Four Tools Move Code Review Before the Commit

Four code review tools shipped within 48 hours of each other, each checking agent-written code before a pull request exists.

The shift matters because agents now generate more code than any reviewer reads before merging, so catching problems has to happen earlier in the flow.

GitWarren reviews the dirty worktree before anything gets committed. It's GPL-3.0 and ships 17 MCP tools. An agent can answer questions about its own changes inside the review, instead of after opening a pull request.

Ponytail runs a stop rule before generation begins, catching problems before code exists. Twinrun runs the old and new versions of a changed function on identical inputs and diffs the outputs. That catches behavior changes a diff view misses.

webmcp-stack generates WebMCP tools straight from an OpenAPI spec, baking confirmation steps into regenerated code regions so they survive the next regeneration.

A GitHub pull request assumes a human opens the diff, reads it, and decides. These four tools intercept earlier: at the worktree, at generation time, at the function boundary, at the spec-to-code regeneration step.

None of the four say how they perform against real review misses, only what they check and when. A tool that catches issues before commit only beats pull request review if it catches issues pull request review would have caught anyway.