Refactor transform decomposition API with skew support, add 'Decompose Skew' node, and fix stroke transform interpolation

[Keavon]

• New node: Decompose Skew, extracts the skew angle from a transform
• Updated node: Decompose Scale, now has a "Magnitude" vs. "Pure" toggle (magnitude gives the visual axis lengths as before; pure gives the signed scale factors with rotation/skew stripped)

Also fixes a bug: stroke interpolation (e.g. when morphing between shapes with different transforms) no longer breaks when transforms have opposing rotations like 0° vs. 180°, which previously caused a division by zero in the renderer.

[gemini-code-assist]

Code Review

This pull request refactors the transformation decomposition logic by introducing a ScaleType enum and expanding the Transform trait with methods like decompose_rotation_scale_skew, scale_magnitudes, and decompose_skew. It updates various parts of the codebase, including stroke interpolation and bounding box calculations, to use these new methods. Review feedback identifies an incorrect area calculation in vector_nodes.rs where scale_magnitudes should be replaced by decompose_scale to correctly account for the transformation determinant, and suggests a mathematical simplification in the skew calculation within transform.rs.

[cubic-dev-ai]

5 issues found across 15 files

Confidence score: 3/5

• There is concrete user-facing correctness risk: node-graph/nodes/vector/src/vector_nodes.rs uses scale_magnitudes() for area, which can miscompute area under skewed transforms (over/under-scaling).
• editor/src/messages/portfolio/document/node_graph/node_properties.rs also uses scale_magnitudes() in transform editing, which can reconstruct mirrored/skewed transforms incorrectly when rotation changes, so regression risk is meaningful.
• A couple of findings are lower impact housekeeping (doc wording in node-graph/nodes/transform/src/transform_nodes.rs, algebra simplification in node-graph/libraries/core-types/src/transform.rs), plus PR-title convention enforcement, so this looks fixable rather than fundamentally unsafe.
• Pay close attention to node-graph/nodes/vector/src/vector_nodes.rs and editor/src/messages/portfolio/document/node_graph/node_properties.rs - both touch transform math where skew/mirroring behavior can become incorrect.

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/node_graph/node_properties.rs">

<violation number="1" location="editor/src/messages/portfolio/document/node_graph/node_properties.rs:26">
P1: Custom agent: **PR title enforcement**

PR title violates the title convention for new node additions: it references a node name without single quotes and does not use the required `New node: 'Node Name'` format.</violation>

<violation number="2" location="editor/src/messages/portfolio/document/node_graph/node_properties.rs:571">
P2: Using `scale_magnitudes()` in the transform property editor causes mirrored/skewed transforms to be reconstructed incorrectly when rotation is changed.</violation>
</file>

<file name="node-graph/nodes/transform/src/transform_nodes.rs">

<violation number="1" location="node-graph/nodes/transform/src/transform_nodes.rs:162">
P3: The doc comment is inaccurate: this node returns a skew angle in degrees, not a skew coefficient.

(Based on your team's feedback about using consistent, precise terminology in names and docs.) [FEEDBACK_USED]</violation>
</file>

<file name="node-graph/nodes/vector/src/vector_nodes.rs">

<violation number="1" location="node-graph/nodes/vector/src/vector_nodes.rs:2537">
P1: Using `scale_magnitudes()` in area calculation breaks area correctness for skewed transforms; it over/under-scales area because magnitudes include skew length distortion.</violation>
</file>

<file name="node-graph/libraries/core-types/src/transform.rs">

<violation number="1" location="node-graph/libraries/core-types/src/transform.rs:47">
P3: The denominator `(sin * sin * scale_x + cos * cos * scale_x)` simplifies to `scale_x` via the Pythagorean identity (sin² + cos² = 1). The current form obscures this.</violation>
</file>

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

[cubic-dev-ai]

1 issue found across 2 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="node-graph/nodes/vector/src/vector_nodes.rs">

<violation number="1" location="node-graph/nodes/vector/src/vector_nodes.rs:7">
P1: Custom agent: **PR title enforcement**

PR title does not follow the new-node title convention: it introduces a node without single-quoting the node name and does not use the dedicated `New node: 'Node Name'` format required by the guideline.</violation>
</file>

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

[cubic-dev-ai]

1 issue found across 2 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="node-graph/nodes/transform/src/transform_nodes.rs">

<violation number="1" location="node-graph/nodes/transform/src/transform_nodes.rs:162">
P1: Custom agent: **PR title enforcement**

Update the PR title to follow the required new-node format and quote the node name, e.g. `New node: 'Decompose Skew'` (and adjust the rest of the title accordingly).</violation>
</file>

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

[cubic-dev-ai]

1 issue found across 1 file (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/transform_utils.rs">

<violation number="1" location="editor/src/messages/portfolio/document/graph_operation/transform_utils.rs:15">
P1: Custom agent: **PR title enforcement**

PR title must use the required new-node format. The rules specify "New node: 'Node Name'" for PRs that add a node, but the current title is a generic sentence instead of the mandated format.</violation>
</file>

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

[cubic-dev-ai]

P1: Custom agent: PR title enforcement

PR title must use the required new-node format. The rules specify "New node: 'Node Name'" for PRs that add a node, but the current title is a generic sentence instead of the mandated format.

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/transform_utils.rs, line 15:

<comment>PR title must use the required new-node format. The rules specify "New node: 'Node Name'" for PRs that add a node, but the current title is a generic sentence instead of the mandated format.</comment>

<file context>
@@ -12,12 +12,12 @@ pub fn update_transform(network_interface: &mut NodeNetworkInterface, node_id: &
 
 	let rotation = rotation.to_degrees();
-	let shear = DVec2::new(skew.atan().to_degrees(), 0.);
+	let skew = DVec2::new(skew.atan().to_degrees(), 0.);
 
 	network_interface.set_input(&InputConnector::node(*node_id, 1), NodeInput::value(TaggedValue::DVec2(translation), false), &[]);
</file context>