Connect your second brain and your to-do list

What is a second brain?

The term comes from Tiago Forte. In his book “Building a Second Brain” (2022), he describes a digital note-taking system that does the remembering for you: thoughts, quotes, meeting notes, sources, and drafts end up in one place where you can find them again for your projects. He sums up the process in four steps, CODE: Capture (keep what resonates), Organize (sort by how you’ll use it), Distill (boil it down to the essence), and Express (turn it into your own work). For organizing, he suggests PARA: Projects, Areas, Resources, Archives.

Which second brain app you use matters less. Many people keep their second brain in Obsidian because every note there is a Markdown file in an ordinary folder, the vault. Notes refer to each other with wikilinks like [[Course outline]], and for every note, Obsidian shows which other notes link to it.

Why tasks and knowledge often live apart

A second brain collects what you know. A to-do app tells you what’s next and reminds you in time. Each needs different tools: A notes app is poor at reminders, due dates, and quick capture on iPhone; a task list is poor at outlines and long texts.

Almost everyone who uses both knows the result:

• The task “Write script for lesson 2” is in the to-do app, the course outline for it in Obsidian. Whoever picks up the task first has to piece the context together.
• Tasks that come up in a meeting note stay there as a checkbox and never reach the to-do list.
• An AI agent sees only one half: either the notes or the tasks. To do good work, it needs both.

The solution doesn’t have to be an app that does everything. It’s enough for tasks and notes to end up in the same folder and for each app to show the part it’s built for.

Connect your task manager and your second brain

TandemLoop stores tasks as Markdown files in a data folder, in the same format as Obsidian. For Obsidian to show the tasks, that folder has to appear in your vault. There are two ways to do this.

Step by step: link the data folder into your vault on a Mac

1. Find the path of the data folder. In TandemLoop, Settings › Data Folder shows where it is. “Open in Finder” shows it to you.
2. Create the link. In the terminal, create a link named TandemLoop in your vault. Replace the placeholders with your paths; the quotation marks protect spaces in the path.

ln -s "<TandemLoop folder>" "<Vault>/TandemLoop"

3. Check in Obsidian. The TandemLoop folder appears in the file explorer. If the data folder itself is inside your vault or contains your vault, Obsidian ignores the link.
4. Set up a backup. Obsidian warns that symbolic links can lead to data loss. If your vault is in Git, Git only stores the link, not the tasks. Time Machine backs up the data folder at its real location.

What works on a Mac and what doesn’t

• iPhone and iPad: Obsidian doesn’t show linked folders there. On the go, you capture, plan, and complete tasks in TandemLoop; in Obsidian on iPhone, you only see your notes.
• A second Mac: A link points to a fixed path. On a second Mac, it only works if the data folder is at the same path there; otherwise, create the link again on that Mac.
• Agents: To an agent, the linked folder is a folder outside its workspace. Claude Code, for example, needs access to the real data folder as well. The guide Claude Code and Obsidian explains how.

The alternative: the data folder directly in your vault

You choose where the data folder lives in TandemLoop during setup or later under Settings › Data Folder. If your vault is in iCloud Drive, you can choose a subfolder there such as TandemLoop. Then you don’t need a link, and Obsidian shows the tasks on all your devices. In return, iCloud syncs notes and tasks together, and Obsidian on iPhone also downloads all task files. Either way, try to work on only one device at a time so no conflict copies are created.

Link to tasks from your notes

Once the tasks are visible in your vault, you link them like any note. In a note, type [[ and part of the title, and Obsidian suggests the file. The text after the vertical bar is what the note displays:

- Lesson 2 needs a script → [[tsk_script-lesson-2|Script for lesson 2]]

When you open the task in Obsidian, the Backlinks pane shows all notes that point to it. So when you plan in TandemLoop, you see just the task; when you think things through in Obsidian, you see the whole context.

The second option is the app link: Copy App Link in a task’s context menu. As a Markdown link in a note, it opens TandemLoop right at the task, on iPhone too:

[Script for lesson 2](tandemloop://open/tsk_…)

Copy Link without “App” creates a link for agents that Obsidian doesn’t resolve. For Obsidian, use the file name or the app link.

A second brain with AI: what an agent does in a connected vault

An agent with file access, such as Claude Code, Codex, or Cursor, works in the folder where you start it. Start it in your vault, and it reads notes and tasks together. For the tasks, it follows the AGENTS.md in the data folder, TandemLoop’s manual. This makes three things possible that separate apps can’t do.

Read notes and tasks together

“What’s still open in the Online Course project, and what do my notes say about it?” The agent reads the project’s open tasks and the notes in the Online Course folder and answers with both: what’s missing, what’s already prepared, and where a task and the outline contradict each other.

Turn meeting notes into tasks in the right project

“Read my note Course planning Oct 20 and create the tasks from it in TandemLoop.” The agent creates each task where it belongs: in the Online Course project, or if needed in a new project, area, or view of its own. What it can do itself, it assigns to itself; what only you can do, like “Confirm access to the course platform,” gets you as the assignee. If you want to see this first, turn on proposals in TandemLoop. The agent then only adds new items to the Inbox directly and files everything else as a proposal that you approve or reject.

Save results as a note and link them on the task

When the agent works on the task “Write script for lesson 2,” it saves the script as a note in the Online Course folder and writes in the task’s log what it did, with a link to the note. The result becomes part of your second brain, and the task comes back to you for review in TandemLoop under Back from Agent.

A short rule in your vault’s instructions is enough for the agent to know the setup:

## Tasks
TandemLoop/ is a link to the data folder of my to-do app.
For tasks, read TandemLoop/AGENTS.md first and follow its rules.
Save results as a note in the matching folder and link them on the task.