Add DocumentMode groundwork with MaskMode and Q toggle

[krVatsal]

This PR implements the early groundwork for Document Mode as planned for community bonding / week 1 in Marquee Selection Masking.
It introduces MaskMode and wires a keyboard toggle, while intentionally avoiding rendering or visual feature work.

What this PR changes?

• Re-enables DocumentMode enum and adds MaskMode
• Stores current document_mode in editor state
• Adds ToggleDocumentMode message
• Handles toggle logic in document message handler:

1. DesignMode -> MaskMode
   

2. MaskMode -> DesignMode
   

• Maps Q to ToggleDocumentMode

Scope and intent

• Pure editor state change only
• No rendering pipeline changes
• No frontend UI additions
• No behavior beyond mode state toggle

[cubic-dev-ai]

No issues found across 4 files

Confidence score: 5/5

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

[gemini-code-assist]

Code Review

This pull request introduces a new DocumentMode enum, including a MaskMode variant, and integrates it into the DocumentMessageHandler to allow toggling and setting the document mode. The review feedback suggests ensuring UI consistency by triggering PortfolioMessage::UpdateDocumentWidgets when the mode changes and recommends uncommenting and updating the fmt::Display implementation for DocumentMode to avoid leaving dead code.

[krVatsal]

I wanted to continue with the work on part of my proposed changes but that needs these changes, should i continue adding further commits to this PR only? It would be great if you review this and then i can follow up with further changes for marquee selection. @Keavon

[Keavon]

These changes comprise a relatively small change set, so you can and should continue adding functionality since this is so far just the user's entry point to a not-yet-built feature.

[cubic-dev-ai]

3 issues found across 4 files (changes from recent commits).

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/document/document_message_handler.rs">

<violation number="1" location="editor/src/messages/portfolio/document/document_message_handler.rs:1161">
P1: Mask group creation can self-parent because parent resolution happens after entering MaskMode and storing the same mask group ID used for the new layer.</violation>

<violation number="2" location="editor/src/messages/portfolio/document/document_message_handler.rs:1192">
P1: Applying mask on `ExitMaskMode` mutates the graph without transaction boundaries, unlike the discard branch, causing inconsistent undo/history behavior.</violation>

<violation number="3" location="editor/src/messages/portfolio/document/document_message_handler.rs:1194">
P1: Mask apply path discards authored mask content by using a placeholder 1x1 white image and then deleting the mask group.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

2 issues found across 3 files (changes from recent commits).

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/document/graph_operation/graph_operation_message_handler.rs">

<violation number="1" location="editor/src/messages/portfolio/document/graph_operation/graph_operation_message_handler.rs:447">
P2: `ApplyMaskStencil` uses `ClipModeToggle`, making mask application state-dependent and capable of un-clipping already clipped target layers.</violation>
</file>

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

<violation number="1" location="editor/src/messages/portfolio/document/document_message_handler.rs:1194">
P1: ExitMaskMode uses a placeholder mask image and deletes the mask group, so user-drawn mask content is not applied.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P2: ApplyMaskStencil uses ClipModeToggle, making mask application state-dependent and capable of un-clipping already clipped target layers.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At editor/src/messages/portfolio/document/graph_operation/graph_operation_message_handler.rs, line 447:

<comment>`ApplyMaskStencil` uses `ClipModeToggle`, making mask application state-dependent and capable of un-clipping already clipped target layers.</comment>

<file context>
@@ -439,6 +439,17 @@ impl MessageHandler<GraphOperationMessage, GraphOperationMessageContext<'_>> for
+
+				// For each target layer, toggle clip mode so the existing clip infrastructure is engaged.
+				for layer in layers {
+					responses.add(GraphOperationMessage::ClipModeToggle { layer });
+				}
+				responses.add(NodeGraphMessage::RunDocumentGraph);
</file context>