# 22 – Mesh Smooth & Flatten Tools (2025-11-25)

**Task:** TASK-012  
**Status:** ✅ Complete  
**Category:** Mesh Tools (Edit Mode)

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## 🎯 Objective

Implement `mesh_smooth` and `mesh_flatten` tools to enable AI-driven vertex smoothing and planar flattening operations in Edit Mode.

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## ✨ New Features

### MCP Server Tools

1. **`mesh_smooth`**
   - **Tag:** `[EDIT MODE][SELECTION-BASED][NON-DESTRUCTIVE]`
   - **Purpose:** Smooths selected vertices using Laplacian smoothing
   - **Parameters:**
     - `iterations` (int, 1-100): Number of smoothing passes
     - `factor` (float, 0.0-1.0): Smoothing strength
   - **Use Case:** Refining organic shapes, removing hard edges

2. **`mesh_flatten`**
   - **Tag:** `[EDIT MODE][SELECTION-BASED][DESTRUCTIVE]`
   - **Purpose:** Flattens selected vertices to a plane perpendicular to specified axis
   - **Parameters:**
     - `axis` (str): "X", "Y", or "Z"
   - **Use Case:** Creating perfectly flat surfaces (floors, walls, cutting planes)

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## 🏗️ Architecture

### Domain Layer
- **File:** `server/domain/tools/mesh.py`
- **Changes:** Added abstract methods:
  - `smooth_vertices(iterations, factor) -> str`
  - `flatten_vertices(axis) -> str`

### Application Layer
- **File:** `server/application/tool_handlers/mesh_handler.py`
- **Changes:** Implemented handlers delegating to RPC client:
  - `MeshToolHandler.smooth_vertices()`
  - `MeshToolHandler.flatten_vertices()`

### Adapter Layer
- **File:** `server/adapters/mcp/server.py`
- **Changes:** Registered MCP tools with standardized docstrings:
  - `@mcp.tool() mesh_smooth()`
  - `@mcp.tool() mesh_flatten()`

### Blender Addon
- **File:** `blender_addon/application/handlers/mesh.py`
- **Changes:** Implemented Blender API logic:
  - `MeshHandler.smooth_vertices()` - Uses `bpy.ops.mesh.vertices_smooth()`
  - `MeshHandler.flatten_vertices()` - Uses `bpy.ops.transform.resize()` with scale-to-zero

- **File:** `blender_addon/__init__.py`
- **Changes:** Registered RPC handlers:
  - `mesh.smooth_vertices`
  - `mesh.flatten_vertices`

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## 📋 Implementation Details

### Mesh Smooth Algorithm
- Uses Blender's built-in Laplacian smoothing operator
- Validates vertex selection before execution
- Returns descriptive feedback with vertex count and parameters

### Mesh Flatten Algorithm
- Maps axis to constraint tuple: `X=(True,False,False)`, `Y=(False,True,False)`, `Z=(False,False,True)`
- Uses `transform.resize()` with scale value `[0.0, 1.0, 1.0]` (example for X-axis)
- Aligns all selected vertices to same coordinate on specified axis

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## ✅ Validation

- ✅ Domain interfaces follow Clean Architecture (no implementation)
- ✅ Application handlers delegate to RPC without business logic
- ✅ Adapter layer has AI-friendly docstrings with semantic tags
- ✅ Blender API layer contains all `bpy` operations
- ✅ Tools registered in MCP server (`mesh_smooth`, `mesh_flatten` visible)
- ✅ Syntax validated for all Python files

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## 📚 Related Documentation

- **Task Specification:** `_docs/_TASKS/TASK-012_Mesh_Smooth_Flatten.md`
- **Architecture Guide:** `_docs/MESH_TOOLS_ARCHITECTURE.md`
- **Docstring Standards:** `_docs/TOOLS_ARCHITECTURE_DEEP_DIVE.md` (Semantic Tagging section)

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## 🔗 Phase Progress

**Phase 2: Mesh Editing (Edit Mode)**
- ✅ Selection & Deletion
- ✅ Extrude & Fill
- ✅ Bevel, Loop Cut, Inset
- ✅ Boolean, Merge, Subdivide
- ✅ **Smooth & Flatten** ← NEW
- ⏳ Advanced Selection (Phase 2.1)
- ⏳ Organic & Deform Tools (Phase 2.2)
