SerenCorpusCallosum

The callosum. A read-only fan that federates N memory stores into one ranked recall surface. Left brain (SerenLoci - structured facts) plus right brain (SerenMemory - episodic memory) plus however many more you hook in - merged into a single ordered list you can hand to a model.

It owns no store of its own. It remembers nothing. It only fans, floors, and merges what the hemispheres hand back. That read-only-by-construction shape is the whole point: the callosum is glue, not a place data lives.

How it works

The callosum never reads raw scores - every store can change its embedder independently, so distances live in incomparable number spaces. Instead it reads rank ordering (position 1, 2, 3 within each store's results) and merges with Reciprocal Rank Fusion:

score(hit) = weight_of_store / (k + rank_in_store)

That's embedder-agnostic by construction: rescale any store's scores however you like, the order is untouched, so the merge is untouched.

Base + overlay config. Stores declared in your yaml are base stores - never rewritten by the UI. Stores added via the Bridge viewer live in a separate runtime-stores.json overlay. Base always wins a name collision, so the overlay can never quietly shadow something you hand-wrote.

Requirements

• GitHub Copilot (Chat) - the extension registers one language-model tool; Copilot Chat is required to use it.
• SerenCorpusCallosum service - the Python backend, from the SerenCorpusCallosum repository.

Quick start

1. Install the SerenCorpusCallosum service

pip install seren-corpus-callosum            # core: just the web stack + httpx
pip install 'seren-corpus-callosum[mcp]'     # + the `search` MCP tool surface

No [vector] extra, ever - the callosum embeds nothing, so it never pulls torch.

2. Configure the extension

Open Settings (Ctrl+Shift+P → Open User Settings) and set:

3. Set your bearer token (if auth is enabled)

Run Ctrl+Shift+P → Seren CorpusCallosum: Set Bearer Token. The token is stored in the OS keychain, never in settings files.

4. Check the status bar

The $(git-merge) CorpusCallosum item in the bottom-right shows service health at a glance: CorpusCallosum ✓ reachable, CorpusCallosum ✗ not (click to retry).

Copilot tools

Once the service is running, Copilot gets one tool. You can also reference it directly in chat with #serenSearch.

It's deliberately the only tool. SCC owns no data, so there's nothing to set, get, or forget here - that's what the SerenLoci and SerenMemory extensions are for. Managing which stores get fanned (add/remove) lives in the Bridge viewer, behind the bearer token, not as a model tool.

Commands

Open the Command Palette (Ctrl+Shift+P) and search Seren CorpusCallosum:

MCP transport (optional)

The service also exposes an MCP HTTP endpoint at /mcp/ (install with the [mcp] extra). This lets a model connect directly via the VS Code or Visual Studio MCP client config without the extension, or use both at once.

.vscode/mcp.json (VS Code):

{
  "servers": {
    "seren-corpus-callosum": {
      "type": "http",
      "url": "http://localhost:7423/mcp/",
      "headers": {
        "Authorization": "Bearer YOUR_TOKEN"
      }
    }
  }
}

Omit the headers block if you didn't set a bearer token. The endpoint exposes a single search tool - the same in-process fan the HTTP API uses.

The family

Source & issues

github.com/ChadRoesler/SerenCorpusCallosum