https://www.stewie.sh/blogThinking on product truth, behavior specs, and building software that teams can reason about.Thu, 14 May 2026 00:00:00 GMThttps://www.stewie.sh/blog/auto-generated-specs-need-human-sign-offAuto-extracted specs read the code, not the decisions behind it. They quietly promote placeholders and fallbacks as if settled. Sign-off is the missing step.Mon, 11 May 2026 00:00:00 GMThttps://www.stewie.sh/blog/auto-generated-specs-need-human-sign-offhttps://www.stewie.sh/blog/three-layer-ai-safe-engineeringAI-native teams need three layers of durable memory — behavior, decisions, execution. Execution has tooling. Most teams lack the behavior layer entirely.Tue, 28 Apr 2026 00:00:00 GMThttps://www.stewie.sh/blog/three-layer-ai-safe-engineeringhttps://www.stewie.sh/blog/the-product-engineer-era-needs-product-truthAs engineers take on more product ownership and AI accelerates shipping, product decisions vanish into Slack and PRs. Behavior specs hold the intent.Mon, 20 Apr 2026 00:00:00 GMThttps://www.stewie.sh/blog/the-product-engineer-era-needs-product-truthhttps://www.stewie.sh/blog/i-rebuilt-my-product-from-scratchAI makes rebuilding cheap. But product decisions are expensive to recreate from memory. Here's how a behavior spec makes 'start fresh' a feature, not a failure.Sun, 19 Apr 2026 00:00:00 GMThttps://www.stewie.sh/blog/i-rebuilt-my-product-from-scratchhttps://www.stewie.sh/blog/generate-a-behavior-contract-in-2-minutesPaste a prompt into Claude or ChatGPT, describe your product module briefly, and get a .pbc.md behavior spec you can view, edit, and commit to your repo.Thu, 09 Apr 2026 00:00:00 GMThttps://www.stewie.sh/blog/generate-a-behavior-contract-in-2-minuteshttps://www.stewie.sh/blog/beyond-claude-md-and-agents-mdCLAUDE.md and AGENTS.md tell agents how to work in your repo. They don't tell agents what your product promises. That's a different artifact — the PBC layer.Tue, 07 Apr 2026 00:00:00 GMThttps://www.stewie.sh/blog/beyond-claude-md-and-agents-mdhttps://www.stewie.sh/blog/write-your-first-behavior-contractA step-by-step guide to writing a .pbc.md file for your product's most critical module. Start with plain Markdown; add structured blocks agents can read.Sun, 05 Apr 2026 00:00:00 GMThttps://www.stewie.sh/blog/write-your-first-behavior-contracthttps://www.stewie.sh/blog/stop-building-the-wrong-thingShipping fast with AI agents feels productive. But the costliest mistake isn't bad code — it's building confidently when nobody wrote down what was decided.Sat, 04 Apr 2026 00:00:00 GMThttps://www.stewie.sh/blog/stop-building-the-wrong-thinghttps://www.stewie.sh/blog/prds-pbcs-and-test-suites-are-a-lifecyclePRDs capture intent. Tests verify assertions. Between them, there's no artifact tracking what the product promises — grounded in code, confirmed by humans.Thu, 02 Apr 2026 00:00:00 GMThttps://www.stewie.sh/blog/prds-pbcs-and-test-suites-are-a-lifecyclehttps://www.stewie.sh/blog/ai-agent-context-still-misses-the-product-layerAI agents have AGENTS.md, memory banks, harnesses, and monitors. They still lack the product context layer — what the product promises and what must hold.Sun, 29 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/ai-agent-context-still-misses-the-product-layerhttps://www.stewie.sh/blog/what-happens-to-product-knowledge-when-the-contract-endsWhen an outsourcing engagement wraps up, product knowledge walks out the door. A living behavior spec keeps it in the codebase — not in someone's head.Sat, 28 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/what-happens-to-product-knowledge-when-the-contract-endshttps://www.stewie.sh/blog/understand-your-product-without-engineersAI can extract product logic from your codebase. Stewie builds a living behavior spec your whole team can read — no code, no docs, no waiting on engineers.Fri, 27 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/understand-your-product-without-engineershttps://www.stewie.sh/blog/five-roles-one-product-contractProduct owners confirm behaviors. BAs clarify logic. QA knows what to protect. New hires onboard fast. Vendors skip reverse-engineering. One shared contract.Fri, 27 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/five-roles-one-product-contracthttps://www.stewie.sh/blog/check-what-your-team-actually-shippedLeaders shouldn't need three meetings to verify whether a product decision was implemented correctly. A living behavior spec is the direct line.Fri, 27 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/check-what-your-team-actually-shippedhttps://www.stewie.sh/blog/why-ai-agents-keep-violating-your-product-rulesYour coding agent ships correct-looking code that breaks product promises. The fix isn't capability — it's the product context layer agents lack.Thu, 26 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/why-ai-agents-keep-violating-your-product-ruleshttps://www.stewie.sh/blog/agents-md-memory-bank-pbcYour repo has workflow instructions, session context, and feature specs. None of them answer what the product promises to do. That's the PBC layer.Tue, 24 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/agents-md-memory-bank-pbchttps://www.stewie.sh/blog/vibe-coding-got-you-hereShipping fast with AI coding tools is genuinely good. The problem isn't the speed — it's what gets left behind. Product reasoning doesn't survive the vibe.Sun, 22 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/vibe-coding-got-you-herehttps://www.stewie.sh/blog/one-file-two-audiencesA .pbc.md file opens in VS Code, renders on GitHub, reads like any Markdown doc. Drop it into pbc.stewie.sh and the same file becomes navigable UI.Sun, 22 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/one-file-two-audienceshttps://www.stewie.sh/blog/pbc-spec-is-liveAfter hitting the same product knowledge gap across multiple SaaS products, I built an open Markdown spec for capturing what your product promises to do.Fri, 20 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/pbc-spec-is-livehttps://www.stewie.sh/blog/what-is-a-product-behavior-contractA Product Behavior Contract (PBC) is a living, code-grounded spec that describes how your product actually behaves — not how you think it does.Wed, 18 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/what-is-a-product-behavior-contracthttps://www.stewie.sh/blog/the-gap-in-your-product-knowledgeProduct knowledge lives in heads, not docs. Here's why that gap compounds — and what a behavior spec does about it.Wed, 18 Mar 2026 00:00:00 GMThttps://www.stewie.sh/blog/the-gap-in-your-product-knowledge