Fail-Open Defaults in Agent PRs: A Provenance Review
The following scene is a composite review scenario. It is not a named customer story. A billing service received an agent pull request on Friday. The patch added retries, caching, and a thin HTTP client. Generated tests were green on the CI run. The reviewer still blocked the merge that afternoon. Three invented defaults would have hidden production failures. Agent patches often look complete at…
A billing service rejected a pull request containing a patch that added retries, caching, and an HTTP client on Friday. Despite the tests passing, the reviewer blocked the merge due to three invented defaults that could have hidden production failures. Agent patches often appear complete at first glance but can introduce hidden runtime contracts.
The article reviews these invented defaults, which include guessed hosts, timeouts, environment keys, and empty catch blocks that mask transport errors. The review sequence for contract-changing agent PRs involves extracting the new contract surface, classifying fail-open versus fail-closed behaviors, demanding a source for every default, and scanning the diff with a heuristic script to identify common invention smells.
Fail-open code turns outages into reported successes, and reviewers should treat it as a contract bug.
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