server-side-authority

server-side-authority is a skill for Claude Code from randommonicle/claude-skills. It costs 147 tokens per session (702 once invoked), scanned A, original, Apache-2.0.

A set of four rules for securing client-facing backends, including server-controlled storage paths, object IDs, and row-level security (RLS), which limits database access by user or row.

In plain words
What is it for?
It helps review or implement backend authorization, storage access, and database update policies.
Why use it?
It addresses risks such as trusting IDs supplied by users or allowing users to change protected account fields, including their own role.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions CLAUDE.md.

Part of the ash plugin — 43 skills, 3 hooks shipped together

Good fit It helps review or implement backend authorization, storage access, and database update policies.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/randommonicle/claude-skills/server-side-authority
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.

Any agent
npx skills add randommonicle/claude-skills --skill server-side-authority
Clone the repo
git clone --depth 1 https://github.com/randommonicle/claude-skills

Made for: Claude Code.

Or install ash, the plugin that ships this one along with the rest of its 43 skills, 3 hooks.

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 server-side-authority

README.md
[![agentmods](https://agentmods.dev/badge/skills/randommonicle/claude-skills/server-side-authority/github.svg)](https://agentmods.dev/skills/randommonicle/claude-skills/server-side-authority)
Your own site
<a href="https://agentmods.dev/skills/randommonicle/claude-skills/server-side-authority"><img src="https://agentmods.dev/badge/skills/randommonicle/claude-skills/server-side-authority/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 server-side-authority

Your own site · 80×15
<a href="https://agentmods.dev/skills/randommonicle/claude-skills/server-side-authority"><img src="https://agentmods.dev/badge/skills/randommonicle/claude-skills/server-side-authority.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 147 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 702 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 $0.00147 $0.00702
Opus 5 $0.00073 $0.00351
Sonnet 5 $0.00029 $0.00140
Haiku 4.5 $0.00015 $0.00070

Measured 10d ago against content hash eba156bed2a8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

server-side-authority 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 10d 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.

server-side-authority/SKILL.md · 53 lines

How it starts

The opening of the file, as written. The whole thing — 53 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Server-side authority

Four rules from an independent security audit's transferable findings, including a role-escalation the audit called its most urgent single change and an IDOR pattern that recurs across repos. Added by committee decision (2-1, dissent recorded in the review record) as one narrow skill rather than four broad ones.

Rule 1 — derive paths and ids server-side from the owned row

Never download, mutate, or serve whatever path or id the client sent, even after checking the caller owns a related record. A photo-analysis route once verified the caller owned the photo row, then downloaded whatever storage_path the request carried — an access-confusion hole. The owned row already knows its own path; read it from there.

Rule 2 — RLS self-update policies scope columns, not just rows

UPDATE ... WHERE auth.uid() = id with no column restriction lets a user set their own role to admin. Restrict the writable columns — a trigger rejecting privileged-column changes, or a column-level REVOKE — not only the row. Row-scoping answers "which records"; it says nothing about "which fields".

Rule 3 — every exposed table: RLS enabled, or grants revoked

A public-schema table is reachable through the API layer regardless of what the code comments assert. "The anon key never touches this table" is a comment, not a control (enforce-invariants-in-build applies). Either enable RLS with real policies or revoke the role grants — and verify from the catalog, not the comment.

Rule 4 — escape all dynamic output in admin surfaces

Escaping only the fields you consider user-supplied leaves the rest as a stored-XSS path into the most privileged session in the system. Names, emails, job titles, and addresses are attacker-writable too. Escape everything dynamic, uniformly, at the render boundary.

What this skill does not do

It does not replace a full security review (the security-review command exists for that), govern client-side validation, or cover the wider audit programme (backups, transfers, seed-data hygiene stay project-side). Four rules, checked at the moments named in the trigger.

Read the full file on GitHub · 53 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. 10d ago First seen · 53 lines · 147 tokens per session scan A eba156bed2a8

Subscribe to this mod's changes

server-side-authority is a skill published in the GitHub repository randommonicle/claude-skills (23 stars, last pushed 3d ago), licensed Apache-2.0. It adds 147 tokens to every session and 702 once invoked, about $0.0007 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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