PROMPT ELEMENT SYSTEM

# Prompt Element System Architecture

**Date:** 2025-10-07
**Status:** Implemented
**Related Files:** `src/langtree/templates/prompt_*.py`, `src/langtree/templates/element_resolution.py`

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## Overview

The Prompt Element System is the core architecture for prompt generation in LangTree DSL. It represents prompts as structured lists of typed elements (titles, text, templates) that can be parsed from markdown, manipulated programmatically, and serialized back to markdown with proper heading level management.

This architecture replaced the previous string-based approach with a structured, type-safe system that enables:
- ✅ Automatic heading level alignment
- ✅ Template variable resolution with context awareness
- ✅ Hierarchical prompt assembly from leaf to root
- ✅ Proper nesting and hierarchy preservation

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## Core Concepts

### PromptElement

Base class for all prompt components. Every piece of a prompt is represented as a `PromptElement`.

**Types of PromptElements:**
1. **PromptTitle** - Markdown headings (`#`, `##`, `###`, etc.)
2. **PromptText** - Plain text content
3. **PromptTemplate** - Template variables (`{PROMPT_SUBTREE}`, `{COLLECTED_CONTEXT}`)

**Common Attributes:**