memory

A two-level memory system for an agent: one file stores lasting facts, while another keeps a searchable, append-only history of past events.

In plain words
What is it for?
Use it to save preferences, project facts, and relationships, then search the event history for earlier information with text-search tools.
Why use it?
It helps the agent retain useful project context and find older conversation details instead of relying only on the current conversation.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/phyagentos/phyagentos-core/memory
Any agent
npx skills add PhyAgentOS/PhyAgentOS-core --skill memory
Clone the repo
git clone --depth 1 https://github.com/PhyAgentOS/PhyAgentOS-core

Made for: Claude Code, Codex.

Per session 11 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 344 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00011 $0.00344
Opus 5 $0.00005 $0.00172
Sonnet 5 $0.00002 $0.00069
Haiku 4.5 $0.00001 $0.00034

Measured 2d ago against content hash 88d73a0d3a72, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

memory scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

  • memory — 100% identical, 0 lines differ
  • memory — 100% identical, 0 lines differ
PhyAgentOS/skills/memory/SKILL.md · 38 lines

What it actually says

Memory

Structure

  • memory/MEMORY.md — Long-term facts (preferences, project context, relationships). Always loaded into your context.
  • memory/HISTORY.md — Append-only event log. NOT loaded into context. Search it with grep-style tools or in-memory filters. Each entry starts with [YYYY-MM-DD HH:MM].

Search Past Events

Choose the search method based on file size:

  • Small memory/HISTORY.md: use read_file, then search in-memory
  • Large or long-lived memory/HISTORY.md: use the exec tool for targeted search

Examples:

  • Linux/macOS: grep -i "keyword" memory/HISTORY.md
  • Windows: findstr /i "keyword" memory\HISTORY.md
  • Cross-platform Python: python -c "from pathlib import Path; text = Path('memory/HISTORY.md').read_text(encoding='utf-8'); print('\n'.join([l for l in text.splitlines() if 'keyword' in l.lower()][-20:]))"

Prefer targeted command-line search for large history files.

When to Update MEMORY.md

Write important facts immediately using edit_file or write_file:

  • User preferences ("I prefer dark mode")
  • Project context ("The API uses OAuth2")
  • Relationships ("Alice is the project lead")

Auto-consolidation

Old conversations are automatically summarized and appended to HISTORY.md when the session grows large. Long-term facts are extracted to MEMORY.md. You don't need to manage this.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 38 lines · 11 tokens per session scan A 88d73a0d3a72

Subscribe to this mod's changes

memory is a skill published in the GitHub repository PhyAgentOS/PhyAgentOS-core (1,908 stars, last pushed 2d ago), licensed MIT. It adds 11 tokens to every session and 344 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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