@piotr-oles/pi-fence

Pi Agent extension: block or warn on fence/divider comments in written code

Packages

Package details

extension

Install @piotr-oles/pi-fence from npm and Pi will load the resources declared by the package manifest.

npm repo home report

$ pi install npm:@piotr-oles/pi-fence

Package: @piotr-oles/pi-fence
Version: 0.1.0
Published: Jun 2, 2026
Downloads: not available
Author: piotr-oles
License: unknown
Types: extension
Size: 9.5 MB
Dependencies: 1 dependency · 2 peers

Pi manifest JSON

{
  "extensions": [
    "./src/index.ts"
  ],
  "image": "https://raw.githubusercontent.com/piotr-oles/pi-extensions/main/packages/pi-fence/media/screenshot.jpeg"
}

Security note

Pi packages can execute code and influence agent behavior. Review the source before installing third-party packages.

README

pi-fence

A pi coding agent extension that detects decorative fence/divider comments in code written by the model and warns, blocks, or removes them automatically.

What it catches

Comments whose inner text (after stripping //, #, /* */ markers) contains a sequence of 3 or more separator characters:

// ---- helpers ----        ← caught
// ===== Auth Module =====  ← caught
# ################          ← caught
/* ~~~ utilities ~~~ */     ← caught
// ────────────────         ← caught (Unicode box-drawing)

// TODO: fix this           ← NOT caught
// Copyright (c) 2024       ← NOT caught

Supported languages

Extension(s)	Language
`.ts`, `.tsx`, `.cts`, `.mts`	TypeScript
`.js`, `.jsx`, `.mjs`, `.cjs`	JavaScript
`.py`	Python
`.go`	Go
`.rs`	Rust
`.rb`	Ruby
`.java`	Java
`.sh`, `.bash`	Shell / Bash
`.c`, `.h`	C
`.css`	CSS

Files with other extensions are passed through without inspection.

Install

pi install npm:@piotr-oles/pi-fence

Modes

Control via the --pi-fence-mode CLI flag (takes precedence) or the PI_FENCE_MODE environment variable:

pi --pi-fence-mode warn    # default: write proceeds, warning shown to model
pi --pi-fence-mode block   # write is blocked; model must remove fences and retry
pi --pi-fence-mode remove  # fence comments are stripped silently before writing

PI_FENCE_MODE=block pi    # same, via env variable

How it works

Injects a short system-prompt instruction telling the model not to add fence comments.
On every write and edit tool call, parses the new content with tree-sitter to extract comment nodes.
Compares against the existing file — only newly introduced fences trigger (a fence at the same line as in the old file is not re-reported).
Acts according to the configured mode.

System-Prompt

Do not insert decorative fence comments like // ---- section ----. Code-smell, if needed, extract to function or file instead.

Development

pnpm install
pnpm test
pnpm typecheck
pnpm check

To test changes manually, pass the source entry point directly to pi with the -e flag:

pi -ne -e src/index.ts
pi -ne -e src/index.ts --pi-fence-mode block
pi -ne -e src/index.ts --pi-fence-mode remove