Bedrock GPT-6 Astra fails after the read tool returns an image

Description

Reading an image with amazon-bedrock/global.openai.gpt-6-astra fails on the next model request:

undefined: This model doesn't support the image field for user messages. Remove image and try again.

The response is HTTP 400 from Bedrock ConverseStream. Retrying the conversation keeps failing because the image remains in the tool history.

Direct AWS SDK tests with the same model, region (us-east-2), and synthetic PNG isolate the problem: a user-level image succeeds, an image inside toolResult.content fails, and moving it beside the tool result succeeds. Astra supports images; it rejects this placement.

supportsMediaInToolResult() currently assumes all Bedrock models accept tool-result images. A local plugin that hoists Astra's tool images fixes both reading new images and resuming the failed conversation. Running the same OpenCode test with --pure reproduces the error.

Plugins

Reproduced with --pure (external plugins disabled).

OpenCode version

1.18.29

Steps to reproduce

1. Configure Amazon Bedrock in us-east-2 with access to global.openai.gpt-6-astra.
2. Run opencode run --pure -m amazon-bedrock/global.openai.gpt-6-astra "Use the read tool to open /absolute/path/to/image.png and describe it."
3. The read tool completes, but the next model request fails with the error above.

Operating System

Linux