---
url: /blog/2026/v0.6.10.md
description: >-
  v0.6.10 adds a $/ prefix for reaching any folder's derived code, and function
  templates that seed layouts and use.ts files too. Plus two fixes.
---

Two additions in `v0.6.10`, and two fixes.
One addition changes the shape of function templates, so check the upgrade note.

## $/: derived code of any folder

`_/` reaches the derived code of the folder you are in. That is the right default,
and it is also its limit: there was no clean way to reach another folder's derived code,
or any folder's at all from a file at the project root.

So a root-level helper that needed the admin folder's base had to hardcode a path into `var/lib/`.

`$/` resolves to `var/lib/`, wherever it is used:

```ts
// a helper at the project root
import { base } from "$/admin/core";

// the admin folder, reading the docs folder's routes
import { apiRouteMap } from "$/docs/core";
```

Inside a folder, `_/core` and `$/<this folder>/core` point at the same file.
Keep `_/` for your own folder, and use `$/` when the code belongs to another one.

[Details ›](/essentials/project-structure#path-mappings)

## Templates for layouts and use.ts

A template seeds a route's file by pattern: the page on the frontend, the route on the backend.
But some source folders, an admin CRUD for example,
want their layouts or `use.ts` files seeded consistently as well.

Rather than a second option with the same patterns repeated, the function form grew.
It now receives the resolved entry, `{ kind, entry }`, and returns the template,
or `undefined` to keep the built-in one.
It is called for routes and for layouts on the frontend, for routes and `use.ts` on the backend:

```ts [kosmo.config.ts]
export default defineConfig({
  frontend: {
    stack: "react",
    base: "/admin",
    templates: {
      "crud/**": ({ kind, entry }) => {
        if (kind === "pageLayout") {
          return adminLayout;
        }
        return adminPage(entry.name);
      },
    },
  },
});
```

One pattern, one place, so the page and its layout cannot drift apart.
A plain string still works as before, and still seeds only the route file.

[Frontend ›](/frontend/custom-templates#template-format) ·
[Backend ›](/backend/custom-templates#template-format)

**Upgrading:** a function template used to receive the route itself.
It now receives `{ kind, entry }`, and is called for layouts or `use.ts` files too,
so return `undefined` for the kinds it should leave alone:

```ts
// before
"admin/**": (route) => adminPage(route.name),

// after
"admin/**": ({ kind, entry }) => {
  return kind === "pageRoute" ? adminPage(entry.name) : undefined;
},
```

## Fixes

> **`base` was `undefined` in folders without a frontend.**

A folder with no frontend, or no base for it, got `base` set to `undefined` in `_/core`,
which broke type checking for code that read it.
The same happened to `backendBase` in folders without a backend.
Both are strings now.

> **Vitest ran every test in both projects.**

The backend and frontend test projects were given the same globs,
so each one loaded the tests of both. Now each project loads only its own:
`api/` tests for the backend, `pages/` tests for the frontend.