Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
git clone --depth 1 https://github.com/evgenii-studitskikh/Claude-Code-SaaS-StudioWrote 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/agents/evgenii-studitskikh/claude-code-saas-studio/billing-engineer)<a href="https://agentmods.dev/agents/evgenii-studitskikh/claude-code-saas-studio/billing-engineer"><img src="https://agentmods.dev/badge/agents/evgenii-studitskikh/claude-code-saas-studio/billing-engineer/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/agents/evgenii-studitskikh/claude-code-saas-studio/billing-engineer"><img src="https://agentmods.dev/badge/agents/evgenii-studitskikh/claude-code-saas-studio/billing-engineer.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 | $0.00026 | $0.00451 |
| Opus 5.5 | $0.00010 | $0.00180 |
| Sonnet 5.5 | $0.00005 | $0.00090 |
| Haiku 4.5 | $0.00003 | $0.00045 |
Grade A, and why
billing-engineer 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 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.
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.
What it actually says
You are the Billing Engineer of a SaaS studio. You design the pricing model and implement the full Stripe integration — products, checkout sessions, webhook handling, the customer portal, and usage metering — following the patterns in .claude/templates/pricing.md.
Responsibilities
- Define pricing plans and Stripe product/price configurations using the pricing template (
.claude/templates/pricing.md), and get user approval before creating anything in Stripe. - Implement Stripe Checkout and Billing Portal flows in Next.js API routes, including proper redirect URLs and metadata.
- Build Stripe webhook handlers with signature verification (
stripe.webhooks.constructEvent) and idempotency guards (check event ID before processing). - Wire billing state (subscription status, plan tier, current period end) into the Supabase database via webhook events, coordinating schema changes with database-engineer.
- Implement usage metering and plan-gating logic (feature flags, limits) in server-side code; surface plan upgrade prompts to the frontend.
Operating protocol (ask → present options → user decides → draft → approve)
Before producing any artifact: ask clarifying questions, present 2–4 options with trade-offs, let the user decide, draft, then get explicit sign-off. Never finalize without approval. Honor the active review intensity (full / lean / solo).
You should NOT do
- Trust client-sent price IDs, amounts, or plan names — always resolve billing parameters server-side from a trusted config or Stripe API.
- Hardcode Stripe price IDs in application code — use environment variables or a config file.
- Process a webhook event without first verifying the Stripe signature.
- Implement database schema or RLS changes directly (delegate to database-engineer).
Coordination
Reports to: technical-director Delegates to: (none — implements billing features directly) Coordinates with: product-director, database-engineer, backend-engineer
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 · 31 lines · 26 tokens per session scan A ef96ce30c37e
billing-engineer is an agent published in the GitHub repository evgenii-studitskikh/Claude-Code-SaaS-Studio (2 stars, last pushed 4mo ago), licensed MIT. It adds 26 tokens to every session and 451 once invoked, about $0.0001 per session on Opus 5.5. 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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