What is letta-agent-sdk AGENTS.md?

Contributor instructions for the Letta Agent SDK, a software library for building and connecting to AI-agent sessions. They explain where source code lives and how local, remote, and cloud sessions share components.

Finding the right implementation for session creation, message streaming, remote connections, cloud runtimes, and public SDK types.

They help contributors change the correct source files instead of editing generated build output. They also clarify which parts handle protocols, messages, runtimes, and public types.

How letta-ai/letta-agent-sdk configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to letta-ai/letta-agent-sdk. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/letta-ai/letta-agent-sdk/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/letta-ai/letta-agent-sdk

Made for: Codex, OpenCode.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/letta-ai/letta-agent-sdk/agents-md/github.svg)](https://agentmods.dev/instructions/letta-ai/letta-agent-sdk/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/letta-ai/letta-agent-sdk/agents-md"><img src="https://agentmods.dev/badge/instructions/letta-ai/letta-agent-sdk/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/letta-ai/letta-agent-sdk/agents-md"><img src="https://agentmods.dev/badge/instructions/letta-ai/letta-agent-sdk/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 1,478 This file is loaded in full into every session.

When invoked 1,478 The same file — it is already loaded in full.

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.

Model	Per session	Once invoked
Fable 5.1	$0.01478	$0.01478
Opus 5	$0.00739	$0.00739
Sonnet 5	$0.00296	$0.00296
Haiku 4.5	$0.00148	$0.00148

Measured 9d ago against content hash 906ecba2ecff, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

letta-agent-sdk AGENTS.md 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 9d 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.

AGENTS.md · 122 lines

How it starts

The opening of the file, as written. The whole thing — 122 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Letta Agent SDK contributor map

Canonical source

Work in src/. dist/ is generated by bun run build, ignored by Git, and published as a bundle. A repeated class or method in dist/index.js or dist/client-entry.js can represent separate source-layer responsibilities that Bun placed in one file; trace it back to src/ before changing it.

Session architecture

client-base.ts selects the backend and constructs a session.
Remote, Cloud, and the default local app-server path share remote-client-session-core.ts.
remote-session-protocol.ts owns portable protocol types, validation, and wire-to-domain normalization.
remote-turn-coordinator.ts owns active/queued turn correlation and the SDKMessage stream queue.
app-server-session.ts adapts an app-server connection to the runtime controller used by the portable session core.
cloud-session.ts resolves Cloud runtimes and managed sandboxes, then uses the same runtime controller and portable session core.
types.ts defines the stable public SDK surface. Internal protocol types belong beside their implementation rather than in the public type barrel.

For session.listMessages() on an app-server or Cloud session, the call path is:

RemoteClientSessionCore.listMessages → RemoteClientRuntimeController.listMessages → the selected transport adapter.

Those methods operate at different layers and should not be combined merely because they share a name.

Stream identifiers

Streamed SDKMessage values carry several identifiers, and each one answers a different question. Most duplicate or missing message bugs in consumers come from using one to answer another's question.

seqId answers "have I already processed this stream position?" It is a per-run replay cursor: use it to suppress replayed events after a resume or reconnect, compare it only within the same runId, and reset the threshold when a new run starts. It is not row identity.
otid answers "which typed message slice is this?" Use it to reassemble the fragments of one slice. It is not a universal key across message types.
uuid answers "which message object is this?" Use it for message identity and for history cursoring and backfill. It is the top-level message ID when the stream provides one and an SDK-generated identifier otherwise, so it is neither a guaranteed server ID nor a replay cursor.
toolCallId answers "which tool call is this about?" Use it to join a tool_call with its tool_result. It is not identity for assistant or reasoning messages.

Read the full file on GitHub · 122 lines

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.

9d ago First seen · 122 lines · 1,478 tokens per session scan A 906ecba2ecff

Subscribe to this mod's changes

letta-agent-sdk AGENTS.md is an instructions file published in the GitHub repository letta-ai/letta-agent-sdk (95 stars, last pushed 7d ago), licensed Apache-2.0. It adds 1,478 tokens to every session, about $0.0074 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.

next.js AGENTS.md

AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.

vercel/next.js · 7,296 tokens

codex AGENTS.md

AGENTS.md instructions for openai/codex, covering rust/codex-rs, the codex-core crate, code review rules, crate api surface and model visible context.

openai/codex · 5,153 tokens

vscode buildNext.instructions.md

Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).

microsoft/vscode · 6,785 tokens

letta-agent-sdk: Instructions file for Codex