Postil vs Copilot code review

Copilot cannot block a merge, by design

Per GitHub's own documentation, Copilot always submits a "Comment" review, never "Request changes," and never counts toward required approvals. Whatever it finds, the merge button stays green. Enterprises asking for an enforcement mode is an open community discussion. Postil separates the two roles: postil/review carries advisory commentary, and postil/gate is a real pass/fail check you can require in branch protection. On operational errors the gate fails closed by default; repos can opt into gate.onError: advisory, which fails open on provider outages only.

AI Credits made review cost a variable

Copilot moved to usage-based "AI Credits" billing on June 1, 2026, and code review now also consumes GitHub Actions minutes per agentic run; legacy plans saw a 13x premium-request multiplier for review. Users report large cost swings, including one who burned an entire month's included credits on a single automatic PR review. Postil charges a flat $10 per developer per month and routes inference through your own key at provider list rates with zero markup, so the bill is known before the month starts. Run your numbers on the cost calculator.

Silence as a product metric, not a blog post

To GitHub's credit, it has published the closest thing to a silence number from any major vendor: Copilot code review stays silent on roughly 29% of reviews. But that figure lives in a blog post. Postil reports your silence rate, on your PRs, as the first number on the dashboard, with the confidence distribution of every finding it shipped, so you can see whether restraint holds on your codebase rather than on an average.

Data handling depends on your plan

On Copilot Free, Pro, and Pro+, interaction data is used for model training unless you opt out (policy since April 2025); Business and Enterprise plans are excluded. There is no model choice and no BYO key on any tier. With Postil, code goes to the inference provider you chose under your own key and your own DPA, and the self-hosted deployment keeps it inside your network entirely. The control plane stores review envelopes, never code.

Where Copilot is ahead

Zero setup if your org already pays for Copilot, the deepest native GitHub integration in the category, and the broadest organizational adoption: Pullflow's analysis of 40.3M public PRs found Copilot leads org adoption among AI reviewers. It is also improving quickly: an agentic architecture went GA in March 2026, followed by severity levels and grouped comments. If you want advisory review with no procurement step, Copilot is the obvious first try.