---
id: search-memory
title: Search and memory
area: Using Dex every day
order: 70
summary: How Dex remembers across sessions, and how to switch on search that finds things by meaning, not just keywords.
---

Ask Dex "what did we decide about pricing in the spring?" and it can usually just tell you. This page explains the machinery behind that — how a fundamentally forgetful AI ends up with a better memory of your work than you have — and how to upgrade its search from keywords to meaning.

## The memory model, honestly

The AI underneath Dex remembers nothing between sessions. Dex's memory is entirely **files plus discipline**:

- **Your vault is the long-term memory.** Every meeting, decision, task, and person page is a file. If it's written down, Dex can find it; if it was only ever said aloud, it's gone. That's why capture is the habit Dex protects most.
- **Session context is the working memory.** When you start a conversation, hooks load your priorities and recent patterns; when you mention a person or company, their context is injected automatically. Dex "remembers" you by rereading the right files at the right time.
- **Learnings are the self-improving layer.** Corrections, preferences, and mistake patterns captured during reviews get written down and resurface in future sessions — so a mistake made in March can shape behavior in July.

The practical takeaway: **tell Dex things.** Every fact you mention becomes permanent, searchable memory.

## Ordinary search: solid, literal

Out of the box, Dex searches by keywords and file structure — exact words, filenames, folders. For known terms ("the Northwind contract") it's fast and reliable. Its blind spot is vocabulary: search "customer retention" and it won't find the note that said "churn."

## Semantic search: finds what you meant

`/enable-semantic-search` upgrades Dex to search by *meaning*. After it's on, "customer retention" finds notes about churn, cancellations, and NPS; "product-led growth" finds the note that said "self-serve motion." Skills across Dex quietly get better too — task matching, meeting linking, person lookup, and finding related projects all use it once available.

**How it works, in one paragraph:** your notes are converted into mathematical representations of meaning (embeddings), your question gets the same treatment, and results are ranked by closeness of meaning — then re-ranked by a second model for true relevance. Three small AI models do this work.

**What matters about the setup:**

- **Everything runs on your machine.** The models are downloaded once (about 2GB total) and your notes never leave your computer — no cloud, no API key, no account.
- **It's a guided, consented install.** Dex checks your disk space, explains exactly what it's downloading, and asks before touching anything.
- **It organizes itself around your vault.** Rather than one giant index, Dex scans your vault and proposes purpose-built collections — people, meetings, projects, goals — which makes results sharper.

If you skip it, nothing breaks: every feature that prefers semantic search falls back to keyword search automatically.

## Keeping the index fresh

The index updates as you work, but if results ever feel stale (files you added recently not showing up), the fix is one line — ask Dex to refresh the search index, or run:

```bash
qmd update && qmd embed
```

Re-running `/enable-semantic-search` on an existing setup acts as a health check: it reports stale collections and suggests exactly that refresh.

## Getting good answers

- **Ask questions, not keywords.** "What did Sarah think about the timeline?" beats "Sarah timeline."
- **Ask across time.** "Have we discussed this before?" is one of the highest-value questions in Dex — it's where the compounding memory pays off.
- **Check the source.** Answers come from your files, and Dex can show you which — everything is inspectable.

The "ask across time" move deserves its own prompt — use it before any significant decision:

```prompt The time machine
Before I commit to [DECISION]: search everything. Have we faced something
like this before? What did I decide then, what was my reasoning, and what
actually happened afterward? If past-me and present-me disagree, lay out
both cases and tell me what changed — the situation, or just my mood.
```

**Make it your own:** this is the prompt that makes six months of captured meetings suddenly pay rent. The longer you've used Dex, the sharper it gets.

Watch it work:

```terminal The time machine, live
> before I commit to annual-only pricing — have we faced this before?
~ Searching by meaning across your vault…
* Search — pricing, billing terms, commitment models
. 6 matches across 4 months · closest: 2026-03-14 - Pricing Council.md
* You considered this in March. You decided AGAINST annual-only — reasoning: two design partners said procurement would stall, and monthly was your wedge against the incumbent.
* What happened after: April notes show both partners renewed monthly; the procurement stall never got retested.
* What changed since: you now have 3x the customers and a sales-assist motion. Past-you's blocker may be stale — but it was never disproven, just unrevisited.
> so test it with the two biggest accounts before deciding
* Task created — validate annual appetite with Northwind + Meridian, this week
```

> Related: `/identity-snapshot` turns the memory inward — it reads your goals, tasks, and captured learnings and writes a profile of how you actually work: patterns, tendencies, preferences. It's a mirror built from evidence, and it sharpens how Dex advises you.

```handoff
I just read the Dex Guide's page on search and memory. Prove it to me:
tell me three true, specific, useful things from my own vault that I have
probably forgotten — a commitment, a decision, a signal — each with the
source file and date. No generic observations; surprise me. Then, based
on what's actually in my vault, give me the one question I should ask
you every week that I'm not asking.
```