Grep Is Dead: Modern Memory for AI Agents

The Problem

Every conversation with Claude Code starts from zero. 700 sessions in 3 weeks — no memory of what happened when.

Mid-session context limit hits at 60% → compact → half the decisions lost. Next day? Don't remember what was happening.

The current paradigm of grepping over files doesn't scale.

## Grep vs BM25 vs Semantic

| Method | Speed | Quality | Use Case |
|--------|-------|---------|----------|
| Grep | Slow (3 min) | 200 files of noise | String matching — finds sleep() when searching "sleep" |
| BM25 | 2 sec | Relevant results | Deterministic full-text, ranks by frequency + rarity |
| Semantic | Fast | Meaning-based | Finds concepts without exact words |
| Hybrid | Fast | Best ranking | Combines both |

Benchmark for "sleep":
- Grep: 200 files, including sleep() code — noise
- BM25: Sleep quality reflection, sleep fragmentation experiment — relevant
- Semantic: "couldn't sleep, bad night" → Bedtime discipline goal from years ago — finds meaning without keywords

## QMD: Local Search Engine

[QMD](https://github.com/tobi/qmd) by Tobias Lütke (Shopify CEO) — local search engine for your Obsidian vault. Finds anything in under a second.

Setup:
- One QMD collection per vault folder (notes, daily, sessions, transcripts)
- Focused search per collection

## The /recall Pattern

Three modes:

### 1. Temporal — /recall yesterday
Reconstructs 39 sessions from one day. Timeline, message counts, what was done when.

### 2. Topic — /recall topic graph
BM25 search across sessions and notes. Returns dashboard, production plan, to-do list in under a minute.

### 3. Graph — /recall graph last week
Interactive visualization: sessions as colored blobs, files clustered by type.

## Our Compound Skill

The Compound skill implements this pattern:

1. Extracts patterns from each session
2. Stores as instincts (not raw transcripts)
3. Hybrid search (70% BM25 + 30% semantic) for retrieval
4. Temporal decay (30-day half-life) keeps memory fresh

Your agent learns. Every session.