# Second Brain Merge

Merge two pages that describe the same thing, preserving every distinct claim...

- Repository: https://github.com/undefined-ui/second-brain-os (1169 stars)
- Category: Engineering
- License: MIT
- Last updated: 2026-10-14
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add undefined-ui/second-brain-os --skill second-brain-merge -g -a claude-code -y`
Codex: `npx skills add undefined-ui/second-brain-os --skill second-brain-merge -g -a codex -y`
Cursor: `npx skills add undefined-ui/second-brain-os --skill second-brain-merge -g -a cursor -y`
Gemini CLI: `npx skills add undefined-ui/second-brain-os --skill second-brain-merge -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add undefined-ui/second-brain-os`

## Description

Merge two pages that describe the same thing, preserving every distinct claim, redirecting inbound links, and recording the merge. Use this skill when the user approves a duplicate merge, says "these are the same page", "merge X into Y", or asks to clean up near-duplicates that a lint run proposed. Do NOT use to merge pages on your own judgement, to delete a page outright, or to split one page into several.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Merge duplicate pages

A merge is irreversible in the way that matters: afterwards you cannot tell
which claim came from which page. Two ideas that look identical from their
summaries are often a general case and a specific one.

## Core rule

Never merge unprompted. Propose, wait for approval, then follow the procedure
exactly.

## Workflow

1. **Pick the survivor** by canonical name, not by which page is longer.
2. **Merge content.** Every distinct claim survives with its source. Overlapping
   claims collapse; differing ones both stay, following the contradiction rules.
3. **Merge aliases,** including the dead page's title as an alias on the
   survivor. This is what keeps old links and the user's memory working.
4. **Redirect inbound links** to the survivor. Check every backlink.
5. **Delete the old page,** or leave a stub only if it was linked from outside
   the vault.
6. **Record in `log.md`:** both names, the date, and why.

## Output format

```
Merged: [[old]] -> [[survivor]]
Claims kept from old page: <n>
Aliases added: <list>
Inbound links redirected: <n>
Conflicts recorded: <none | description>
```

## Calibration

If the two pages disagree about anything factual, that is a signal they may not
be duplicates. Surface the disagreement and ask before proceeding.

Never merge a page marked `maintained_by: human` into another without explicit
confirmation naming that page.