PREFERRED way to change code in a REAL repository: fix a GitHub issue, fix a bug, add/implement a function or feature, or make any edit to a project the user names by a filesystem path (e.g. /tmp/foo, ~/code/bar) or a git URL. Clones the repo, runs an OpenSquilla agent on the host to make the change on a task branch, then independently VERIFIES it with a red→green→regression test loop and reports a structured result. STRONGLY prefer this over hand-editing the user's files yourself in this session: editing files directly skips the isolation and the runner-verified red→green proof, so it is not equivalent. Use it whenever the request names a real on-disk repo/path or a repo URL and asks to fix/add/implement/change code. Examples: 'fix issue 412 in github.com/acme/widgets', '给 /tmp/calc 加个 average 函数', '帮我改一下 ~/proj 里的 X', 'implement CSV export in my project'. Docker-free host execution; treat the target repo as TRUSTED. GitHub issue mode needs the `gh` CLI. For self-contained, TESTABLE code from scratch when NO repo is named (e.g. 'write a function that maps A-Z to pitches'), use `--verification-mode scratch` with no --repo: it scaffolds a throwaway project, writes the code plus a test, and verifies it green. Only truly trivial one-liners or conceptual/non-testable questions are answered inline.