[feat] add MCP file browsing and cancellable transfers

apps/mcp/src/native.ts

@@ -174,7 +174,8 @@ export class NativeClient {
       return Promise.reject(new Failure("BUSY", false, true));
     const id = ++this.sequence;
     const sideEffect = method === "action" || method === "unlock" ||
-      (method === "clipboard" && args.operation === "set");
+      (method === "clipboard" && args.operation === "set") ||
+      (method === "files" && ["upload", "download", "cancel"].includes(args.operation));
     const line = JSON.stringify({ ...args, id, method }) + "\n";
     if (Buffer.byteLength(line) > 65536)
       return Promise.reject(new Failure("MESSAGE_TOO_LARGE"));

apps/mcp/src/server.ts

@@ -124,7 +124,8 @@ export function createServer(
       inputSchema: schema,
       annotations: {
         readOnlyHint: !!d.readOnly,
-        destructiveHint: ["crossdesk_action", "crossdesk_unlock"].includes(d.name),
+        destructiveHint: ["crossdesk_action", "crossdesk_unlock", "crossdesk_clipboard_set",
+          "crossdesk_files_transfer", "crossdesk_files_cancel"].includes(d.name),
         openWorldHint: true,
       },
       ...(d.ui || d.app
@@ -316,6 +317,28 @@ export function createServer(
     "Read the remote text clipboard within the authorized control session.",
     async (p, ctx) => output(await sessions.clipboard({ ...p, operation: "get" }, ctx.mcpReq.signal)),
     { readOnly: true });
+  const filePath = z.string().max(4096).refine((path) => !path.includes("\0"));
+  add("crossdesk_files_list", z.strictObject({ session_id: id, path: filePath.default(""),
+    request_id: z.int().min(1).max(4294967295).optional(), offset: z.int().min(0).default(0) }),
+    "List a remote directory. Empty path selects the remote home and @roots lists filesystem roots. Results contain up to 256 entries. Continue with request_id and next_offset while present. A timed-out listing remains queryable with its request_id.",
+    async (p, ctx) => output(await sessions.files({ ...p, operation: "list" }, ctx.mcpReq.signal)),
+    { readOnly: true });
+  add("crossdesk_files_transfer", z.strictObject({ session_id: id, operation_id: id,
+    direction: z.enum(["upload", "download"]), paths: z.array(filePath.min(1)).min(1).max(256),
+    destination: filePath.min(1) }),
+    "Upload local files/folders or download remote files/folders into an existing absolute destination directory. paths are absolute source paths. Returns a transfer operation to monitor with crossdesk_files_status. Reuse the same operation_id and arguments to query the original transfer. Existing destination files receive a distinct name on conflict.",
+    async (p, ctx) => {
+      const { direction, ...args } = p;
+      return output(await sessions.files({ ...args, operation: direction }, ctx.mcpReq.signal));
+    });
+  add("crossdesk_files_status", z.strictObject({ session_id: id, operation_id: id,
+    offset: z.int().min(0).default(0) }),
+    "Get transfer progress, per-file completion and errors. Continue file entries with next_offset. Wait for completed, failed or cancelled before reporting a finished transfer.",
+    async (p, ctx) => output(await sessions.files({ ...p, operation: "status" }, ctx.mcpReq.signal)),
+    { readOnly: true });
+  add("crossdesk_files_cancel", z.strictObject({ session_id: id, operation_id: id }),
+    "Cancel a transfer and remove its unfinished staging files. Completed files remain available.",
+    async (p, ctx) => output(await sessions.files({ ...p, operation: "cancel" }, ctx.mcpReq.signal)));
   add("crossdesk_clipboard_set", z.strictObject({ session_id: id, operation_id: id,
     text: z.string().max(16384).refine((text) => Buffer.byteLength(text) <= 16384 && !text.includes("\0")) }),
     "Set or clear the remote text clipboard. Reuse the same operation_id to query the original result. Returns applied after the remote clipboard update.",
@@ -414,7 +437,8 @@ export function createServer(
           inputSchema,
           annotations: {
             readOnlyHint: !!d.readOnly,
-            destructiveHint: ["crossdesk_action", "crossdesk_unlock"].includes(d.name),
+            destructiveHint: ["crossdesk_action", "crossdesk_unlock", "crossdesk_clipboard_set",
+              "crossdesk_files_transfer", "crossdesk_files_cancel"].includes(d.name),
             openWorldHint: true,
           },
           ...((d.ui || d.app) && apps(ctx)

apps/mcp/src/sessions.ts

@@ -473,6 +473,34 @@ export class Sessions {
     if (s.unlock && this.unlockPending(s.unlock)) throw new Failure("UNLOCK_PENDING");
     return s.native.request("clipboard", args, 7000, signal);
   }
+  async files(p: Data, signal?: AbortSignal): Promise<Data> {
+    const { session_id, ...args } = p;
+    const s = this.session(session_id);
+    this.checkUnlock(s);
+    if (s.unlock && this.unlockPending(s.unlock) && !["status", "cancel"].includes(args.operation))
+      throw new Failure("UNLOCK_PENDING");
+    if (args.operation !== "list") return s.native.request("files", args, 7000, signal);
+    const requestId = args.request_id ?? (await s.native.request("files",
+      { operation: "list", path: args.path ?? "" }, 7000, signal)).request_id;
+    try {
+      const deadline = Date.now() + 25000;
+      while (true) {
+        const result = await s.native.request("files", {
+          operation: "list_result", request_id: requestId, offset: args.offset ?? 0,
+        }, 7000, signal);
+        if (result.state !== "pending") {
+          if (result.next_offset == null)
+            await s.native.request("files", { operation: "list_cancel", request_id: requestId });
+          return result;
+        }
+        if (Date.now() >= deadline) return { request_id: requestId, state: "pending", wait_timed_out: true };
+        await delay(100, undefined, { signal });
+      }
+    } catch (error) {
+      await s.native.request("files", { operation: "list_cancel", request_id: requestId }).catch(() => {});
+      throw error;
+    }
+  }
   async control(id: string, enabled: boolean) {
     if (!enabled) this.cancelUnlock(this.session(id));
     return this.session(id).native.request("control", { enabled });