fix(ai-amazon-bedrock): strip thinking from additionalModelRequestFields when using generateObject

[Zelys-DFKH]

Type

• Bug Fix

Description

generateObject fails with "Thinking may not be enabled when tool_choice forces tool use" when extended thinking is configured via withConfigOverride. This affects both direct generateObject calls and the common case where a parent generateText propagates the Config service (via Effect.provideService) into a tool handler that internally calls generateObject.

Root cause

makeRequest builds the Bedrock request by spreading ...config first, which puts additionalModelRequestFields.thinking into the request object. The additionalModelRequestFields override at the end of the request object only fires when additionalTools is present. When additionalTools is undefined (the usual case), nothing overwrites the thinking key that ...config already placed, and the request is rejected.

Fix

Pre-compute requestAdditionalFields before the request object. In the json path (generateObject), merge config.additionalModelRequestFields with additionalTools and strip thinking. Return an explicit object even when empty so the final spread overwrites whatever ...config put in the request. When no additional fields are configured at all, return undefined to avoid injecting an empty object.

Tests

Adds packages/ai/amazon-bedrock/test/AmazonBedrockLanguageModel.test.ts with four cases:

• thinking is stripped for generateObject (forced toolChoice) and toolChoice.tool is set correctly
• thinking is preserved for generateText (no forced toolChoice)
• No additionalModelRequestFields is set when none was configured and generateObject is used
• Non-thinking fields survive alongside thinking being stripped from a mixed additionalModelRequestFields

Note: PR #6160 is also open and adds AmazonBedrockLanguageModel.test.ts (token usage in streaming). If that merges first, the two files can be merged with no conflicts - the describe blocks cover unrelated behavior.

Related

• Closes @effect/ai-amazon-bedrock: withConfigOverride thinking config leaks into tool call handlers, breaking generateObject #6185

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Name	Type
@effect/ai-amazon-bedrock	Patch

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