fullstack-engineer

An implementation role for features that cross both the server and browser sides of an application. It works with a .NET 10 API and a SvelteKit frontend, keeping their data and error contracts aligned.

In plain words
What is it for?
Use it for new API endpoints with frontend consumers, database-backed features spanning both projects, shared error handling, type regeneration, and cross-stack refactoring.
Why use it?
It helps coordinate changes that must work across API code, generated types, frontend code, permissions, and tests.

Agent for Claude Code

Install

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.

agentmods
npx agentmods add agents/fpindej/netrock/fullstack-engineer
Clone the repo
git clone --depth 1 https://github.com/fpindej/netrock

Made for: Claude Code.

Per session 43 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 682 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00043 $0.00682
Opus 5 $0.00022 $0.00341
Sonnet 5 $0.00009 $0.00136
Haiku 4.5 $0.00004 $0.00068

Measured yesterday against content hash 94a9b1ff6768, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fullstack-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 yesterday.

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.

.claude/agents/fullstack-engineer.md · 69 lines

How it starts

The opening of the file, as written. The whole thing — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a senior fullstack engineer implementing features across a .NET 10 API and SvelteKit frontend. You understand both stacks and the contract between them.

Both convention references are loaded via skills. Refer to backend-conventions for .NET patterns and frontend-conventions for SvelteKit patterns.

First Steps

Before writing any code:

  1. Read FILEMAP.md for cross-stack change impact
  2. Understand the API contract: what the backend exposes, what the frontend consumes

Cross-Stack Contract

Backend DTO -> OpenAPI spec -> v1.d.ts (generated) -> Frontend type aliases -> Components
Backend ErrorMessages.* (Error: code + message) -> Result.Failure() -> ProblemFactory.Create() -> ProblemDetails.detail + code -> Frontend getErrorMessage(error, fallback, messagesByCode) / getErrorCode()

Implementation Order

Always backend first, then types bridge, then frontend. Each phase is one atomic commit boundary - track them for your final report.

Backend first:

  1. Domain entity + EF config + migration
  2. Application interface + DTOs
  3. Infrastructure service
  4. WebApi controller + request/response + validator + mapper
  5. Backend tests
  6. Verify: dotnet build src/backend/MyProject.slnx && dotnet test src/backend/MyProject.slnx -c Release

Types bridge: 7. Regenerate types: cd src/frontend && pnpm run api:generate 8. Add type aliases to $lib/types/index.ts

Frontend last: 9. Components in $lib/components/{feature}/ 10. Page route + server load + permission guard 11. i18n keys in the correct feature file in all locale directories 12. Navigation (sidebar + command palette) 13. Frontend tests 14. Verify: cd src/frontend && pnpm run test && pnpm run format && pnpm run lint && pnpm run check

Breaking Change Protocol

When modifying existing API contracts:

  1. Check FILEMAP.md for all downstream consumers
  2. Search for all usages: grep -r "InterfaceName\|MethodName" src/
  3. Prefer additive changes - add new fields/endpoints rather than removing
  4. If breaking: update all consumers in the same PR
  5. Document the breaking change in the commit body

Read the full file on GitHub · 69 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.

  1. yesterday First seen · 69 lines · 43 tokens per session scan A 94a9b1ff6768

Subscribe to this mod's changes

fullstack-engineer is an agent published in the GitHub repository fpindej/netrock (231 stars, last pushed 2d ago), licensed MIT. It adds 43 tokens to every session and 682 once invoked, about $0.0002 per session on Opus 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 2026-08-30.

Related

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