Add unified MCPConfigRenderer to eliminate duplication across engines

[Copilot]

Currently, MCP configuration rendering is duplicated across 4 engines (Claude, Copilot, Codex, Custom) with ~85% code similarity, creating maintenance burden and increasing bug surface.

Changes

New unified renderer

• pkg/workflow/mcp_renderer.go - MCPConfigRendererUnified with configurable rendering for all MCP server types
• pkg/workflow/mcp_renderer_test.go - 20 test cases covering all engines and format combinations

Options struct

MCPRendererOptions controls engine-specific variations:

• IncludeCopilotFields bool - Adds "type": "local" and "tools": ["*"] for Copilot
• InlineArgs bool - Single-line args (Copilot) vs multi-line (Claude/Custom)
• Format string - Supports "json" and "toml"
• IsLast bool - Controls trailing comma placement

Unified methods

All wrap existing rendering functions for backward compatibility:

• RenderGitHubMCP() - Local (Docker) and remote modes
• RenderPlaywrightMCP() - JSON/TOML with configurable arg formatting
• RenderSafeOutputsMCP() - JSON/TOML with proper env var escaping
• RenderAgenticWorkflowsMCP() - JSON/TOML support

Usage

// Copilot engine
renderer := NewMCPConfigRenderer(MCPRendererOptions{
    IncludeCopilotFields: true,
    InlineArgs:           true,
    Format:               "json",
    IsLast:               false,
})

// Claude engine
renderer := NewMCPConfigRenderer(MCPRendererOptions{
    IncludeCopilotFields: false,
    InlineArgs:           false,
    Format:               "json",
    IsLast:               true,
})

// Codex engine
renderer := NewMCPConfigRenderer(MCPRendererOptions{
    Format: "toml",
})

Existing engine code remains unchanged; this provides a cleaner API for future refactoring.

Original prompt

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This section details on the original issue you should resolve

<issue_title>[task] Create unified MCPConfigRenderer with base implementations</issue_title>
<issue_description>## Objective
Create a new pkg/workflow/mcp_renderer.go file with a unified MCP configuration renderer that eliminates duplication across 20+ similar rendering functions.

Context

Currently, MCP configuration rendering is duplicated across 4 engine implementations (Claude, Copilot, Codex, Custom) with ~85% code similarity. This creates maintenance burden and increases bug surface. Related to #3942.

Approach

1. Create new file pkg/workflow/mcp_renderer.go
2. Define MCPRendererOptions struct with engine-specific configuration options:
   • IncludeCopilotFields bool
   • InlineArgs bool
   • Format string (yaml/toml)
   • IsLast bool
3. Implement MCPConfigRenderer struct with unified rendering methods:
   • RenderGitHubMCP(yaml *strings.Builder, githubTool any, workflowData *WorkflowData)
   • RenderPlaywrightMCP(yaml *strings.Builder, playwrightTool any)
   • RenderSafeOutputsMCP(yaml *strings.Builder)
   • RenderAgenticWorkflowsMCP(yaml *strings.Builder)
4. Add constructor NewMCPConfigRenderer(opts MCPRendererOptions) *MCPConfigRenderer

Files to Create

• pkg/workflow/mcp_renderer.go - New unified renderer implementation

Acceptance Criteria

• MCPConfigRenderer struct created with unified rendering logic
• MCPRendererOptions supports all engine-specific variations
• All 4 MCP types have unified Render* methods
• Constructor NewMCPConfigRenderer() properly initializes options
• Code compiles without errors
• Unit tests created for the new renderer in pkg/workflow/mcp_renderer_test.go
• Tests verify YAML and TOML output formats
• Tests cover all option combinations
  Related to [refactor] 🔧 Semantic Function Clustering Analysis: Refactoring Opportunities #3942

AI generated by Plan Command for #3942</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [task] Create unified MCPConfigRenderer with base implementations #4018

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[Copilot]

Pull Request Overview

This PR introduces a unified MCPConfigRenderer to eliminate code duplication across four engine implementations (Claude, Copilot, Codex, Custom) that were rendering MCP server configurations with ~85% code similarity. The refactoring consolidates common MCP rendering logic into a single, configurable renderer.

Key changes:

• New MCPConfigRendererUnified struct with engine-agnostic rendering methods
• MCPRendererOptions struct to configure engine-specific behavior (Copilot fields, inline args, format, trailing commas)
• Four unified render methods: RenderGitHubMCP, RenderPlaywrightMCP, RenderSafeOutputsMCP, RenderAgenticWorkflowsMCP

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
pkg/workflow/mcp_renderer.go	New unified renderer implementation with configurable options for all MCP server types (175 lines)
pkg/workflow/mcp_renderer_test.go	Comprehensive test suite with 20 test cases covering all engines and format combinations (523 lines)

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