Stewie
Product Intelligence for Technical Founders

Your product truth shouldn't be trapped in code.

Stewie reads your repo and helps you author a living product behavior spec — grounded in real code, not guesswork.

Request early access →See the open foundation

Most teams don't have a shared product spec. They have a codebase.

The real behavior of your product lives in code, decisions, and people's heads — scattered, undocumented, and invisible to everyone but you.

Product logic lives in your head

You re-explain how your system behaves to new hires, contractors, and AI tools constantly. There's no shared record of decisions.

Docs drift from day one

PRDs, wikis, and Confluence pages go stale within weeks. The only truth left is the code — and only you know how to read it.

Every new hire restarts from zero

Onboarding means reading thousands of lines of code with no behavioral reference. Months pass before they're autonomous.

How It Works

Four steps from codebase to living behavior spec.

  1. 1

    Connect your repo

    Read-only access, no code stored. Stewie never writes to your codebase.

  2. 2

    Review the candidate map

    Stewie extracts candidate modules and behaviors — each with a confidence score and file-level evidence. Everything starts as a candidate, not a claim.

  3. 3

    Confirm, reject, or defer

    Each claim shows its supporting evidence. Your decisions promote it from inferred to trusted. Nothing is locked in without your sign-off.

  4. 4

    Get your living spec

    A set of .pbc.md files grounded in real code, versioned in git, readable by your whole team.

What Stewie Does

Map your codebase. Confirm what's true. Get a living product spec.

Step 1 — Map

Stewie reads your repo and surfaces how it behaves

Connect your GitHub repo (read-only). Stewie extracts candidate modules, behaviors, and invariants — each with a confidence score and file-level evidence. Everything starts as a candidate, not a claim.

product-map.yaml
# product-map.yaml (candidates)
modules:
  - name: auth
    confidence: high
    status: trusted
    files: 12
  - name: billing
    confidence: medium
    status: in_review
    assumptions: ["Stripe is authority-of-truth"]
 
behaviors:
  - claim: "Session tokens expire after 60 minutes"
    status: trusted
    evidence: [src/auth/session.ts:42]
  - claim: "All API routes enforce workspace tenancy"
    status: in_review
    falsifiers: ["3 routes bypass middleware"]
Grounding Question #2

Where is billing state mastered — Stripe, your database, or both?

Why we're asking

Stripe webhook handlers sync to a local table, but 2 API routes read limits directly from Stripe.

Stripe is primaryBoth — we syncCustom

Step 2 — Confirm

You decide what's true

Stewie asks targeted questions derived from what it actually found. Your answers promote claims from inferred to confirmed. Nothing is trusted until you say so.

Step 3 — Specify

A living spec your whole team can read

Confirmed claims become Product Behavior Contracts — structured .pbc.md files with Given/When/Then behaviors, evidence links, and status. Grounded in real code, not static docs.

auth.pbc.md
# auth.pbc.md
 
behavior: Session token expiry
  given: A user has an active session
  when: 60 minutes pass without activity
  then:
    - Session is invalidated server-side
    - User is redirected to /login
    - Audit event "session_expired" is logged
  status: trusted
  evidence: [src/auth/session.ts:42, src/middleware/auth.ts:18]

Candidate confirmation

Confirm, reject, or defer each extracted claim. Nothing becomes trusted until you approve it.

Evidence provenance

Every claim is backed by file-level evidence from your codebase. You can see exactly why Stewie believes what it believes.

Markdown-first output

Your spec lives as .pbc.md files you own. Version-controlled, portable, readable by anyone.

Built on an open foundation

Product Behavior Contracts are a public, vendor-neutral spec. Stewie is the product built on top of it.

Open format

The .pbc.md file format is a public spec. Your behavior contracts are plain markdown — version-controlled, portable, readable without Stewie.

CLI + reference viewer

The spec ships with a reference CLI (validate, list, stats) and a browser viewer that renders structured PBC blocks as rich UI — state diagrams, behavior panels, actor grids.

Stewie is the product

AI analysis, grounding workflow, and living spec synthesis are the proprietary layer. Open foundation, closed intelligence.

The spec, CLI tooling, and reference viewer are live at github.com/stewie-sh/pbc-spec. The format is in active development — Stewie is built on it.

View the spec

Built for teams who read the fine print.

Security and data handling designed for production code with AI in the loop.

Read-only access

Never writes to your repo, opens PRs, or modifies code.

No model training

Your code never trains any model. Contractual commitment.

Manual analysis only

No background scanning. You trigger analysis, and only then.

Derived artifacts only

We store structure maps and summaries — not repo copies. Full data deletion on request.

Early beta access

We are onboarding a small group of technical founders now. Beta scope, limits, and pricing may evolve as we learn.

Free Beta

Lightweight access · single-product evaluation

$0

A lightweight path to evaluate the core workflow and join the beta queue.

  • —1 product, up to 3 modules
  • —Markdown PBC export
  • —1 guided product analysis
  • —Candidate confirmation flow
  • —Evidence provenance
  • —You own the resulting .pbc.md files
  • —Access scope may evolve during beta
Join the beta waitlist →
Limited spots

Founding Design Partners

Paid early access · founder feedback loop

$19/ month

Deeper access, closer collaboration, and direct input into what gets built next.

Everything in the beta waitlist path, plus:

  • —Paid early access
  • —Expanded beta access for deeper usage
  • —Multiple analyses during the beta period
  • —Shareable read-only spec link
  • —Git-backed spec workflow
  • —Standard Library modules (Auth, Billing, Tenancy, Entitlements)
  • —Priority support + direct founder feedback channel
  • —Shape the roadmap before public launch
Request design-partner access →

Beta scope, limits, and future pricing are still evolving.

Stewie is not a coding agent. Not a wiki.

Coding agents write code. Wikis document intent. Stewie connects the gap — a living spec grounded in what your code actually does.

vs. coding agents

Copilot, Cursor, and Devin generate implementation fast.

Stewie

Stewie captures what the code means. Coding agents write — Stewie makes explicit the intent behind what was built.

vs. docs & wikis

PRDs and wikis explain what you planned. They drift the moment code ships.

Stewie

Stewie produces a living spec grounded in your actual codebase — every claim backed by file-level evidence.

vs. PM tools

Jira, Linear, and Notion track work. They describe what you plan to build, not what actually runs.

Stewie

Stewie captures verified product behavior — what your code actually does today, with evidence you can trace.

Design partners wanted

Your product logic deserves to be explicit.

We're onboarding a small group of technical founders before public launch. Shape the product. Get Founder Early Access pricing locked in for life.

Request early access →See the open foundation