Isolation Mode

Isolation Mode restricts what the renderer draws and hit-tests to a specific subtree of the current scene. When active, only the isolation root and its descendants are painted and pointer-tested. Everything else in the scene graph stays loaded, laid out, and cached -- the rest of the pipeline is untouched. It is a pure viewport filter, not a mutation of the document.

This is the same primitive Blender calls "Local View", Maya/Max/C4D call "Isolate Select", Illustrator calls "Isolation Mode", and After Effects calls "Solo".

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Semantics

Aspect	Behavior
Scope	One node. The isolated root + all descendants are drawn.
Hit-testing	Scoped identically. Clicking outside the isolated subtree hits nothing.
Scene background, grid, guides	Unaffected.
Picture caches, layout, geometry, R-tree	Unaffected. Isolation is a late filter, not a cache invalidation.
Export (export_node_as)	Ignores isolation entirely. Isolation is viewport-only.
Outside the isolated subtree	Hard-hide (nothing drawn). No fade, no dim (v1).
Persistence	None. Resets on scene load / document reset. Not in undo history.
Multiple roots	Not supported in v1. Struct is extensible for future multi-root.

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RenderFilter Extensibility

All viewport-time filters live on a single RenderFilter struct owned by the Renderer. Isolation Mode is the first slot. Future slots include:

• outside: OutsideStyle -- "hide" (v1 default), "fade", "cover" for the content outside the isolated subtree.
• roots: Vec<NodeId> -- multi-root isolation for showing several disjoint subtrees simultaneously.
• hit_test: bool -- optionally scope hit-testing independently of draw-scoping.
• Visibility overrides -- force-show / force-hide individual nodes regardless of schema visibility.
• Layer-type filters -- show only text layers, only images, etc.
• Debug tints -- overlay colored tints on specific node types.

Adding a new filter category means adding a field to RenderFilter and reading it in the draw loop and/or hit-tester. No plumbing changes elsewhere.

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API Shape

Rust types (crates/grida-canvas/src/runtime/filter.rs)

pub struct IsolationMode {
    pub root: NodeId,
}

pub struct RenderFilter {
    pub isolation_mode: Option<IsolationMode>,
}

Renderer methods (crates/grida-canvas/src/runtime/scene.rs)

impl Renderer {
    pub fn set_isolation_mode(&mut self, mode: Option<IsolationMode>);
    pub fn isolation_mode(&self) -> Option<&IsolationMode>;
    pub fn isolation_set(&self) -> Option<&HashSet<NodeId>>;
}

set_isolation_mode precomputes a HashSet<NodeId> of the root + all descendants (via SceneGraph::descendants). The draw loop and hit-tester use this set for O(1) per-layer filtering.

ChangeFlags (crates/grida-canvas/src/runtime/changes.rs)

pub const RENDER_FILTER: Self = Self(1 << 9);

No cache invalidation is performed for this flag. It only ensures a frame is queued so the filter change becomes visible immediately.

ApplicationApi trait method (crates/grida-canvas/src/window/application.rs)

fn runtime_renderer_set_isolation_mode(&mut self, root_user_id: Option<&str>);

Accepts a user-facing string ID (Option<&str>). Some("node-id") enables isolation; None clears it. The implementation converts the string ID to an internal NodeId via user_id_to_internal.

WASM C-ABI (crates/grida-canvas-wasm/src/wasm_application.rs)

pub unsafe extern "C" fn runtime_renderer_set_isolation_mode(
    app: *mut UnknownTargetApplication,
    id_ptr: *const u8,
    id_len: usize,
);

Pass (null, 0) to clear. Pass (ptr, len) pointing to a UTF-8 node ID string to set.

TypeScript wrapper (crates/grida-canvas-wasm/lib/modules/canvas.ts)

class Scene {
  runtime_renderer_set_isolation_mode(nodeId: string | null): void;
}

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What This Feature Does NOT Do

• Does NOT mutate the document or scene graph.
• Does NOT invalidate caches (picture, compositor, geometry, layout, R-tree).
• Does NOT affect export (export_node_as).
• Does NOT persist across scene loads.
• Does NOT appear in undo/redo history.
• Does NOT support multiple isolation roots (v1).
• Does NOT fade or dim content outside the isolated subtree (v1 is hard-hide).
• Does NOT change camera, pan/zoom clamp, or viewport behavior.
• Does NOT touch editor state, React code, or any UI layer.