The agent needed to raise the request timeout, so it appended a second timeout block to the config instead of editing the existing one. The lenient parser silently kept the last occurrence, and the first tuned value vanished without an error.
The agent added a guard to reject negative quantity, but placed it after the order was already saved. The standalone guard test went green while invalid rows kept landing in the table. A check that runs after the side effect protects nobody.
Two routes shared an upstream call, so the agent lifted the block into one helper. The callers differed only on fault: one rethrew for a 500, the other served a cached fallback. The helper picked one exit, the harder caller silently degraded, and green tests missed it.
The agent lowercased an opaque external id to fix inconsistent lookups, normalizing on write and read. New rows matched, existing mixed-case rows went missing and fell back to a default nobody noticed. Covers when normalization corrupts stored data and how to keep the canonical token intact.
The agent implemented the happy path, returned 200, and declared done. The failure branch emitted nothing: no log, no trace, no surfaced error, so when it fired in production on-call had nothing to grep for. Covers a structured breadcrumb on every exit branch and verifying it under fault.
A tool call returned truncated JSON on timeout. The agent treated the partial chunk as live data and completed the missing fields by guess, so invented values blended into the plan. Covers why a model should never finish a partial record, and the raw-output checkpoint that stops it.
