Borrowing it
Nothing to install: this file belongs to ai-screams/Howl. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/ai-screams/Howl/main/CLAUDE.mdgit clone --depth 1 https://github.com/ai-screams/HowlWrote 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.
[](https://agentmods.dev/instructions/ai-screams/howl/claude-md)<a href="https://agentmods.dev/instructions/ai-screams/howl/claude-md"><img src="https://agentmods.dev/badge/instructions/ai-screams/howl/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.
<a href="https://agentmods.dev/instructions/ai-screams/howl/claude-md"><img src="https://agentmods.dev/badge/instructions/ai-screams/howl/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.03615 | $0.03615 |
| Opus 5.5 | $0.01446 | $0.01446 |
| Sonnet 5.5 | $0.00723 | $0.00723 |
| Haiku 4.5 | $0.00362 | $0.00362 |
Grade A, and why
Howl CLAUDE.md 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 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
- **Dependabot does not see tools a workflow installs itself** — golangci-lint (`version:` in quality-lint.yaml), gitleaks (curl + sha256 in security-secrets.yaml), svu (wget + sha256 in auto-release.yaml), govulncheck ( How it starts
The opening of the file, as written. The whole thing — 145 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
Howl — a Go statusline HUD for Claude Code. Reads JSON from stdin (event-driven: Claude Code re-runs the command on new messages, /compact, mode changes, a refreshInterval timer, and rate-limit or prompt-cache expiry, debounced at 300ms), computes 4 derived metrics (context%, cache efficiency, API wait ratio, cost/min) with feature toggles, and outputs ANSI-formatted lines. Zero external dependencies (stdlib only), CGO_ENABLED=0, ~10ms cold start.
Module: github.com/ai-screams/howl
Commands
make build # CGO_ENABLED=0 go build → build/howl
make install # build + copy to ~/.claude/hud/howl
make unit-test # go test ./... -v -cover -coverprofile=coverage.out
make test # smoke test: pipes sample JSON into built binary
make lint # golangci-lint run
make fmt # go fmt ./...
make fmt-docs # prettier on *.md *.yaml *.yml
make check # fmt + fmt-docs + lint + unit-test
make setup # configure .githooks + install prettier
make release-dry # goreleaser snapshot build into dist/ (no publish)
make release-check # validate .goreleaser config
Run a single test:
go test ./internal -run TestComputeMetrics -v
go test ./cmd/howl -run TestE2E_VersionFlag -v
Architecture
Some checkouts carry an untracked AGENTS.md tree covering the same directories at more length. It is excluded in .git/info/exclude, so it is per-clone and reaches nobody else — never treat it as the source of truth, and never assume a reader has it. Its copy of the preset table listed a removed metric and omitted four live toggles for months, which is the argument against a second copy of anything: when docs disagree, the code wins.
Data Pipeline (main.go)
stdin JSON → json.Decode(StdinData) → LoadConfig → ComputeMetrics → GetGitInfo → UsageFromRateLimits → ParseTranscript → GetAccountInfo → ReadUpdateNotice → Render → stdout (ANSI lines, spaces → NBSP)
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 Changed · +24 lines · +1,214 tokens per session 12eab8f8fbe3
- 1mo ago Changed · +17 lines · +615 tokens per session 8c555ce17c05
- 1mo ago Changed · +7 lines · +238 tokens per session 2831622caa09
- 1mo ago First seen · 97 lines · 1,548 tokens per session scan A 0fb1f44970bd
Howl CLAUDE.md is an instructions file published in the GitHub repository ai-screams/Howl (5 stars, last pushed 6d ago), licensed MIT. It adds 3,615 tokens to every session, about $0.0145 per session on Opus 5.5. 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 2026-08-31.
Other instructions, from other repositories
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).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
deepseek-harness AGENTS.md
AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.