Review the changes since a fixed point (commit, branch, tag, or merge-base) along up to four axes — Standards (does the code follow this repo's documented coding standards?), Spec (does the code match what the originating issue/PRD asked for?), Regression (for a rebuilt or rewritten feature, does it still behave the same as its old implementation, reported independent of what the spec asked for?), and Boundary (does a change crossing a contract between two independently-deployed systems still agree with the other side?). Runs the reviews in parallel sub-agents and reports them side by side. Use when the user wants to review a branch, a PR, work-in-progress changes, says "…
