Add package documentation to 9 MCP core files

[Copilot]

MCP integration code (10,979 LOC) had 4.0% comment ratio with no package-level documentation across 9 critical files, creating steep learning curve for contributors.

Changes

Added Go-style package documentation to:

• mcp_gateway_config.go - Gateway configuration: defaults, port/domain/API key management, sandbox detection
• mcp_environment.go - Environment variable collection: GitHub tokens (custom/app/default precedence), safe-outputs/inputs, Playwright secrets, HTTP MCP headers
• mcp_setup_generator.go - Setup orchestration: Docker images, config files, HTTP servers (safe-outputs:3001, safe-inputs:3000), gateway startup, engine-specific rendering
• mcp_gateway_constants.go - Port constants with historical context
• mcp_github_config.go - GitHub MCP configuration: local/remote modes, security (read-only/lockdown/automatic detection), toolsets expansion, GitHub App token minting
• mcp_config_utils.go - URL rewriting for Docker networking (localhost → host.docker.internal)
• mcp_config_playwright_renderer.go - Playwright containerization: Docker args, domain restrictions, expression extraction
• mcp_renderer.go - Unified rendering: engine-specific formats (Copilot/Claude/Codex/Custom), HTTP vs stdio transport, variable resolution patterns
• mcp_config_builtin.go - Built-in servers: safe-outputs (HTTP), agentic-workflows (stdio), transport differences, environment passthrough

Each file documents:

• Purpose and key responsibilities
• Architecture and configuration patterns
• Related files and cross-references
• Security considerations and token precedence
• Transport types and engine compatibility

Example

// Package workflow provides MCP gateway configuration management for agentic workflows.
//
// MCP Gateway Configuration
//
// The MCP gateway acts as a proxy between AI engines and MCP servers, providing
// protocol translation, connection management, and security features.
//
// Token precedence for GitHub MCP:
//  1. GitHub App token (if app configuration exists)
//  2. Custom github-token from tool configuration
//  3. Top-level github-token from frontmatter
//  4. Default GITHUB_TOKEN secret

Total: 507 lines of documentation added across 9 files.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Code Quality] Add package documentation to 9 MCP core files</issue_title>
<issue_description>### Description

Add comprehensive package-level documentation to 9 critical MCP files currently missing documentation. This addresses a significant documentation gap where the MCP integration code (10,979 LOC) has only a 4.0% comment ratio, far below the 30% target in AGENTS.md validation guidelines.

Current State

Files missing package documentation:

1. pkg/workflow/mcp_gateway_config.go
2. pkg/workflow/mcp_environment.go
3. pkg/workflow/mcp_setup_generator.go
4. pkg/workflow/mcp_gateway_constants.go
5. pkg/workflow/mcp_github_config.go
6. pkg/workflow/mcp-config-utils.go
7. pkg/workflow/mcp-config-playwright.go
8. pkg/workflow/mcp_renderer.go
9. pkg/workflow/mcp-config-builtin.go

Impact:

• Steep learning curve for contributors
• Increased onboarding time
• Difficulty understanding MCP architecture
• Lack of clear documentation of design decisions

Documentation Pattern

Follow Go documentation conventions for each file:

// Package workflow provides MCP gateway configuration for workflow compilation.
//
// The MCP gateway acts as a proxy between AI engines and MCP servers, providing:
// - Protocol translation and connection management
// - Secret injection and credential handling
// - HTTP header support for authentication
// - Network isolation and domain restrictions
//
// Configuration is defined in workflow frontmatter and compiled into
// GitHub Actions workflow YAML. The gateway runs as a containerized service
// during workflow execution.
//
// Related files:
//   - mcp_gateway_constants.go: Gateway version and container constants
//   - mcp_gateway_schema_validation.go: Configuration validation
//   - mcp_setup_generator.go: Setup step generation
//
// Example usage:
//   config := &GatewayConfig{
//       Version: constants.DefaultMCPGatewayVersion,
//       Container: constants.DefaultMCPGatewayContainer,
//   }
package workflow

File-Specific Documentation Topics

1. mcp_gateway_config.go: MCP gateway configuration types and validation
2. mcp_environment.go: Environment variable generation for MCP server execution
3. mcp_setup_generator.go: GitHub Actions setup steps for MCP server initialization
4. mcp_gateway_constants.go: Version constants and default values for MCP gateway
5. mcp_github_config.go: GitHub MCP server configuration and toolset management
6. mcp-config-utils.go: Utility functions for MCP configuration processing
7. mcp-config-playwright.go: Playwright MCP server configuration and Docker setup
8. mcp_renderer.go: YAML rendering for MCP server definitions in GitHub Actions
9. mcp-config-builtin.go: Built-in MCP server definitions and defaults

Success Criteria

• All 9 files have comprehensive package-level documentation
• Comments explain purpose, responsibilities, and key concepts
• Follow Go documentation style (complete sentences, starts with package name)
• Include examples where appropriate
• Link related files and packages
• Comment ratio improves from 4.0% toward 30% target
• make agent-finish passes without errors

Priority

Medium - Improves maintainability and contributor onboarding

Estimated Effort

Small (6-8 hours) - Focused documentation task

Source

Extracted from MCP Server Integration Quality Report githubnext/gh-aw#11508 (Task 3)

Workflow Run: §21287628398

AI generated by Discussion Task Miner - Code Quality Improvement Agent

• expires on Feb 13, 2026, 9:09 PM UTC

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

• Fixes [Code Quality] Add package documentation to 9 MCP core files #12826

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.