feat: add comprehensive AI assistant guide for Wrappers project

[burmecia]

Summary

This PR adds CLAUDE.md, a comprehensive guide designed to help AI assistants understand the Wrappers project structure, architecture, and development workflows. This document serves as a reference for code generation, debugging, and contributing to the project.

Key Changes

• Project Overview: Documented the purpose of Wrappers as a PostgreSQL FDW framework written in Rust
• Repository Structure: Mapped out the workspace organization including core framework, native FDWs, and Wasm FDWs
• Core Components: Detailed the ForeignDataWrapper trait interface with all required and optional methods
• Data Types Reference: Documented key types like Cell, Row, Column, Qual, Sort, and Limit
• Available FDWs: Created a comprehensive table of all 15 native FDWs and 12 Wasm FDWs with write support indicators
• Development Workflows: Provided step-by-step instructions for:
  • Prerequisites and toolchain setup
  • Building native and Wasm FDWs
  • Running interactive development with pgrx
  • Testing with Docker Compose
  • Code quality checks (fmt, clippy)
• Code Patterns: Included practical examples for:
  • Error handling with custom error types
  • FDW implementation template
  • File organization conventions
  • Query pushdown usage
• Common Tasks: Documented procedures for adding new FDWs, debugging, and working with options
• CI/CD Reference: Listed GitHub Actions workflows for testing and releases
• Important Notes: Highlighted key constraints like native FDW contribution restrictions and materialized view caveats

Implementation Details

The guide is structured to be both a learning resource and a quick reference, with:

• Clear code examples using actual patterns from the codebase
• Feature flag mappings for PostgreSQL version support
• Workspace configuration details (Rust 1.88.0, pgrx 0.16.1)
• Links to external documentation (fdw.dev, docs.rs)

This document will help AI assistants provide more accurate and contextual assistance when working on Wrappers-related tasks.

https://claude.ai/code/session_01EYhGdmQMcA4JJK69tXTUYq

[Copilot]

Pull request overview

This PR adds CLAUDE.md, an AI-assistant–focused guide that documents the Wrappers project’s architecture, core traits and types, FDW inventory, and standard development workflows. It is intended as a central reference for automated tools generating or reviewing code in this repository.

Changes:

• Added a high-level project and workspace overview, including key components (ForeignDataWrapper trait, core types, and macros).
• Documented native and Wasm FDWs, along with build, test, and CI/CD workflows, and common implementation patterns (error handling, FDW layout, query pushdown, options handling).
• Captured contribution-related guidance and operational notes (feature flags, version support, rowid semantics, and contribution preferences for Wasm vs native FDWs).

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