# Claude Cowork as a second brain: where the memory lives, and how a team keeps it

> A Claude Cowork second brain is a folder plus project memory, both scoped to one person. How to put the notes where every teammate's Cowork can reach them.

Source: https://baalda.com/blog/claude-cowork-second-brain
Site: Baalda, https://baalda.com
Published: 2026-10-22

**Short answer.** A Claude Cowork second brain is a connected folder of markdown notes plus a Cowork project holding instructions and memory. Both belong to one person: sessions cannot be shared and local folders work only while the desktop app is open. For a team, keep the notes in a shared vault Cowork reaches as a folder or a custom connector.

A Claude Cowork second brain is a folder of plain markdown files that Cowork reads at the start of a task and writes back to at the end, with a Cowork project holding the instructions and memory around it. Most guides stop there, and that works for one person on one laptop. The catch is that the folder, the project memory and the session history all belong to that one person, and a teammate's Cowork cannot reach any of them.

That is the dividing line worth knowing before you build one. Put the notes somewhere the whole team can reach and the second brain belongs to the team. Leave them in your own folder and project and it belongs to you, however good it gets. Baalda, a team second brain built on plain markdown files, is one way to do the first, and this post covers both routes it offers into Cowork, plus where it does not help.

## What does a second brain in Claude Cowork actually consist of?

Three parts, and only one of them is a file you can open.

- **A connected folder.** Anthropic's help centre is plain about the boundary: "Claude can only read and write files in folders you've connected." On desktop it reads and writes those local files directly, with no uploads.
- **A project.** Cowork projects "group related tasks into dedicated workspaces with their own files, context, instructions, and memory." Claude remembers context from earlier tasks in the same project and applies it to later ones. That memory does not carry over to other projects.
- **Instructions.** Global instructions apply to every Cowork session. Folder instructions add context when you select a local folder on desktop, and per the help centre Claude can also update these itself during a session.

The guides currently ranking for this (courses, webinars, newsletters) mostly build the first part: a folder holding a profile note, a memory note and some project notes, often an Obsidian vault, because a vault is a folder of `.md` files and Cowork needs nothing else to read it. That choice is sound. Files outlive whichever assistant is reading them this year.

## Why does a Cowork second brain stay personal?

Because every part of it is scoped to one account or one machine, according to Anthropic's own documentation as of 22 October 2026.

| Part | Where it lives | Can a teammate's Cowork use it? |
|---|---|---|
| The connected folder | your computer | only if the folder reaches their computer too |
| Project memory | your project, in your account | only if you share the project (Team and Enterprise) |
| Session history | on your computer for local sessions, in your account for cloud ones | no, and admins cannot centrally manage the local copy |
| Sessions | your account | no: "Sessions can't be shared with others" |

Shared projects help on Team and Enterprise plans, with "Can view" or "Can edit" access. They do not change where the notes are. Project memory is something Claude assembles about past tasks, not a document your team reads, edits and argues over, and it is not a file you can take with you when the team moves to a different assistant.

So the part of the second brain that has to be shared is the folder. That turns the question into a sync and permissions question, which is the one [a team second brain](/blog/team-second-brain) exists to answer.

## Where can Cowork actually reach your files from?

This is the detail most setup guides were written too early to catch. Cowork launched on 12 January 2026 as a research preview that ran locally on your computer in an isolated VM. Remote sessions arrived on 7 July 2026, and the help centre now says "Cowork sessions run in the cloud by default." Each cloud session gets its own sandbox, and local file access works only "through the desktop app, and only while it's open."

Scheduled tasks always run in the cloud, which is their selling point: they "don't need your computer to be awake or the desktop app open."

Put those together and a folder on your laptop is a second brain only for the tasks you run while the desktop app is open. A scheduled Monday summary that is meant to read the team's notes and write a digest back into them cannot rely on a folder on anyone's laptop. It needs the notes behind a URL.

## How do you connect Cowork to a shared Baalda vault?

Baalda keeps every note as a plain `.md` file on each member's disk, syncs edits between members in real time over a CRDT, and exposes the same vault over MCP at `/api/mcp`. That gives Cowork two ways in, and they land in the same files.

**Route 1: connect the vault folder, for desktop sessions.** In Cowork on desktop, connect your Baalda vault's folder the way you would any folder. Cowork edits the markdown directly. Baalda's watcher notices the change on disk, turns it into CRDT operations and syncs it live to everyone else in the vault, so a note Cowork rewrites on your machine updates on your teammate's screen. The folder only holds what you can read: when you join a vault, the server sends the notes your permissions allow, and a private folder you were never given access to is not on your disk at all.

**Route 2: add Baalda as a custom connector, for cloud sessions and scheduled tasks.** Anthropic's connector article says custom connectors using remote MCP "are available on Claude, Cowork, and Claude Desktop." On Pro and Max you add one under Customize, then Connectors, then Add custom connector, with a name and a URL:

```text
https://api.baalda.com/api/mcp
```

Self-hosted, it is your own server address plus `/api/mcp`. Baalda advertises `/.well-known/oauth-protected-resource`, so Claude runs an OAuth sign-in instead of asking for a token, and you pick the vault on the consent screen. On a Team plan, only Owners and Primary Owners add custom connectors, under Organization settings, and each member then connects it under their own login. [The Claude Desktop setup post](/blog/claude-desktop-second-brain) walks through the consent screen and the vault binding in more detail.

Through the connector Cowork gets `search_notes`, `read_note`, `create_note`, `edit_note`, `update_note`, `append_note`, `list_attachments` and `read_attachment_text`, among others. Every call runs through the same per-folder and per-note access control a person is held to, under the identity of whoever signed in. A folder you cannot open is a folder your Cowork cannot read, and your colleague's Cowork sees what your colleague can see, not what you can.

## Which route should a team use?

| Situation | Route |
|---|---|
| You work in Cowork on desktop, app open, notes in your vault folder | connect the folder |
| Cowork's default cloud sessions | custom connector |
| A scheduled task that reads or writes team notes | custom connector |
| Several people, each with their own Cowork | both work: each person uses their own folder or their own sign-in |

Most teams end up with both. The folder route is the lowest-friction one for live work. The connector is the one that keeps working when nobody's laptop is awake.

One difference matters once two assistants write to the same note. Through the connector, `read_note` returns a `revision`, and passing it back as `expectedRevision` makes a write against a note that changed in the meantime fail instead of landing on top. `edit_note` applies anchored replace, insert and delete operations, and an anchor that matches zero times or more than once fails the whole call with nothing written. The folder route has neither check on Baalda's side: whatever Cowork writes reaches the watcher as a finished change to the file, and the CRDT merges it with whatever else arrived. For notes that several assistants update on a schedule, the connector is the safer writer.

## What should go in the vault, and what should stay in Cowork?

Keep the split simple. Anything a teammate would need if you were off for a month goes in the vault as a note: decisions and the reasons behind them, how a process runs, the state of a client, the brief for a recurring task. Anything that is only about how you like to work stays in your own global instructions and project memory.

A useful habit is to end a Cowork task by having it append what it learned to the relevant note, rather than trusting project memory to hold it. Project memory is good at carrying context between your own tasks. A note is what the next person, or the next assistant, can actually read.

## Where does this not help?

Baalda does not replace any part of Cowork. It does not run tasks, schedule them or hold Cowork's project memory, and it is not a Cowork plugin. It is the place the notes live.

The other honest limits:

- **One vault per connector, per person.** The vault you pick at sign-in is bound to that connector. Switching vaults means re-authorising.
- **Team admins have to add the connector.** On a Team plan a member cannot add a custom connector on their own.
- **The folder route needs the desktop app open**, and it skips the revision check described above.
- **Cowork itself needs a paid Claude plan.** Pro, Max, Team or Enterprise, per Anthropic's getting-started article.

If you work alone, an Obsidian vault connected as a Cowork folder is a perfectly good second brain, and Obsidian's plugin ecosystem is far deeper than Baalda's. It stops being enough at the second person, because Obsidian Sync shares a whole vault with everyone on the same footing, which is the gap [the per-file permissions post](/blog/obsidian-per-file-permissions) covers. If your team's knowledge is mostly tables and views, Notion's databases do something markdown files do not, and [the Notion comparison](/compare/notion) is the honest place to weigh that.

## FAQ

### How do I build a second brain with Claude Cowork?

Connect a folder of plain markdown notes in Cowork on desktop, put recurring tasks in a Cowork project so instructions and memory carry between them, and have each task write what it learned back into a note. For a team, make that folder a shared vault, or add the vault as a custom connector so cloud sessions can reach it too.

### Can Claude Cowork use my Obsidian vault?

Yes. An Obsidian vault is a folder of markdown files, so you can connect it in Cowork on desktop like any other folder, and Cowork reads and writes the notes directly. It only works while the desktop app is open, and the vault is still yours alone unless something syncs it to your teammates.

### Does Claude Cowork remember things between sessions?

Within a project, yes. Anthropic's help centre says Claude remembers context from earlier tasks in a project and applies it to later ones in the same project, and that memory does not carry over to other projects. Sessions themselves cannot be shared with other people.

### Can a scheduled Cowork task read files on my computer?

Not reliably. Scheduled tasks run in the cloud so they work while your computer is asleep, and local folders are reachable only through the desktop app while it is open. A scheduled task that needs the team's notes should reach them through a remote connector instead.

### Who can add a custom connector to Cowork on a Team plan?

Only Owners and Primary Owners, under Organization settings, per Anthropic's connector documentation. Once they add it, each member connects to it individually with their own login, so the assistant gets that member's permissions rather than the admin's.