Intent-first engineering

Code review is dead.
Review intent instead.

AI writes code faster than any human can read it. Checking diffs is a fool's errand. Review the decisions instead. Sigil makes specs, ADRs, and architectural constraints the unit of review — and enforces them in CI.

See a PR get blocked → Install in 30s

Open-source · Python CLI · Zero platform dependencies · GitHub ↗

Sigil intent graph — 36 nodes, 87 edges, showing the full architecture of a bookstore application

Shelf bookstore demo

36 nodes 87 edges 9 components

The enforcement moment

A gate caught what code review missed.

A developer changed the payment gateway. The diff looked clean. But GATE-0005 knew that any change to services/payments/ can't touch raw card numbers. PR blocked until intent is updated.

sigil-bot commented on PR #312

🔮 Sigil Intent Review

Coverage     89%
Intent changes 2 (spec/ADR)
Gates        4/5 ❌
Ungoverned   0

Gate results (4/5 passing) ⛔
✅ GATE-0001 Catalog API compat
✅ GATE-0002 Auth no plaintext
✅ GATE-0003 Order service deps
✅ GATE-0004 Spec quality
❌ GATE-0005 Payment no raw cards

  services/payments/checkout.py:47
  accesses raw_card_number directly —
  only tokenized methods allowed
  (PCI scope expansion risk)

⛔ This PR cannot merge
        

Before Sigil

PR #312 gets 6 approvals. The diff looks clean. The PCI constraint exists in someone's head. Nobody catches that raw card data just leaked into the checkout path. It ships.

With Sigil

GATE-0005 catches it automatically. The constraint was written once, three sprints ago. The developer gets a clear error: what failed, why, and how to fix it. PR blocked. Intent updated. Merged clean.

What you get

Architecture you can diff.

📐

Specs that stay alive

Components, specs, ADRs, gates, and interface contracts live as structured YAML and markdown in your Git repo — next to the code they describe, not in a wiki nobody reads.

Run sigil serve before a sprint to review the full architecture picture together. Gaps show up red.

🕸️

Queryable knowledge graph

Everything connects with typed relationships. Ask sigil why src/auth.ts and trace from file to component to spec to ADR. Ask sigil impact COMP-payments and see blast radius before touching anything.

8 interactive views: graph, hierarchy, coverage, drift, timeline, matrix, and more.

🔒

Gates block merges

Write a constraint once. Enforce it forever. Gates run on every PR via GitHub Actions, post an intent diff comment, and block merges that violate what was decided.

One step in CI: uses: fielding/sigil@v1. No platform, no setup.

🔀

Intent diffs on every PR

Every PR gets an automatic intent analysis comment: coverage percentage, which specs govern the changed code, which gates passed or failed, and which files have no architectural owner.

Review intent first. Then verify the code.

📡

Drift detection

Code that exists outside the intent graph is flagged. sigil drift finds components without specs, files without owners, and interfaces nobody consumes.

Architecture can't drift from the plan when the plan is enforced.

⚡

Zero setup, zero platform

Single Python file. One dependency (PyYAML). Works with GitHub Actions today. pip install sigil-cli && sigil init and you're running in under a minute.

No hosted platform. No account. Just files in your repo.

How it works

Three steps. One loop.

STEP 01

Spec it first

Before writing code, define what you're building. Register components, write specs, record architectural decisions, define interface contracts, set the constraints that must hold forever.

sigil new spec auth-service "Token refresh flow"
sigil new gate "Auth token expiry" --applies-to COMP-auth

STEP 02

Review the graph

Run sigil serve before the sprint. Everyone sees the same architecture picture — what's planned, what's connected, what's missing. Align before the code starts.

sigil serve
# opens interactive graph in browser

STEP 03

Ship with gates

Once specs are agreed, gates enforce them automatically. Every PR gets an intent diff. Code can't drift from what was decided — the constraint is in the repo, running in CI forever.

sigil check
# all gates pass → merge

Code review is dead. Review intent instead.

A gate caught what code review missed.

Architecture you can diff.

Three steps. One loop.

Up and running in 30 seconds.

Code review is dead.
Review intent instead.