Production failures often contain enough evidence to explain what went wrong, but not enough structure to become an executable test. A trace may expose the failing request path, a log may contain the exception, and downstream spans may reveal the dependency response that triggered the defect. The useful engineering step is to transform that evidence into a deterministic regression test rather than another incident summary. Recent bug-reproduction systems follow the same principle that a useful reproducer should fail on the buggy revision for the reported reason and become passing evidence after the defect is fixed. Issue2Test and ReProAgent both use execution feedback instead of treating test generation as a single prompt-and-response operation.