amnesia

amnesia is a skill for Claude Code, Codex from definite-d/agent-skills. It costs 205 tokens per session (1,380 once invoked), scanned A, original, MIT.

A file-based memory system for long coding tasks. It stores the agent’s plans, history, and current state in PROMPT.md, PLAN.md, and HISTORY.md so work can resume after a context reset.

In plain words
What is it for?
Long builds, research tasks, and multi-commit features that need autonomous progress across context resets.
Why use it?
It prevents decisions and next steps from disappearing when the conversation is shortened or restarted. This is useful for multi-step work that may span sessions.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Long builds, research tasks, and multi-commit features that need autonomous progress across…

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Install with agentmods
npx agentmods add skills/definite-d/agent-skills/amnesia
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.

Any agent
npx skills add definite-d/agent-skills --skill amnesia
Clone the repo
git clone --depth 1 https://github.com/definite-d/agent-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for amnesia

README.md
[![agentmods](https://agentmods.dev/badge/skills/definite-d/agent-skills/amnesia.svg)](https://agentmods.dev/skills/definite-d/agent-skills/amnesia)
Your own site
<a href="https://agentmods.dev/skills/definite-d/agent-skills/amnesia"><img src="https://agentmods.dev/badge/skills/definite-d/agent-skills/amnesia.svg" alt="Measured on agentmods" height="20"></a>
Per session 205 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,380 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00205 $0.01380
Opus 5 $0.00102 $0.00690
Sonnet 5 $0.00041 $0.00276
Haiku 4.5 $0.00020 $0.00138

Measured 6d ago against content hash 709188595bda, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

amnesia 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 6d 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.

skills/amnesia/SKILL.md · 107 lines

How it starts

The opening of the file, as written. The whole thing — 107 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Amnesia — context-wipe-resistant autonomous work

The problem

Context windows get reset or compacted mid-task. Everything held only in working memory is lost: decisions, partial plans, learned facts, the "what do I do next" state. amnesia fixes this by treating the filesystem as external memory — state lives in three files on disk, and the agent rehydrates from them on every resume.

Core principle

If it matters and is in your head only, it will be forgotten. Write it down before it matters.

Rule of thumb: write state before starting a risky/long step and after every meaningful step. When in doubt, write.

When to set up

Initialize the triad at the start of any task that is:

  • multi-step (3+ steps) and autonomous ("I'll leave you to it", "work autonomously")
  • likely to hit long compiles/builds, web fetches, or deep research (context heavy)
  • explicitly flagged for resets ("your context will be reset", "maximize your context window")
  • single-shot per-message work does NOT need this — skip for quick Q&A or one-command fixes

The state triad

Place the three files at the task root (the directory the agent owns). Use the templates in assets/ for the initial structure.

File Purpose Written when
PROMPT.md Self-contained context brief — lets a fresh, cold agent resume without prior conversation init + whenever key facts change
PLAN.md Checkboxed task tracker with claimed states every step completion
HISTORY.md Append-only decision log: decisions, rationale, pitfalls, facts gathered at every decision/finding

Optionally add a context/ subdir for research dumps or probe outputs if PROMPT.md would bloat.

PROMPT.md rules

  • Write it so a fresh context can execute cold: goal, constraints, exact commands, exact paths, key identifiers (function names, file:line, crate versions), current state, next actions.
  • Include a short "Current state / next actions" section that is updated continuously.
  • No conversational filler. Dense, terse, machine-parseable.
  • Preserve exact file paths, commands, version pins, and identifiers verbatim — fuzzy memory of a command line or flag costs a full re-discovery cycle.

Read the full file on GitHub · 107 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 6d ago First seen · 107 lines · 205 tokens per session scan A 709188595bda

Subscribe to this mod's changes

amnesia is a skill published in the GitHub repository definite-d/agent-skills (2 stars, last pushed 5d ago), licensed MIT. It adds 205 tokens to every session and 1,380 once invoked, about $0.0010 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 2026-08-31.

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