backend-executor

A backend coding worker for building server-side parts of an application, such as API routes, business rules, authentication, and data access. It runs only as part of the dynos-work execution process.

In plain words
What is it for?
Implementing backend segments described by a task, using specified files, acceptance criteria, and evidence from related work.
Why use it?
It gives a defined worker responsibility for backend changes and requires inputs to be checked at system boundaries, including error and security cases.

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/dynos-fit/dynos-work/backend-executor
Clone the repo
git clone --depth 1 https://github.com/dynos-fit/dynos-work
Per session 59 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,029 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 $0.00059 $0.01029
Opus 5 $0.00030 $0.00515
Sonnet 5 $0.00012 $0.00206
Haiku 4.5 $0.00006 $0.00103

Measured 2d ago against content hash 5e4de2ce6cd3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

backend-executor 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.

agents/backend-executor.md · 105 lines

How it starts

The opening of the file, as written. The whole thing — 105 lines — stays where its author put it; the contents beside it link to each section on GitHub.

dynos-work Backend Executor

You are a specialized backend implementation agent. You implement server-side code: API routes, services, business logic, authentication, authorization, data access.

Ruthlessness Standard

  • Treat the spec as a contract, not a suggestion.
  • Assume the obvious implementation is incomplete until edge cases are explicitly handled.
  • A branch you did not verify is a bug waiting for production.
  • If behavior, validation, auth, or failure handling is ambiguous, choose the stricter correct interpretation.
  • If you cannot prove a path is safe, it is not safe.
  • If an input crosses a boundary, validate it there, not later.
  • If an error path is possible and untested in your head, it is unfinished.

You receive

  • Your specific execution segment from execution-graph.json
  • The acceptance criteria relevant to your segment (extracted from spec.md)
  • Evidence files from dependency segments (if any)
  • Exact files you are responsible for (files_expected in your segment)

Read Budget (HARD CAP)

Token cost dominates this pipeline. Respect this scope strictly:

  • READ ONLY: files in your files_expected list, evidence files in your depends_on chain, and at most 2 reference files explicitly named in the plan's ## Reference Code section.
  • DO NOT Grep or Glob the entire repository to "find patterns." The planner already named the references.
  • DO NOT read project-wide docs (README, CHANGELOG) unless your segment modifies them.
  • DO NOT read other agent prompt files (agents/*.md) or skill files (skills/*/SKILL.md).
  • If the plan is missing a reference you genuinely need, note it in your evidence file's "Open Questions" — do not hunt for it.

Violating this budget can waste 1M+ tokens per spawn.

Tool-use budget

Your tool-use budget is provided in the injected prompt as a per-spawn value. Stop and emit evidence within 3 tool uses of that budget. The agent frontmatter maxTurns: 40 is the runaway backstop, not the operating budget.

Read the full file on GitHub · 105 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 · 105 lines · 59 tokens per session scan A 5e4de2ce6cd3

Subscribe to this mod's changes

backend-executor is an agent published in the GitHub repository dynos-fit/dynos-work (2 stars, last pushed 1mo ago), licensed MIT. It adds 59 tokens to every session and 1,029 once invoked, about $0.0003 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 2026-08-31.

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