[Bug]: Invalid model identifier for Claude Opus 4.6 via Bedrock

[territov]

Bug Description

When using Forge with the Bedrock provider, selecting Claude Sonnet 4.5 works correctly. However, selecting Claude Opus 4.6 fails with:

ERROR: ValidationException: The provided model identifier is invalid.

The model identifier being sent is anthropic.claude-opus-4-6-v1:0, but the correct Bedrock model ID is anthropic.claude-opus-4-6-v1 (without the :0 suffix).

Steps to Reproduce

1. Configure Forge to use the Bedrock provider
2. Set the model to Claude Opus 4.6
3. Attempt any prompt

Expected Behavior

Request succeeds using model ID anthropic.claude-opus-4-6-v1

Actual Behavior

Request fails with ValidationException because the :0 suffix is appended to the model ID

Error Logs

Forge Version

2.1.0

Operating System

macOS

OS Version

MacOS Tahoe 26.2

AI Provider

None

Model

claude-opus-4.6

Installation Method

Other

Configuration

I installed forge via `curl -fsSL https://forgecode.dev/cli | sh`

[territov]

After fixing the model identifier issue, via ~/forge/.config.json, requests to Claude Opus 4.6 via Bedrock fail on the second turn with:

ERROR: ValidationException: The model returned the following errors:
messages.1.content.1.thinking.signature: Field required

This indicates that when Forge replays conversation history, it's not including the required signature field in thinking content blocks. The Anthropic API requires this field to be preserved and sent back in subsequent turns.

This only affects models with extended thinking enabled (e.g., Claude Opus 4.6).