# Claude Code v1.0.64

> Claude Code v1.0.64, released 30 Jul 2025 (2025-07-30). 4 entries read out of the shipped bundle. Unofficial, and not affiliated with Anthropic.

Web version: https://changelogs.core-directive.com/v/1.0.64

## Changes

### New Features

Agent Model Configuration

- **Configurable AI models for agents**: Agents can now specify which Claude model they should use (Sonnet, Opus, or Haiku)
- **"Inherit" model option**: Agents can inherit the model from the parent conversation, allowing for flexible model usage
- **Environment variable override**: New `CLAUDE_CODE_SUBAGENT_MODEL` environment variable to globally override agent model selection

`  export CLAUDE_CODE_SUBAGENT_MODEL=haiku
  claude # All agents will use Haiku regardless of their configuration`
️ Enhanced Agent Management

- **Edit Model option**: New menu option "Edit model" when managing agents through the interactive UI
- **Model validation**: Agent files now validate model specifications against allowed values (sonnet, opus, haiku, inherit)
- **Agent file model syntax**: Agents can specify their model in the frontmatter:

`  name: my-agent
  description: Description of what this agent does
  model: opus  # New field
  tools: [Read, Write, Bash]`
MCP (Model Context Protocol) Improvements

- **Resource management**: Better handling of MCP resources with proper cleanup and state management
- **Tool namespacing**: MCP tools are now properly namespaced with `mcp__<server-name>__` prefix for better organization
- **Connection stability**: Improved reconnection logic for SSE (Server-Sent Events) based MCP connections

Status Hook Integration

- **External status monitoring**: New internal status hook system for external tools to monitor Claude Code's status
- **JSON-based status communication**: Status information can be passed to external commands via JSON
- **Configurable timeout**: Status hook operations have a 5-second default timeout

### Improvements

UI/UX Enhancements

- **Model display in agent info**: Agent model selection is now displayed in the agent information
- **Better model descriptions**: Clear descriptions for each model option:
- Sonnet: "Balanced performance - best for most agents"
- Opus: "Most capable for complex reasoning tasks"
- Haiku: "Fast and efficient for simple tasks"
- Inherit: "Use the same model as the main conversation"

Bug Fixes

- **Removed duplicate MCP management code**: Cleaned up redundant MCP server management implementation
- **Fixed agent file path handling**: Improved path resolution for agent files across different locations
- **Better error messages**: More descriptive error messages for invalid agent configurations

### Technical Changes

️ Architecture

- **Modular agent system**: Agents now have a more structured configuration with model preferences
- **Improved type safety**: Better validation of agent properties including model selection
- **Resource cleanup**: Proper cleanup of MCP resources when connections are terminated

Compatibility

- **Backward compatible**: Existing agents without model specifications default to Sonnet
- **Survey system**: Added force display option via `CLAUDE_FORCE_DISPLAY_SURVEY` environment variable for testing

### Usage Examples

**Creating an agent with a specific model:**

`# In your .claude/agents/fast-analyzer.md name: fast-analyzer description: Quick code analysis using Haiku for speed model: haiku tools: [Read, Grep, Glob] Your agent prompt here...` **Using the inherit model option:**

`# If you're using Opus in your main conversation claude --model opus # This agent will also use Opus when called name: inherit-example description: Uses the same model as the parent conversation model: inherit tools: [*]` **Global model override:**

`# Force all agents to use Haiku for faster responses export CLAUDE_CODE_SUBAGENT_MODEL=haiku claude` This update focuses on giving users more control over agent behavior through model selection, improving the MCP integration, and enhancing the overall agent management experience.