CommentService tests (10 tests): - Successful comment creation - Auth failure when no session - Network error handling - 401 response handling - Invalid responses (null data, missing uri, empty uri) - Server error handling - Nested reply request format CommentsProvider.createComment tests (12 tests): - Validation: empty content, whitespace-only, exceeds limit - Emoji counting with grapheme clusters - Error states: no post loaded, no CommentService - Top-level comment (reply to post) - Nested comment (reply to comment) - Content trimming - Refresh after success - Exception propagation - Boundary testing at max length All 52 tests pass. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>