What is tempest CLAUDE.md?

A repository guidance document for Tempest, a macOS developer tool built with TypeScript, React, and Electrobun. It explains the app’s two-process design, technology choices, and special dependency requirements.

Use it when modifying Tempest’s Electrobun integration, Bun backend, React interface, terminal, native webview behavior, or fork-specific documentation.

It helps coding agents understand how the backend, web interface, terminal, and native webview fit together before changing the project.

How MattFlower/tempest configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to MattFlower/tempest. 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/MattFlower/tempest/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/MattFlower/tempest

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/mattflower/tempest/claude-md/github.svg)](https://agentmods.dev/instructions/mattflower/tempest/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/mattflower/tempest/claude-md"><img src="https://agentmods.dev/badge/instructions/mattflower/tempest/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/mattflower/tempest/claude-md"><img src="https://agentmods.dev/badge/instructions/mattflower/tempest/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 893 This file is loaded in full into every session.

When invoked 893 The same file — it is already loaded in full.

Security scan B 1 finding. 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.

Model	Per session	Once invoked
Fable 5.1	$0.00893	$0.00893
Opus 5.5	$0.00357	$0.00357
Sonnet 5.5	$0.00179	$0.00179
Haiku 4.5	$0.00089	$0.00089

Measured 1mo ago against content hash 540e2abc8ddc, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade B, and why

tempest CLAUDE.md scanned grade B 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 1mo 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.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

| Per-session MCP tool injection (`show_webpage`, `show_mermaid_diagram`, `show_markdown`) | Yes (`--mcp-config`) | — | **No** — Codex reads MCP from `~/.codex/config.toml` globally |

CLAUDE.md · 67 lines

How it starts

The opening of the file, as written. The whole thing — 67 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Tempest — Electrobun Rewrite

Overview

Tempest is a macOS developer tool rewritten from Swift/SwiftUI to Electrobun/TypeScript. Two-process architecture: Bun backend + React webview frontend, communicating via typed RPC.

Tech Stack

Framework: Electrobun (private fork, see below) — Bun + native WebView.
UI: React 19 + Tailwind CSS 4 + Zustand
Terminal: xterm.js 6 with WebGL renderer + Bun.Terminal PTY
Browser: System webview (WKWebView on macOS) via <electrobun-webview>

Forked Electrobun

The electrobun dependency in package.json is not the published npm package. It's a tarball URL pointing at a release on MattFlower/electrobun (branch auto-mask-overlays, local checkout at ~/code/electrobun). The fork is rebased on upstream v1.18.1 and adds two things Tempest relies on: an auto-mask attribute on <electrobun-webview> for popups over native browser panes, and a re-sync bugfix in OverlaySyncController. (Traffic-light positioning via setWindowButtonPosition was previously a fork patch but has since landed in upstream — Tempest now consumes it directly.)

Read AI_DOCS/electrobun-fork.md before changing anything that touches <electrobun-webview>, the bun-side electrobun APIs, or the native window chrome — and before answering questions about how the electrobun dependency is wired. Cutting a new fork release uses the runbook at ~/code/electrobun/RELEASING-TEMPEST-FORK.md.

Key Architectural Rules

Terminal lifecycle: Never unmount terminal components on tab switch. Use opacity-0 + pointer-events-none.
PaneNode is immutable: All tree operations return new trees.
RPC hot path: Terminal I/O uses fire-and-forget messages. Base64 encode PTY data. Sequence numbers for ordering.
Microtask coalescing: PTY output batched via queueMicrotask.

Coding Agents

Tempest supports three terminal-hosted coding agents. Their integration depth differs because each CLI exposes different extension points.

Read the full file on GitHub · 67 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.

1mo ago First seen · 67 lines · 893 tokens per session scan B 540e2abc8ddc

Subscribe to this mod's changes

tempest CLAUDE.md is an instructions file published in the GitHub repository MattFlower/tempest (8 stars, last pushed 7d ago), licensed MIT. It adds 893 tokens to every session, about $0.0036 per session on Opus 5.5. A static security scan graded it B with 1 finding (reads agent configuration directories). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Building agents Claude Code codex-cli pi-coding-agent

vscode buildNext.instructions.md

Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).

microsoft/vscode · 9,715 tokens

tempest: Instructions file for Claude Code