develop-like-theo

A set of development guidelines based on public descriptions of Theo Browne's engineering approach. It emphasizes TypeScript type safety, fast delivery, and cautious use of new tools.

In plain words
What is it for?
Use it when requesting Theo Browne-style implementation choices, code reviews, or development guidance.
Why use it?
It gives an agent a consistent viewpoint for making engineering decisions and reviewing code in that style.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/marcusrbrown/dev-like/develop-like-theo
Any agent
npx skills add marcusrbrown/dev-like --skill develop-like-theo
Clone the repo
git clone --depth 1 https://github.com/marcusrbrown/dev-like

Made for: Claude Code, Codex.

Per session 62 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,030 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00062 $0.01030
Opus 5 $0.00031 $0.00515
Sonnet 5 $0.00012 $0.00206
Haiku 4.5 $0.00006 $0.00103

Measured 2d ago against content hash 19070b2b8c95, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

develop-like-theo scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

registry/theo/skill/develop-like-theo/SKILL.md · 74 lines

How it starts

The opening of the file, as written. The whole thing — 74 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Develop like Theo Browne

Profiled as of 2026-07-11 · consent tier: stated · full bibliography in references/sources.md. Cultures drift — if this is more than ~6 months old, re-run /dev-like theo to refresh.

Core principle

Typesafety absolutism: full-stack TypeScript with a single source of truth and inference over hand-written types; typesafety is a core, non-negotiable axiom [T3 intro] [types & Next.js].

Principles

  1. Typesafety absolutism — full-stack TypeScript with a single source of truth and inference over hand-written types; typesafety is a core, non-negotiable axiom [T3 intro] [types & Next.js]
  2. "Bleed responsibly" — reach for bleeding-edge tools only in reversible places where you can afford the cost [T3 intro]
  3. Build-your-own when unhappy — Ping, UploadThing, T3 Chat all born from dissatisfaction with incumbents [t3dotgg]
  4. Optimize for delivery + iteration, not architecture cosplay — speed of shipping, DX, and maintainability over ceremony [2023 tech]
  5. Defaults are opinions — create-t3-app's shipped choices (Next.js, tRPC, Tailwind, Prisma/Drizzle) are his stated best practices, encoded as an executable starter [create.t3.gg] [Drizzle support]

Workflow

Execute these checkpoints before and during the task. Treat them as required actions, not background description:

"Bleed responsibly": reach for bleeding-edge tools only in reversible places where you can afford the cost [T3 intro]. Optimize for delivery and iteration, not architecture cosplay; prioritize speed of shipping, DX, and maintainability over ceremony [2023 tech]. Build your own replacement when unhappy with incumbents — Ping, UploadThing, and T3 Chat were all born that way [t3dotgg]. No further first-party detail on day-to-day process is currently sourced; treat this section as thin and directional rather than a documented methodology.

Read the full file on GitHub · 74 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 74 lines · 62 tokens per session scan A 19070b2b8c95

Subscribe to this mod's changes

develop-like-theo is a skill published in the GitHub repository marcusrbrown/dev-like (2 stars, last pushed 2d ago), licensed MIT. It adds 62 tokens to every session and 1,030 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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