GitHub Copilot review alternative for named project 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 GitHub Copilot code review's detection rate.

Perch vs GitHub Copilot code review: 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.

GitHub Copilot review alternative for named project requirements

Give Copilot a requirement it can verify with perch check after editing. Perch's rules are independently selectable checks with method context, and the CLI works from the shell. A team's Perch bill follows fresh checks rather than Copilot subscription seats.

Review before committing

GitHub Copilot code review: Supported editors review file diffs; Copilot CLI is available, with a distinct command workflow. GitHub Copilot code review 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?

GitHub Copilot code review: Repository and path instructions, REVIEW.md, skills and MCP context. GitHub Copilot code review 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 GitHub Copilot code review's billing unit and Perch's usage estimate

Is the CLI open source and offline?

GitHub Copilot code review: Commercial review service. GitHub Copilot code review 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 GitHub Copilot code review fit the workflow?

Copilot provides GitHub PR and supported-editor review alongside its coding tools. Separate subscription credits, review effort and Actions minutes before estimating a review bill.

Estimate the review bill

Perch and GitHub Copilot code review: 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.