The Codex

The Codex is your business written down in plain files: how you sound, who you serve, the decisions you have made, and how you do the work. You write it once and edit it forever, and every Claude session reads from it. This is where Claude stops being a generic assistant and starts being yours.

This chapter holds two wins. First, an afternoon that gets Claude sounding like you (Win 2). Then, over your first week, the rest of the files that let Claude answer questions about your actual business (Win 3). You do not need to finish it all at once. Do the voice file today; add the rest as you go.

Why this comes first

Every conversation Claude has, in every other chapter, reads from the Codex. Without it, Claude knows about business in general, not about your business. With it, a draft comes back in your words, naming your real customers, following decisions you actually made. The Codex is the difference between “the AI is clever” and “the AI runs my business.”

Skip it and try to wire up automations or connectors first, and you will spend weeks wondering why nothing sounds like you. The fastest path through this whole guide is to build the Codex first.

Win 2: make it sound like you (an afternoon)

Start with one file, voice.md, because voice is the easiest thing to capture and the fastest thing to feel. It describes how you write, concretely enough that Claude can produce text that lands as yours.

Do not try to describe your voice from memory. Let Claude find it in your real writing. Paste ten of your recent emails or posts and ask:

Here are 10 things I've written. Don't summarize them. List every sentence
pattern you notice, every word I reach for on purpose, and everything I never
do. Then write me a 3-line summary I could paste at the top of any prompt.

Save what comes back into voice.md. Here is the shape:

# Voice Profile

## Sentence rhythm
- typical length: [short / medium / long]
- short sentences for: [emphasis, closings]
- longer sentences for: [context, explanation]

## Words I use on purpose
- [3 to 7 words or phrases]

## Things I never do
- [3 to 7, e.g. no jargon, no "excited to share", no forced hooks]

## Real examples
- [3 to 5 sentences pulled straight from your own writing]

## Voice fingerprint (paste at the top of any prompt)
[3 lines that sum up the above]

The test that you are done: open a fresh Claude session with no other context and ask it to draft a follow-up email to a real recent contact. If it reads like you wrote it, you have Win 2. Most people feel this the same afternoon they write the file.

The one mistake to avoid: writing abstract descriptions (“direct, punchy, no fluff”) instead of real examples. Claude cannot write from adjectives. Three real sentences of yours beat ten adjectives every time.

Win 3: make it know your work (your first week)

Voice is how you sound. The rest of the Codex is what you know. Add these files over your first week, one at a time, and Claude can start answering real questions about your business instead of guessing.

`icp.md`: who you serve

One specific kind of customer, not “everyone.” The person with the specific problem you have actually solved before.

# Who I Serve

## In one line
[who they are + what they're stuck on + what you solve]

## About them
- their situation, a normal day, what they've already tried

## What they actually feel (in their words)
| What they need | Something a real one said |
|---|---|
| [need] | "[a real quote]" |

## When they come looking / when they're the wrong fit

The antidote to wishful thinking here is the quotes column. If you cannot quote a real person saying it, leave it out.

`decisions.md`: what you have decided

Every decision that matters, dated, newest on top. You add to this file; you never erase from it. When a new decision replaces an old one, the new entry names what it replaced. This is what stops you and Claude from re-litigating the same call six months later. To fill it the first time:

Look at my recent notes and messages and list the consequential decisions I've
made in the last month. For each, draft a dated entry: what I decided, and why.

Write it in past tense. It is a record of choices already made, not a to-do list.

`sops/`: how you do the repeatable things

One short file per process you run often enough that writing it down saves time the third time. Start with three: onboarding someone new, your most frequent recurring task, and your most error-prone one. Keep them to five steps. Only write an SOP for something you have done at least three times, or you are writing a guess.

`meetings/`: where your calls land

One file per meeting. This fills itself once you wire up the Meeting Cortex (Win 4), so for now just make the folder and drop in the occasional summary by hand. It becomes the single highest-leverage habit in the whole guide, because it makes the Codex grow without you typing.

Tie it together with an index

A top-level index.md that points to every file, and links between files written as [[voice.md]], [[icp.md]], and so on. When Claude reads one file and sees a link to another, it knows to pull that one in too. The web of links is what makes the whole thing smarter than the sum of its files.

Pitfalls (the “if this, then that” guide)

Situation	What to do
You already have a voice or brand doc somewhere	Do not rewrite it. Point to it or copy it in. Keep one source of truth.
Your ideal customer changed in the last year	Write both, dated. Mark the old one as replaced. Never delete it.
You want to write a 50-page SOP because the process is complex	Stop. Write the 5-step version. Add detail only where a step has actually gone wrong.
The meetings folder is empty because nothing is wired yet	Fine. Drop in hand-written summaries for now. The auto-capture comes in Win 4.
You cannot tell where your voice lives in your writing	Do not introspect. Use the extractor prompt above and let Claude pattern-match across 10 real samples.
A decision feels too small to log	If you have explained the reason to anyone in the last month, log it. If a new hire would need it, log it.
Not sure whether something is a decision, an SOP, or voice	Default to `decisions.md`. It is dated and append-only, so it is the safe place. Move it later.

A worked version: Maya’s Codex

Maya runs an online store and a small service business, plus a content channel. Her Codex is not one big file, it is a handful, shaped to her world:

File	What Maya put in it
`voice.md`	Pulled from her real captions and customer emails. Warm, direct, a little playful. No corporate speak.
`icp.md`	Two short profiles, one per business: her repeat store customers, and the kind of client her service work is for.
`decisions.md`	“Dropped the wholesale line (too much support for the margin).” “Moved shipping to flat rate.” Each with the why.
`sops/`	Restocking the store, onboarding a new client, publishing a video. Three files, five steps each.
`index.md`	Links to all of it, so any Claude session can navigate her whole business by following links.

The thing to notice: Maya never wrote a document about her business. She wrote a few small files, each one thing, linked together. Now when she asks Claude to reply to a supplier or draft a video description, it already knows her voice, her margins, and the calls she has already made.

You’ve got it when

A fresh Claude session, with no other context, drafts something that sounds like you (Win 2)
voice.md, icp.md, and decisions.md all exist, and decisions.md has a few real entries
At least one SOP exists for a process you actually repeat
Files link to each other, and an index.md points to everything
You have asked Claude a real question about your business and gotten a real answer, not a guess (Win 3)

Win 2 is the afternoon. Win 3 fills in over the week. The Codex keeps growing after that, and that is the point.

The skills that help here

A few installable commands make the Codex easier to feed and keep clean: /kb-ingest (pull a long source into your knowledge base), /vault-ingest and /vault-apply (propose and confirm changes to your files), and /vault-lint (catch anything stale or broken). They are in the starter kit, and the full list with what each does is in ../03-habits/01-skills-and-commands.md. You do not need any of them to finish this chapter by hand.

→ Next: Win 4 - Meetings file themselves (../03-habits/03-the-meeting-cortex.md), or keep building Memory with 02-the-wiki.md.