securing-code

A set of enforced secure-coding rules for server-side code, including API routes, login systems, user input, database queries, and package installation. It covers checks such as authentication, request validation, safe queries, and dependency controls.

In plain words
What is it for?
Use it when writing API handlers, processing user input, changing authentication, querying databases, adding dependencies, or auditing sensitive operations.
Why use it?
It reduces common security mistakes by requiring checks and safer defaults before server code handles requests or new packages.

Skill for Claude CodeCodex

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 skills/codeverbojan/claude-code-kickstart/securing-code
Any agent
npx skills add codeverbojan/claude-code-kickstart --skill securing-code
Clone the repo
git clone --depth 1 https://github.com/codeverbojan/claude-code-kickstart

Made for: Claude Code, Codex.

Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 544 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 $0.00544
Opus 5 $0.00019 $0.00272
Sonnet 5 $0.00008 $0.00109
Haiku 4.5 $0.00004 $0.00054

Measured yesterday against content hash 6df09c5fa9d9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

securing-code 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/skills/securing-code/SKILL.md · 94 lines

How it starts

The opening of the file, as written. The whole thing — 94 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Secure Code Patterns

API Route Handler Order

Always follow this sequence in every server-side handler:

1. Auth check
2. CSRF check (mutations only)
3. Input validation (schema-based)
4. Business logic (parameterized queries only)
5. Response

Non-Obvious Rules

  • CSRF tokens on ALL mutations (POST, PUT, DELETE) — not just forms
  • Rate limit auth endpoints specifically (login, reset, signup)
  • sameSite=strict on session cookies, not lax
  • Set X-Content-Type-Options: nosniff — prevents MIME sniffing attacks
  • Audit log sensitive operations (rate changes, user management, role changes)

Supply Chain

Pin versions, block scripts, enforce soak periods. These are enforceable guards, not advice — configure them in the project.

Node.js (.npmrc)

# Block postinstall scripts by default (would have stopped the Axios attack)
ignore-scripts=true

# 7-day soak period — don't install packages published in the last week
minimum-release-age=10080

# Pin exact versions — no ^ or ~
save-exact=true

# Enforce peer deps and run audit on every install
strict-peer-dependencies=true
audit=true

After adding ignore-scripts=true, explicitly allow trusted scripts:

pnpm config set allow-scripts "esbuild,sharp,prisma"

Python (pip)

# Pin with hashes for integrity verification
pip install --require-hashes -r requirements.txt

# Generate pinned requirements with hashes
pip-compile --generate-hashes requirements.in

Go

# Verify module checksums against public transparency log
GONOSUMCHECK= GOFLAGS=-mod=readonly go build ./...

Rust

# Cargo.toml — use exact versions
[dependencies]
serde = "=1.0.210"
# Audit for known vulnerabilities
cargo audit

When adding ANY new dependency

  1. Check: maintainer count, download volume, last publish date
  2. Review: postinstall / build scripts in the package
  3. Verify: no phantom transitive dependencies added
  4. Wait: prefer packages with 7+ days since last publish

Read the full file on GitHub · 94 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 · 94 lines · 39 tokens per session scan A 6df09c5fa9d9

Subscribe to this mod's changes

securing-code is a skill published in the GitHub repository codeverbojan/claude-code-kickstart (2 stars, last pushed 4mo ago), licensed MIT. It adds 39 tokens to every session and 544 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 2026-08-31.

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