--- id: how-dex-works title: What Dex is and how it works area: Start here order: 10 summary: The five building blocks behind Dex — and why understanding them makes you better at working with AI everywhere. --- Dex is a personal chief-of-staff that lives on your computer. It plans your day, preps you for meetings, remembers every person you work with, tracks your tasks and goals, and gets more useful the longer you use it — because everything it learns is written into files you own. There is no Dex app to open and no Dex server anywhere. Dex runs inside **Claude Code** (or Cursor), an AI assistant you talk to in plain English. Dex is what happens when that assistant is given a memory, a playbook, and a set of tools that turn it from a clever chatbot into a system that actually runs your working life. That design has a nice side effect: learning Dex *is* learning how modern AI assistants work. Every skill you pick up here transfers. ```roles What compounding memory means in your world Sales :: Walking into a renewal with every promise ever made to that account — theirs and yours — plus what the champion said three quarters ago. Product :: Every decision and its reasoning, findable — so "why did we cut that feature?" has an answer instead of archaeology. Legal :: Matter history, positions taken, and who agreed to what — with the exact wording, because it's all written down. People :: Every 1:1 thread, growth conversation, and flagged concern per person — so nothing surfaces at review time as a surprise. Customer Success :: The full health story per account: sentiment shifts, unkept promises in both directions, and the early-warning pattern before churn. Marketing :: Campaign decisions, what actually shipped versus planned, and which messages the field said landed — across quarters, not memory. ``` ## The problem Dex solves AI assistants have a fundamental limitation: they forget everything between conversations. Close the window and tomorrow's session starts from zero — no memory of your projects, your people, or what you decided yesterday. Dex's trick is simple: **store everything in files, and reload the right context at the right moment.** Your meetings, tasks, people, and goals live as ordinary text files on your machine. When you start a session, Dex loads what matters. When you mention a person, it quietly pulls up their history. The assistant is stateless; your system is not. ## The five building blocks Everything Dex does comes from five pieces working together. (You can ask Dex to explain any of this live — the `/xray` command shows you exactly what happened under the hood of your last conversation.) ### 1. Your vault — files you own All your data is plain text files (Markdown) in one folder, called your vault. No database, no cloud service, no hidden format. You can open any file, read exactly what Dex knows, and edit it yourself. If you stopped using Dex tomorrow, every note would still open in any text editor — in twenty years, too. The vault is organized by the PARA method: an **Inbox** for quick capture, **Projects** for time-bound work, **Areas** for ongoing things like people and companies, **Resources** for reference, and **Archives** for the past. ### 2. CLAUDE.md — the standing instructions One file, `CLAUDE.md`, is read at the start of every conversation. It tells the assistant who you are, how you like to communicate, and how Dex behaves. In AI terms this is a "system prompt" — instructions that shape every response before you type a word. There's a protected section inside it just for your personal instructions, which survives every update. ### 3. Skills — the playbook Skills are packaged workflows you invoke by typing a slash command, like `/daily-plan` or `/meeting-prep`. Each skill is just a text file of step-by-step instructions the assistant follows. Dex ships with about two dozen core skills, plus role-specific ones for product, sales, marketing, and more. Skills load only when you use them — that keeps conversations fast and cheap. And because a skill is only structured text, you can read any of them, change them, or write your own. ### 4. MCP tools — the reliable hands Some things shouldn't be left to an AI's best guess: creating a task with the right ID, syncing a completion across five files, reading your calendar. For those, Dex uses **MCP servers** — small local programs that give the assistant precise, validated operations. (MCP, the Model Context Protocol, is an open standard for connecting AI assistants to tools.) The rule of thumb Dex is built on: *files are knowledge, tools are actions.* When Dex creates a task, a deterministic program does the bookkeeping — the AI decides *what*, the tool guarantees *how*. ### 5. Hooks — the quiet automation Hooks are small scripts that run automatically at certain moments. When you start a session, one shows Dex your priorities and recent patterns. When a file mentions a person you know, another silently injects their context so Dex responds with full history. You never see hooks run — you just notice Dex seems unusually well-informed. ## What a session actually looks like Put it together and a morning with Dex looks like this: 1. You open a session. A hook loads your pillars, goals, and this week's priorities. 2. You type `/daily-plan`. That skill loads, reads your calendar through the Calendar tool, checks your tasks and priorities, and builds a plan for the day. 3. You mention "the Acme renewal" — Dex quietly pulls the Acme company page and the people involved. 4. Anything you decide gets written back into your vault, so tomorrow's Dex knows about it. ```terminal A Tuesday morning, condensed > /daily-plan ~ Building your plan… * Calendar — reading today . 4 meetings · free 14:00–15:30 * Work — checking tasks against this week's priorities . 2 Musts match · 1 commitment overdue * Today, Tuesday July 28: . MUST — Prep board metrics (due tomorrow, serves "Q3 story") . MUST — 2pm Northwind renewal, one open promise ⚠ . SHOULD — Reply to Priya re: platform migration . COULD — Draft the launch announcement > what's the open promise with Northwind? * Search — meeting notes, Northwind commitments . 1 match · 2026-07-07 - Northwind QBR.md * Three weeks ago you told Elena you'd send the usage-by-region breakdown "this week". It hasn't been sent. Want it as today's first task? > yes — and prep the numbers before the 2pm ``` That warning glyph is the whole product in miniature: Dex remembered a promise you'd forgotten, because it was written down. > Everything you're experiencing is text transformation: files in, thinking, files out. That transparency is the point — you can always look behind the curtain with `/xray`. ```handoff I just read the Dex Guide page about how Dex works — the vault, CLAUDE.md, skills, tools, and hooks. You know my role and my vault. Re-teach me those five building blocks using MY system as the example: show me the most important lines in my own CLAUDE.md, the three skills that would pay off most for someone with my job, the tools you can actually reach right now, and one hook that's quietly working for me. Then tell me which building block I'm underusing — and set it up with me. ``` ## Where to go next - **[Installing Dex](install.html)** — get from zero to your first conversation. - **[Your first conversation](onboarding.html)** — what Dex asks when you meet, and why. - **[Understanding Claude Code](claude-code-primer.html)** — a deeper primer on the engine underneath. - **[Prompts to steal](prompts-to-steal.html)** — copy-paste moves that use all of this differently.