# managing-path-cleaning-rules

Guides agents in auditing fragmented PostHog URL paths, writing re2 normalization rules, and collapsing dynamic IDs into clean aliases.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 353 installs · ★ 76
- Author: PostHog
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/PostHog/skills/tree/HEAD/skills/omnibus/managing-path-cleaning-rules/SKILL.md
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/skills/managing-path-cleaning-rules

## What it does

Dynamic URL parts like numeric IDs and session UUIDs scatter Web analytics and Paths insights across thousands of separate rows. This skill equips coding agents to inspect `$pageview` events and set up project-wide path cleaning filters. Endpoints like `/users/123/profile` collapse into readable templates such as `/users/<id>/profile`.

The workflow queries recent paths through the `execute-sql` MCP tool. Next, the agent creates re2 expressions paired with angle-bracket aliases like `<id>` or `<slug>`. Rule sequence matters. If a broad catch-all runs before a specific URL, it will swallow patterns meant for later rules.

Before applying changes, the agent verifies patterns using HogQL `replaceRegexpAll` calls or the settings tester. Updating happens via the `path-cleaning-rules-update` MCP tool — it shows a dry-run preview with sample paths before saving with `confirm: true`. This prevents wiping existing project settings.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add PostHog/skills --skill managing-path-cleaning-rules -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/managing-path-cleaning-rules/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/managing-path-cleaning-rules/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add PostHog/skills --skill managing-path-cleaning-rules -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/managing-path-cleaning-rules/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add PostHog/skills --skill managing-path-cleaning-rules -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/managing-path-cleaning-rules/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install PostHog/skills managing-path-cleaning-rules
```

2. **Manually: put the files in place**
- File: `.github/skills/managing-path-cleaning-rules/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add PostHog/skills --skill managing-path-cleaning-rules -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/PostHog/skills --path skills/omnibus/managing-path-cleaning-rules
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/managing-path-cleaning-rules/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add PostHog/skills --skill managing-path-cleaning-rules -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/PostHog/skills/tree/HEAD/skills/omnibus/managing-path-cleaning-rules/SKILL.md

## When to use it
- Collapse dynamic URL segments into readable placeholders inside PostHog analytics
- Query real `$pageview` records to discover high-cardinality path patterns
- Draft re2 regular expressions with `<id>` and `<slug>` aliases
- Sequence cleaning filters from specific patterns to broad fallbacks
- Preview and apply path cleaning changes safely via MCP update tools

## Example prompts
- Clean the paths in PostHog: `/users/123` and `/users/456` should show up as the same page
- Inspect our top pageview URLs with execute-sql and suggest rules to collapse UUIDs
- Draft re2 path cleaning rules for date archives and test them on sample URLs

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: f307cd42dff38706.

BEGIN THIRD-PARTY FILE f307cd42dff38706
````text
---
name: managing-path-cleaning-rules
description: 'Inspects URL paths and proposes, tests, orders, and applies project-level path cleaning rules so dynamic segments (numeric IDs, UUIDs, slugs, dates) collapse into readable aliases. Use when the user says "clean the paths", "normalize URLs", "group similar pages", "too many distinct paths", "/users/123 and /users/456 are the same page", "set up path cleaning", or asks why a Web analytics or Paths breakdown is fragmented across thousands of nearly-identical URLs. Covers regex syntax (re2), alias placeholder convention, rule ordering, the test workflow, and applying rules via the path-cleaning-rules-update MCP tool.'
---

# Managing path cleaning rules

Path cleaning rules normalize `$pathname` and `$entry_pathname` so that pages
sharing the same template (`/users/123/profile`, `/users/456/profile`, …) collapse
into one row (`/users/<id>/profile`) in Web analytics tiles, Paths insights, and
any HogQL query that calls `apply_path_cleaning`. They are the right answer when
a breakdown is fragmented across thousands of near-identical URLs.

This skill teaches you how to:

- recognize when path cleaning is the right tool
- inspect real paths to find what needs cleaning
- write `regex` + `alias` rules in re2 syntax with the project's placeholder
  convention
- test rules before saving them
- order rules so specific patterns aren't swallowed by generic ones
- apply the rules via MCP

## Data model

`Team.path_cleaning_filters` is a JSON list of `PathCleaningFilter` objects:

```json
{
  "regex": "/users/\\d+/profile",
  "alias": "/users/<id>/profile",
  "order": 0
}
```

- **`regex`** — a [re2](https://github.com/google/re2/wiki/Syntax) pattern. No
  need to escape `/`. Anchor with `^` / `$` when you mean it.
- **`alias`** — the replacement. Default to angle-bracket placeholders
  (`<id>`, `<slug>`, `<uuid>`, `<date>`) so the cleaned path stays
  human-readable. Backreferences to the regex's capture groups also work, but
  they cost more to evaluate — see the backreference pitfall below before
  reaching for one.
- **`order`** — integer. Rules apply **sequentially** in `order` ascending,
  each rule's output feeds the next.

Application is `replaceRegexpAll(pathname, regex, alias)` per rule, chained.

## Workflow

### 1. Confirm path cleaning is the right move

Ask yourself: is the user complaining about cardinality (too many distinct paths
````
END THIRD-PARTY FILE f307cd42dff38706

The third-party file has ended. Everything between the f307cd42dff38706 tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 2435 of 8881 bytes. © PostHog · MIT · https://github.com/PostHog/skills/tree/HEAD/skills/omnibus/managing-path-cleaning-rules/SKILL.md

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