feat: copy and paste scene settings

[YoavLevavi]

What

Copy and paste scene settings between scenes.

• Copy / Paste buttons on a selected scene in the sidebar.
• ⌘⇧C / ⌘⇧V on selected scene segments in the timeline.
• Copies the layout mode, split layout, and transitions.
• Pasting applies to every selected scene and leaves each scene's timing untouched.

This makes it quick to set up one scene and reuse its framing across a long edit.

Implementation

• scene-clipboard.ts: pure helpers that extract the settings from a scene segment and apply them to others, keeping start/end.
• The copied settings live in a module-level signal. The editor context's pasteSceneSettings applies them to the selected scenes in one setProject call, so each paste is a single undo step.

Testing

• Unit tests for the copy/apply helpers, including preserving timing.
• Desktop Vitest suite passes; Biome and tsc --noEmit are clean.

🤖 Generated with Claude Code

Confidence Score: 4/5

The PR is not safe to merge until copying a scene with a layout override works from the store-backed editor.

Findings

1.  Copying scene layouts throws ▶

Fix with agent prompt

### Issue 1
apps/desktop/src/routes/editor/scene-clipboard.ts:18
When a scene has a `splitLayout`, both Copy buttons and the timeline shortcut pass a scene from the Solid store to this helper. `structuredClone` cannot clone the nested store proxy, so copying throws before the settings reach the clipboard. Pasting that scene’s settings is therefore unavailable. Unwrap the layout before cloning it; the current test uses a plain object and does not cover this path.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Summary

The PR adds scene-setting copy and paste through sidebar buttons and timeline shortcuts, applying layout and transitions to selected scenes while preserving their timing.

• Pasting multiple scenes uses one project update.
• Copying scenes with layout overrides fails because the new clone receives a store proxy.

_{Reviews (1) · Last reviewed commit: "feat: copy and paste scene settings"}

[greptile-apps]

Copying scene layouts throws

When a scene has a splitLayout, both Copy buttons and the timeline shortcut pass a scene from the Solid store to this helper. structuredClone cannot clone the nested store proxy, so copying throws before the settings reach the clipboard. Pasting that scene’s settings is therefore unavailable. Unwrap the layout before cloning it; the current test uses a plain object and does not cover this path.

Prompt To Fix With AI

This is a comment left during a code review.
Path: apps/desktop/src/routes/editor/scene-clipboard.ts
Line: 18

Comment:
**Copying scene layouts throws**

When a scene has a `splitLayout`, both Copy buttons and the timeline shortcut pass a scene from the Solid store to this helper. `structuredClone` cannot clone the nested store proxy, so copying throws before the settings reach the clipboard. Pasting that scene’s settings is therefore unavailable. Unwrap the layout before cloning it; the current test uses a plain object and does not cover this path.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

[YoavLevavi]

Fixed in daaa3bc. The split layout is now copied field by field instead of with structuredClone, so a scene from the store proxy copies correctly. Added a regression test that passes a Proxy-wrapped layout; structuredClone throws on it, and copying now succeeds.