posthog-foss: Skill for Claude Code

.agents/skills/adding-personhog-rpc/SKILL.md

adding-personhog-rpc is a skill for Claude Code, Codex from PostHog/posthog-foss. It costs 88 tokens per session (1,930 once invoked), scanned A, original, MIT.

An engineering guide for adding a new RPC, a remote procedure call that lets one service request an operation from another, to personhog-replica and personhog-router. It covers the interface definition, generated clients, Rust implementation, routing, and database compatibility.

In plain words
What is it for?
Use it when adding a supported person, group, cohort, feature-flag override, or related data operation to the personhog service.
Why use it?
It helps developers confirm that the requested data belongs in personhog and follow the full implementation path across services and clients.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

This is PostHog/posthog-foss's own configuration. It tells Claude Code and Codex how to work on posthog-foss 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 posthog-foss configures →

Reuse

Borrowing it

Nothing to install: this file belongs to PostHog/posthog-foss. 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/PostHog/posthog-foss/master/.agents/skills/adding-personhog-rpc/SKILL.md
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.

agentmods badge for adding-personhog-rpc

README.md
[![agentmods](https://agentmods.dev/badge/skills/posthog/posthog-foss/adding-personhog-rpc.svg)](https://agentmods.dev/skills/posthog/posthog-foss/adding-personhog-rpc)
Your own site
<a href="https://agentmods.dev/skills/posthog/posthog-foss/adding-personhog-rpc"><img src="https://agentmods.dev/badge/skills/posthog/posthog-foss/adding-personhog-rpc.svg" alt="Measured on agentmods" height="20"></a>
Per session 88 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,930 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00088 $0.01930
Opus 5 $0.00044 $0.00965
Sonnet 5 $0.00018 $0.00386
Haiku 4.5 $0.00009 $0.00193

Measured 8d ago against content hash b52d43b08cc8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

adding-personhog-rpc 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 8d 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/skills/adding-personhog-rpc/SKILL.md · 165 lines

How it starts

The opening of the file, as written. The whole thing — 165 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Adding a personhog RPC

This skill walks through adding a new RPC end-to-end: proto definition, code generation, Rust implementation, and client updates.

Before you start: eligibility check

Personhog serves person, distinct ID, group, group type mapping, cohort membership, and feature flag hash key override data. If the data being accessed doesn't live in one of these tables, this RPC doesn't belong in personhog:

Table Data category Routing
posthog_person PersonData Reads: replica (eventual) or leader (strong). Writes: leader
posthog_persondistinctid PersonData Same as person
posthog_group NonPersonData All ops: replica
posthog_grouptypemapping NonPersonData All ops: replica
posthog_cohortpeople NonPersonData All ops: replica
posthog_featureflaghashkeyoverride NonPersonData All ops: replica
posthog_personoverride PersonData Reads/writes follow person routing
posthog_personlessdistinctid PersonData Same as person

If the table is not listed above, stop — this data should not go through personhog.

Step 0: design the data access pattern

Before writing any proto, figure out the SQL query you need. Then validate it against the available indexes — see references/database-indexes.md.

Key questions:

  • What table(s) does this query hit?
  • Does the WHERE clause match an existing index? Every query must be an index scan, never a sequential scan.
  • Is this a read or write? This determines routing (see table above).
  • For reads: does the caller need strong consistency (primary pool) or is eventual (replica pool) acceptable?
  • For batch lookups: is the batch within a single team or cross-team?

Read the full file on GitHub · 165 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 8d ago First seen · 165 lines · 88 tokens per session scan A b52d43b08cc8

Subscribe to this mod's changes

adding-personhog-rpc is a skill published in the GitHub repository PostHog/posthog-foss (714 stars, last pushed today), licensed MIT. It adds 88 tokens to every session and 1,930 once invoked, about $0.0004 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.

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