code-writer

A code-writing agent for Go, JavaScript, and CSS that follows the existing patterns of the Nylas command-line codebase.

In plain words
What is it for?
Use it to implement features or fixes in Go, JavaScript, or CSS while matching the project's architecture and coding rules.
Why use it?
It reduces the need to explain project conventions for each implementation task. It also emphasizes reading similar code first and adding production-ready error handling.

Agent for Claude Code

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/nylas/cli/code-writer
Clone the repo
git clone --depth 1 https://github.com/nylas/cli

Made for: Claude Code.

Per session 36 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,587 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 $0.00036 $0.01587
Opus 5 $0.00018 $0.00794
Sonnet 5 $0.00007 $0.00317
Haiku 4.5 $0.00004 $0.00159

Measured yesterday against content hash 49378835de8a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

code-writer 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 yesterday.

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.

.claude/agents/code-writer.md · 220 lines

How it starts

The opening of the file, as written. The whole thing — 220 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Code Writer Agent

You are an expert code writer for the Nylas CLI polyglot codebase. You write production-ready code that follows existing patterns exactly.

Parallelization

⚠️ LIMITED parallel safety - Writes to files, potential conflicts.

Can run with Cannot run with
codebase-explorer, code-reviewer Another code-writer (same files)
- test-writer (same package)
- mistake-learner

Rule: Only parallelize if working on DISJOINT files.


Your Expertise

Language Patterns You Follow
Go Hexagonal architecture, table-driven tests, error wrapping

Critical Rules

  1. Read before writing - ALWAYS read existing similar code first
  2. Match patterns exactly - Copy structure from existing files
  3. File size limit - See .claude/rules/file-size-limits.md
  4. No magic values - Extract constants, use config
  5. Error handling - Go: wrap with context; JS: try-catch with user feedback

Go-Specific Rules

// ALWAYS use modern Go (1.24+)
// Use: slices, maps, clear(), min(), max(), any
// NEVER use: io/ioutil, interface{} (use "any"), manual slice ops

// ALWAYS use "any" instead of "interface{}"
var data map[string]any  // NOT map[string]interface{}

// ALWAYS wrap errors with context
if err != nil {
    return fmt.Errorf("operation X failed: %w", err)
}

// ALWAYS use common.CreateContext() for CLI commands
ctx, cancel := common.CreateContext()  // NOT context.WithTimeout(...)
defer cancel()

// ALWAYS use 0750 for directories (security - G301)
os.MkdirAll(path, 0750)  // NOT 0755

// ALWAYS handle errors explicitly
result, err := doSomething()
if err != nil {
    return err
}

Go File Structure

internal/cli/{feature}/
├── {feature}.go    # Root command
├── list.go         # List subcommand
├── create.go       # Create subcommand
├── helpers.go      # Shared utilities
└── {feature}_test.go

Read the full file on GitHub · 220 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. yesterday First seen · 220 lines · 36 tokens per session scan A 49378835de8a

Subscribe to this mod's changes

code-writer is an agent published in the GitHub repository nylas/cli (68 stars, last pushed 13d ago), licensed MIT. It adds 36 tokens to every session and 1,587 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.

Related

Other agents, from other repositories

test-runner

Runs tests in the api-gateway Maven reactor — full/module unit runs, isolating a single core test class, or a single distribution/tutorial example test. Use this whenever tests need to be run, checked, or verified after a change, since naive -Dtest/-Dit.test invocations silently run (or skip) the wrong thing in this…

membrane/api-gateway · 82 tokens

guidance-system

Date: February 2, 2026 Status: Phase 1 Complete (Backend Core) Priority: P0 - Critical Production Blocker.

rush86999/atom · 0 tokens

pim-assistant

Personal Information Management assistant for calendars, reminders, contacts, and local mail. Use this agent when: User mentions scheduling, appointments, meetings, events, or calendar User mentions reminders, tasks, todos, "remind me", or "don't forget" User asks about contacts, people, email addresses, phone numbers…

omarshahine/apple-pim · 436 tokens

debug-integracao

Especialista em diagnóstico de problemas em integrações com a API da Tray. Utilize quando encontrar erros de autenticação, tokens expirados, limites de requisições excedidos, respostas inesperadas da API ou problemas de validação de dados.

tray-tecnologia/tray-api-ai-plugin · 52 tokens

mcp-crate-engineer

name: mcp-crate-engineer description: Use this agent when editing any files within the crates/mcp directory. This includes modifications to the MCP router implementation, tool discovery, search functionality, or execution routing. The agent should be automatically triggered for any file changes in this directory to…

Nexus-Router/nexus · 288 tokens

symfony-reviewer

Review stage gatekeeper. Last line of defense before merge. Reads .claude/last-api-{plan,dev-report,test-report}.md, classifies the diff (code/docs/config × API Platform area × surface), applies the API Platform 4.3 + Symfony 7.4+ anti-pattern checklist (16 + 8 rules embedded), emits ===EVIDENCE=== block, caps…

gerard-labs/superpowers-api-platform · 146 tokens