspace, target);
+  const components = rel.split(sep);
+  if (components[0] === ".cph" && components[1] !== DELIVERABLE_CPH_DIRECTORY) {
+    throw new WorkspaceFileBoundaryError(
+      `platform runtime files cannot be delivered: ${candidate}`,
+      candidate,
+      "boundary",
+    );
+  }
+}
+
 function candidatePaths(token: string): string[] {
   if (isAbsolute(token)) return [token];
   const candidates = [token];