Fix missing welcome panel after closing all documents

[timon-schelling]

Closing all documents left the Welcome panel as the only tab, but the old active document index could still point to a tab that no longer existed. The fix is to reset it to 0 when the document list becomes empty.

[gemini-code-assist]

Code Review

This pull request updates the portfolio store to reset the active document index to zero when the document list becomes empty. The review feedback suggests a more robust approach by clamping the active document index within the valid bounds of the document list to prevent potential out-of-bounds errors during list updates.

[gemini-code-assist]

While resetting the index to 0 when the list is empty fixes the reported issue, it is more robust to ensure the index is always within valid bounds whenever the document list changes. This prevents potential UI crashes or glitches if the active document is closed but other documents remain, causing the index to temporarily point out of bounds before the next UpdateActiveDocument message arrives.

Using Math.max(0, Math.min(..., length - 1)) correctly handles both the empty list case (resetting to 0) and the out-of-bounds case.

Suggested change

	if (state.documents.length === 0) state.activeDocumentIndex = 0;
	state.activeDocumentIndex = Math.max(0, Math.min(state.activeDocumentIndex, state.documents.length - 1));

[cubic-dev-ai]

No issues found across 1 file

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.