> ## Documentation Index > Fetch the complete documentation index at: https://docs.r28.ai/charter/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > Charter works for any HTTP API, including the user's own. The packs are examples of the result, not the limit: an API with no pack is declared the same way, following https://raw.githubusercontent.com/r28ai/charter/main/docs/.mintlify/skills/declaring-charter-tools/SKILL.md. > Charter is for agents that act in customers' accounts: every call is checked field by field before it's sent, the app says whose account each call is for, and the same declarations list what each tool can reach. https://docs.r28.ai/charter/llms.txt says what it is and lists every page. # Register a Linear OAuth application > The OAuth application your users' Linear workspaces authorize: the form, the switch that lets other workspaces install it, and the credentials, with a screenshot for each. Before your users can connect their Linear workspaces, Linear needs an OAuth application that you own and they authorize. You register it once, from a workspace you're an admin of, and it takes about three minutes. Only connecting your own workspace? A personal API key from [linear.app/settings/account/security](https://linear.app/settings/account/security) is all the [`linear`](https://docs.r28.ai/charter/charter/packs/linear) pack needs. Set it as `LINEAR_API_KEY`. Every Linear link below opens in a new tab, so this page stays where you left it. **1. Start a new OAuth application** Open [linear.app/settings/api](https://linear.app/settings/api) and, under **OAuth Applications**, click **New OAuth application**. ![Linear's API settings page, with a New OAuth application button in the OAuth Applications section.](https://mintcdn.com/r28-ai-inc/xppyW240SSmPx0hQ/charter/images/setup/linear/01-new-oauth-app.webp?fit=max\&auto=format\&n=xppyW240SSmPx0hQ\&q=85\&s=621ba3cfd94f57ecaff410319edf4a85) **2. Fill in the form** ![The new OAuth application form: application name Example App, developer name Example Inc., developer URL https://app.example.com, callback URL https://app.example.com/oauth/linear/callback (highlighted), an empty GitHub username, Public switched on, and Client credentials and Webhooks switched off.](https://mintcdn.com/r28-ai-inc/xppyW240SSmPx0hQ/charter/images/setup/linear/02-app-form.webp?fit=max\&auto=format\&n=xppyW240SSmPx0hQ\&q=85\&s=7edb218f6919fe3e5f22d1c7ed220816) * **Application name**, **Developer name**, **Developer URL**: what your users see on the consent screen. * **Callback URLs**: your app's callback route, one per line. Linear redirects only to a URL listed here. * **GitHub username**: leave it empty. It only matters for apps that act as themselves and want their commits attributed. * **Public**: switch it **on**. With it off, only the workspace you're in can authorize the app, which is fine for testing and wrong for your users. * **Client credentials**: leave it off. That grant is for an app acting on its own workspace, and this flow acts on behalf of each user. Click **Create**. **3. Copy the client ID and secret** Linear opens the application's page. Under **OAuth credentials**, copy the **Client ID** and the **Client secret**. ![The application's page: developer, redirect URIs and availability, then an OAuth credentials panel with the client ID, a masked client secret, and a developer token row.](https://mintcdn.com/r28-ai-inc/xppyW240SSmPx0hQ/charter/images/setup/linear/03-credentials.webp?fit=max\&auto=format\&n=xppyW240SSmPx0hQ\&q=85\&s=37d202d6350d5d18f7031b5a4bb25a9a) ```bash theme={null} export LINEAR_CLIENT_ID=3f9a1c07be52d4e8a6b0c91d27e4f538 export LINEAR_CLIENT_SECRET=... ``` **4. Connect a workspace** Your app's "Connect Linear" button opens the link that [`flow.authorize()`](https://docs.r28.ai/charter/charter/reference/oauth#oauth2flow-authorize) builds. Linear shows what the app is asking for, and the user clicks **Authorize**. ![Linear's consent screen: Example App is requesting access to the Example Workspace workspace, with read and write access listed, and Cancel and Authorize buttons.](https://mintcdn.com/r28-ai-inc/xppyW240SSmPx0hQ/charter/images/setup/linear/04-consent.webp?fit=max\&auto=format\&n=xppyW240SSmPx0hQ\&q=85\&s=16c866ba22266b8507810b3c342aea5b) `read` and `write` cover the pack's tools. Don't ask for `admin`: it adds a line about managing settings and people to this screen, and no tool needs it. The server constant and the per-user client are in the [Linear provider page](https://docs.r28.ai/charter/charter/auth/providers/linear.md). Two details from there matter here. Linear's access tokens last 24 hours and its refresh tokens rotate, so `on_refresh` has to store each new one. And Linear separates scopes with commas, which the constant already declares. ## When it does not work > **Users in other workspaces can't authorize the app** > > **Public** is off. Open the application from > [linear.app/settings/api](https://linear.app/settings/api), switch it on and > save. > **invalid\_request: Invalid refresh token, on a refresh that worked yesterday** > > The refresh token was used and its replacement was never saved. Linear > rotates refresh tokens, and the old one stops working 30 minutes after it > was used. Linear says so with `invalid_request` rather than > `invalid_grant`. Store the new one in `on_refresh`, then have the user > connect again. > **401 on a token that should be valid** > > Linear wants an OAuth token sent as `Bearer` and a personal API key sent > with no scheme at all. The pack tells them apart by the key's `lin_api_` > prefix, so make sure what you hand it is the access token, not the client > secret. ## Related * [Linear OAuth](https://docs.r28.ai/charter/charter/auth/providers/linear.md) — the server constant, and a pasted key beside OAuth in one configuration * [Getting the grant](https://docs.r28.ai/charter/charter/auth/oauth-flow.md) — the two routes, `state` and PKCE, inside your app * [Linear](https://docs.r28.ai/charter/charter/packs/linear.md) — the pack, and why a personal key goes out with no scheme This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.