# Changelog #37 - Phase 2.1: Advanced Selection Tools

**Date:** 2025-11-28
**Branch:** feature/mesh_phase_2_1
**Task:** TASK-015 (7 sub-tasks)

---

## Summary

Implemented Phase 2.1: Advanced Selection Tools - 8 new mesh selection tools that enable programmatic geometry selection, spatial queries, and boundary detection. These tools are critical for advanced mesh workflows including targeted hole filling and multi-part boolean operations.

---

## New Tools (8)

### 1. mesh_select_loop (TASK-015-1)
- **Tag:** `[EDIT MODE][SELECTION-BASED][SAFE]`
- **Purpose:** Selects an edge loop (continuous line of edges) based on target edge index
- **Args:** `edge_index: int`
- **Use Case:** Selecting borders, seams, or topological rings

### 2. mesh_select_ring (TASK-015-2)
- **Tag:** `[EDIT MODE][SELECTION-BASED][SAFE]`
- **Purpose:** Selects an edge ring (parallel edges) based on target edge index
- **Args:** `edge_index: int`
- **Use Case:** Selecting parallel edge bands for inset/bevel operations

### 3. mesh_select_linked (TASK-015-3)
- **Tag:** `[EDIT MODE][SELECTION-BASED][SAFE]`
- **Priority:** CRITICAL
- **Purpose:** Selects all geometry connected to current selection (islands)
- **Args:** None
- **Use Case:** Selecting mesh islands after join_objects for boolean operations

### 4. mesh_select_more (TASK-015-4)
- **Tag:** `[EDIT MODE][SELECTION-BASED][SAFE]`
- **Purpose:** Grows the current selection by one step
- **Args:** None
- **Use Case:** Expanding selection to neighboring geometry

### 5. mesh_select_less (TASK-015-4)
- **Tag:** `[EDIT MODE][SELECTION-BASED][SAFE]`
- **Purpose:** Shrinks the current selection by one step
- **Args:** None
- **Use Case:** Contracting selection away from boundaries

### 6. mesh_get_vertex_data (TASK-015-5)
- **Tag:** `[EDIT MODE][READ-ONLY][SAFE]`
- **Priority:** CRITICAL
- **Purpose:** Returns vertex positions and selection states for programmatic analysis
- **Args:** `object_name: str`, `selected_only: bool = False`
- **Returns:** Dictionary with `vertex_count`, `selected_count`, `returned_count`, and `vertices` array
- **Use Case:** Foundation for programmatic selection decisions

### 7. mesh_select_by_location (TASK-015-6)
- **Tag:** `[EDIT MODE][SELECTION-BASED][SAFE]`
- **Purpose:** Selects geometry within coordinate range on specified axis
- **Args:** `axis: str ('X'|'Y'|'Z')`, `min_coord: float`, `max_coord: float`, `mode: str = 'VERT'`
- **Use Case:** "Select all vertices above Z=0.5" without knowing indices

### 8. mesh_select_boundary (TASK-015-7)
- **Tag:** `[EDIT MODE][SELECTION-BASED][SAFE]`
- **Priority:** CRITICAL
- **Purpose:** Selects boundary edges (1 adjacent face) or boundary vertices
- **Args:** `mode: str ('EDGE'|'VERT')`
- **Use Case:** Targeting specific holes for mesh_fill_holes

---

## Architecture

All tools follow clean architecture pattern:

### Layers Modified
1. **Domain Layer** (`server/domain/tools/mesh.py`)
   - Added 8 abstract methods to `IMeshTool` interface

2. **Application Layer** (`server/application/tool_handlers/mesh_handler.py`)
   - Implemented 8 handler methods delegating to RPC

3. **Adapter Layer** (`server/adapters/mcp/areas/mesh.py`)
   - Added 8 MCP tool endpoints with comprehensive docstrings

4. **Blender Addon** (`blender_addon/application/handlers/mesh.py`)
   - Implemented 8 methods using bmesh API

5. **Registration** (`blender_addon/__init__.py`)
   - Registered 8 RPC endpoints

---

## Testing

### New Test Files
- **`tests/test_mesh_selection_advanced.py`** (16 tests)
  - TestMeshSelectLoop (2 tests)
  - TestMeshSelectRing (2 tests)
  - TestMeshSelectLinked (2 tests)
  - TestMeshSelectMoreLess (4 tests)
  - TestMeshSelectBoundary (4 tests)
  - TestMeshSelectByLocation (2 tests)

- **`tests/test_mesh_introspection.py`** (5 tests)
  - TestMeshGetVertexData (5 tests)
    - All vertices retrieval
    - Selected only filtering
    - Object not found error
    - Non-mesh object error
    - Mode restoration

### Test Results
```
127 passed, 19 skipped in 231.81s
```

---

## Technical Details

### BMesh Operations
All tools use bmesh for low-level mesh manipulation:

```python
def select_boundary(self, mode='EDGE'):
    obj, previous_mode = self._ensure_edit_mode()
    bm = bmesh.from_edit_mesh(obj.data)

    # Deselect all first
    for v in bm.verts:
        v.select = False
    for e in bm.edges:
        e.select = False

    selected_count = 0
    if mode == 'EDGE':
        for edge in bm.edges:
            if edge.is_boundary:  # Only 1 adjacent face
                edge.select = True
                selected_count += 1

    bmesh.update_edit_mesh(obj.data)

    if previous_mode != 'EDIT':
        bpy.ops.object.mode_set(mode=previous_mode)

    return f"Selected {selected_count} boundary edge(s)"
```

### Mode Management
All tools use consistent `_ensure_edit_mode()` pattern:
- Ensures mesh object is active
- Switches to EDIT mode if necessary
- Returns `(obj, previous_mode)` tuple
- Restores original mode at end

---

## Unblocked Workflows

### 1. Targeted Hole Filling
```
mesh_select_boundary(mode='EDGE') -> mesh_fill_holes()
```
Instead of filling all holes, can now target specific boundary edges.

### 2. Boolean After Join
```
modeling_join_objects(...) -> mesh_select_by_index(...) -> mesh_select_linked() -> mesh_boolean(...)
```
Enables boolean operations on specific mesh islands after joining.

### 3. Spatial Operations
```
mesh_get_vertex_data(...) -> [analyze coordinates] -> mesh_select_by_location(...)
```
Programmatic selection based on vertex positions.

---

## Git Commits (7)

1. `feat: implement mesh_select_loop (TASK-015-1)`
2. `feat: implement mesh_select_ring (TASK-015-2)`
3. `feat: implement mesh_select_linked (TASK-015-3) CRITICAL`
4. `feat: implement mesh_select_more/less (TASK-015-4)`
5. `feat: implement mesh_get_vertex_data (TASK-015-5) CRITICAL`
6. `feat: implement mesh_select_by_location (TASK-015-6)`
7. `feat: implement mesh_select_boundary (TASK-015-7) CRITICAL`

---

## Statistics

- **Tools Implemented:** 8
- **Critical Tools:** 3
- **New Tests:** 21
- **Total Tests Passing:** 127
- **Files Modified:** 5 (domain, application, adapter, blender handler, registration)
- **New Test Files:** 2

---

**Status:** Complete
**Phase:** Phase 2.1 - Advanced Selection
**Version Impact:** Minor version bump recommended (new features)
