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]

P1: Applying mask on ExitMaskMode mutates the graph without transaction boundaries, unlike the discard branch, causing inconsistent undo/history behavior.

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/document_message_handler.rs, line 1192:

<comment>Applying mask on `ExitMaskMode` mutates the graph without transaction boundaries, unlike the discard branch, causing inconsistent undo/history behavior.</comment>

<file context>
@@ -1133,16 +1142,69 @@ impl MessageHandler<DocumentMessage, DocumentMessageContext<'_>> for DocumentMes
+				} else {
+					// Rasterize the mask group and apply it to target layers
+					if let Some(mask_group_id) = self.mask_group_id {
+						responses.add(GraphOperationMessage::ApplyMaskStencil {
+							layers: self.mask_target_layers.clone(),
+							mask_image: graphene_std::raster::Image::new(1, 1, graphene_std::Color::WHITE),
</file context>

[cubic-dev-ai]

P1: Mask apply path discards authored mask content by using a placeholder 1x1 white image and then deleting the mask group.

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/document_message_handler.rs, line 1194:

<comment>Mask apply path discards authored mask content by using a placeholder 1x1 white image and then deleting the mask group.</comment>

<file context>
@@ -1133,16 +1142,69 @@ impl MessageHandler<DocumentMessage, DocumentMessageContext<'_>> for DocumentMes
+					if let Some(mask_group_id) = self.mask_group_id {
+						responses.add(GraphOperationMessage::ApplyMaskStencil {
+							layers: self.mask_target_layers.clone(),
+							mask_image: graphene_std::raster::Image::new(1, 1, graphene_std::Color::WHITE),
+						});
+						responses.add(NodeGraphMessage::DeleteNodes {
</file context>

[cubic-dev-ai]

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.

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/document_message_handler.rs, line 1161:

<comment>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.</comment>

<file context>
@@ -1133,16 +1142,69 @@ impl MessageHandler<DocumentMessage, DocumentMessageContext<'_>> for DocumentMes
+				responses.add(DocumentMessage::AddTransaction);
+
+				// Create the mask group layer as an empty custom layer container
+				graph_modification_utils::new_custom(mask_group_id, Vec::new(), self.new_layer_parent(true), responses);
+
+				// Set the mask group opacity to 50% so the user can see artwork beneath
</file context>