# Specification: Structural File Editor

## 1. Overview
The user wants to combine the current AST Inspector and Slices Editor into a single, unified "Structural File Editor". This modal will provide a comprehensive visualization of both auto-detected AST elements and user-defined custom slices, allowing users to precisely tailor the context sent to the AI, especially in combination with "skeleton" or other filtered view modes.

## 2. Functional Requirements
*   **Unified Interface:** Merge the UI elements of `render_ast_inspector_modal` and `render_slices_editor_modal` into a new `render_structural_file_editor_modal`.
*   **Visualization:** Display a unified graph or list showing the file's structure. This includes AST nodes (classes, functions, etc.) and custom slices seamlessly integrated.
*   **Custom Slices:** Allow users to define arbitrary text ranges as "custom slices" that exist independently of the AST graph but are visualized alongside it.
*   **Filtering:** The editor must clearly indicate which parts of the file will be included based on the current `view_mode` (e.g., if `view_mode='skeleton'`, only signatures and explicitly selected custom slices/AST nodes are included).

## 3. Non-Functional Requirements
*   **Performance:** The unified editor must remain responsive even for large files with complex ASTs.

## 4. Acceptance Criteria
*   Clicking a "Structure" or "Edit Slices" button on a file opens the new unified modal.
*   The modal clearly displays both AST elements and custom slices.
*   Users can add, modify, and delete custom slices within this single interface.