Applying a configuration overlay currently loses unrelated values inside nested objects. Repair the merge behavior so only the values covered by the overlay change.
Build the implementation in TypeScript 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 base and patch JSON objects. Recursively merge when both values are objects; otherwise patch replaces base, including lists and null. Preserve untouched keys. Reject root values that are not objects. Return an independent merged object.
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.