Second Brain
Scoping an AI-searchable store of Google Drive, TrinityMetrics and the rest
Reminder, 2026-09-30. Nothing is built. The purpose in Section 1 is a first guess, and Section 5 lists the questions that have to be answered before choosing a tool.
1. Goal
Set up a second brain: one place holding the documents, notes and code accumulated over the years, searchable by an AI assistant that can answer a question from them and say which document the answer came from.
The first guess at the purpose has two parts.
- Find past work. A question such as “where did I work out the EC50 identifiability argument?” should return the document, not a search of four places by hand.
- Keep learning. Feeding the store and querying it is itself practice with the tools, and the store makes connections between old and new projects visible.
2. Out of Scope
- Not published. The store holds private material. Nothing from Google Drive is copied into this repository, and this page describes the plan only.
- Not Collected Wisdom. That project indexes the personal Google Docs on meaning, parenting and music as a site. This one is a private search tool over everything, work material included. The Google Drive inventory in Section 3 can serve both.
3. Sources
| # | Source | What it holds | Notes |
|---|---|---|---|
| 1 | Google Drive | Documents, slides and spreadsheets from years of work | Have an agent scour it and propose what is useful before loading anything |
| 2 | TrinityMetrics | Every project, blog post and guide on this site | Already in git and in Markdown, so the easiest source to load |
| 3 | Other GitHub repositories | synpmx, xgxr and the rest |
Code and vignettes |
| 4 | Papers | The PDFs and reference manager library behind the literature reviews | |
| 5 | Email and meeting notes | Decisions and the reasons for them | Most sensitive; decide last |
| 6 | Claude conversations | Sessions that worked something out and were never written up | Check what can be exported |
| 7 | Bookmarks and read-later lists | Things meant to be read |
Rows 1 and 2 come first. The rest wait until the purpose in Section 5 is settled, since each one widens what has to be kept private.
For Google Drive, the first pass is an inventory rather than a load: a list of folders and documents, a sentence on each, and a mark for keep, skip or private. An agent with read access to Drive can draft it; Andy decides the marks.
4. Candidate Tools
A second brain in this sense is two parts: a store of documents, and a retrieval step that finds the passages relevant to a question and hands them to a language model to answer from. The second part is called retrieval-augmented generation (RAG). The tools below differ in where the store lives and who runs the retrieval.
| Tool | Store | Fits |
|---|---|---|
| NotebookLM | Google, reads Drive directly | Google Drive with no copying; limits on source count per notebook |
| Claude Projects | Uploaded files in claude.ai | A few dozen documents per project |
| A folder of Markdown files, queried by Claude Code | Local disk, in git | TrinityMetrics and other repositories as they already are |
| Obsidian | Local Markdown with links between notes | Writing new notes as well as searching old ones |
None has been tried for this yet. The term “second brain” comes from Tiago Forte’s Building a Second Brain (2022), which is about organizing notes by hand; the AI retrieval step is the newer part.
5. Open Questions
- What question should the store answer that cannot be answered now? Two or three real examples decide the tool better than a feature list.
- Work and personal together, or apart? Work material may have rules on where it can be uploaded.
- Load a copy, or point at the original? A copy goes stale; a pointer depends on the tool reading Drive or git directly.
- Who adds to it, and when? A store that is loaded once and never updated stops being useful within a year.
6. First Steps
- Write down three questions the second brain should be able to answer.
- Have an agent inventory Google Drive, as in Section 3.
- Try NotebookLM on a handful of Drive documents and Claude Code on TrinityMetrics, and compare the answers to the three questions.