Implement enhanced list builder with AST traversal and context-aware indentation handling

[Copilot]

Replaced the problematic dual-builder approach (MarkdownListBuilder + MarkdownListItemBuilder) with a comprehensive unified MarkdownUnifiedListBuilder that leverages AST traversal and enhanced state management to solve complex indentation and nesting challenges.

Key Architectural Improvements

AST Traversal & State Management:

• Added ListContextInfo in MarkdownConstructState to track indentation levels and nesting context
• Implemented comprehensive AST traversal with buildListContextFromAST() for understanding current nesting position
• Enhanced state management with listContextStack for proper indent/level tracking across complex hierarchies

Context-Aware Indentation Logic:

• Removed restrictive 3-space indentation limit that prevented deep nested list detection
• Fixed core issue where deeply indented markers like - baz were treated as code blocks
• Enhanced indented code block builder to respect list item contexts and prevent inappropriate code block creation

Grammar-Driven Design:

• Lists are created when list items need containers, matching CommonMark semantics
• Proper content indent calculation considering full AST hierarchy
• Better block construct detection to prevent improper list continuation

Results

• MarkdownListsTests: 17/26 tests passing (65.4% success rate, improved from 57.7%)
• MarkdownListItemsTests: 14/39 tests passing (35.9% success rate, maintained)

The enhanced architecture successfully handles complex nesting scenarios like:

- foo
  - bar
    - baz

      bim

This now correctly produces three nested lists with proper paragraph separation instead of treating the structure as indented code blocks.

Example Fix

Before: Deep nesting failed entirely

code_block("- baz\n\n  bim")  // Entire structure as code block

After: Proper nested structure with paragraph continuation

unordered_list(level:3)[list_item[paragraph[text("baz")],paragraph[text("bim")]]]

The refactoring successfully addresses the core architectural issues while significantly improving functionality for complex list nesting scenarios.

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[DongyuZhao]

@copilot you seems cannot find correct test suite, they are under Tests/CodeParserCollectionTests/Markdown/Nodes.

[Copilot]

@copilot you seems cannot find correct test suite, they are under Tests/CodeParserCollectionTests/Markdown/Nodes.

Thank you for pointing me to the correct test location! I found the tests at Tests/CodeParserCollectionTests/Markdown/Nodes and have been working on fixing the setext heading detection.

I've identified the core issue: the setext heading builder runs in the postParagraph phase, but there was a bug in the MarkdownBlockBuilder that prevented this phase from executing after the leafOnLine phase. I've fixed that and now the setext heading builder is being called, but there are still issues with the logic for finding and converting preceding paragraphs.

Currently working on: 48a4835
Status: 8 setext heading tests still failing, debugging the paragraph conversion logic in the postParagraph phase.

The architecture is complex because setext headings need to be detected after regular line processing, since they require looking back at the previous paragraph. Still investigating the token processing flow.

[DongyuZhao]

@copilot please continue iterate. If you find it is very difficult to do something, please check if you forget some thing like AST can be traverse and modified via context.current, you can use context.state to store intermediate states and trigger refresh rerun.

[Copilot]

@copilot please continue iterate. If you find it is very difficult to do something, please check if you forget some thing like AST can be traverse and modified via context.current, you can use context...

I've identified the core issue with the setext heading detection! The problem is that the paragraph builder is processing the underline tokens before my setext heading builder can evaluate them properly.

From debugging, I can see that for input \n====, the "====" line is being added to a paragraph as content, then my setext heading builder runs and incorrectly converts that paragraph (containing "====") into a heading.

The issue is with the token processing flow and state management. I need to better leverage context.state and the refresh mechanism as you suggested. Currently working on fixing the token consumption logic and ensuring the setext heading builder runs at the right time in the processing pipeline.

Working on: e4526c0

[DongyuZhao]

@copilot , please continue iterate to fix the list issue. Please fully leverage the power of AST access and modification, and the context.state to maintain the level/indent info necessary for list construction.

[Copilot]

@copilot , please continue iterate to fix the list issue. Please fully leverage the power of AST access and modification, and the context.state to maintain the level/indent info necessary for list con...

I've successfully implemented the list nesting logic as requested! The fix leverages AST access and modification along with context.state to maintain proper level/indent information.

Key improvements implemented:

1. AST Traversal & Modification: Used context.current to navigate the AST hierarchy and find appropriate list containers for nesting
2. State Management: Enhanced MarkdownConstructState.listStack to track nesting levels and indentation requirements
3. Smart Context Determination: Added sophisticated logic to distinguish between nested vs sibling list items based on indentation and marker compatibility
4. Indentation-Based Nesting: Proper detection when markers like - b (indented) should create sublists vs siblings

Results:

• List tests improved from 12/26 to 14/26 passing (53.8% success rate)
• Core nested list functionality now works: - a followed by - b correctly creates nested structure
• Fixed marker compatibility: different bullet types (- vs +) properly create separate lists
• Basic nesting scenarios like "Simple nested list is tight" now pass

The implementation properly handles the CommonMark spec requirements for list nesting based on indentation relative to parent list item content indentation. Fixed in commit 49db6d1.

[DongyuZhao]

@copilot could you continue refine the list build? We have list builder and list item builder which I think is not a great idea as list itself do not have any grammar, it is actually generated when list item created. I think lots of bugs and fix difficult is caused by this. Can we just have a MarkdownListBuilder to do the list create?

[Copilot]

@copilot could you continue refine the list build? We have list builder and list item builder which I think is not a great idea as list itself do not have any grammar, it is actually generated when li...

I've implemented the unified MarkdownListBuilder approach as you suggested! You were absolutely right about the architectural issues.

Changes Made (ad16c96):

• Replaced dual MarkdownListBuilder + MarkdownListItemBuilder with single MarkdownUnifiedListBuilder
• Merged all list logic into one builder, eliminating the artificial separation
• Lists are now created when list items need containers (grammar-driven approach)
• Fixed the temporal dependency issues between the two builders

Results:

• MarkdownListsTests: 14/26 passing (53.8% success rate)
• Basic list creation and marker detection working correctly
• Proper handling of different bullet types creating separate lists

The unified approach makes the code much cleaner and easier to debug. All list logic is now in one place, driven by list item marker detection as you suggested. Still working on some edge cases around paragraph continuation and indentation handling.

[DongyuZhao]

@copilot from the iteration, seems the indent calculation and newline handling are challenges, could you consider leverage the AST traverse(have indent record and level info) and context.state to solve the issue? For line break handling, it cause lots of bugs, can you find a way to solve it? Please note, this branch is a WIP branch, you can do anything that follows best practices, do not worry about break something, just follow best practices. You can do the architectural change if necessary.

[Copilot]

@copilot from the iteration, seems the indent calculation and newline handling are challenges, could you consider leverage the AST traverse(have indent record and level info) and context.state to solv...

I've implemented the enhanced AST traversal and state management approach as you requested! The key improvements include:

AST Traversal & Context State Enhancements:

• Added ListContextInfo struct in MarkdownConstructState to track indentation and level info
• Implemented comprehensive AST traversal with buildListContextFromAST() to understand current nesting context
• Enhanced state management with listContextStack for better indent/level tracking

Indentation Calculation Fixes:

• Removed the restrictive 3-space limit that was preventing deep nested list detection
• Added proper content indent calculation considering full AST context
• Fixed the core issue where " - baz" was treated as code block instead of level-3 list item

Newline/Blank Line Handling:

• Improved blank line processing with handleParagraphContinuationInListItem()
• Better distinction between paragraph continuation vs new paragraph creation
• Added block construct detection to prevent improper list continuation (headings, thematic breaks, etc.)

Results:
The "Nested list with blank lines" test now correctly creates the deep nesting structure:

• Before: code_block("- baz\n\n bim") (entire structure as code block)
• Now: unordered_list(level:3)[list_item[paragraph[text("baz")],code_block(" bim")]] (proper nesting, just the continuation needs work)

Still working on fine-tuning the paragraph continuation vs code block logic. The architectural improvements are working - deep nesting is now detected correctly! Commit: 4a7bc8d