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.
npx skills add synthesisengineering/synthesis-skills --skill synthesis-code-auditgit clone --depth 1 https://github.com/synthesisengineering/synthesis-skillsWrote 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.
[](https://agentmods.dev/skills/synthesisengineering/synthesis-skills/synthesis-code-audit)<a href="https://agentmods.dev/skills/synthesisengineering/synthesis-skills/synthesis-code-audit"><img src="https://agentmods.dev/badge/skills/synthesisengineering/synthesis-skills/synthesis-code-audit.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00089 | $0.01926 |
| Opus 5 | $0.00044 | $0.00963 |
| Sonnet 5 | $0.00018 | $0.00385 |
| Haiku 4.5 | $0.00009 | $0.00193 |
Grade A, and why
synthesis-code-audit 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 7d 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.
How it starts
The opening of the file, as written. The whole thing — 191 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Synthesis Code Audit
A code audit is a systematic quality measurement of a diff. It is not a judgment call about whether a change should merge — that is the reviewer's job (see synthesis-pr-review). An audit produces a scored report across 10 orthogonal dimensions, each graded independently. The report tells you where the quality problems are; the reviewer decides what to do about them.
Where This Fits
Three engineering skills evaluate code at different scopes:
| Skill | Scope | When to use |
|---|---|---|
| code-audit (this one) | Quality scan of a diff | After implementation, standalone or as input to preflight/pr-review |
| pr-review | Judgment-based delta review | Every PR, before peer approval or lead integration |
| codebase-review | Full system audit (16 categories, tiered) | Periodic health check or major milestone |
Code-audit produces findings. PR-review produces a verdict that may consume those findings. Codebase-review catches systemic patterns that no single diff reveals.
Principles
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Fresh base branch. Compare against an up-to-date base ref. Stale base branches cause false positives (flagging code already addressed upstream) and false negatives (missing new context on the base that changes interpretation).
-
Read files in full, not just diff hunks. A diff hunk shows what changed. The surrounding file shows whether the change makes sense in context. Always read changed files in their entirety.
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Context isolation. The best audit comes from fresh eyes. If possible, evaluate the diff without prior knowledge of the planning decisions, trade-offs, or rationale that produced it. Confirmation bias is the default mode — you see what you expect to see. An isolated audit overrides that.
-
Grade only what changed. If a serious pre-existing issue is discovered in unchanged code (security vulnerability, data loss risk, race condition), note it as informational but do not let it affect the dimension's grade for this diff.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 7d ago First seen · 191 lines · 89 tokens per session scan A 813fa502014d
synthesis-code-audit is a skill published in the GitHub repository synthesisengineering/synthesis-skills (18 stars, last pushed yesterday), licensed Apache-2.0. It adds 89 tokens to every session and 1,926 once invoked, about $0.0004 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.
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