[BUG] Input tag 'reasoning' found using 'type' does not match any of the expected tags on Claude Sonnet 4.5

[cardil]

Problem (one or two sentences)

Persistent error started happening lately: Input tag 'reasoning' found using 'type' does not match any of the expected tags

Context (who is affected and when)

I think it happens when the context is starting to fill up >70%. Doesnot matter if reasoning is enabled or disabled.

Reported here as well: #9392 (comment)

Reproduction steps

1. Do the agent stuff on new session
2. When context fills up to about 160k/200k tokens you may see the error

Expected result

Message should be correct and accepted by API

Actual result

Error is shown. Can't be retried. New session is the only way to continue.

Variations tried (optional)

No response

App Version

3.34.3

API Provider (optional)

Google Vertex AI

Model Used (optional)

Claude Sonnet 4.5

Roo Code Task Links (optional)

No response

Relevant logs or errors (optional)

400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.1.content.0: Input tag 'reasoning' found using 'type' does not match any of the expected tags: 'document', 'image', 'redacted_thinking', 'search_result', 'text', 'thinking', 'tool_result', 'tool_use'"},"request_id":"req_vrtx_011CVUxYcMYbPv2DnWqqt7nb"}

[cardil]

[roomote]

I'm exploring a potential fix for this issue. The problem appears to be that the AnthropicVertexHandler is not filtering out reasoning type messages before sending them to the Vertex AI API, which doesn't recognize this tag. I'll open a PR to share progress.

[roomote]

Opened a PR with my attempt at addressing this issue: #9584. Feedback welcome!

[QuinRiva]

I'm experiencing the same issues - I suspect this might be something to do with Vertex AI. I have experienced it with both Gemini 3 and Claude Opus 4.5.

Most recently with Claude, I was only using 57k out of 200k context, and it occurred on the 8th API call. Roo attempted to read a 30Mb json file, then I immediately received this error.

400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.1.content.0: Input tag 'reasoning' found using 'type' does not match any of the expected tags: 'document', 'image', 'redacted_thinking', 'search_result', 'text', 'thinking', 'tool_result', 'tool_use'"},"request_id":"req_vrtx_011C...truncated..."}