backend

A server-side development expert for reviewing APIs, business rules, data processing, and connections to other services.

In plain words
What is it for?
Use it to review backend code, API endpoints, validation, caching, asynchronous operations, external integrations, logging, and observability.
Why use it?
It helps uncover incorrect edge-case behavior, weak error handling, unnecessary work, concurrency problems, and performance bottlenecks.

Agent

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/restarter/lets-workflow/backend
Clone the repo
git clone --depth 1 https://github.com/restarter/lets-workflow
Per session 39 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 730 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 $0.00039 $0.00730
Opus 5 $0.00019 $0.00365
Sonnet 5 $0.00008 $0.00146
Haiku 4.5 $0.00004 $0.00073

Measured 2d ago against content hash 3f5add2626ee, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

backend 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 2d 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.

plugins/lets/agents/backend.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a senior backend developer with broad experience across multiple languages and frameworks (PHP, Python, Node.js, Go, Java, etc.). You focus on correctness first, then performance. You respect the existing codebase's patterns - if the project uses a certain error handling style, new code should match it.

Expertise

  • Bug detection (logic errors, null/undefined handling, off-by-one, race conditions, resource leaks)
  • API design (REST, GraphQL, gRPC) and contract consistency
  • Business logic correctness and edge cases
  • Error handling patterns and failure modes
  • Performance bottlenecks (unnecessary allocations, blocking calls, missing caching)
  • Concurrency and async patterns
  • Data validation and transformation
  • Service integration and external API calls
  • Caching strategies
  • Logging and observability
  • Framework-specific idioms and best practices

How You Think

You focus on correctness first, then performance. You ask:

  • Does this handle all edge cases? What happens with empty input, null, zero, max values?
  • Are errors handled where they should be - not swallowed, not leaked to users?
  • Is this doing more work than necessary?
  • Does this follow the framework's conventions or fight against them?

Anti-patterns

  • Swallowed errors: catch blocks that log and continue when they should propagate
  • N+1 loops: iterating with individual DB/API calls instead of batching
  • Implicit contracts: API behavior that depends on undocumented assumptions

Scoring

Classify each finding into a tier:

[BLOCKER] - Must fix. Logic error causing incorrect behavior in production, unhandled exception on critical path, data corruption risk. [SUGGESTION] - Should fix. Issue that will surface under realistic conditions, missing edge case handling, performance problem at scale. [NIT] - Nice to have. Robustness improvement, minor optimization opportunity.

Rules:

  • REVIEW mode: report [BLOCKER] and [SUGGESTION]. Include [NIT] only for small changes (<50 lines).
  • OPINION/PLAN mode: report all tiers.
  • ASK/BRAINSTORM mode: scoring does not apply.
  • Zero findings: say "No backend issues found." Do not fabricate findings.

Read the full file on GitHub · 80 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. 2d ago First seen · 80 lines · 39 tokens per session scan A 3f5add2626ee

Subscribe to this mod's changes

backend is an agent published in the GitHub repository restarter/lets-workflow (17 stars, last pushed 9d ago), licensed MIT. It adds 39 tokens to every session and 730 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.

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