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arc-2-zen: Instructions file for Claude Code

CLAUDE.md

arc-2-zen CLAUDE.md is an instructions file for Claude Code from What-Do-I-Know/arc-2-zen. It costs 2,678 tokens per session, scanned A, original, MIT.

Repository instructions for a Python migration tool that moves pinned sidebar tabs from Arc, a web browser, into Zen browser workspaces. They document the project, required setup, and migration commands.

In plain words
What is it for?
Use them when developing or running the migration: extract Arc’s pinned tabs, then import them into a Zen profile while preserving folders, ordering, and workspace assignments.
Why use it?
They give the coding agent the project context and operating steps needed to work safely with the browser data and migration process.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: mentions CLAUDE.md; mentions Claude Code.

This is What-Do-I-Know/arc-2-zen's own configuration. It tells Claude Code how to work on arc-2-zen 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 arc-2-zen configures →

not rated 5repo 7mo ago A scan 2,678 tokens original MIT
View source ↗ What-Do-I-Know/arc-2-zen
Reuse

Borrowing it

Nothing to install: this file belongs to What-Do-I-Know/arc-2-zen. 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/What-Do-I-Know/arc-2-zen/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/What-Do-I-Know/arc-2-zen

Made for: Claude Code.

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Per session 2,678 This file is loaded in full into every session.
When invoked 2,678 The same file — it is already loaded in full.
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.02678 $0.02678
Opus 5 $0.01339 $0.01339
Sonnet 5 $0.00536 $0.00536
Haiku 4.5 $0.00268 $0.00268

Measured 8d ago against content hash 2cbf7b34d6d3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

arc-2-zen CLAUDE.md 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.

CLAUDE.md · 263 lines

How it starts

The opening of the file, as written. The whole thing — 263 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

This is a Python-based migration tool that converts Arc browser pinned sidebar tabs (with nested folders) into Zen browser workspaces with proper folder hierarchy. The tool preserves Arc's organizational structure including nested folders, tab ordering, and workspace assignments.

Key Achievement: Successfully migrated 850+ tabs with 83 nested folders across 4 workspaces, preserving Arc's exact visual ordering and 3+ level folder hierarchies.

Common Commands

Migration Commands

# Step 1: Extract Arc pinned tabs
python3 src/arc_pinned_tab_extractor.py

# Step 2: Run the migration to your Zen profile
python3 zen_sessions_importer_v4.py

Prerequisites:

  • Python 3.7+
  • pip3 install lz4 (for Mozilla's LZ4 compression format)
  • Close Zen browser before running migration
  • Recommended: Create fresh Zen profile for testing

Architecture Overview

Migration Pipeline (2-Step Process)

  1. Arc Data Extraction (src/arc_pinned_tab_extractor.py)

    • Extracts from ~/Library/Application Support/Arc/StorableSidebar.json
    • Identifies Arc spaces and pinned sidebar tabs (NOT open tabs)
    • Preserves folder hierarchy and visual ordering via container childrenIds
    • Handles orphaned Essential tabs (creates separate "Orphaned" workspace)
    • Outputs: arc_pinned_tabs_export.json

  2. Zen Session Import (zen_sessions_importer_v4.py)

    • Reads exported Arc data
    • Builds nested folder structure with proper parentId relationships
    • Creates Zen workspaces, folders, and tabs
    • Writes to zen-sessions.jsonlz4 using Mozilla's LZ4 compression
    • Creates automatic backup before modifications

Key Components

src/arc_pinned_tab_extractor.py - Arc data extraction (core component)

  • Parses Arc's nested JSON structure with Firebase sync data
  • Extracts ONLY pinned tabs (containers between 'pinned' and 'unpinned' markers)
  • Preserves Arc's visual ordering using container childrenIds arrays
  • Builds folder hierarchy with full path tracking
  • Handles orphaned Essential tabs from inactive profiles
  • Data classes: ArcPinnedTab, ArcFolder, ArcSpace
  • Critical fix: pinned_index < idx < unpinned_index for correct container selection

Read the full file on GitHub · 263 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.

  1. 8d ago First seen · 263 lines · 2,678 tokens per session scan A 2cbf7b34d6d3

Subscribe to this mod's changes

arc-2-zen CLAUDE.md is an instructions file published in the GitHub repository What-Do-I-Know/arc-2-zen (5 stars, last pushed 7mo ago), licensed MIT. It adds 2,678 tokens to every session, about $0.0134 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 2026-08-31.

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