The rolling report omits the final complete window. Fix the calculation so each valid window contributes exactly one total and incomplete windows follow the documented behavior.
Build the implementation in C++ under /app, with /app/run.sh as its entry point. Read one JSON request from standard input and write one JSON result to standard output. Input has integer values and positive integer width. Return sums for every complete contiguous window, in order. Width exceeding the input length yields an empty list. Reject boolean/noninteger/nonpositive width.
Reject inputs that violate an explicit validation rule with exit status 2, no standard output, and {"error":"invalid_input"} on standard error. For valid input, exit with status 0. Keep the implementation reusable for new inputs; it must work offline and must not depend on the example data being the only data it receives.
Repair or replace the unfinished /app/run.sh and add source files under /app. Malformed JSON must use the same invalid-input response. Do not read /tests or /oracle from the application.