pi-memory-blocks

Letta/MemGPT-style persistent memory blocks for Pi coding agents. Gives the agent self-editable memory that survives across sessions.

What it does

• Creates persistent memory blocks stored as Markdown files with frontmatter (.pi/memory-blocks/<key>.md)
• Injects all memory blocks into the system prompt every turn
• Provides an updateMemory tool the LLM can use to update its own memory
• Ships with two default blocks: user (facts about you) and agent (facts about its role and context)
• Each block has a configurable character limit (default: 2000 chars)

The LLM sees its memory blocks in the system prompt and can decide to persist important information — user preferences, project context, its own role — using the updateMemory tool. Memory accumulates over sessions, giving the agent long-term recall.

Installation

pi install npm:@gordonb/pi-memory-blocks

How it works

Memory blocks

Each block is a .md file in .pi/memory-blocks/ with YAML frontmatter:

---
description: Information about the user
limit: 2000
---

Prefers functional programming style. Uses TypeScript and Deno.
Name is Gordon.

• description — tells the LLM what the block is for
• limit — maximum character count for the block's content

On first run, the extension creates two default blocks (user.md and agent.md) if they don't exist. You can add more blocks manually — just create a new .md file with the frontmatter format above.

The updateMemory tool

The LLM can call updateMemory with:

Parameter	Required	Description
blockKey	Yes	Block to update (e.g. "user", "agent")
oldText	No	Text to find and replace. Omit to append instead.
newText	Yes	Replacement text, or text to append if no oldText.

The tool supports two modes:

• Replace — finds oldText in the block and replaces it with newText
• Append — if oldText is omitted, appends newText to the block

Content is truncated to the block's character limit if it exceeds it. The LLM can only write to existing blocks — it cannot create new ones.

The /memory command

Type /memory in the Pi TUI to see all memory blocks, their usage bars, and content previews.

Adding custom blocks

Create a new .md file in .pi/memory-blocks/:

---
description: Current project architecture decisions
limit: 4000
---

The block key is the filename without .md. The LLM will see it in its system prompt and can update it with updateMemory.

Inspiration

Inspired by Letta (formerly MemGPT), which pioneered the idea of giving LLMs self-editable memory blocks with bounded capacity.

License

MIT