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 agentmods add skills/decodingai-magazine/building-a-coding-agent-from-scratch-course/review-diffnpx skills add decodingai-magazine/building-a-coding-agent-from-scratch-course --skill review-diffgit clone --depth 1 https://github.com/decodingai-magazine/building-a-coding-agent-from-scratch-courseWrote 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/decodingai-magazine/building-a-coding-agent-from-scratch-course/review-diff)<a href="https://agentmods.dev/skills/decodingai-magazine/building-a-coding-agent-from-scratch-course/review-diff"><img src="https://agentmods.dev/badge/skills/decodingai-magazine/building-a-coding-agent-from-scratch-course/review-diff.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 | $0.00016 | $0.00207 |
| Opus 5 | $0.00008 | $0.00103 |
| Sonnet 5 | $0.00003 | $0.00041 |
| Haiku 4.5 | $0.00002 | $0.00021 |
Grade A, and why
review-diff 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 5d 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.
What it actually says
You review the current working-tree changes for defects and unnecessary complexity. You do not edit the code and you do not commit — you report.
- Read the change with
git diff(andgit diff --cachedfor staged work). Ground every comment in a specificfile:lineyou actually read. - Review against two lenses, in order:
- Correctness — logic errors, unhandled edge cases, broken invariants, regressions in adjacent code paths, missing error handling.
- Over-engineering — speculative abstractions, dead code, indirection with a single caller, and changes larger than the problem requires. Prefer the smallest change that works.
- Separate blocking problems from optional suggestions, and end with a one-line verdict: ready to merge, or the specific blockers that must be fixed first.
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.
- 5d ago First seen · 17 lines · 16 tokens per session scan A 2d0236f3e5ac
review-diff is a skill published in the GitHub repository decodingai-magazine/building-a-coding-agent-from-scratch-course (352 stars, last pushed yesterday), licensed Apache-2.0. It adds 16 tokens to every session and 207 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 2026-08-30.
Other skills, from other repositories
review
Review a change for correctness, security, and missing tests.
hooks
Create and manage lifecycle hooks that vixd fires automatically on agent-loop events (a tool about to run, a prompt submitted, a thread starting, a turn finishing). Use when the user wants to enforce a rule, block or rewrite a tool call, validate prompts, auto-format, notify, or react to what the agent does.
workflow
Author and edit vix workflows — declarative multi-step pipelines (agent/bash/tool/if/fanout/fanin nodes) stored in config/workflow.json or embedded inline in a job/hook. Use when the user asks to create, modify, or understand a workflow, or to fan work out across many items and join the results.
jobs
Create and manage scheduled jobs (cron tasks, reminders, heartbeat checks, polling watchers) that vixd runs automatically. Use when the user asks to schedule, automate, monitor, watch, or be reminded about something.
review-pr
Deeply review a GitHub pull request.
vix-help
Answer questions about vix itself — the TUI (keybindings, tabs, threads, slash commands), configuration (settings.json, deny lists, permissions), agents & tools, models & providers, jobs, hooks, skills, workflows, MCP servers, the brain/code intelligence, headless/CLI usage, and installation. Use whenever the user…