Linear adapter: refreshClientCredentialsToken() omits app:mentionable scope

[Fouadktb]

Bug Description

The LinearAdapter.refreshClientCredentialsToken() method hardcodes the OAuth scope to read,write,comments:create,issues:create — it does not include app:mentionable.

Steps to Reproduce

1. Create a Linear OAuth app with client credentials enabled and agent session events enabled
2. Install the app to a workspace with actor=app and scope=read,write,comments:create,issues:create,app:mentionable
3. Confirm the app shows as "Agent" in Linear and appears in @mention autocomplete
4. Start your server — the adapter calls refreshClientCredentialsToken() during initialize()
5. Check Linear — the app has switched from "Agent" to "App" and is no longer @mentionable

Expected Behavior

The app should remain as "Agent" with app:mentionable capabilities after adapter initialization. The client credentials token request should include all scopes the app was installed with.

Actual Behavior

The adapter requests a client credentials token with only read,write,comments:create,issues:create (hardcoded on https://github.com/vercel/chat/blob/main/packages/adapter-linear/src/index.ts), omitting app:mentionable. This downgrades the app from Agent to App on every server restart/token refresh.

Additionally, AgentSessionEvent webhooks (required for app:mentionable apps) are silently ignored — the adapter only handles Comment and Reaction types.

Code Sample

Workaround — pre-fetch token with correct scopes and bypass the adapter's built-in token request:

  const res = await fetch('https://api.linear.app/oauth/token', {
    method: 'POST',
    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
    body: new URLSearchParams({
      grant_type: 'client_credentials',
      client_id: process.env.LINEAR_CLIENT_ID!,
      client_secret: process.env.LINEAR_CLIENT_SECRET!,
      scope: 'read,write,comments:create,issues:create,app:mentionable',
    }),
  })
  const { access_token } = await res.json()

  const bot = new Chat({
    adapters: {
      linear: createLinearAdapter({ accessToken: access_token }),
    },
  })

Chat SDK Version

4.20.1

Node.js Version

No response

Platform Adapter

Linear

Operating System

macOS

Additional Context

The adapter also silently ignores AgentSessionEvent webhooks (required for app:mentionable apps). First-class support for Linear Agent Sessions (emitting activities via agentActivityCreate) would be valuable.