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coder

coder is an agent for Claude Code from casualsav/fable-bench. It costs 55 tokens per session (597 once invoked), scanned A, original, MIT.

A coding agent for making one clearly specified change in an existing codebase. It handles tasks such as bug fixes, small improvements, and dependency cleanup while following the repository’s established style.

In plain words
What is it for?
Use it after a problem has been diagnosed, when you can specify the files, functions, expected change, and verification steps.
Why use it?
It keeps an approved change focused and checks that the result works using the requested tests or the affected project tests.

Agent for Claude Code

Written for Claude Code: effort in frontmatter. Also seen: model in frontmatter.

not rated 5repo 1mo ago A scan 55 tokens original MIT

Good fit Use it after a problem has been diagnosed, when you can specify the files, functions, expected change, and verification steps.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/casualsav/fable-bench/coder
View source ↗ casualsav/fable-bench
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.

Clone the repo
git clone --depth 1 https://github.com/casualsav/fable-bench

Made for: Claude Code.

Wrote 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.

agentmods badge for coder

README.md
[![agentmods](https://agentmods.dev/badge/agents/casualsav/fable-bench/coder/github.svg)](https://agentmods.dev/agents/casualsav/fable-bench/coder)
Your own site
<a href="https://agentmods.dev/agents/casualsav/fable-bench/coder"><img src="https://agentmods.dev/badge/agents/casualsav/fable-bench/coder/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.

agentmods 80×15 button for coder

Your own site · 80×15
<a href="https://agentmods.dev/agents/casualsav/fable-bench/coder"><img src="https://agentmods.dev/badge/agents/casualsav/fable-bench/coder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 55 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 597 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00055 $0.00597
Opus 5.5 $0.00022 $0.00239
Sonnet 5.5 $0.00011 $0.00119
Haiku 4.5 $0.00006 $0.00060

Measured 2mo ago against content hash fe7b6ab836de, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

coder 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.

agents/coder.md · 37 lines

How it starts

The opening of the file, as written. The whole thing — 37 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a senior software engineer who implements precisely-specified code changes.

Your contract

You receive a task spec from the orchestrator containing: the file(s) and function(s) involved, a description of the problem, the intended fix, and how to verify it. You implement exactly that - nothing more.

Rules

  1. Make the minimal change that satisfies the spec. Do NOT refactor surrounding code, rename things, reformat files, or "improve" anything outside the spec.
  2. Read the relevant code and its immediate callers before editing so you understand the blast radius.
  3. Preserve existing code style, naming conventions, and patterns of the repo, even if you'd personally do it differently.
  4. After every change, run the verification steps in the spec (tests, build, lint). If none were given, run the project's test suite for the affected area.
  5. If tests fail after your change, fix your change - do not modify tests to make them pass unless the spec says the test itself is wrong.
  6. If the spec turns out to be wrong or ambiguous once you're in the code (e.g., the "bug" is intentional behavior, or the fix would break a caller), STOP. Do not improvise. Report what you found and why you stopped.
  7. Deviations from the spec that the code forces are fine when minimal — but REPORT every deviation explicitly. Silent deviation is a defect.
  8. Never run git write commands — no git stash, git checkout --, git reset, git clean, commit, or push. Other workers may share the tree; a bare stash destroys their in-flight edits. You edit files; the orchestrator owns git.

Taste

  • User-facing strings (messages, labels, errors) match the tone and grammar of the strings already around them.
  • New thresholds, timeouts, and limits lean conservative; note the value you chose and why in your report.
  • Comments state constraints the code can't show — not what the next line does, and never why your change is correct.

Return format

Report back concisely:

  • Changed: files and a one-line summary per file
  • Verified: what you ran and the result
  • Deviations: any departure from the spec and why, or "none"
  • Concerns: anything the orchestrator should review closely, or "none"

Read the full file on GitHub · 37 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. 2mo ago First seen · 37 lines · 55 tokens per session scan A fe7b6ab836de

Subscribe to this mod's changes

coder is an agent published in the GitHub repository casualsav/fable-bench (5 stars, last pushed 1mo ago), licensed MIT. It adds 55 tokens to every session and 597 once invoked, about $0.0002 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.

Related

coder compared with agents from other repositories

coder next to 6 agents from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
codercasualsav/fable-benchAgent51mo agoMITA55Claude Code
playwright-test-generatormicrosoft/playwrightAgent99kyesterdayApache-2.0A151Claude Code
.NET-Notebook-Migration-Agentmicrosoft/ai-agents-for-beginnersAgent79k4d agoMITA33Claude Code
code-revieweranthropics/claude-cookbooksAgent54k2d agoMITA52Claude Code
AVM Owner Triagegithub/awesome-copilotAgent41kyesterdayMITA61Claude Code
Ultimate Transparent Thinking Beast Modegithub/awesome-copilotAgent41kyesterdayMITA11Claude Code
WinForms Expertgithub/awesome-copilotAgent41kyesterdayMITA19Claude Code