ArchSteer

Living Architecture Control Plane for the AI-Dev Era.

AI agents now write code faster than any architect can review, document, or govern it. Docs rot instantly, the real architecture is invisible, structural decisions get made silently, and intended architecture drifts with every edit. ArchSteer is the always-current architecture system of record + governance plane: it derives the real architecture from code, keeps living docs and ADRs auto-built, surfaces every major decision for the architect to ratify, enforces declared intent as code-level fitness functions, and steers AI agents to conform instead of replicating local slop.

Everything is a projection of one code-derived model — .archsteer/model.json.

                    .archsteer/model.json  (single source of truth)
                                 │
   MAP ──── DOCUMENT ──── GOVERN ──── STEER ──── EVOLVE
  model    living docs   fitness     agent     report.html
  from     + auto ADRs   functions   guardrails  (drift/
  source   + diagrams    + ratchet   + MCP       decisions)

Install

pip install archsteer                 # regex engine + the local MCP server, zero native deps
pip install "archsteer[treesitter]"   # optional native acceleration

(Since 0.4.1 the MCP server ships in the base install; pip install "archsteer[mcp]" still works as a no-op alias.)

Quickstart

archsteer init      # scaffold .archsteer/ + seed intent (Express → Next.js + repository)
archsteer map       # build model.json from source
archsteer docs      # regenerate .archsteer/architecture.md (deterministic, Mermaid)
archsteer govern    # conformance + drift score by rule
archsteer adr       # draft ADRs for new structural decisions (architect-in-the-loop)
archsteer baseline  # accept current debt — the ratchet
archsteer steer -f src/controllers/payment.js -t "add refund endpoint"
archsteer check     # CI/pre-commit: fail on NET-NEW violations only
archsteer report    # self-contained .archsteer/report.html

The three design guarantees

1. Ratchet, not freeze. archsteer check blocks only net-new violations against a baseline — teams keep shipping features while debt can only shrink.
2. Conservative, architect-in-the-loop ADRs. Only external-boundary changes (new dependency, new datastore, new layer) draft an ADR — never internal reshuffles, never auto-committed.
3. Sharp agent steering. Guardrails injected into CLAUDE.md / AGENTS.md are scoped to the files in play and point at the governing ADR — they don't dump the whole model into the context window.

Declaring intent — .archsteer/architecture.yaml

target: "Migrate Express + raw SQL to Next.js route handlers + the repository pattern"
layers: [route, controller, service, repository, model]
rules:
  - id: no-raw-sql-outside-repository
    type: required_layer_for_data_access
    allowed_layers: [repository]
    operations: [RAW]
    severity: error
    adr: .archsteer/adr/0001-repository-pattern.md
    steer: "Wrap all queries in a repository under src/repositories/. No raw SQL elsewhere."

Rule types: required_layer_for_data_access, forbidden_import, forbidden_data_access, forbidden_layer_edge.

Using with AI agents (MCP)

archsteer mcp runs a local MCP server over stdio — spawned by your own editor/agent, never hosted by us. It reads only what init/map/govern already wrote to .archsteer/ on disk, so there's no network call and nothing leaves your machine. It exposes three tools:

• current_architecture — component/layer counts, conformance/drift, the declared target.
• get_target_pattern — the invariants that apply to a file, before you write to it.
• check_file — whether a file you just edited conforms, without waiting for CI.

Add it to Claude Code:

claude mcp add archsteer -- archsteer mcp

Add it to Cursor with one click: Install in Cursor →

Or to any MCP-compatible client's config:

{ "mcpServers": { "archsteer": { "command": "archsteer", "args": ["mcp"] } } }

Also published to the official MCP registry as io.github.einvoice-dev1/archsteer (runnable via uvx archsteer mcp).

CI / pre-commit

• GitHub Action: .github/workflows/archsteer.yml (maps, drafts ADRs, runs the net-new gate, uploads report.html).
• Git hook: cp hooks/pre-commit .git/hooks/pre-commit && chmod +x .git/hooks/pre-commit.

Conformance badge

If your repo pushes snapshots to the situation room (archsteer push), its latest conformance score is a live badge — the one at the top of this README is this repo governing itself:

[![ArchSteer conformance](https://img.shields.io/endpoint?url=https%3A%2F%2Fwww.archsteer.com%2Fapi%2Fbadge%2FYOUR-REPO)](https://www.archsteer.com)

Replace YOUR-REPO with the repo name archsteer push reports. Green at ≥90%, grey while you're still x-ray-only (no architecture.yaml declared yet).

Try the demo

cd examples/demo-repo
archsteer init && archsteer map && archsteer report   # open .archsteer/report.html

Roadmap

• Shipped — cloud control plane (Next.js + Supabase): multi-repo situation room with drift/decision time-series. archsteer mcp: a local MCP server so agents query the live model + intent mid-edit. An org-wide, hosted MCP server (Team tier) so agents can ask cross-repo questions against the situation room — "what's our drift index," "which repos have pending ADRs" — the same data as the dashboard, over MCP.
• Later — auth, org/repo model, billing.

Development

python3.11 -m venv .venv && source .venv/bin/activate
pip install -e ".[dev]"
pytest -q