[Reply To Review Comments] Phase 1: Core Tool Implementation

[lossyrob]

Phase 1: Core Tool Implementation

This PR implements the core ReplyToReviewComment MCP tool that enables AI agents to reply directly to pull request review comment threads, maintaining conversation context at specific code locations.

Changes Made

Implementation (pkg/github/pullrequests.go):

• Added ReplyToReviewComment function following established MCP tool patterns
• Tool name: reply_to_review_comment
• Parameters: owner, repo, pull_number, comment_id, body
• Uses RequiredBigInt for comment_id (int64 type)
• Calls GitHub REST API's CreateCommentInReplyTo method
• Returns MinimalResponse with reply ID and URL on success (HTTP 201)
• Proper error handling with ghErrors.NewGitHubAPIErrorResponse
• Marked as write tool (ReadOnlyHint: false)

Verification Results

✅ Automated Checks:

• Code compiles successfully: go build ./cmd/github-mcp-server
• All tests pass: script/test
• No linting errors: script/lint (0 issues)
• Function signature matches established patterns

✅ Manual Review:

• Follows exact pattern from CreatePullRequest and other PR tools
• All required parameters properly defined with correct types
• Parameter validation uses appropriate helpers
• Error handling follows ghErrors pattern
• Status code check correctly catches edge cases
• Response body properly closed after API call
• No unused parameters, dead code, or over-engineering

Implementation Plan

Related to Phase 1 in .paw/work/reply-to-review-comments/ImplementationPlan.md

Next Phases:

• Phase 2: Toolset Integration - Register tool in pull_requests toolset
• Phase 3: Testing - Add unit tests and toolsnaps
• Phase 4: Documentation - Generate updated README.md

Issue Reference

Implements: github#1323

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🐾 Generated with PAW

[lossyrob]

🐾 Implementation Reviewer 🤖:

Phase 1 implementation has been reviewed and is ready for human review.

Review Summary

The Implementation Agent delivered an excellent implementation that follows all established patterns correctly. The code is clean, well-structured, and requires no improvements.

Code Quality Assessment

✅ Pattern Compliance:

• Follows exact pattern from CreatePullRequest and other PR tools in the codebase
• Function signature, tool definition, and handler implementation are all correct
• Proper use of RequiredParam, RequiredInt, and RequiredBigInt for parameter validation
• Error handling follows ghErrors.NewGitHubAPIErrorResponse pattern

✅ Design Quality:

• No unused parameters or dead code
• No over-engineering or unnecessary complexity
• Status code check is necessary (catches cases where err==nil but status≠201)
• MinimalResponse format used consistently

✅ Documentation:

• Clear function doc comment
• Descriptive tool description for users
• All parameters have helpful descriptions
• Code is self-documenting

Testing Results

✅ All tests pass: script/test
✅ No linting errors: script/lint (0 issues)
✅ Code compiles successfully

Commits Pushed

• f5140d4 - Implementation Agent's functional code (Add ReplyToReviewComment tool)
• No additional commits from review (code quality was excellent as-is)

The PR is ready for human review. No changes were needed from the implementation review phase.