posthog-foss: Skill for Claude Code

.agents/skills/implementing-warehouse-sources/SKILL.md

implementing-warehouse-sources is a skill for Claude Code, Codex from PostHog/posthog-foss. It costs 69 tokens per session (18,469 once invoked), scanned A, original, MIT.

A development guide for adding or extending PostHog data-warehouse import sources. A data warehouse is a system that stores data for analysis; these sources bring data from external services into it.

In plain words
What is it for?
For building source connectors, adding datasets or endpoints, validating credentials, importing pages of data, resuming interrupted imports, and receiving webhook data.
Why use it?
It provides the project-specific checks and patterns needed for imports, including credentials, pagination, incremental and resumable syncing, and webhooks.

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/implementing-warehouse-sources/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 implementing-warehouse-sources

README.md
[![agentmods](https://agentmods.dev/badge/skills/posthog/posthog-foss/implementing-warehouse-sources.svg)](https://agentmods.dev/skills/posthog/posthog-foss/implementing-warehouse-sources)
Your own site
<a href="https://agentmods.dev/skills/posthog/posthog-foss/implementing-warehouse-sources"><img src="https://agentmods.dev/badge/skills/posthog/posthog-foss/implementing-warehouse-sources.svg" alt="Measured on agentmods" height="20"></a>
Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 18,469 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 2 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Privilege Escalation · line 716
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • medium MCP Rug Pull · line 284
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
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 $0.00069 $0.18469
Opus 5 $0.00034 $0.09234
Sonnet 5 $0.00014 $0.03694
Haiku 4.5 $0.00007 $0.01847

Measured 4d ago against content hash 8f363f3a83e2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

implementing-warehouse-sources scanned grade A with 1 finding 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 4d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

**Deleting that line is mandatory, and it is not gated on anything you can't do in your environment.** In particular, "I couldn't curl the live API" or "I couldn't verify against a real account" is NOT a reason to keep t
.agents/skills/implementing-warehouse-sources/SKILL.md · 884 lines

How it starts

The opening of the file, as written. The whole thing — 884 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Implementing Data warehouse sources

Use this skill when building or updating Data warehouse sources in products/warehouse_sources/backend/temporal/data_imports/sources/.

Read first

Before coding, read:

  • products/warehouse_sources/backend/temporal/data_imports/sources/source.template (the top-of-file TODOs are the bootstrap checklist; still verify target files against current source implementations, since the template can drift)
  • products/warehouse_sources/backend/temporal/data_imports/sources/README.md
  • products/warehouse_sources/backend/temporal/data_imports/sources/SOURCES.md — inventory of every registered source with its communication method (HTTP / vendor SDK / gRPC / DB protocol / webhook) and tracked-transport state. Skim this first to see how similar sources are wired and what state today's source you're touching is in. Keep it in sync — see "Updating SOURCES.md" below.
  • products/warehouse_sources/backend/temporal/data_imports/sources/common/base.py — base classes (SimpleSource, ResumableSource, WebhookSource) and the FieldType union
  • products/warehouse_sources/backend/temporal/data_imports/sources/common/resumable.pyResumableSourceManager
  • products/warehouse_sources/backend/temporal/data_imports/sources/common/webhook_s3.pyWebhookSourceManager
  • chargebee/ — the canonical reference for a new REST source. It uses the shared rest_source framework (declarative RESTAPIConfig + rest_api_resource, framework auth + paginators, tracked+retrying transport) and is resumable — proof the framework covers the dominant "paginate a list endpoint and yield, resumably" shape. Read it first, alongside "Prefer the shared REST framework" below. Read klaviyo/ or github/ only as a bespoke-transport fallback: they hand-roll their client for edge cases (custom query-string encoding, multi-level fan-out, JSON:API reshaping) that most sources don't have — don't copy that boilerplate into a source that doesn't need it. For dependent-resource fan-out (parent→child with type: "resolve"), also read products/warehouse_sources/backend/temporal/data_imports/sources/common/rest_source/__init__.py and config_setup.py (e.g. process_parent_data_item, make_parent_key_name).
  • For webhook-capable sources, read products/warehouse_sources/backend/temporal/data_imports/sources/stripe/source.py as the reference implementation.

Read the full file on GitHub · 884 lines

Files

What ships with it

1 file 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. 4d ago Changed · +1 lines 8f363f3a83e2
  2. 8d ago First seen · 883 lines · 69 tokens per session scan A 7e195545ca62

Subscribe to this mod's changes

implementing-warehouse-sources is a skill published in the GitHub repository PostHog/posthog-foss (714 stars, last pushed today), licensed MIT. It adds 69 tokens to every session and 18,469 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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