Second Brain Lint
NicholasSpisak/second-brain
Health-check the wiki for contradictions, orphan pages, stale claims, and missing cross-references.
Audit a second-brain vault for structural problems and repair them: broken wikilinks, orphan pages, empty stubs, frontmatter that violates the schema, near-duplicate pages, and stale index entries.
Install Second Brain Lint
$ npx skills add undefined-ui/second-brain-os --skill second-brain-lint -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-lint --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/undefined-ui/second-brain-os.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/second-brain-lint .claude/skills/second-brain-lint && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "second-brain-lint" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-lint into .claude/skills/second-brain-lint/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-lint", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-lintType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add undefined-ui/second-brain-os --skill second-brain-lint -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-lint --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/undefined-ui/second-brain-os.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/second-brain-lint .agents/skills/second-brain-lint && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "second-brain-lint" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-lint into .agents/skills/second-brain-lint/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-lint", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add undefined-ui/second-brain-os --skill second-brain-lint -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-lint --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/undefined-ui/second-brain-os.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/second-brain-lint .cursor/skills/second-brain-lint && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "second-brain-lint" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-lint into .cursor/skills/second-brain-lint/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-lint", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/undefined-ui/second-brain-os.git --path skills/second-brain-lint--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add undefined-ui/second-brain-os --skill second-brain-lint -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-lint --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/undefined-ui/second-brain-os.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/second-brain-lint .gemini/skills/second-brain-lint && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "second-brain-lint" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-lint into .gemini/skills/second-brain-lint/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-lint", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install undefined-ui/second-brain-os second-brain-lintInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add undefined-ui/second-brain-os --skill second-brain-lint -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/undefined-ui/second-brain-os.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/second-brain-lint .github/skills/second-brain-lint && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "second-brain-lint" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-lint into .github/skills/second-brain-lint/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-lint", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add undefined-ui/second-brain-os --skill second-brain-lint -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-lint --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/undefined-ui/second-brain-os.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/second-brain-lint .opencode/skills/second-brain-lint && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "second-brain-lint" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-lint into .opencode/skills/second-brain-lint/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-lint", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
second-brain-lint- GitHub stars
- 999
- Token cost
- ~678 tokens
- SKILL.md length
- 282 words
- Files
- 1
- Skills in repo
- 23
- Repo updated
- First seen
- Licence
- MIT
At a glance
Audit a second-brain vault for structural problems and repair them: broken wikilinks, orphan pages, empty stubs, frontmatter that violates the schema, near-duplicate pages, and stale index entries.
- Works in 8 steps: Inventory. Count pages by type. Build… → Broken links. Links pointing at pages… → Orphans. Pages with no inbound links.… → …
- The user asks to lint
- SKILL.md covers Core rule, Workflow, Output format and Calibration
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
Second Brain Lint is an agent skill from undefined-ui/second-brain-os. Audit a second-brain vault for structural problems and repair them: broken wikilinks, orphan pages, empty stubs, frontmatter that violates the schema, near-duplicate pages, and stale index entries. Use this skill whenever the user asks to lint, clean, audit or check the health of their vault, says pages feel messy or links are broken, after a large bulk import, or when a scheduled maintenance run fires. Do NOT use for ingesting new sources, for answering questions from the vault, or for rewriting page content…
Its SKILL.md is about 680 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
It sits in Knowledge Management, covering Second brain and Linting and formatting. The repository describes itself as: An AI second brain that maintains itself. Full guide, starter vault, agent skills and scripts for a self-organizing knowledge base in Claude Code and Obsidian. The licence is MIT.
When your agent uses it
- The user asks to lint
- Check the health of their vault
- Says pages feel messy
- Links are broken
Example prompts
- “/second-brain-lint”
Workflow steps
8 steps, taken from the first numbered list in SKILL.md.
- Inventory. Count pages by type. Build the link graph by parsing every
- Broken links. Links pointing at pages that do not exist. Distinguish
- Orphans. Pages with no inbound links. For each, either find where it
- Stubs. Pages under roughly 40 words with no links. Usually a failed
- Schema. Missing or malformed frontmatter, wrong type, missing dates,
- Near-duplicates. Pages with very similar titles or aliases. Propose
- Index drift. Pages missing from index.md, index entries pointing
- Repair, then append the run to log.md.
What it can do on your machine
Read from SKILL.md and the folder at commit d6861cc. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Second Brain Lint loads about 678 tokens when it runs. Until then it costs about 144 tokens; SKILL.md has 282 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from undefined-ui/second-brain-os at commit d6861cc, republished under its MIT licence (© undefined-ui). 282 words, ~678 tokens.
Download SKILL.mdSave it as
.claude/skills/second-brain-lint/SKILL.md (or your agent's skills folder).- name
- second-brain-lint
- description
- Audit a second-brain vault for structural problems and repair them: broken wikilinks, orphan pages, empty stubs, frontmatter that violates the schema, near-duplicate pages, and stale index entries. Use this skill whenever the user asks to lint, clean, audit or check the health of their vault, says pages feel messy or links are broken, after a large bulk import, or when a scheduled maintenance run fires. Do NOT use for ingesting new sources, for answering questions from the vault, or for rewriting page content that is structurally fine but reads badly.
Lint the vault
Structural rot is silent. Nothing errors, nothing crashes, the vault just slowly stops answering questions well because a third of its pages are unreachable. Linting is the only thing that catches it before the owner does.
Core rule
Report before repairing. Fix the mechanical problems automatically, but never delete or merge a page without listing it first and getting a yes, because the owner may have written it by hand.
Workflow
- Inventory. Count pages by type. Build the link graph by parsing every
[[wikilink]]. - Broken links. Links pointing at pages that do not exist. Distinguish
two cases: a typo or rename, which you fix, and a genuine gap, which goes
into
index.mdunder Gaps. - Orphans. Pages with no inbound links. For each, either find where it should be linked from and add the link, or flag it as a candidate for deletion.
- Stubs. Pages under roughly 40 words with no links. Usually a failed
ingest. Flag for re-ingest from the original source in
raw/. - Schema. Missing or malformed frontmatter, wrong
type, missing dates, tags outside the existing vocabulary. - Near-duplicates. Pages with very similar titles or aliases. Propose merges; do not perform them unsolicited.
- Index drift. Pages missing from
index.md, index entries pointing nowhere. - Repair, then append the run to
log.md.
Output format
Vault: <n> pages (<n> sources, <n> concepts, <n> entities, <n> synthesis)
Link graph: <n> links, average <n> per page, <n> orphans
Fixed automatically:
- <list>
Needs a decision:
- <list, each with the recommended action>
Health: orphan rate <n>%, broken link rate <n>%, stub rate <n>%Calibration
An aggressive linter that merges pages on its own judgement destroys work. A timid one that only reports produces a list nobody acts on. The split above is the useful line: mechanical fixes happen, semantic decisions get proposed.
Do not run a full lint after every ingest. Weekly, or after an import of more than about twenty sources.
© undefined-ui, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
Just SKILL.md in skills/second-brain-lint of undefined-ui/second-brain-os.
Open the folder on GitHubat commit d6861cc
Compare with similar skills
Second Brain Lint next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Second Brain Lint this skillundefined-ui/second-brain-os | 999 | — | ~678 | Automated safety check: Pass | MIT | |
| Second Brain LintNicholasSpisak/second-brain | 735 | — | ~1k | Automated safety check: Notes | None | |
| Second Brain DelintPieroSierra/SecondBrain | 152 | — | ~1k | Automated safety check: Pass | None | |
| Second Braincoreyhaines31/makerskills | 844 | — | ~2.9k | Automated safety check: Pass | MIT | |
| Second Brain LintPieroSierra/SecondBrain | 152 | — | ~2.1k | Automated safety check: Pass | None | |
| Mindbasefrankchu91/mindbase-llm-wiki | 128 | — | ~1.1k | Automated safety check: Pass | MIT |
Similar skills
Second Brain Delint
PieroSierra/SecondBrain
Work through open findings in the latest lint report one at a time — propose a fix, apply on approval, skip on rejection.
Second Brain
coreyhaines31/makerskills
When you want to capture into, compile, query, lint, or connect your personal Second Brain.
Second Brain Lint
PieroSierra/SecondBrain
Scan wiki/ for quality issues — contradictions, unsupported claims, and content gaps — and save a structured report to outputs/.
Mindbase
frankchu91/mindbase-llm-wiki
Maintain a persistent AI-tended research wiki. An agent skill from frankchu91/mindbase-llm-wiki.
Obsidian Canvas Boards
AgriciDaniel/claude-obsidian
Creates, inspects and updates Obsidian JSON Canvas boards in a vault, with text, file, link, group and edge nodes, using safe recoverable edits.
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Turn a vague task into a testable definition of done and generate an executable goal-test script for it, optionally with a bounded retry loop around a headless agent.
Harness Audit
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Audit an agent's harness against the four rings: containment, guides, sensors, permissions.
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Related
Categories
Questions about Second Brain Lint
What does Second Brain Lint do?
Audit a second-brain vault for structural problems and repair them: broken wikilinks, orphan pages, empty stubs, frontmatter that violates the schema, near-duplicate pages, and stale index entries. Second Brain Lint is an agent skill from undefined-ui/second-brain-os. Audit a second-brain vault for structural problems and repair them: broken wikilinks, orphan pages, empty stubs, frontmatter that violates the schema, near-duplicate pages, and stale index entries.
When should I use Second Brain Lint?
Second Brain Lint fits situations like: the user asks to lint; check the health of their vault; says pages feel messy; links are broken.
How do I install Second Brain Lint in Claude Code?
Run `npx skills add undefined-ui/second-brain-os --skill second-brain-lint -a claude-code`. Or copy the skill folder (skills/second-brain-lint in undefined-ui/second-brain-os) into .claude/skills/second-brain-lint in your project. Claude Code loads it when a task matches its description.
How do I install Second Brain Lint in Codex?
Run `npx skills add undefined-ui/second-brain-os --skill second-brain-lint -a codex`. Or copy the skill folder (skills/second-brain-lint in undefined-ui/second-brain-os) into .agents/skills/second-brain-lint in your project. Codex loads it when a task matches its description.
Can I use Second Brain Lint in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add undefined-ui/second-brain-os --skill second-brain-lint -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/second-brain-lint, .gemini/skills/second-brain-lint, .github/skills/second-brain-lint and .opencode/skills/second-brain-lint in your project.
What does Second Brain Lint need to run?
SKILL.md names no scripts, command-line tools or credentials: Second Brain Lint is instructions for the agent only.
Does Second Brain Lint access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Second Brain Lint safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Second Brain Lint use?
Second Brain Lint is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Second Brain Lint use?
About 678 tokens (SKILL.md is roughly 2.7k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Second Brain Lint?
Skills that share tags, products or a category with Second Brain Lint: Second Brain Lint (NicholasSpisak/second-brain, 735 stars), Second Brain Delint (PieroSierra/SecondBrain, 152 stars), Second Brain (coreyhaines31/makerskills, 844 stars) and Second Brain Lint (PieroSierra/SecondBrain, 152 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Second Brain Lint?
undefined-ui (a GitHub user) maintains it in undefined-ui/second-brain-os, which has 999 GitHub stars. The repository holds 23 skills in this directory. The repository was last updated on September 29, 2026.
Source: undefined-ui/second-brain-os on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.