Field Note Nº 02·Building with AI

Master Prompt to Operating System

August 29, 2025·4 min read

1. Context

Inspired by Tiago Forte’s Master Prompt Method, go check it out and let me know if you’d approach it differently, my mind was blown, this started with me trying to solve a simple problem: how do I apply this thinking to my work and teams? At first, I threw everything into one giant “Master Prompt.” It had behavior rules, case studies, team values, even naming conventions. It worked!

Until it didn’t.


2. What I Tried

At first, I split everything into giant BIOS and culture files.

RE: BIOS I’m not a programmer, but building my own gaming PCs back in the day taught me that familiar blue BIOS screen… usually when I had totally crashed the system and had to do a fresh install. In this AI chapter, BIOS for me is Behavioral, not Basic.

Okay back to the process. BIOS and Culture files strapped to agents/copilots weren’t behaving naturally. They felt more like a lecturing parent than a helpful guide. That’s when I stumbled into the value of pruning. Raw transcripts of decks and knowledge dumps were too heavy, but inside them was the raw material for something better: principles and ethos.

So I built a two-step loop:

  1. Capture the raw text (the source material).
  2. Prune with AI + human judgment into lighter, principle-driven guidance.

This shift made the BIOS files stronger, smaller in character count, and far more effective in guiding agents. From there, I settled on the minimum set of files that actually matter: Core Behavior (BIOS), Culture Core (team values), OS Router Shell (an index, not a library), and optional Knowledge Packs depending on the domain.


3. What Happened

Massive improvements! Agents stopped sounding like stiff lecturers and started acting more like collaborative copilots.

Good robot.

The BIOS files, once bloated and clunky, became lean enough that the AI could actually “breathe” inside them. (More on this later, I learned about the concept of “budget.” Yes, I’m still a PM at heart.) I also noticed something subtle: when you distilled raw transcripts into principles, you don’t lose the details, you clarified it. The ethos carried more weight than a wall of text, yet that ethos was only possible because I’d gone through the verbatim work first. With this setup, I could layer in just what was needed: BIOS for behavior, Culture Core for values, Router Shell to point to the rest, and Knowledge Packs for the specific domain. It felt less like forcing AI to memorize everything (and watching it be rigid and forgetful after 2 questions), and more like giving it a map, a compass, and monitored confidence.


4. Takeaway

The big unlock wasn’t adding more files. It was trimming them into the right shape. Raw transcripts gave me the ingredients, but pruning turned them into principles that AI could actually run on. BIOS sets the behaviors, Culture Core keeps the heart, Router Shell points to the rest, and Knowledge Packs fill in the details.

Lesson: Don’t cram everything into one master file. Give AI the essentials, then let it reach for what it needs. A map, a compass, and a little monitored confidence. Give it room to breathe. Kind of like teaching a kid, or three in my case.


5. Adapt This

If you’ve got a monster master prompt on your hands, try this quick loop:

  1. Capture the raw stuff. Don’t overthink it, dump the decks, notes, or transcripts in full.
  2. Prune it down. Use AI to shrink and reshape, with thoughtful intent, then add your judgment on top. Look for principles, not paragraphs.
  3. Sort into core files. BIOS (behavior), Culture Core (values), Router Shell (pointers), Knowledge Packs (domain-specific). These become markdown or .txt files to upload into your Agent/Copilot/Project Folders. You’ll end up with a lighter, more flexible setup that brings consistency on how you, and your teams, think, write, and work.

6. Reflection

This whole thing started as me mimicking what a “Master Prompt” might look like at work. I didn’t set out to invent an operating system. I was just curious: is there a way to use AI differently than cranking out another tool, something that actually carries our context? What I stumbled into was the need to make knowledge transfer less clunky. That’s where my project management brain showed up: connecting dots so these companions could feel more like steady teammates, not clever PhD. interns who miss the point. They needed to act like a good brief, a project hub, and the guardrails we lean on to do better work together. And the purpose wasn’t speed for speed’s sake. It was memory. Carrying the stuff teams always forget: history, context, the why behind the work. So when we show up, we’re not restarting from zero or rehashing the same reminders: we’re already a step deeper. What struck me is how much this mirrors leadership. Leaders don’t solve every task. They take the noise: the drama, the problems, the conversations, and distill it into principles that give the team an environment to thrive. The clearer the anchors and trajectories, the better the outcome.

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