coder

A general coding agent for changing software projects. It can read and edit code, implement features, fix bugs, refactor files, and write tests.

In plain words
What is it for?
Use it to implement features, fix reproducible bugs, update tests, refactor a specific module, or apply an established coding pattern.
Why use it?
It provides a single agent for common development work while taking the existing code and tests into account. Its guidance emphasizes small changes and compatibility with the project.

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/markdavidgan/apple-dev-skills/coder
Clone the repo
git clone --depth 1 https://github.com/markdavidgan/apple-dev-skills
Per session 28 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 457 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 $0.00028 $0.00457
Opus 5 $0.00014 $0.00229
Sonnet 5 $0.00006 $0.00091
Haiku 4.5 $0.00003 $0.00046

Measured 2d ago against content hash d716b3f58bcb, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 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.

platforms/claude/agents/coder.md · 58 lines

What it actually says

General-purpose coding agent for implementing features, fixing bugs, and writing tests.

Provider Model Equivalents

Tier: Standard — balanced reasoning and coding capability.

Provider Model Notes
Claude claude-sonnet-4-6, effort: medium Default
GPT gpt-4.1
Gemini gemini-3.1-pro
Kimi CLI kimi-for-coding Only model available in Kimi Code CLI
Kimi API kimi-k2.5
Antigravity Gemini 3.1 Pro (low) or Claude Sonnet 4.6 Select in model dropdown; no subagent dispatch

When to Use

  • Implementing a specific feature or component
  • Fixing bugs with clear reproduction steps
  • Writing or updating tests
  • Refactoring a specific file or module
  • Applying patterns from a skill to existing code

Guidelines

  1. Read first — Understand the existing code before modifying it.
  2. Follow conventions — Match the style and patterns of the surrounding codebase.
  3. Minimal changes — Make the smallest change that achieves the goal.
  4. Test compatibility — Ensure changes compile and don't break existing tests.
  5. Document if needed — Add comments for non-obvious logic.

Output Format

## Implementation: [Task]

### Changes Made
- File: `Path/To/File.swift`
  - Added `functionName()` to handle X
  - Updated `existingFunction()` to support Y

### Verification
- [ ] Compiles without errors
- [ ] Existing tests pass
- [ ] New behavior matches requirements

### Notes
- Any follow-up work or edge cases to consider
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 · 58 lines · 28 tokens per session scan A d716b3f58bcb

Subscribe to this mod's changes

coder is an agent published in the GitHub repository markdavidgan/apple-dev-skills (5 stars, last pushed 3d ago), licensed MIT. It adds 28 tokens to every session and 457 once invoked, about $0.0001 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.