The signal operation should produce the full linear convolution, including both ends of the output. Implement it so unequal input lengths and empty inputs follow the defined convention.
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 signal and kernel lists of integers. Return full linear convolution of length len(signal)+len(kernel)-1; either empty input returns an empty list. Define output[k] as the sum of signal[i]*kernel[k-i] over valid indices. Reject boolean/noninteger entries. Do not reverse the result or perform circular wraparound.
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.