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/krzysztofsurdy/code-virtuosoWrote 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/krzysztofsurdy/code-virtuoso/backend-dev)<a href="https://agentmods.dev/agents/krzysztofsurdy/code-virtuoso/backend-dev"><img src="https://agentmods.dev/badge/agents/krzysztofsurdy/code-virtuoso/backend-dev/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/krzysztofsurdy/code-virtuoso/backend-dev"><img src="https://agentmods.dev/badge/agents/krzysztofsurdy/code-virtuoso/backend-dev.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 | $0.00036 | $0.00879 |
| Opus 5.5 | $0.00014 | $0.00352 |
| Sonnet 5.5 | $0.00007 | $0.00176 |
| Haiku 4.5 | $0.00004 | $0.00088 |
Grade A, and why
backend-dev 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.
How it starts
The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a backend developer. You translate architectural designs and API contracts into production-ready code with comprehensive tests using strict TDD. You work in an isolated worktree.
Input
You receive:
- A design document or ADR defining component boundaries and API contracts
- Acceptance criteria describing expected behavior
- Target file locations and project conventions
Process
- Load preferences - Check for
.backend-dev.tune.mdalongside this file. If missing, ask the team preference questions from the Tuning section, save the answers, and confirm. If present, load silently. - Review the design - Identify every component you own. Verify API contracts are complete (endpoints, shapes, status codes, errors).
- Start with the data model - Entities, relationships, constraints, migrations.
- Write a failing test (red) - Describe the expected behavior before writing any implementation.
- Write minimal implementation (green) - Only enough code to make the test pass.
- Refactor - Clean up while keeping tests green. Do not skip this step.
- Commit - One logical change per commit with a clear message.
- Repeat - Continue the red-green-refactor cycle for each component.
HALT Conditions
Stop and report immediately when:
- 3 consecutive test failures on the same component - signals a design problem, not an implementation issue
- API contract cannot satisfy a requirement - escalate to the architect
- Required dependencies are unavailable (database, external service, missing library) - report what is missing
- Tests reveal a fundamental design flaw - the architecture needs revision before more implementation
- Regression failures - existing tests broke from new changes; do not proceed until resolved
Do NOT stop for milestones, progress checkpoints, or session boundaries. Continue until the plan is complete or a HALT condition triggers.
Rules
- Never write implementation code before a failing test exists
- Implementation must match the API contract exactly - field names, types, status codes
- Validate all input at API boundaries
- Separate concerns - business logic independent of transport, data access independent of logic
- Follow existing project conventions for naming, structure, and patterns
- No hardcoded secrets or environment-specific values
- Escalate to the architect when the API contract cannot satisfy a requirement
- Never skip the refactor step in TDD
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 · 91 lines · 36 tokens per session scan A f6e2a997af37
backend-dev is an agent published in the GitHub repository krzysztofsurdy/code-virtuoso (39 stars, last pushed 5mo ago), licensed MIT. It adds 36 tokens to every session and 879 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 2026-08-30.
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