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 brain-bootstrap/claude-code-brain-bootstrap --skill diffgit clone --depth 1 https://github.com/brain-bootstrap/claude-code-brain-bootstrapWrote 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/brain-bootstrap/claude-code-brain-bootstrap/diff)<a href="https://agentmods.dev/skills/brain-bootstrap/claude-code-brain-bootstrap/diff"><img src="https://agentmods.dev/badge/skills/brain-bootstrap/claude-code-brain-bootstrap/diff/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.
<a href="https://agentmods.dev/skills/brain-bootstrap/claude-code-brain-bootstrap/diff"><img src="https://agentmods.dev/badge/skills/brain-bootstrap/claude-code-brain-bootstrap/diff.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00037 | $0.00472 |
| Opus 5.5 | $0.00015 | $0.00189 |
| Sonnet 5.5 | $0.00007 | $0.00094 |
| Haiku 4.5 | $0.00004 | $0.00047 |
Grade A, and why
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 1mo 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
Diff Skill
Analyze the current branch's diff against its merge-base with main.
Usage
/diff # Stat overview (default)
/diff full # Full patch output
/diff files # List changed files only
/diff commits # List commits on this branch
/diff overlap feature/other-branch # Check for file overlap with another branch
⚠️ Critical: Always Use Merge-Base
# CORRECT — only shows YOUR changes
git diff $(git merge-base main HEAD)..HEAD
# WRONG — includes main's forward progress as noise
git diff main
Instructions
Determine action from $ARGUMENTS:
| Argument | Action |
|---|---|
stat or (empty) |
git --no-pager diff $(git merge-base main HEAD)..HEAD --stat |
full |
git --no-pager diff $(git merge-base main HEAD)..HEAD | head -200 |
files |
git --no-pager diff $(git merge-base main HEAD)..HEAD --name-only |
commits |
git --no-pager log $(git merge-base main HEAD)..HEAD --oneline |
overlap <branch> |
Cross-branch file overlap check (see below) |
Cross-Branch Overlap Check:
BRANCH_A_FILES=$(git --no-pager diff $(git merge-base main HEAD)..HEAD --name-only)
BRANCH_B_FILES=$(git --no-pager diff $(git merge-base main <other-branch>)..<other-branch> --name-only)
# Show files that appear in both
comm -12 <(echo "$BRANCH_A_FILES" | sort) <(echo "$BRANCH_B_FILES" | sort)
Report Format
For stat/default mode, report:
- Files changed (count)
- Lines added / removed
- Any files that look unexpectedly large (>200 lines changed)
- Any test files missing for changed source files
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.
- 1mo ago First seen · 57 lines · 37 tokens per session scan A 34a0b08d632a
diff is a skill published in the GitHub repository brain-bootstrap/claude-code-brain-bootstrap (11 stars, last pushed 5mo ago), licensed MIT. It adds 37 tokens to every session and 472 once invoked, about $0.0001 per session on Opus 5.5. 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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