Evolith Core

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Your architecture rules, running on every PR.

Real output of the published CLI on an empty repository (2026-09-14, abridged; full 71-row capture).

Evolith is an architecture linter for CI. It reads your repository — structure, workflows, manifests, architecture decisions — and checks it against a library of rules: layering, dependencies, security, CI/CD. If a blocking rule fails, the PR fails.

What sets it apart from other linters: it also counts the rules it could not evaluate. A blocking rule that never ran fails the PR exactly as one that failed. Coverage and compliance are never painted the same green.

It is for engineering teams that want their architecture decisions enforced in CI rather than reviewed by hand, for platform teams blocking non-conformant artifacts before production, and for AI agents that need to validate their own output against the same rules.

Try it · Four terms · In CI · What is inside · What it is not · Documentation · Interactive atlas

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Try it in two minutes

You need Node ≥ 18. No database, no server, no Docker; your code never leaves your machine.

npx -y @beyondnet/evolith-cli init --name my-project --yes   # writes evolith.yaml in the current directory
npx -y @beyondnet/evolith-cli validate --engine opa          # evaluates; exits 2 if anything blocking did not pass

The first run will fail, and that is fine: it is a baseline, not a grade. Many rules assume a layout your repository does not have yet. To start only from what you have already adopted:

npx -y @beyondnet/evolith-cli rulesets                        # lists the packs your installation loads
npx -y @beyondnet/evolith-cli validate --engine opa --select rulesets/acl/anti-corruption-layer.rules.json

init writes evolith.yaml with the product's name, type and phase and your stack; --engine opa picks the engine with the most coverage today (why, in Known limitations). What a first run looks like, row by row: capture. Full guide: Quickstart.

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Four terms you need

• Rule — a check with an id, a priority (MUST / SHOULD / COULD) and a verdict: passed, failed or skipped (could not be evaluated). A MUST that ends skipped blocks exactly as a failed one.
• Pack — a *.rules.json file grouping rules by topic (ACL, security, CI…). evolith rulesets lists them; --select picks which ones to apply.
• Topology — the architecture style you declare: modular-monolith, distributed-modules, microservices, event-driven, serverless, edge-computing, data-mesh or agentic-ai. The same rules follow you when the monolith splits into services.
• Phase — where the product is in its lifecycle: Discovery → Design → Construction → QA → Delivery. Each phase has gates that block the move to the next one.

An ADR (Architecture Decision Record) is an architecture decision in writing; evolith adr create drafts one, and many rules are derived from them. Full glossary.

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In CI

- uses: beyondnetcode/evolith_arch32@v1
  with:
    fail-on-violation: true

Exit codes: 0 pass · 1 the tool failed · 2 the gate blocked · 3 invalid invocation. 1 and 3 mean the repository was not evaluated: they are not weaker forms of non-compliant, and the job summary says so in words.

For an AI agent, the same engine as an MCP server over stdio (Node ≥ 20):

{ "mcpServers": { "evolith": { "command": "npx", "args": ["-y", "@beyondnet/evolith-mcp"] } } }

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What is inside

Product	Role
Evolith Core	The library of rules, ADRs and phase schemas. MIT and free: files you can read, edit and version
Evolith CLI	Evaluates your repository locally or in CI; manages ADRs and phase gates
MCP Services	The rules as live context for an agent
Core API	REST to query and evaluate remotely
Agent Runtime	Drives the Core from an agent, through Ports and Adapters. Experimental
Evolith Tracker	Commercial lifecycle-governance product. Not yet launched; it will be the only paid one

How many rules, packs and ADRs your installation loads is printed by evolith rulesets; the tree's counts are measured by CI on every PR and published in the corpus inventory.

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What it is not

• Not a replacement for ArchUnit, Conftest or dependency-cruiser; it complements them. Rules live outside the codebase, as data that governs many repositories and that an agent can read. Evolith is OPA underneath, and adds the rule library, the ADR-to-rule derivation and the coverage accounting.
• It does not read your code's AST. It inspects structure, workflows, manifests and governance artifacts; the subset that looks at dependencies and linters assumes a Node/TypeScript repository.
• It does not call any LLM. No command in the published CLI reaches one; "the LLM proposes, a deterministic verifier disposes" is a documented direction, not shipped behaviour. Network egress disclosure: Security Policy.

What this front page does not say — what each engine covers, counts that disagree, real adoption, unverified platforms — lives on a single dated page: Known limitations. It exists because a README that only tells the good part is exactly the defect Evolith detects.

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Documentation

To…	Go to
Start from your role	Start by Role
Understand the rules and ADRs	Evolith Core hub
See the executable corpus	Rulesets · OPA policies · Schemas
Choose or migrate a topology	Topologies hub
Use the CLI, MCP or REST	Interfaces hub · Evolith CLI hub
See the project's state	Known limitations · Gap board · Maturity
Answer a specific question	Q&A · Glossary
Walk the whole corpus	Master Index · Product hub · Repository Taxonomy

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Contributing

Start here: issues that are good for a first contribution — most touch a single file. Unsure before opening a PR? Discussions.

Three ways to contribute without writing TypeScript: correct a count that disagrees between docs and code · translate a hub into Spanish · add a rule to src/rulesets/.

Before the PR: Contribution Guide · Security Policy · AGENTS.md · CHANGELOG

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License

Released under the MIT License.