Second Brain Lint
NicholasSpisak/second-brain
Health-check the wiki for contradictions, orphan pages, stale claims, and missing cross-references.
Turn raw source material in a second-brain vault into linked wiki pages: read the source, split it into concepts and entities, write or update pages, connect them to existing pages, and record the…
Install Second Brain Ingest
$ npx skills add undefined-ui/second-brain-os --skill second-brain-ingest -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-ingest --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-ingest .claude/skills/second-brain-ingest && 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-ingest" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-ingest into .claude/skills/second-brain-ingest/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-ingest", 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-ingestType 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-ingest -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-ingest --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-ingest .agents/skills/second-brain-ingest && 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-ingest" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-ingest into .agents/skills/second-brain-ingest/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-ingest", 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-ingest -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-ingest --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-ingest .cursor/skills/second-brain-ingest && 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-ingest" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-ingest into .cursor/skills/second-brain-ingest/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-ingest", 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-ingest--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-ingest -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-ingest --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-ingest .gemini/skills/second-brain-ingest && 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-ingest" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-ingest into .gemini/skills/second-brain-ingest/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-ingest", 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-ingestInstalls 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-ingest -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-ingest .github/skills/second-brain-ingest && 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-ingest" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-ingest into .github/skills/second-brain-ingest/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-ingest", 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-ingest -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-ingest --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-ingest .opencode/skills/second-brain-ingest && 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-ingest" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-ingest into .opencode/skills/second-brain-ingest/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-ingest", 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-ingest- GitHub stars
- 1k
- Token cost
- ~873 tokens
- SKILL.md length
- 411 words
- Files
- 1
- Skills in repo
- 23
- Repo updated
- First seen
- Licence
- MIT
At a glance
Turn raw source material in a second-brain vault into linked wiki pages: read the source, split it into concepts and entities, write or update pages, connect them to existing pages, and record the…
- Works in 7 steps: Read the source completely before… → Check what already exists. Search the… → Write the source page in wiki/sources/.… → …
- The user drops a file into raw/
- SKILL.md covers Core rule, Workflow, Output format and Calibration, plus 1 more section
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
Second Brain Ingest is an agent skill from undefined-ui/second-brain-os. Turn raw source material in a second-brain vault into linked wiki pages: read the source, split it into concepts and entities, write or update pages, connect them to existing pages, and record the run in the log. Use this skill whenever the user drops a file into raw/, pastes an article, transcript or PDF and asks to add it to the vault, says "ingest this", "add this to my second brain", "process raw", or asks to catch up on unprocessed sources, even if they do not name the ingest command. Do NOT use for…
Its SKILL.md is about 870 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 drops a file into raw/
- Pastes an article
- PDF and asks to add it to the vault
- Says ingest this
Example prompts
- “ingest this”
- “add this to my second brain”
- “process raw”
- “/second-brain-ingest”
Workflow steps
7 steps, taken from the first numbered list in SKILL.md.
- Read the source completely before writing anything. Partial reads
- Check what already exists. Search the wiki for the main entities and
- Write the source page in wiki/sources/. Record claims as claims, with
- Extract concepts and entities. One page per idea. If a concept page
- Link in both directions. The source page links to every concept and
- Update index.md and append to log.md in the same run, because an
- Report what changed.
What it can do on your machine
Read from SKILL.md and the folder at commit c7fa35b. 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 Ingest loads about 873 tokens when it runs. Until then it costs about 163 tokens; SKILL.md has 411 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 c7fa35b, republished under its MIT licence (© undefined-ui). 411 words, ~873 tokens.
Download SKILL.mdSave it as
.claude/skills/second-brain-ingest/SKILL.md (or your agent's skills folder).- name
- second-brain-ingest
- description
- Turn raw source material in a second-brain vault into linked wiki pages: read the source, split it into concepts and entities, write or update pages, connect them to existing pages, and record the run in the log. Use this skill whenever the user drops a file into raw/, pastes an article, transcript or PDF and asks to add it to the vault, says "ingest this", "add this to my second brain", "process raw", or asks to catch up on unprocessed sources, even if they do not name the ingest command. Do NOT use for answering questions from an existing vault, for linting or repairing pages, or for editing notes the user wrote by hand.
Ingest a source
An ingest that only writes a summary page produces a vault that grows without getting smarter. The whole value is in the second half of the job: connecting the new material to what is already there. A page that lands unlinked is invisible within a week.
Core rule
Nothing is ingested until it is linked. Every run ends with the new pages connected to existing pages in both directions.
Workflow
- Read the source completely before writing anything. Partial reads produce pages built from the introduction, which is where sources are least specific.
- Check what already exists. Search the wiki for the main entities and concepts. Ingesting into an empty vault and ingesting into a vault of 300 pages are different jobs: in the second, most of your work is updating pages, not creating them.
- Write the source page in
wiki/sources/. Record claims as claims, with the source attached. - Extract concepts and entities. One page per idea. If a concept page
exists, add what this source contributes and update
updated:. If it contradicts what is there, record both positions rather than replacing. - Link in both directions. The source page links to every concept and
entity it touches; each of those links back. Add any missing target pages,
or list them under Gaps in
index.md. - Update
index.mdand append tolog.mdin the same run, because an index that lags is how a vault starts drifting. - Report what changed.
Show full SKILL.md (164 more words)Show less
Output format
End every run with this exact shape:
Ingested: <source name>
New pages: <n> (list)
Updated pages: <n> (list)
Links added: <n>
Contradictions found: <none | description>
Gaps created: <list of linked pages that do not exist yet>Calibration
Over-extraction is the common failure: ten thin concept pages from one article, each a restated paragraph. A source usually yields one to three concepts worth their own page. If a candidate concept cannot be explained without referring back to this one source, it belongs inside the source page instead.
Under-extraction shows up as source pages that contain three separate ideas and link to nothing. If a page needs section headings for unrelated topics, split it.
Example
Input: the user drops raw/karpathy-llm-wiki.md, a clipped gist, into a vault
that already has pages for [[Obsidian]] and [[Claude Code]].
Output: one source page; a new concept page [[LLM wiki]] explaining the
pattern in plain language; an entity page [[Andrej Karpathy]]; updates to
[[Obsidian]] and [[Claude Code]] noting their role in the pattern; a link
from the existing [[Personal knowledge management]] concept to the new one;
index and log updated; report showing 3 new, 3 updated, 11 links.
© 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-ingest of undefined-ui/second-brain-os.
Open the folder on GitHubat commit c7fa35b
Compare with similar skills
Second Brain Ingest 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 Ingest this skillundefined-ui/second-brain-os | 1k | — | ~873 | Automated safety check: Pass | MIT | |
| Second Brain LintNicholasSpisak/second-brain | 736 | — | ~1k | Automated safety check: Notes | None | |
| Second Brain DelintPieroSierra/SecondBrain | 152 | — | ~1k | Automated safety check: Pass | None | |
| Second Braincoreyhaines31/makerskills | 848 | — | ~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.
Second Brain
NicholasSpisak/second-brain
Set up a new Obsidian knowledge base with the LLM Wiki pattern.
More from undefined-ui/second-brain-os
All 23 skills in this repoGoal Test
undefined-ui/second-brain-os
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.
Context Audit
undefined-ui/second-brain-os
Audit an agent's context layout against the four places: system prompt, tools, history, tail.
Evals Bootstrap
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Scaffold a first eval suite for an agent: mine real failures into cases, write behavioural checks over traces, and generate the runner.
Gate Check
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Find the decisions in a pipeline that do not need the expensive model and propose the gate for each: a rule, a classic classifier, or a small model, with fail-closed routing.
Harness Audit
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Audit an agent's harness against the four rings: containment, guides, sensors, permissions.
Second Brain Chat Import
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Triage an exported chat history into what to ingest, what to archive and what to delete, with a privacy pass first.
Related
Categories
Questions about Second Brain Ingest
What does Second Brain Ingest do?
Turn raw source material in a second-brain vault into linked wiki pages: read the source, split it into concepts and entities, write or update pages, connect them to existing pages, and record the…. Second Brain Ingest is an agent skill from undefined-ui/second-brain-os. Turn raw source material in a second-brain vault into linked wiki pages: read the source, split it into concepts and entities, write or update pages, connect them to existing pages, and record the run in the log.
When should I use Second Brain Ingest?
Second Brain Ingest fits situations like: the user drops a file into raw/; pastes an article; PDF and asks to add it to the vault; says ingest this.
How do I install Second Brain Ingest in Claude Code?
Run `npx skills add undefined-ui/second-brain-os --skill second-brain-ingest -a claude-code`. Or copy the skill folder (skills/second-brain-ingest in undefined-ui/second-brain-os) into .claude/skills/second-brain-ingest in your project. Claude Code loads it when a task matches its description.
How do I install Second Brain Ingest in Codex?
Run `npx skills add undefined-ui/second-brain-os --skill second-brain-ingest -a codex`. Or copy the skill folder (skills/second-brain-ingest in undefined-ui/second-brain-os) into .agents/skills/second-brain-ingest in your project. Codex loads it when a task matches its description.
Can I use Second Brain Ingest 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-ingest -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-ingest, .gemini/skills/second-brain-ingest, .github/skills/second-brain-ingest and .opencode/skills/second-brain-ingest in your project.
What does Second Brain Ingest need to run?
SKILL.md names no scripts, command-line tools or credentials: Second Brain Ingest is instructions for the agent only.
Does Second Brain Ingest 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 Ingest 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 Ingest use?
Second Brain Ingest 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 Ingest use?
About 873 tokens (SKILL.md is roughly 3.5k 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 Ingest?
Skills that share tags, products or a category with Second Brain Ingest: Second Brain Lint (NicholasSpisak/second-brain, 736 stars), Second Brain Delint (PieroSierra/SecondBrain, 152 stars), Second Brain (coreyhaines31/makerskills, 848 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 Ingest?
undefined-ui (a GitHub user) maintains it in undefined-ui/second-brain-os, which has 1,009 GitHub stars. The repository holds 23 skills in this directory. The repository was last updated on October 7, 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.