[BUG] Bedrock: responses cut at the output token limit end with an unrelated error, and the limit cannot be raised

[LouisClt]

Describe the bug
When a Bedrock response reaches the output token limit, AWS returns stopReason: "max_tokens", but the Bedrock provider ignores it. The response just stops (often mid-thinking, before any tool call), and the task then reports an unrelated error such as "You did not use a tool…" instead of saying the output limit was reached.

This is more likely on adaptive-thinking models (Claude 4.7+), where Zoo Code sends effort: "xhigh" without a thinking budget, so thinking can use most of the limit.

The user also cannot work around it: with reasoning enabled, the "Max Output Tokens" slider stops at 16,384 on Bedrock, while the direct Anthropic provider allows up to 64k/128k for the same models.

To Reproduce
Steps to reproduce the behavior:

1. Select the Amazon Bedrock provider and anthropic.claude-opus-4-8, with reasoning enabled.
2. Open the "Max Output Tokens" slider: its maximum is 16,384.
3. Give a complex task (e.g. a large refactor or a long file to write).
4. If thinking and output exceed the limit, the response stops mid-way and the task reports a generic error.

Expected behavior

• When a response hits the output limit, the user gets a clear message (e.g. "Output token limit reached, consider increasing Max Output Tokens").
• The slider can go up to the model's documented limit, as with the Anthropic provider. The 16,384 default can stay: a high max_tokens reserves Bedrock quota up front and reduces the context available for the conversation.

Screenshots

Video

What version of zoo are you running
3.82.1

Additional context

• messageStop events are skipped without reading stopReason in the Bedrock stream loop (src/api/providers/bedrock.ts).
• In packages/types/src/providers/bedrock.ts, maxTokens is 8192 for Claude Sonnet 4.5/4.6/5 and Opus 4.7/4.8/5, versus 64_000/128_000 in packages/types/src/providers/anthropic.ts. With reasoning enabled, the slider maximum is max(model maxTokens, 16_384), hence 16,384 on Bedrock. AWS documents 64K max output tokens for Claude Sonnet 4.5: https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-anthropic-claude-sonnet-4-5.html
• Trade-offs of a higher limit: Bedrock deducts input + max_tokens from the tokens-per-minute quota at request start (https://docs.aws.amazon.com/bedrock/latest/userguide/quotas-token-burndown.html), and Zoo Code reserves max_tokens from the context window (src/core/context-management/index.ts).