# Introducing Tessl Verifiers: Enforce AI Coding Standards in Every Change

## Executive summary

Tessl Verifiers introduce a mechanism to enforce complex, high-level coding standards and invariants in a codebase that traditional linters and unit tests cannot reliably cover. Verifiers allow developers to write rules in plain language, which are then automatically checked on every code change. This capability is designed to improve code quality consistency, especially when dealing with code generated by AI agents, by making previously subjective rules into deterministic, enforceable checks that can be run locally, pre-commit, or as a CI gate.

## Key takeaways

- Verifiers vs. Traditional Checks: Verifiers sit between open-ended code review and deterministic linting. They enforce rules that require a degree of judgment (e.g., 'every user-facing error must tell the user what to do next') but can be codified into a clear, repeatable rule set.
- Addressing AI/Agent Code Drift: As AI agents write more code, Verifiers provide a way to codify specific conventions and invariants that human reviewers or agents might forget or fail to consistently apply, ensuring standards are met every time.
- Enforcement Scope: Verifiers are suitable for narrow, critical rules (e.g., 'all user-facing text must be in US English') and can be run affordably on every single commit in a CI pipeline, allowing for tens of thousands of judgments.

## Technical details

- Verifier Functionality: Verifiers are rules about codebase invariance that are checked using a model as a judge. They allow developers to write rules in plain language to enforce standards like: 1) Every user-facing error must guide the user on the next steps. 2) Every API route must use typed response helpers. 3) Handlers must not log sensitive data (request headers, tokens, passwords).
- Implementation and Usage: To get started, users can interact with the Tessle agent via the CLI, asking open-ended questions or utilizing built-in loops like 'review my PRs.' Verifiers can be integrated into the development workflow as local checks, pre-commit hooks, or mandatory CI gates.

## Practical implications

- Build engineers can integrate Verifiers into the CI pipeline to enforce complex, non-deterministic coding standards that traditional unit tests miss.
- This tool provides a structured way to codify best practices, reducing reliance on human memory or subjective code review judgment.
- Verifiers can act as a powerful gatekeeper, ensuring that critical invariants (like proper error handling or data sanitization) are maintained across all code changes, especially those generated by AI agents.

## Topics

Code Quality, CI/CD, AI Code Generation, Software Standards Enforcement, Testing Paradigms, Tessl Verifiers Documentation, Tessla Agent CLI

Source: https://www.youtube.com/watch?v=1FDAowpMReo