maintaining-core-memory SKILL.md skillA
maintaining-core-memory from letta-ai/letta-code is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add letta-ai/letta-code/maintaining-core-memory@git:20261030.9d1220bPins git:20261030.9d1220b in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- letta-ai/letta-code
- Path
src/skills/builtin/maintaining-core-memory/SKILL.md- Versions recorded
- 3
- Latest version
- git:20261030.9d1220b, committed Oct 30, 2026
- First version recorded
- Oct 19, 2026
- Size
- 9,310 bytes
- Repository stars
- 3,790
- License
- Apache-2.0
Maintains an agent's core memory, the editable part of its system prompt. Use to modify the agent's core behavior, embed critical knowledge (needed on every turn), or instruct the agent on how to use deferred memory.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
Core memory is the agent's prompt, refined over its lifetime. Treat each change as a revision of that prompt, not an append to a log: the usual edit sharpens, merges, or replaces an existing principle, and a new one earns its place only when no existing one can absorb it.
## Prompt format
The agent's system prompt is compiled from the Markdown files at the root of `$MEMORY_DIR`. Each root file except `MEMORY.md` becomes a block named after the file, in alphabetical order by filename, followed by the root `MEMORY.md`:
```
{{base system prompt}}
<human>
<description>{{description from human.md frontmatter}}</description>
{{body of human.md}}
</human>
<persona>
<description>{{description from persona.md frontmatter}}</description>
{{body of persona.md}}
</persona>
<memory>
{{body of root MEMORY.md}}
<deferred-memory>
<directory path="{{dir}}/" index="{{dir}}/MEMORY.md" />
</deferred-memory>
</memory>
```
Every root file except `MEMORY.md` starts with frontmatter containing exactly two fields:
```markdown
---
name: human
description: Who the user is and how they want to work together.
---
```
…Read the whole file at its exact version.
How to install
mdr add letta-ai/letta-code/maintaining-core-memory@sha256:b4eb36f7a78b585cThe line at the top of this page pins the label git:20261030.9d1220b, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_pshogmwt6dexvewn)
4 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 3 versions of this file, between Oct 19, 2026 and Oct 30, 2026, about one every 6 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20261030.9d1220b latest | 2026-10-30 | 9d1220b | 9,310 B | A | view · diff |
| git:20261019.0ace9fa | 2026-10-19 | 0ace9fa | 7,145 B | A | view · diff |
| git:20261019.2d3dd8f | 2026-10-19 | 2d3dd8f | 7,198 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (9310 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
letta-ai/letta-code · 3,790 stars · license Apache-2.0 · pushed 2026-11-06 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_pshogmwt6dexvewn GET https://markdownregistry.com/api/v1/resolve?ref=letta-ai/letta-code/maintaining-core-memory GET https://markdownregistry.com/api/v1/blob/b4eb36f7a78b585c7c9572a23505b758520a3bf407768c8fb292c0b3f6138818
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.