Sub-Agent Customization UI

[EricsenSemedo]

PRD: Sub-Agent Customization UI

Problem

T3 Code supports .claude/agents/ configuration files for sub-agents, but there's no UI to manage them. Users must manually edit YAML/JSON files.

Goals

• Visual UI for managing sub-agent configurations
• Tool selection per agent (whitelist/blacklist)
• Model routing (assign specific models to specific agents)
• System prompt editor with syntax highlighting
• Agent memory configuration

User Stories

• As a user, I want to create/edit/delete sub-agents from the UI
• As a user, I want to select which tools each agent can access
• As a user, I want to assign different AI models to different agents
• As a user, I want to write and test system prompts in an editor

Requirements

• File-backed: Changes persist to .claude/agents/ directory
• Live preview: See agent config as it would be interpreted
• Validation: Show errors for invalid configurations
• Import/export: Share agent configs between projects

Success Metrics

• Users can create a working agent config without touching files
• Zero data loss on save/load cycles
• Config changes take effect on next agent invocation

Scope

• In scope: CRUD UI for agents, tool picker, model selector, prompt editor
• Out of scope: Agent execution UI, multi-agent orchestration, runtime monitoring

Priority

Later milestone (after canvas MVP)