# Memory

> Unified four-tier memory system for AI agents. Tier 1 Semantic (Serena+Forgetful search), Tier 2 Episodic (session replay), Tier 3 Causal (decision patterns). Enables memory-first architecture per ADR-007.

- Skill: `majiayu000/memory-18` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/memory-18`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/memory-18/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: MIT
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/majiayu000/memory-18

---

# Memory System Skill

Unified memory operations across four tiers for AI agents.

---

## Quick Start

```powershell
# Check system health
pwsh .claude/skills/memory/scripts/Test-MemoryHealth.ps1

# Search memory (Tier 1)
pwsh .claude/skills/memory/scripts/Search-Memory.ps1 -Query "git hooks"

# Extract episode from session (Tier 2)
pwsh .claude/skills/memory/scripts/Extract-SessionEpisode.ps1 -SessionLogPath ".agents/sessions/2026-01-01-session-126.md"

# Update causal graph (Tier 3)
pwsh .claude/skills/memory/scripts/Update-CausalGraph.ps1
```

---

## Memory-First as Chesterton's Fence

**Core Insight**: Memory-first architecture implements Chesterton's Fence principle for AI agents.

> "Do not remove a fence until you know why it was put up" - G.K. Chesterton

**Translation for agents**: Do not change code/architecture/protocol until you search memory for why it exists.

### Why This Matters

**Without memory search** (removing fence without investigation):

- Agent encounters complex code, thinks "this is ugly, I'll refactor it"
- Removes validation logic that prevents edge case
- Production incident occurs
- Memory contains past incident that explains why validation existed

**With memory search** (Chesterton's Fence investigation):

- Agent encounters complex code
- Searches memory: `Search-Memory.ps1 -Query "validation logic edge case"`
- Finds past incident explaining why code exists
- Makes informed decision: preserve, modify, or replace with equivalent safety

### Investigation Protocol

When you encounter something you want to change:

| Change Type | Memory Search Required |
|-------------|------------------------|
| Remove ADR constraint | `Search-Memory.ps1 -Query "[constraint name]"` |
| Bypass protocol | `Search-Memory.ps1 -Query "[protocol name] why"` |
| Delete >100 lines | `Search-Memory.ps1 -Query "[component] purpose"` |
| Refactor complex code | `Search-Memory.ps1 -Query "[component] edge case"` |
| Change workflow | `Search-Memory.ps1 -Query "[workflow] rationale"` |

### What Memory Contains (Git Archaeology)

**Tier 1 (Semantic)**: Facts, patterns, constraints

- Why does PowerShell-only constraint exist? (ADR-005)
- Why do skills exist instead of raw CLI? (usage-mandatory)
- What incidents led to BLOCKING gates? (protocol-blocking-gates)

**Tier 2 (Episodic)**: Past session outcomes

- What happened when we tried approach X? (session replay)
- What edge cases did we encounter? (failure episodes)

**Tier 3 (Causal)**: Decision patterns

- What decisions led to success? (causal paths)
- What patterns should we repeat/avoid? (success/failure patterns)

### Memory-First Gate (BLOCKING)

**Before changing existing systems, you MUST**:

1. `pwsh .claude/skills/memory/scripts/Search-Memory.ps1 -Query "[topic]"`
2. Review results for historical context
3. If insufficient, escalate to Tier 2/3
4. Document findings in decision rationale
5. Only then proceed with change

**Why BLOCKING**: <50% compliance with "check memory first" guidance. Making it BLOCKING achieves 100% compliance (same pattern as session protocol gates).

**Verification**: Session logs must show memory search BEFORE decisions, not after.

### Connection to Chesterton's Fence Analysis

See `.agents/analysis/chestertons-fence.md` for:

- 4-phase decision framework (Investigation → Understanding → Evaluation → Action)
- Application to ai-agents project (ADR-037 recursion guard, skills-first violations)
- Decision matrix for when to investigate
- Implementation checklist

**Key takeaway**: Memory IS your investigation tool. It contains the "why" that Chesterton's Fence requires you to discover.

---

## Triggers

| Trigger Phrase | Maps To |
|----------------|---------|
| "search memory for X" | Tier 1: Search-Memory.ps1 |
| "what do we know about X" | Tier 1: Search-Memory.ps1 |
| "extract episode from session" | Tier 2: Extract-SessionEpisode.ps1 |
| "what happened in session X" | Tier 2: Get-Episode -SessionId "X" |
| "find sessions with failures" | Tier 2: Get-Episodes -Outcome "failure" |
| "update causal graph" | Tier 3: Update-CausalGraph.ps1 |
| "what patterns led to success" | Tier 3: Get-Patterns |
| "check memory health" | Test-MemoryHealth.ps1 |

---

## Quick Reference

| Operation | Name | Key Parameters |
|-----------|------|----------------|
| Search facts/patterns | `Search-Memory.ps1` | `-Query`, `-LexicalOnly`, `-MaxResults` |
| Get single session | `Get-Episode` | `-SessionId` |
| Find multiple sessions | `Get-Episodes` | `-Outcome`, `-Task`, `-Since` |
| Trace causation | `Get-CausalPath` | `-FromLabel`, `-ToLabel` |
| Find success patterns | `Get-Patterns` | `-MinSuccessRate` |
| Extract episode | `Extract-SessionEpisode.ps1` | `-SessionLogPath` |
| Update patterns | `Update-CausalGraph.ps1` | `-EpisodePath`, `-DryRun` |
| Health check | `Test-MemoryHealth.ps1` | `-Format` (Json/Table) |

---

## Decision Tree

```text
What do you need?
│
├─► Current facts, patterns, or rules?
│   └─► TIER 1: Search-Memory.ps1
│
├─► What happened in a specific session?
│   └─► TIER 2: Get-Episode -SessionId "..."
│
├─► Recent sessions with specific outcome?
│   └─► TIER 2: Get-Episodes -Outcome "failure" -Since 7days
│
├─► Why did decision X lead to outcome Y?
│   └─► TIER 3: Get-CausalPath -FromLabel "..." -ToLabel "..."
│
├─► What patterns have high success rate?
│   └─► TIER 3: Get-Patterns -MinSuccessRate 0.7
│
├─► Need to store new knowledge?
│   ├─ From completed session? → Extract-SessionEpisode.ps1
│   └─ Factual knowledge? → using-forgetful-memory skill
│
└─► Not sure which tier?
    └─► Start with TIER 1 (Search-Memory), escalate if insufficient
```

---

## Anti-Patterns

| Anti-Pattern | Do This Instead |
|--------------|-----------------|
| Skipping memory search | Always search before multi-step reasoning |
| Tier confusion | Follow decision tree explicitly |
| Forgetful dependency | Use `-LexicalOnly` fallback |
| Stale causal graph | Run `Update-CausalGraph.ps1` after extractions |
| Incomplete extraction | Only extract from COMPLETED sessions |

---

## See Also

| Document | Content |
|----------|---------|
| [quick-start.md](references/quick-start.md) | Common workflows |
| [skill-reference.md](references/skill-reference.md) | Detailed script parameters |
| [tier-selection-guide.md](references/tier-selection-guide.md) | When to use each tier |
| [memory-router.md](references/memory-router.md) | ADR-037 router architecture |
| [reflexion-memory.md](references/reflexion-memory.md) | ADR-038 episode/causal schemas |
| [troubleshooting.md](references/troubleshooting.md) | Error recovery |
| [benchmarking.md](references/benchmarking.md) | Performance targets |
| [agent-integration.md](references/agent-integration.md) | Multi-agent patterns |

---

## Storage Locations

| Data | Location |
|------|----------|
| Serena memories | `.serena/memories/*.md` |
| Forgetful memories | HTTP MCP (vector DB) |
| Episodes | `.agents/memory/episodes/*.json` |
| Causal graph | `.agents/memory/causality/causal-graph.json` |

---

## Verification

| Operation | Verification |
|-----------|--------------|
| Search completed | Result count > 0 OR logged "no results" |
| Episode extracted | JSON file in `.agents/memory/episodes/` |
| Graph updated | Stats show nodes/edges added |
| Health check | All tiers show "available: true" |

```powershell
pwsh .claude/skills/memory/scripts/Test-MemoryHealth.ps1 -Format Table
```

---

## Related Skills

| Skill | When to Use Instead |
|-------|---------------------|
| `using-forgetful-memory` | Deep Forgetful operations (create, update, link) |
| `curating-memories` | Memory maintenance (obsolete, deduplicate) |
| `exploring-knowledge-graph` | Multi-hop graph traversal |