The document service should accept an edit only when its expected revision matches the current revision. Implement the edit log so rejected writes leave both content and revision unchanged.
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 initial JSON value and operations containing expected nonnegative integer revision and value. Begin at revision zero. Accept an operation only when expected equals current revision, replacing value and incrementing revision by one; rejected operations change nothing. Return revision, value and accepted booleans. Reject malformed revision values.
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.