agentmods.dev

mailbox: Instructions file for Codex

AGENTS.md

mailbox AGENTS.md is an instructions file for Codex, OpenCode from SDK-E/mailbox. It costs 555 tokens per session, scanned A, original, MIT.

Repository instructions for AI agents working on the SDK-E/mailbox project, including its TypeScript stack, commands, rules, and layout.

In plain words
What is it for?
Use them when changing the mailbox repository to run verification, preserve API message shapes, follow dependency and file-size rules, and use the documented commands.
Why use it?
They give coding agents the project’s required checks and constraints, reducing the risk of breaking APIs, tests, or repository conventions.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md. Also seen: mentions AGENTS.md.

This is SDK-E/mailbox's own configuration. It tells Codex and OpenCode how to work on mailbox itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything mailbox configures →

not rated 0repo 2mo ago A scan 555 tokens original MIT
View source ↗ SDK-E/mailbox
Reuse

Borrowing it

Nothing to install: this file belongs to SDK-E/mailbox. 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/SDK-E/mailbox/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/SDK-E/mailbox

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.

agentmods badge for mailbox AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/sdk-e/mailbox/agents-md/github.svg)](https://agentmods.dev/instructions/sdk-e/mailbox/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/sdk-e/mailbox/agents-md"><img src="https://agentmods.dev/badge/instructions/sdk-e/mailbox/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.

agentmods 80×15 button for mailbox AGENTS.md

Your own site · 80×15
<a href="https://agentmods.dev/instructions/sdk-e/mailbox/agents-md"><img src="https://agentmods.dev/badge/instructions/sdk-e/mailbox/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 555 This file is loaded in full into every session.
When invoked 555 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00555 $0.00555
Opus 5.5 $0.00222 $0.00222
Sonnet 5.5 $0.00111 $0.00111
Haiku 4.5 $0.00056 $0.00056

Measured 2mo ago against content hash 7966bd5525b7, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

mailbox 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 2mo 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 · 41 lines

How it starts

The opening of the file, as written. The whole thing — 41 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md

Guidance for AI agents working in this repo.

Stack

Single-package TypeScript ESM library + CLI bins. pnpm 11, Node >= 20 (CI runs 22). Vitest 4. No build framework — tsc to dist/.

Commands

  • pnpm verify — full gate: format:check, lint, typecheck, test:run, build. Must exit 0 with no warnings.
  • pnpm dev — run the sink from source (tsx).
  • Individual: pnpm run lint | format | typecheck | test:run | build.

Rules

  1. Run pnpm verify before declaring any task done.
  2. The HTTP API (/api/health, /api/email, /api/email/:id, /api/email/all, /) and the message JSON shape are a stable wire protocol — consumers (app, auth, analytics repos) depend on exact shapes. Never break; extend only.
  3. Zero runtime dependencies except smtp-tester, @modelcontextprotocol/sdk, zod. Ask before adding anything else.
  4. Keep files under ~200 lines. Exception: src/ui.ts is one embedded HTML template string by design (ships inside the package without fs reads).
  5. Bins must keep their shebang line as the first line; tsc preserves it.
  6. Tests bind ephemeral/free ports only — never hardcode 11025/11090 in tests.
  7. Conventional Commits (feat:, fix:, chore: …).
  8. No code comments unless required (e.g. eslint-disable rationale on its own line above).

Layout

  • src/server.ts — startMailbox() library entry: SMTP capture + HTTP API.
  • src/ui.ts — embedded inbox UI.
  • src/shared.ts — message types/formatting shared by server, CLI and MCP.
  • src/client.ts — API client helpers used by CLI/MCP bins.
  • src/env.ts — env resolution (MAIL_*), dotenv loading, production guard.
  • src/bin/* — executable entries (mailbox, mailbox-cli, mailbox-mcp).
  • test/raw-smtp.ts — dependency-free SMTP client used by tests.

Defaults worth remembering

  • Ports: SMTP 11025, HTTP 11090 (env: MAIL_SMTP_PORT, MAIL_HTTP_PORT; URL override: MAIL_HTTP_URL).
  • Loopback bind by default; refuses to start when NODE_ENV=production.
  • wait matches only messages arriving after invocation.

Read the full file on GitHub · 41 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.

  1. 2mo ago First seen · 41 lines · 555 tokens per session scan A 7966bd5525b7

Subscribe to this mod's changes

mailbox AGENTS.md is an instructions file published in the GitHub repository SDK-E/mailbox (0 stars, last pushed 2mo ago), licensed MIT. It adds 555 tokens to every session, about $0.0022 per session on Opus 5.5. 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.

Related

mailbox AGENTS.md compared with instructions from other repositories

mailbox AGENTS.md next to 6 instructions from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
mailbox AGENTS.mdSDK-E/mailboxInstructions file02mo agoMITA555Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA9,719GitHub Copilot
next.js AGENTS.mdvercel/next.jsInstructions file143kyesterdayMITA7,461Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchainInstructions file149kyesterdayMITA4,680Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA5,516GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA3,093GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harnessInstructions file274k2d agoMITA4,313Codex, OpenCode