fix(provider): filter empty text content blocks for Bedrock

[zerone0x]

Summary

Fixes #15715
Fixes #13811

Problem

AWS Bedrock rejects API requests that contain empty text content blocks with:

ValidationException: messages: text content blocks must be non-empty

Root Cause

normalizeMessages() in transform.ts already filters out empty text/reasoning content blocks — but the guard only applied to @ai-sdk/anthropic. AWS Bedrock (@ai-sdk/amazon-bedrock) has the same constraint on the API level, so it was silently passing empty blocks through.

Fix

Extend the existing empty-content filter to cover @ai-sdk/amazon-bedrock as well:

- // Anthropic rejects messages with empty content - filter out empty string messages
+ // Anthropic and Bedrock reject messages with empty content - filter out empty string messages
  // and remove empty text/reasoning parts from array content
- if (model.api.npm === "@ai-sdk/anthropic") {
+ if (model.api.npm === "@ai-sdk/anthropic" || model.api.npm === "@ai-sdk/amazon-bedrock") {

Tests

Added a new describe block mirroring the Anthropic empty-content filtering tests for Bedrock, covering:

• Empty string content messages
• Empty text parts in array content
• All-empty messages being removed entirely
• Non-text/reasoning parts preserved even when text parts are empty

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[github-actions]

The following comment was made by an LLM, it may be inaccurate:

I found a potentially related PR:

Related PR:

• fix: filter empty content blocks for Bedrock provider #14586 - "fix: filter empty content blocks for Bedrock provider" (fix: filter empty content blocks for Bedrock provider #14586)

This appears to be addressing the exact same issue as the current PR #15777. Both are about filtering empty content blocks for the Bedrock provider. You should verify whether #14586 was already merged or closed, and if so, whether the current PR (#15777) is based on or supersedes it.

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