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];

hub/src/feishu/fileDeliveryTool.ts

@@ -15,6 +15,7 @@ export interface FileDeliveryToolOptions {
   readonly runId: string;
   readonly workspaceRoot?: string | undefined;
   readonly workspaceDir: string;
+  readonly maxFileBytes?: number | undefined;
   readonly sendOptions?: SendMessageOptions | undefined;
   readonly approvalManager: ApprovalManager;
   readonly onDelivered?: (path: string) => void;
@@ -29,7 +30,7 @@ export function createFileDeliveryMcpServer(options: FileDeliveryToolOptions): M
     tools.push(
       tool(
         "send_file",
-        "Upload an existing file from the current project workspace to the current Feishu chat. The path must point to a concrete no-symlink file, for example build/student.pdf or README.md.",
+        "Upload any existing regular file from the current project workspace to the current Feishu chat. The path must point to a concrete no-symlink file and must not be inside platform runtime directories.",
         {
           path: z.string().describe("Workspace-relative path, or an absolute path physically inside the current workspace."),
           name: z.string().optional().describe("Optional display filename. Defaults to the file's basename."),
@@ -46,12 +47,18 @@ export function createFileDeliveryMcpServer(options: FileDeliveryToolOptions): M
               content: [{ type: "text", text: "File delivery is unavailable because workspace isolation is not configured." }],
             };
           }
+          if (options.maxFileBytes === undefined) {
+            throw new Error("Agent file delivery requires a configured maximum file size");
+          }
           let file;
           try {
-            file = await resolveDeliverableFile(args.path, workspaceRoot, options.workspaceDir);
+            file = await resolveDeliverableFile(args.path, workspaceRoot, options.workspaceDir, options.maxFileBytes);
           } catch (error) {
             const boundaryViolation = error instanceof WorkspaceFileBoundaryError && error.reason === "boundary";
-            const log = boundaryViolation ? options.rt.logger.warn.bind(options.rt.logger) : options.rt.logger.error.bind(options.rt.logger);
+            const limitViolation = error instanceof WorkspaceFileBoundaryError && error.reason === "limit";
+            const log = boundaryViolation || limitViolation
+              ? options.rt.logger.warn.bind(options.rt.logger)
+              : options.rt.logger.error.bind(options.rt.logger);
             log(
               {
                 runId: options.runId,
@@ -61,12 +68,20 @@ export function createFileDeliveryMcpServer(options: FileDeliveryToolOptions): M
               },
               boundaryViolation
                 ? "Agent file delivery refused by workspace boundary"
-                : "Agent file delivery failed during workspace file access",
+                : limitViolation
+                  ? "Agent file delivery refused by file size limit"
+                  : "Agent file delivery failed during workspace file access",
             );
+            if (limitViolation) {
+              return {
+                isError: true,
+                content: [{ type: "text", text: `File exceeds the configured delivery limit: ${args.path}` }],
+              };
+            }
             if (!boundaryViolation) throw error;
             return {
               isError: true,
-              content: [{ type: "text", text: "File path is outside the current workspace or uses a symlink." }],
+              content: [{ type: "text", text: "File path is outside the current workspace, belongs to platform runtime, or uses a symlink." }],
             };
           }
           if (file === null) {

hub/src/feishu/trigger.ts

@@ -444,6 +444,7 @@ export function makeTriggerHandler(deps: TriggerDeps): TriggerHandler {
       runId: run.id,
       workspaceRoot: projectWorkspaceRoot,
       workspaceDir: project.workspaceDir,
+      maxFileBytes: deps.resourceLimits?.maxBytesPerFile,
       sendOptions,
       approvalManager,
       tools: cphHubMcpToolsForRole(roleTools),