Fix additional panel docking and restoration bugs

[Keavon]

Fixes more bugs from #4015. Partly closes #195.

[gemini-code-assist]

Code Review

This pull request enhances the workspace panel layout system by improving how panels are restored to their previous positions. It introduces a SavedPanelPosition struct to capture more context, such as sibling groups and slot sizes, which allows for more accurate restoration even when the original panel group has been pruned. Key additions include logic for finding sibling groups and inserting panels adjacent to them. Feedback suggests refining the document panel detection logic to be more robust across subdivisions and optimizing tree traversals in the insertion logic.

[cubic-dev-ai]

1 issue found across 2 files

Confidence score: 3/5

• There is a concrete regression risk in editor/src/messages/portfolio/utility_types.rs: switching saved_positions from tuple entries to SavedPanelPosition entries can break deserialization of previously persisted workspace layouts.
• Because this is a user-facing compatibility path (loading existing saved layouts) and the issue is high severity/high confidence (7/10, 9/10), the merge risk is moderate rather than low.
• Pay close attention to editor/src/messages/portfolio/utility_types.rs - ensure backward-compatible deserialization for older persisted layout formats.

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="editor/src/messages/portfolio/utility_types.rs">

<violation number="1" location="editor/src/messages/portfolio/utility_types.rs:211">
P1: Changing `saved_positions` from tuple entries to `SavedPanelPosition` entries breaks backward deserialization of previously persisted workspace layouts.</violation>
</file>

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