Second Brain
NicholasSpisak/second-brain
Set up a new Obsidian knowledge base with the LLM Wiki pattern.
Trace where the user's recorded position on something has shifted: superseded claims, contradictions between sources of different dates, and what evidence moved them.
Install Second Brain Changed My Mind
$ npx skills add undefined-ui/second-brain-os --skill second-brain-changed-my-mind -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-changed-my-mind --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-changed-my-mind .claude/skills/second-brain-changed-my-mind && 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-changed-my-mind" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-changed-my-mind into .claude/skills/second-brain-changed-my-mind/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-changed-my-mind", 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-changed-my-mindType 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-changed-my-mind -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-changed-my-mind --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-changed-my-mind .agents/skills/second-brain-changed-my-mind && 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-changed-my-mind" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-changed-my-mind into .agents/skills/second-brain-changed-my-mind/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-changed-my-mind", 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-changed-my-mind -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-changed-my-mind --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-changed-my-mind .cursor/skills/second-brain-changed-my-mind && 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-changed-my-mind" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-changed-my-mind into .cursor/skills/second-brain-changed-my-mind/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-changed-my-mind", 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-changed-my-mind--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-changed-my-mind -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install undefined-ui/second-brain-os second-brain-changed-my-mind --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-changed-my-mind .gemini/skills/second-brain-changed-my-mind && 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-changed-my-mind" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-changed-my-mind into .gemini/skills/second-brain-changed-my-mind/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-changed-my-mind", 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-changed-my-mindInstalls 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-changed-my-mind -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-changed-my-mind .github/skills/second-brain-changed-my-mind && 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-changed-my-mind" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-changed-my-mind into .github/skills/second-brain-changed-my-mind/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-changed-my-mind", 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-changed-my-mind -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-changed-my-mind --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-changed-my-mind .opencode/skills/second-brain-changed-my-mind && 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-changed-my-mind" agent skill from https://github.com/undefined-ui/second-brain-os/tree/main/skills/second-brain-changed-my-mind into .opencode/skills/second-brain-changed-my-mind/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "second-brain-changed-my-mind", 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-changed-my-mind- GitHub stars
- 1k
- Token cost
- ~486 tokens
- SKILL.md length
- 185 words
- Files
- 1
- Skills in repo
- 23
- Repo updated
- First seen
- Licence
- MIT
At a glance
Trace where the user's recorded position on something has shifted: superseded claims, contradictions between sources of different dates, and what evidence moved them.
- Works in 5 steps: Find superseded claims across concept… → Reconstruct the sequence: what the page… → Distinguish real revision from… → …
- The user asks what they have changed their mind about
- 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 Changed My Mind is an agent skill from undefined-ui/second-brain-os. Trace where the user's recorded position on something has shifted: superseded claims, contradictions between sources of different dates, and what evidence moved them. Use this skill when the user asks what they have changed their mind about, how their thinking on a topic developed, what they used to believe, or wants a quarterly look back at their own positions. Do NOT use for finding contradictions between sources with no time dimension, or for a current-state answer.
Its SKILL.md is about 490 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. 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 what they have changed their mind about
- How their thinking on a topic developed
- What they used to believe
- Wants a quarterly look back at their own positions
Example prompts
- “/second-brain-changed-my-mind”
Workflow steps
5 steps, taken from the first numbered list in SKILL.md.
- Find superseded claims across concept pages, and contradictions where the
- Reconstruct the sequence: what the page said, when, based on what; what
- Distinguish real revision from correction. A factual error being fixed is
- Flag unresolved ones. Contradictions still sitting open are the most
- Say how firm the current position is, based on what moved it.
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 Changed My Mind loads about 486 tokens when it runs. Until then it costs about 126 tokens; SKILL.md has 185 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). 185 words, ~486 tokens.
Download SKILL.mdSave it as
.claude/skills/second-brain-changed-my-mind/SKILL.md (or your agent's skills folder).- name
- second-brain-changed-my-mind
- description
- Trace where the user's recorded position on something has shifted: superseded claims, contradictions between sources of different dates, and what evidence moved them. Use this skill when the user asks what they have changed their mind about, how their thinking on a topic developed, what they used to believe, or wants a quarterly look back at their own positions. Do NOT use for finding contradictions between sources with no time dimension, or for a current-state answer.
Trace changed positions
This is the query a vault can answer that nothing else can, and the reason the supersession rules exist. It only works because contradictions are recorded rather than overwritten.
Core rule
Report the change with both positions, both dates and the evidence between them. A conclusion without its history is just the current claim.
Workflow
- Find superseded claims across concept pages, and contradictions where the sources differ in date.
- Reconstruct the sequence: what the page said, when, based on what; what changed it, when.
- Distinguish real revision from correction. A factual error being fixed is not a change of mind. A conclusion being revised on better evidence is.
- Flag unresolved ones. Contradictions still sitting open are the most actionable output here.
- Say how firm the current position is, based on what moved it.
Output format
## <topic>
Was: <claim> (<source>, <date>)
Now: <claim> (<source>, <date>)
What moved it: <evidence>
Firmness: <what would move it again>
## Still unresolved
<contradictions with no current position>Calibration
If nothing has changed in the period, say so in one line. Manufacturing an apparent revision from two pages that never disagreed is worse than an empty result.
Never present the more recent source as correct by virtue of being recent.
© 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-changed-my-mind of undefined-ui/second-brain-os.
Open the folder on GitHubat commit c7fa35b
Compare with similar skills
Second Brain Changed My Mind 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 Changed My Mind this skillundefined-ui/second-brain-os | 1k | — | ~486 | Automated safety check: Pass | MIT | |
| Second BrainNicholasSpisak/second-brain | 736 | 1 repos | ~1.5k | Automated safety check: Notes | None | |
| 3D Brainnateherkai/AIS-OS | 1.6k | — | ~2.1k | Automated safety check: Pass | Custom licence | |
| Obsidian Canvas BoardsAgriciDaniel/claude-obsidian | 15k | — | ~1.4k | Automated safety check: Pass | MIT | |
| Icm ArchitectRinDig/icm-architect | 1.8k | — | ~3.2k | Automated safety check: Pass | MIT | |
| Obsidian CLI Read TransportAgriciDaniel/claude-obsidian | 15k | 1 repos | ~762 | Automated safety check: Pass | MIT |
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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.
Context Audit
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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 Changed My Mind
What does Second Brain Changed My Mind do?
Trace where the user's recorded position on something has shifted: superseded claims, contradictions between sources of different dates, and what evidence moved them. Second Brain Changed My Mind is an agent skill from undefined-ui/second-brain-os. Trace where the user's recorded position on something has shifted: superseded claims, contradictions between sources of different dates, and what evidence moved them.
When should I use Second Brain Changed My Mind?
Second Brain Changed My Mind fits situations like: the user asks what they have changed their mind about; how their thinking on a topic developed; what they used to believe; wants a quarterly look back at their own positions.
How do I install Second Brain Changed My Mind in Claude Code?
Run `npx skills add undefined-ui/second-brain-os --skill second-brain-changed-my-mind -a claude-code`. Or copy the skill folder (skills/second-brain-changed-my-mind in undefined-ui/second-brain-os) into .claude/skills/second-brain-changed-my-mind in your project. Claude Code loads it when a task matches its description.
How do I install Second Brain Changed My Mind in Codex?
Run `npx skills add undefined-ui/second-brain-os --skill second-brain-changed-my-mind -a codex`. Or copy the skill folder (skills/second-brain-changed-my-mind in undefined-ui/second-brain-os) into .agents/skills/second-brain-changed-my-mind in your project. Codex loads it when a task matches its description.
Can I use Second Brain Changed My Mind 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-changed-my-mind -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-changed-my-mind, .gemini/skills/second-brain-changed-my-mind, .github/skills/second-brain-changed-my-mind and .opencode/skills/second-brain-changed-my-mind in your project.
What does Second Brain Changed My Mind need to run?
SKILL.md names no scripts, command-line tools or credentials: Second Brain Changed My Mind is instructions for the agent only.
Does Second Brain Changed My Mind 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 Changed My Mind 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 Changed My Mind use?
Second Brain Changed My Mind 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 Changed My Mind use?
About 486 tokens (SKILL.md is roughly 1.9k 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 Changed My Mind?
Skills that share tags, products or a category with Second Brain Changed My Mind: Second Brain (NicholasSpisak/second-brain, 736 stars), 3D Brain (nateherkai/AIS-OS, 1.6k stars), Obsidian Canvas Boards (AgriciDaniel/claude-obsidian, 15k stars) and Icm Architect (RinDig/icm-architect, 1.8k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Second Brain Changed My Mind?
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.