Sourcery alternative for rerunnable English requirements

Catch the fix an agent removes later.

A saved requirement makes a recurring mistake checkable. In this Perch capture from September 20, 2026, the same rule flags a missing guard and passes after the guard is restored.

def refund(order, payment):
    payment.refund(order.total)
    order.status = "refunded"
    return order

def refund(order, payment):
    if order.status == "refunded":
        return order
    payment.refund(order.total)
    order.status = "refunded"
    return order

Source: public order-service checkout.py at the linked commit. The captured standalone file is refund.py. Perch command output and timestamp. This saved-rule demonstration does not measure Sourcery's detection rate.

Perch vs Sourcery: what your team runs.

Perch turns project behavior into focused checks that agents can run before committing. Use these differences to choose the review workflow and billing model your team needs.

Sourcery alternative for rerunnable English requirements

Turn a correction into a targeted requirement the next agent session can execute. Perch's local CLI checks uncommitted files against saved project, file and method rules. Its usage bill remains independent of the number of developers using that workflow.

Review before committing

Sourcery: IDE reviews files, HEAD and branches; standalone CLI review was not verified. Sourcery workflow documentation.

Perch reads the current working file with perch check. For a known requirement, select its rule name and method instead of requesting another broad review. A local CLI describes where the command runs; Perch sends relevant source to hosted TypeSafe models for analysis.

How do saved requirements differ?

Sourcery: English scoped rules, with a 3,000-character rule limit. Sourcery rule documentation.

Perch stores English ensure rules in perch.yaml or .perch/rules/. Project, file and method scopes determine what is checked. Run the named check after an edit and after the repair; a rule finding can fail the command and a CI gate. Perch rules · Working-file checks.

What does the review bill depend on?

Compare Sourcery's billing unit and Perch's usage estimate

Is the CLI open source and offline?

Sourcery: Commercial service; free public-repository reviews. Sourcery product or license source.

Perch’s CLI is MIT-licensed; hosted model inference is a separate paid service included in its published check rate. It does not run the model offline. Unchanged requests can reuse cached answers for free. Fresh judgments can vary, and a passing requirement check does not prove application correctness. Perch MIT license.

When does Sourcery fit the workflow?

Sourcery supports IDE and PR reviews, and Team adds repository scanning. Free public-repository review may fit open-source work; a standalone local AI review CLI was not verified.

Estimate the review bill

Perch and Sourcery: pricing, allowances and workload calculator

Make the agent check its next edit.

npm install -g @lakeday/perch

perch rules add refund-once \
  --where refund.py --each method \
  --ensure "Refunded orders cannot be refunded again."

perch check refund.py::refund --rules refund-once

Use perch scan for repository code at Git HEAD and changed-code CI checks for pull requests. New model judgments can vary. Repeatability comes from cached answers for unchanged requests; a pass does not prove application correctness.