@yuanbopang/frugal

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Agents deploy to Vercel, spin up Neon databases, run E2B sandboxes, push commits that trigger GitHub Actions — all metered — and non-technical users only find out on the monthly bill. frugal makes the agent spend consciously: check usage before spending, announce paid resources in one line, tear down what it provisions.

Works across Claude Code, Codex, GitHub Copilot, Qoder, Gemini CLI, OpenCode, pi, Cursor, Windsurf, Cline, and Kiro — one ruleset, one source of truth.

How it saves you money

Two layers, both context-cheap (~1.5 KB of rules per session + at most 5 full reminders per day — after that, new services still get a numbers-only line — never blocking), with intensity levels like a volume knob:

Level	Session + inject	When to use
quiet	Free-tier / key quota numbers only	Hate noise but still want numbers
normal (default)	Numbers + one trap; dig optional	Most people
strict	+ real-bill context; confirm scary actions	Non-technical / vibe-coding

• Session rules (SessionStart): one short line on first touch, announce lasting paid resources, kill ephemeral things, escalate only for scary spend.
• Just-in-time data (PreToolUse): vercel → short Vercel line, wrangler r2 → R2, git push with workflows → Actions — once per provider per session. Horror-dollar amounts stay in strict (and the skill), not every deploy.

This is scoped to normal usage that quietly runs up a bill — wrong tier, a forgotten resource, a loop that hits a paid meter, a config default nobody checked. Not credential leaks or fraud; that's a security problem, not a billing-awareness one. Real incidents from the 272-story X corpus this plugin internalizes — and the tripwire that now fires first:

Real bill	What happened	frugal tripwire
$36,000/mo	Cloudflare queue re-enqueue loop (3.13B KV writes)	wrangler → "NO hard cap anywhere on CF — guard recursion"
$104,000	Netlify viral-traffic bill (pre-reform)	netlify → credits system + hard-pause explained
$46,000	viral traffic hit Vercel; Spend Management only emailed	vercel → Spend Management notifies at $200 — enable auto-pause
$25,672	GCP spend blew past a $10 budget (alerts lag 24-48h)	rule: alerts are not brakes — pair with quota caps
~$700/mo	agent push loop running full CI on macOS runners	git push with workflows → timeout-minutes + concurrency + macOS≈10x
$5,000/mo	Firestore useEffect read loop at 100 users	firebase → per-READ billing + maxInstances + recursion check
$1,200	Claude CLI silently billing API instead of subscription	claude with ANTHROPIC_API_KEY set → dual-rail warning

What it does

1. Session rules — injected at session start (mode-scaled).

2. In-the-moment reminders — PreToolUse watches shell commands. Mode picks how loud each hit is — once per provider per session, never blocking:

# normal (default) — free-tier numbers + one trap; dig optional
frugal: Vercel — Hobby (non-commercial): 1M inv + 1M edge reqs, 360 GB-hr mem,
100 GB transfer, 100 deploys/day — hard-pauses ~30d at quota. Pro fails open.
Spend Management defaults to notify-only at $200 — enable its auto-pause for
a real stop. Optional: `vercel usage`.

brief always carries the decisive free-tier numbers (what agent needs to reason). Horror dollars stay in strict. Dig is optional (skip if no creds). Detection is sub-service aware: wrangler r2, gh workflow run, git push with workflows, dual-rail agent CLI when an API key is in the env.

3. Researched quota data — the reminders and the skill's cheat-sheet carry real numbers (researched 2026-07, dual-engine: parallel Claude web research + grok CLI runs per provider, cross-checked against official pricing pages). Full plan tables, overage prices, cost traps, and sources: skills/frugal/references/providers.md. The complete raw research — both engines' reports per provider plus the merged machine-readable factsheets — is archived in research/.

Covered: Vercel, Cloudflare (Workers/R2/KV/D1), Neon, Railway, Fly.io, E2B, Browserbase, GitHub (Actions/Codespaces), Supabase, AWS/GCP/Azure, Terraform/Pulumi.

4. /frugal — cheat-sheet + spend audit. Levels: /frugal quiet|normal|strict|off, persist with /frugal default <level>, or set FRUGAL_MODE / ~/.config/frugal/config.json.

Install

npm package: @yuanbopang/frugal

Claude Code

/plugin marketplace add yuanboP/frugal
/plugin install frugal

Start a new session; you should see FRUGAL MODE ACTIVE — level: normal.

Codex

codex plugin marketplace add yuanboP/frugal
codex plugin add frugal@frugal

Same hooks, Codex-shaped output (detected via PLUGIN_DATA). Covers the Codex desktop app too — restart it after installing.

GitHub Copilot CLI

copilot plugin marketplace add yuanboP/frugal
copilot plugin install frugal@frugal

Or the slash equivalents inside a session (/plugin marketplace add ...). Session-start injection via hooks/copilot-hooks.json.

grok

grok plugin install https://github.com/yuanboP/frugal.git --trust

The skill (rules + cheat-sheet) activates on billing/deploy topics; grok does not execute Claude-style lifecycle hooks.

Gemini CLI

gemini extensions install https://github.com/yuanboP/frugal

Loads AGENTS.md as always-on context via gemini-extension.json.

OpenCode

{ "plugin": ["@yuanbopang/frugal"] }

Or from a checkout: { "plugin": ["./.opencode/plugins/frugal.mjs"] }. Appends the ruleset every turn and registers the skills directory.

pi

pi install git:github.com/yuanboP/frugal

Injects the ruleset via before_agent_start.

Cursor / Windsurf / Cline / Kiro

Static rule copies ship in .cursor/rules/, .windsurf/rules/, .clinerules/, .kiro/steering/ — picked up automatically from a checkout. Cursor user-level install: copy .cursor/rules/frugal.mdc to ~/.cursor/rules/.

Qoder / CodeWhale / Swival (AGENTS.md hosts)

These auto-load AGENTS.md from the repo root — zero setup from a checkout. Qoder can additionally wire the per-command reminder via hooks/qoder-hooks.json.

How it works

Piece	Role
skills/frugal/SKILL.md	On-demand cheat-sheet + full rules for explicit /frugal asks.
skills/frugal/references/providers.md	Full researched quota/plan/trap tables with sources.
hooks/frugal-config.js	Mode resolution: env → session flag → config file → normal.
hooks/frugal-runtime.js	Host detection (env vars) + per-host hook output shapes.
hooks/frugal-activate.js	SessionStart: inject mode-scaled AGENTS.md.
hooks/frugal-mode-tracker.js	UserPromptSubmit: /frugal quiet|normal|strict|off.
hooks/frugal-pretool.js	PreToolUse(Bash): mode-scaled reminder via providers.js.
hooks/providers.js	Provider table: brief / trap / horror / dig layers.
AGENTS.md	Compact ruleset — canonical body for static rule copies.
scripts/check-rule-copies.js	Drift guard: static copies must equal AGENTS.md.
scripts/check-versions.js	All 8 manifests share one version.

Static rule copies

Edit AGENTS.md, then regenerate:

BODY=$(cat AGENTS.md)
printf -- '---\ndescription: Cloud cost awareness — spend consciously on metered services\nglobs:\nalwaysApply: true\n---\n\n%s\n' "$BODY" > .cursor/rules/frugal.mdc
printf -- '---\ntitle: Frugal\ninclusion: always\n---\n\n%s\n' "$BODY" > .kiro/steering/frugal.md
for f in .windsurf/rules/frugal.md .clinerules/frugal.md .qoder/rules/frugal.md .github/copilot-instructions.md .agents/rules/frugal.md; do printf -- '%s\n' "$BODY" > "$f"; done

npm test fails if they drift.

Development

npm test   # detection tests + rule-copy drift guard + version consistency

Pipe-test the hooks directly:

node hooks/frugal-activate.js
echo '{"session_id":"t1","tool_input":{"command":"npx vercel deploy"}}' | node hooks/frugal-pretool.js

License

MIT