What is ActivityPub AGENTS.md?

A project guide for Ghost’s ActivityPub server, which lets independent websites publish to the Fediverse, a network of social platforms that can communicate with one another.

Use it when working on the TryGhost/ActivityPub codebase, especially for running linting, formatting, type checks, unit and integration tests, end-to-end tests, or migrations.

It gives coding agents the project’s architecture, boundaries, commands, and testing rules so they can change the code without overlooking important conventions.

How TryGhost/ActivityPub configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to TryGhost/ActivityPub. 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/TryGhost/ActivityPub/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/TryGhost/ActivityPub

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/tryghost/activitypub/agents-md/github.svg)](https://agentmods.dev/instructions/tryghost/activitypub/agents-md)

Your own site

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

Per session 1,949 This file is loaded in full into every session.

When invoked 1,949 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	$0.01949	$0.01949
Opus 5.5	$0.00780	$0.00780
Sonnet 5.5	$0.00390	$0.00390
Haiku 4.5	$0.00195	$0.00195

Measured 24d ago against content hash 1907a7a048a8, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

ActivityPub 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 24d 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 · 169 lines

How it starts

The opening of the file, as written. The whole thing — 169 lines — stays where its author put it; the contents beside it link to each section on GitHub.

ActivityPub — agent guide

A multitenant ActivityPub server for Ghost, built with Fedify, that publishes independent websites to the Fediverse. See README.md for the human overview and /adr for the Architecture Decision Records that own the rationale behind the patterns below.

Stack (versions in package.json / docker-compose.yml): Node + TypeScript, Hono, Fedify, Awilix (DI), Zod, Knex + MySQL, Vitest (unit/integration), Cucumber + Wiremock (e2e), Biome (lint/format), esbuild. Runs in Docker Compose locally; Google Cloud Run in production.

Commands

Tests run inside a Docker container via pnpm, so extra flags passed to pnpm do not reach the test runner — use the dedicated scripts below.

pnpm lint                       # Biome lint
pnpm fmt                        # Biome format
pnpm test:types                 # type check
pnpm test                       # everything (slow)
pnpm test:unit                  # unit only (fast)
pnpm test:integration           # integration only (slow)
pnpm test:cucumber              # e2e only (slow)
pnpm test:single 'path/to/test' # single unit/integration test (fast)

Run a single e2e test by tagging a Feature or Scenario with @only, then pnpm test:cucumber @only.

pnpm dev            # start app (also runs pending migrations)
pnpm logs           # tail app logs  (pnpm dev && pnpm logs to do both)
pnpm stop           # stop app + service deps
pnpm wipe-db        # wipe the database
pnpm fix            # attempt to repair a broken local environment

Local services: app :8080, MySQL :3307 (user ghost / pass password / db activitypub), Pub/Sub emulator :8085, GCS emulator :4443. Ghost's pnpm dev proxies ActivityPub routes to 127.0.0.1:8080 (set ACTIVITYPUB_PROXY_TARGET explicitly on older Ghost checkouts). Expose Ghost's development port (2368, or a worktree's GHOST_DEV_PORT) with tailscale funnel --bg 2368, and start Ghost with url=https://<your-tailnet-url>/ pnpm dev.

Read the full file on GitHub · 169 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.

24d ago Changed · +4 lines · +75 tokens per session 1907a7a048a8
1mo ago Changed · +6 lines · +66 tokens per session 75b478132191
2mo ago First seen · 159 lines · 1,808 tokens per session scan A df8b9de5479a

Subscribe to this mod's changes

ActivityPub AGENTS.md is an instructions file published in the GitHub repository TryGhost/ActivityPub (239 stars, last pushed yesterday), licensed MIT. It adds 1,949 tokens to every session, about $0.0078 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 2026-08-30.

Backend and APIs activitypub fediverse fediverse-server ghost ghost-cms

ActivityPub AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
ActivityPub AGENTS.mdTryGhost/ActivityPub	Instructions file	239	yesterday	MIT	A	1,949	Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	today	MIT	A	7,461	Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	yesterday	MIT	A	4,680	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

ActivityPub: Instructions file for Codex