Composer 2.5 Classic via Custom ACP

Support Help
,
1

Summary

When using the Cursor agent via ACP in Zed editor, Composer 2.5 is permanently locked to Fast mode. There is no way to switch to the classic (non-fast) variant through settings or configuration.

Details

I was trying to disable Fast mode for Composer 2.5 in my Zed settings.json using the favorite_config_option_values config:

"agent_servers": {
  "cursor": {
    "favorite_config_option_values": {
      "model": [
        "default[]",
        "composer-2.5[fast=true]"
      ]
    },
    "type": "registry"
  }
}

Impact

Fast mode is 6x more expensive than the standard tier (input: $3.00 vs $0.50 per million tokens). Users who prefer the standard variant for cost savings or unattended/background tasks have no way to opt out when using Cursor via ACP.

5

Hey, this is a known limitation of the ACP integration. Third-party ACP clients like Zed and IntelliJ don’t declare the capability our backend uses to show model variants, so every model collapses to its default variant. For Composer 2.5, the default is Fast, and the non-Fast variant isn’t sent to the client at all. That’s why favorite_config_option_values in Zed doesn’t change anything, there’s no choice list on the server side.

We’re working on a fix by moving to the standard ACP Session Config Options, so any spec-compliant client can natively render variant selection and thinking level. I can’t share an ETA yet.

Related thread with the same question and explanation: Can't select thinking level or variant in Cursor ACP. I’ll post an update when there’s news.