Add specifications for two-times upscale and unified depth plane features

- Introduced the two-times upscale specification detailing requirements for unified output, fixed model presets, arbitrary dimensions, and consistent job behavior.
- Added scenarios for existing models, repeated upscale, and handling of alpha preservation.
- Created the unified depth plane specification outlining geometry modes, stable interface, and asset evaluation.
- Defined scenarios for mode switching, relief and camera preservation, and validation of delivered assets.

openspec/changes/archive/2026-09-17-weight-cutout-boundary-smoothing/proposal.md

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+## Why
+
+`O Image Depth Cutout` 的 Split 边与原始 Outline 对几何平滑的需求不同：Split 边需要完整强度消除切缝折痕，而 Outline 只需轻微整理，避免轮廓被过度软化。
+
+## What Changes
+
+- `Boundary Smooth` 继续作为唯一的边界平滑次数控制，默认值改为 `4`。
+- Split 边使用完整 `Smooth Weight`，Outline 使用其 `0.1` 倍；两类影响相交时由 Split 强度优先。
+- 保持 `Boundary Smooth = 0` 完全关闭边界平滑。
+
+## Capabilities
+
+### New Capabilities
+
+- `cutout-boundary-smoothing`: 定义 Depth Cutout 对 Split 边与 Outline 的差异化平滑强度和默认控制值。
+
+### Modified Capabilities
+
+无。
+
+## Impact
+
+影响 `tools/nodes/common/boundary_smoothing.py`、`tools/nodes/groups/image_depth_cutout.py`、相关节点测试和 `src/anyimage/assets/O_AnyImage.blend`；不增加或移除公开输入。