[BUG] V1 blockBinding: false opt-out is ignored after upgrading to V2

[dmitrii-galantsev]

Description

V1 lets a model opt out of Anthropic thinking block binding with blockBinding: false (#46820). After moving to V2, that opt-out does nothing, so endpoints that reject the field fail again:

thinking.adaptive.block_binding: Extra inputs are not permitted

The V2 config migration copies thinking.blockBinding into the model settings, but V2 decides from compatibility.supportsThinkingBlockBinding and never reads the setting. Model.Compatibility also doesn't declare that field yet, so it's dropped from config either way.

#48793 covers this in the protocol layer but no longer applies to v2. #51864 and #52172 add the compatibility field but don't touch the V1 config path.

Plugins

None

OpenCode version

2.0.18 (also current v2)

Steps to reproduce

1. Use a legacy (provider) config for an Anthropic-compatible endpoint that rejects block_binding, with the V1 opt-out on a Claude 5.1+ model:

   {
     "provider": {
       "gateway": {
         "npm": "@ai-sdk/anthropic",
         "options": { "baseURL": "https://gateway.example.com/v1" },
         "models": {
           "claude-opus-5-5": {
             "options": { "thinking": { "type": "adaptive", "blockBinding": false } }
           }
         }
       }
     }
   }

2. opencode run -m gateway/claude-opus-5-5 "hi"

3. The request fails with thinking.adaptive.block_binding: Extra inputs are not permitted. The same config works on V1.

Screenshot and/or share link

N/A

Operating System

Linux

Terminal

N/A (opencode run)

[github-actions]

---

This issue might be a duplicate of an existing issue. Please check:

• [FEATURE]: allow config to opt out of Anthropic thinking block binding in V2 #48757: Requests V2 support for opting out of Anthropic thinking block binding; this report describes the legacy V1 blockBinding: false setting no longer taking effect after upgrading to V2.

[rekram1-node]

merged fix