Copilot coding agent and Codex cloud vs a local, verified pipeline
GitHub Copilot’s cloud agent and OpenAI’s Codex cloud run a coding agent in a hosted environment and hand you a pull request or a diff to review. Provefab runs the same kind of agents on your own Mac, runs your repository’s own checks as the gate, and has a model from another vendor review before the pull request opens. All three leave the merge to a person by default; the difference is where the work runs and what has to pass before you look.
Side by side
| Copilot cloud agent | Codex cloud | Provefab | |
|---|---|---|---|
| Where the agent runs | “its own ephemeral development environment, powered by GitHub Actions” (GitHub docs) | “isolated cloud environments” (OpenAI docs) | Your Mac, in an isolated worktree behind a guard |
| How work starts | Assign an issue to Copilot (GitHub docs) | A task in Codex, on a connected repository (OpenAI docs) | A label on a GitHub issue |
| What decides it is ready | The agent can “execute automated tests and linters”; you “review the diff, iterate, and create a pull request when you’re ready” (GitHub docs) | The agent “runs checks, and tries to validate its work”, using AGENTS.md for commands (OpenAI docs) | Your configured format, lint and test commands must pass, plus a reproduction for a bug |
| Second review | Not described in the agent docs cited here | Not described in the task docs cited here | A model from a different provider reviews; each finding becomes a test |
| Merge | “must be reviewed and merged by a human” (GitHub docs) | You “open a pull request when the work is ready” (OpenAI docs) | Core: a person merges. Pro: optional auto-merge of small, tested changes |
| Who pays for what | GitHub Actions minutes and AI credits (GitHub docs) | Included in ChatGPT plans; API-key use has “No cloud-based features” (OpenAI pricing) | Your own Claude or ChatGPT plans or API keys; Pro is EUR 79 per month per organization |
The difference in one paragraph
Hosted agents are convenient: nothing to install, and the work runs on someone else’s machines. What you get back is a proposal that you still have to check. Provefab moves the checking before the pull request: your own commands decide, a test removed or disabled is reported, and a model from another vendor has to accept the change. You review a pull request that already carries its evidence, on code that never left your machine except through the model providers you already use.
When a hosted agent is the better choice
If your team is not on macOS, if you do not want a service running on a developer machine, or if your checks cannot run locally, a hosted agent is simpler. Copilot’s cloud agent is “available for all paid Copilot plans” (GitHub docs), so many teams already have it.
Using them together
They do not exclude each other. Some teams let a hosted agent draft, then gate what gets merged. Provefab is built for the second half: making a pull request prove itself before a person spends time on it. Read How to verify AI-generated pull requests for the checklist, and see Provefab’s own pull requests for real examples.