bob-diff-review

bob-diff-review is a skill for Claude Code, Codex from vmihalis/hacker-bob. It costs 100 tokens per session (3,989 once invoked), scanned A, original, Apache-2.0.

An automated pipeline for reviewing a code change. It examines changed sections, identifies affected parts of the codebase, and writes review findings to a JSON file.

In plain words
What is it for?
Use it when a runner needs headless, multi-step review of a unified diff with separate evaluators for impacted code surfaces.
Why use it?
It helps organize review around the parts of the system affected by a diff, while keeping credentials out of logs and output files.

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/vmihalis/hacker-bob/bob-diff-review
Any agent
npx skills add vmihalis/hacker-bob --skill bob-diff-review
Clone the repo
git clone --depth 1 https://github.com/vmihalis/hacker-bob

Made for: Claude Code, Codex.

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 bob-diff-review

README.md
[![agentmods](https://agentmods.dev/badge/skills/vmihalis/hacker-bob/bob-diff-review.svg)](https://agentmods.dev/skills/vmihalis/hacker-bob/bob-diff-review)
Your own site
<a href="https://agentmods.dev/skills/vmihalis/hacker-bob/bob-diff-review"><img src="https://agentmods.dev/badge/skills/vmihalis/hacker-bob/bob-diff-review.svg" alt="Measured on agentmods" height="20"></a>
Per session 100 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,989 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 $0.00100 $0.03989
Opus 5 $0.00050 $0.01995
Sonnet 5 $0.00020 $0.00798
Haiku 4.5 $0.00010 $0.00399

Measured 5d ago against content hash 0707513fb44f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

bob-diff-review 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.

.claude/skills/bob-diff-review/SKILL.md · 316 lines

How it starts

The opening of the file, as written. The whole thing — 316 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are the bob-diff-review pipeline orchestrator. You run headlessly, invoked by bob-runner.ts. Parse $ARGUMENTS, execute the S2-S6 pipeline steps in order, and write diff-review-findings.json to --output-dir.

Environment Requirements

The runner environment MUST supply:

  • Exactly one Anthropic credential injected by the runner — see Authentication. The runner spawns this skill inside an already-authenticated claude subprocess, so the skill inherits whichever credential the runner chose (CLAUDE_CODE_OAUTH_TOKEN preferred, or ANTHROPIC_API_KEY fallback). The skill does not select auth itself.
  • No GitHub or package-install tokens. bob-runner.ts allowlists the child environment and strips workflow inputs, GitHub tokens, BOB_INSTALL_TOKEN, proxy credentials, and unrelated operator secrets before invoking Claude.

No credential value must appear in any log or output file. Do not inspect, print, or shell-check credential environment variables from this skill; the runner is responsible for authenticating the subprocess before invocation.

Authentication

bob-diff-review supports dual auth for the headless claude subprocess: OAuth-token auth (preferred) and API-key auth (fallback). The runner injects exactly one credential into the child environment with deterministic precedence — OAuth wins and the API key is never injected alongside it.

Credential Env var the CLI reads Action input Workflow secret
OAuth token (preferred, from claude setup-token) CLAUDE_CODE_OAUTH_TOKEN anthropic-oauth-token ANTHROPIC_OAUTH_TOKEN
API key (pay-per-use fallback) ANTHROPIC_API_KEY anthropic-api-key ANTHROPIC_API_KEY

Runner precedence (single injection, OAuth wins):

  • If an OAuth token is present, the runner sets CLAUDE_CODE_OAUTH_TOKEN and does not set ANTHROPIC_API_KEY at all. This prevents the API key from silently shadowing OAuth and exhausting credits.
  • Otherwise (only the API key is present), the runner sets ANTHROPIC_API_KEY and does not set the OAuth var.
  • Exactly one credential is injected, never both.

Read the full file on GitHub · 316 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. 5d ago First seen · 316 lines · 100 tokens per session scan A 0707513fb44f

Subscribe to this mod's changes

bob-diff-review is a skill published in the GitHub repository vmihalis/hacker-bob (97 stars, last pushed 7d ago), licensed Apache-2.0. It adds 100 tokens to every session and 3,989 once invoked, about $0.0005 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 skills, from other repositories