Overview

Replace the current langchaingo-based agent orchestration framework with the GitHub Copilot SDK (github.com/github/copilot-sdk/go) for �zd agent mode.

Motivation

• Production agent runtime: Copilot SDK uses the same battle-tested engine powering Copilot CLI
• Built-in session management: Create, resume, destroy sessions; automatic conversation history
• Multi-model support: GPT-4, GPT-5, Claude via Copilot subscription without per-provider code
• Native MCP server loading: SDK supports MCPServerConfig natively with stdio and http transports
• Built-in tool permissions: PermissionHandler, PreToolUseHandler, AvailableTools/ExcludedTools
• Reduce maintenance: Remove ~2500 lines of custom orchestration, model providers, and consent system
• Agent modes: Built-in Autopilot, Interactive, Plan, Shell modes

Key Decisions

• Copilot subscription recommended for agent mode (no offline/Ollama fallback)
• langchaingo fully removed — no parallel path
• 13 of 24 built-in tools deprecated — Copilot CLI provides identical file I/O, search, and command execution
• Entire consent system replaced by SDK's PermissionHandler + PreToolUseHandler + AvailableTools/ExcludedTools
• azd config system (�i.agent.* keys) enables customization of model, MCP servers, tool control
• 11 azd-specific MCP guidance tools kept — served via �zd mcp start

Architecture

azd (Go application) → copilot.NewClient() → copilot-sdk/go (thin client) → (JSON-RPC over stdio) → copilot-agent-runtime → LLM APIs (GPT-4, GPT-5, Claude, etc.)

Migration Approach (3 Phases)

1. Phase 1: Add SDK Foundation — New code alongside existing (no deletions)
2. Phase 2: Update Call Sites — Switch to new implementation
3. Phase 3: Remove Old Code — Delete unused langchaingo code

Each phase is independently landable as a PR.

Child Issues

See linked issues below for detailed work items per phase.