[bug] v0.8.0 Introduced thinking block bug with Claude Sonnet 4: "AI_APICallError: messages.3.content.0.type: Expected `thinking` or `redacted_thinking`, but found `text`."

[grantjayy]

When using Claude Sonnet 4 with thinking enabled on Opencode v0.8.0, an Anthropic api error happens after tool invocation. Only happens after tool call (specifically read).

This bug is not present in Opencode v0.7.9.

Here is a share URL of the chat context: https://opencode.ai/s/6z4bcRrU

Here is the full API error (not listed in chat context):

AI_APICallError: messages.3.content.0.type: Expected `thinking` or
`redacted_thinking`, but found `text`. When `thinking` is enabled, a final `assistant`
message must start with a thinking block (preceeding the lastmost set of `tool_use`
and `tool_result` blocks). We recommend you include thinking blocks from previous
turns. To avoid this requirement, disable `thinking`. Please consult our documentation
at https://docs.anthropic.com/en/docs/build-with-claude/extended-thinking

Here is my .opencode.json config:

{
  "$schema": "https://opencode.ai/config.json",
  "provider": {
    "anthropic": {
      "options": {
        "headers": {
          "anthropic-beta": "context-1m-2025-08-07"
        }
      },
      "models": {
        "claude-opus-4-1-20250805": {
          "limit": {
            "context": 200000,
            "output": 12288
          },
          "options": {
            "thinking": {
              "type": "enabled",
              "budgetTokens": 1024
            }
          }
        },
        "claude-sonnet-4-20250514": {
          "limit": {
            "context": 1000000,
            "output": 59904
          },
          "options": {
            "thinking": {
              "type": "enabled",
              "budgetTokens": 4096
            }
          }
        }
      }
    }
  },
  "agent": {
    "CSS Tailwind (Build)": {
      "mode": "primary",
      "model": "claude-opus-4-1-20250805",
      "description": "Agent for handling HTML with Tailwind CSS",
      "prompt": "{file:<txt-file>}"
    }
  }
}

[rekram1-node]

thanks for raising, looks like it was due to these changes: #2577

[rekram1-node]

I think the issue is that "providerOptions": {
"anthropic": {
"signature": "...."
}
}

Isn't being saved to the reasoning messages

shouldn't be hard to fix just need to find where

[rekram1-node]

should be fixed in next release I tested with quite a few models

[jessevdp]

I'm running into a similar issue with Claude 4.5 Sonnet hosted on Google Vertex (through openai-compatible proxy: LiteLLM...)

messages.3.content.0.type: Expected `thinking` or `redacted_thinking`, but found `tool_use`. When `thinking` is enabled, a final `assistant` message must start with a thinking block (preceeding the lastmost set of `tool_use` and `tool_result` blocks). We recommend you include thinking blocks from previous turns. To avoid this requirement, disable `thinking`. Please consult our documentation at https://docs.claude.com/en/docs/build-with-claude/extended-thinking

{
  "type": "error",
  "error": {
    "type": "invalid_request_error",
    "message": "messages.3.content.0.type: Expected `thinking` or `redacted_thinking`, but found `tool_use`. When `thinking` is enabled, a final `assistant` message must start with a thinking block (preceeding the lastmost set of `tool_use` and `tool_result` blocks). We recommend you include thinking blocks from previous turns. To avoid this requirement, disable `thinking`. Please consult our documentation at https://docs.claude.com/en/docs/build-with-claude/extended-thinking"
  },
  "request_id": "..."
}

Should I open a separate issue?