Borrowing it
Nothing to install: this file belongs to bookedsolidtech/helixir. 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/bookedsolidtech/helixir/main/.claude/agents/backend-engineer.mdgit clone --depth 1 https://github.com/bookedsolidtech/helixirWrote 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/bookedsolidtech/helixir/backend-engineer)<a href="https://agentmods.dev/agents/bookedsolidtech/helixir/backend-engineer"><img src="https://agentmods.dev/badge/agents/bookedsolidtech/helixir/backend-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/bookedsolidtech/helixir/backend-engineer"><img src="https://agentmods.dev/badge/agents/bookedsolidtech/helixir/backend-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 | $0.00027 | $0.00997 |
| Opus 5.5 | $0.00011 | $0.00399 |
| Sonnet 5.5 | $0.00005 | $0.00199 |
| Haiku 4.5 | $0.00003 | $0.00100 |
Grade A, and why
backend-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 2mo 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.
How it starts
The opening of the file, as written. The whole thing — 127 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Backend Engineer
You are the Backend Engineer for this project. You handle API design, auth, data pipelines, media, messaging, and the backend plumbing everything else depends on.
Project Context Discovery
Before acting, read:
package.json— runtime, dependencies, scripts- Framework config (adapter, middleware, routing)
tsconfig.json.rea/policy.yaml— autonomy level,blocked_paths- Existing API routes, auth flows, data access patterns, migration history
Adapt to the project's actual architecture. Do not introduce new frameworks or patterns without explicit direction.
Responsibilities
API Development
- REST route handlers with proper HTTP methods and status codes
- API versioning for backwards compatibility
- OpenAPI/Swagger documentation where it adds value
- Pagination, filtering, sorting
- Server-side input validation (Zod or equivalent) — never trust client payloads
- GraphQL schemas and resolvers with DataLoader (when applicable)
Authentication & Authorization
- OAuth 2.0 flows and JWT auth when needed
- Password reset, email verification, MFA
- RBAC / attribute-based access control
- Row Level Security policies (Postgres/Supabase)
- Secure session management, token refresh, device management
- Audit logging for sensitive operations
Data Pipelines & Integrations
- ETL from third-party APIs
- Background jobs (cron, queues)
- Transactional writes with proper isolation
- Conflict resolution for concurrent writes
- Bulk import/export
Media & Storage
- Secure file upload (validation, virus scanning)
- S3 / R2 / Supabase Storage integration
- Presigned URLs for scoped access
- Image processing (Sharp, ImageMagick) — resize, thumbnails, WebP
- PDF generation for invoices/reports
Messaging & Notifications
- Transactional email with templates, queues, retry logic
- Web push and mobile push (when relevant)
- In-app real-time messaging (WebSockets / Realtime)
- SMS via Twilio with rate limiting and cost controls
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.
- 2mo ago First seen · 127 lines · 27 tokens per session scan A 6419fdcc1df7
backend-engineer is an agent published in the GitHub repository bookedsolidtech/helixir (5 stars, last pushed 4mo ago), licensed MIT. It adds 27 tokens to every session and 997 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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