---
title: "0.4.0: Only the Verification Layer"
source: https://www.refactron.dev/changelog/only-the-verification-layer
site: Refactron
---

# 0.4.0: Only the Verification Layer

Aug 6, 2026 · Pivot

Breaking, despite being a minor. The refactoring product this package grew out of has been removed: six commands, the 20 AST transforms, the interactive TUI, blast-radius scoring and the tier taxonomy. They were the demo of the verification engine, not the product. verify-diff and the MCP tool are untouched.

## Highlights

- **Six commands gone**: analyze, run, document, rollback, preflight and init are removed, and bare refactron prints help instead of opening the TUI. Pin refactron@0.3.1 if you use any of them.
- **refactron login**: Only login --print-token was ever dispatched, and it discarded the status callback, so the device code and verification URL were never displayed. It is a real command now.
- **A library entry point**: main has pointed at dist/index.js since before 0.2.0, but no such file existed. import { verifyDiff } from 'refactron' resolves for the first time.

Refactron is now only a verification layer. `verify-diff` and the `verify_change` MCP tool are exactly what they were in 0.3.0, down to the report shape. Everything that surrounded them, the refactoring product this package grew out of, has been removed from it.

Under semver a `0.x` release may carry breaking changes in a minor, and this one does. Read the Removed section before upgrading: there is no major-version bump to warn you, so `^0.3.0` will not pull this in but `refactron@latest` will. The 0.3.0 entry below says nothing was renamed, removed, or redefined. That was true of 0.3.0 and is explicitly untrue of this release.

## Removed

Six commands, the transforms behind them, and the interactive UI.

| Removed | Was |
| --- | --- |
| `refactron analyze` | scan for transform patterns, blast radius, tier |
| `refactron run` | plan, verify and apply transforms |
| `refactron document` | generate docstrings and changelog prose |
| `refactron rollback` | undo the last applied refactor |
| `refactron preflight` | SQLAlchemy 1.x to 2.0 safety report |
| `refactron init` | scaffold `.refactronrc.json` |
| bare `refactron` | the interactive Ink REPL |

Also removed: the 20 AST transforms and their LibCST sidecars, the autofix fixers, blast-radius scoring, the tier taxonomy, the `.refactron/` session store, the legacy verification engine, the language-adapter layer, and the `src/core/models.ts` and `src/adapters/interface.ts` locked contracts.

> PIN IT: If you use any of it, pin `refactron@0.3.1`. The code is archived with its full history and is not currently published under any name.

Why: they were the demo of the verification engine, not the product. They were also most of the package. What remains is about a sixth of the source and all of what people install it for.

## Changed

- **Bare `refactron` prints help and exits 2** instead of opening the TUI.
- **An unknown command exits 2** and says so, rather than failing to resolve a module.
- **`refactron login` is a real command.** Previously only `login --print-token` was dispatched, and it discarded the status callback, so the device code and verification URL were never displayed. Status now goes to stderr, which keeps `--print-token` pipeable.
- **`--help` describes this product.** It advertised six departed commands and called Refactron “safety-first refactoring”, the pre-pivot positioning.

## Added

- **A library entry point.** `main` and `types` have pointed at `dist/index.js` since before 0.2.0, but no such file existed, so `import { verifyDiff } from 'refactron'` never resolved. `src/index.ts` now exports `verifyDiff`, `RefactronVerifier`, `checkPythonSyntax`, `checkTypescriptSyntax`, `reportCoverage`, the `VerdictReport` type and the `contracts.ts` surface.
- **A help-drift test.** `tests/unit/cli/help-drift.test.ts` asserts that every verb the help advertises is actually dispatched, against the built binary.

## Fixed

- **`build:copy-py` could fail silently.** Its trailing `|| true` bound to the whole `&&` chain, so a failure to copy the *verification* sidecars exited 0: green build, green CI, then every Python verdict failing at runtime against a missing sidecar. The build now asserts all three sidecars reach `dist/`.

## Internal

- 18 unused runtime dependencies dropped, including `ink`, `react`, `ts-morph` and the three `tree-sitter` packages. Five remain.
- The pre-merge gate no longer runs `analyze src/` against this repo. It gates the shipped artifact instead. It deliberately does **not** run `verify-diff` against this repo either: coverage attestation is Python-only, so a TypeScript repo verifying itself caps at `UNPROVEN` permanently.

`TransformId` still lists the 20 transform literals. Narrowing a locked contract in the same release that restructures the repo would make any regression un-bisectable, so it waits for a later major.