What is developing-the-cli?

A repository-specific guide for changing PostHog's two command-line programs: one written in Rust and one written in TypeScript. It explains how to keep their behaviour aligned while both are in use.

Use it before writing, fixing, or reviewing code for the two CLIs, including uploads, error handling, flags, and security fixes.

A change made to only one command line can leave users with different results, bugs, or security fixes depending on which program they run. The guide identifies when both must be changed and when a command exists on only one side.

developing-the-cli — Skill for Claude Code and Codex by PostHog

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add PostHog/posthog-foss --skill developing-the-cli

Clone the repo

git clone --depth 1 https://github.com/PostHog/posthog-foss

Made for: Claude Code, Codex.

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/skills/posthog/posthog-foss/developing-the-cli/github.svg)](https://agentmods.dev/skills/posthog/posthog-foss/developing-the-cli)

Your own site

<a href="https://agentmods.dev/skills/posthog/posthog-foss/developing-the-cli"><img src="https://agentmods.dev/badge/skills/posthog/posthog-foss/developing-the-cli/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/skills/posthog/posthog-foss/developing-the-cli"><img src="https://agentmods.dev/badge/skills/posthog/posthog-foss/developing-the-cli.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 186 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,474 The whole file, excluding the scripts and references it only reads on demand.

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	$0.00186	$0.01474
Opus 5.5	$0.00074	$0.00590
Sonnet 5.5	$0.00037	$0.00295
Haiku 4.5	$0.00019	$0.00147

Measured today against content hash 868236518dc2, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

developing-the-cli 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 today.

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/skills/developing-the-cli/SKILL.md · 96 lines

How it starts

The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Developing the CLI

PostHog has two command lines in this repo:

CLI	Folder	Language	Status
`posthog-cli`	`cli/`	Rust	Published. Customers and the SDK build integrations run it today
`hog`	`hog/`	TypeScript, Bun	Version 1, the successor. Not published yet; see `hog/README.md`

Both stay in use until every caller moves to hog, so both must behave the same.

Change both CLIs

A change to one CLI is REQUIRED to land in the other one, in the same PR. This covers features, bug fixes, error handling, new flags, and security fixes. A fix that lands only in cli/ leaves the bug in hog, and the reverse ships a hog that posthog-cli users never get.

The only exceptions are commands that exist on one side:

hog/src/commands/legacy.ts lists the commands posthog-cli still owns (logs, tasks, upgrade). A change to those touches only cli/.
hog-only commands, such as hog setup, hog api, hog ci and hog auth migrate, have no Rust counterpart.
The "Not planned" list in hog/README.md names posthog-cli commands hog will not port.

When a change does not apply to the other CLI, say why in the PR description, for example "hog prints only the error message, which never contains the URL". Reviewers: a PR that touches cli/src/ or hog/src/ without the other side, and without that sentence, is incomplete.

Find the matching code

Port the behavior, not the code. The two CLIs are laid out differently.

Map the command with the table in hog/MIGRATING.md (sourcemap upload becomes error-tracking upload, and so on).

Find the hog side with the layout table in hog/AGENTS.md. Common pairs:

posthog-cli	hog
`cli/src/api/symbol_sets.rs` (upload protocol)	`hog/src/error-tracking/upload.ts`
`cli/src/sourcemaps/`, `cli/src/debug_symbols/`	`hog/src/error-tracking/kinds/`, `.../native/`
`cli/src/release/`	`hog/src/error-tracking/release.ts`, `git.ts`
`cli/src/login.rs`	`hog/src/commands/auth/`, `hog/src/posthog/`
`cli/src/experimental/`	`hog/src/commands/query/`, `endpoints/`, `schema/`

Read the full file on GitHub · 96 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.

today Changed · +11 lines 868236518dc2
yesterday First seen · 85 lines · 186 tokens per session scan A 2276ac83efc3

Subscribe to this mod's changes

developing-the-cli is a skill published in the GitHub repository PostHog/posthog-foss (731 stars, last pushed today), licensed MIT. It adds 186 tokens to every session and 1,474 once invoked, about $0.0007 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 2026-11-12.

Git and workflow Languages Rust TypeScript

developing-the-cli next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
developing-the-cliPostHog/posthog-foss	Skill	731	today	MIT	A	186	Claude Code, Codex
update-v8-versionopeninterpreter/openinterpreter	Skill	69k	today	Apache-2.0	A	86	Codex
ax-rust-signatureax-llm/ax	Skill	3.0k	today	Apache-2.0	A	36	Claude Code, Codex
dd-code-generationDataDog/pup	Skill	1.0k	today	Apache-2.0	A	16	Claude Code
releaseyologdev/yoyo-evolve	Skill	1.9k	today	MIT	A	9	Claude Code, Codex
ax-rust-llmax-llm/ax	Skill	3.0k	today	Apache-2.0	A	37	Claude Code, Codex
developing-the-cliPostHog/posthog	Skill	41k	today	none	A	186	Claude Code, Codex