fix(core): refresh default multi-canvas views after canvas reorder

[pujitha24]

Closes #10602

Background

Reordering _canvases changes the default target for views without a canvasId, but the eventManagers map kept its identity, so such views could keep viewports and controllers for the former first canvas.

Change List

• CanvasManager: replace eventManagers map when canvas order changes
• Unit tests

This PR was written in part with the assistance of generative AI.

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Note

Low Risk
Targeted fix to multi-canvas order handling with regression tests; no auth, data, or broad API changes.

Overview
Fixes multi-canvas setups where reordering _canvases left views without a canvasId bound to the wrong canvas because CanvasManager kept the same eventManagers object when only presentation order changed.

CanvasManager now compares canvas order with _haveSameOrder and replaces the eventManagers map when order changes (even if the same EventManager instances are reused), so Deck/ViewManager see an eventManagers identity change and rebuild default-target viewports and input routing. Tests assert reordering swaps the default canvas, refreshes the left view’s event root and viewport width, and restores them when order is reverted.

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[greptile-apps]

Confidence Score: 4/5

[Medium impact] Changes how canvas reordering triggers viewport refresh.

The fix appears safe to merge, with a non-blocking gap in controller test coverage.

Findings

1.  Controller movement remains untested ▶

Summary

CanvasManager now replaces the eventManagers map when canvas order changes, so default views rebuild against the new first canvas.

• Views without a canvas ID follow the newly first canvas.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A[Canvas order changes] --> B[New eventManagers map]
  B --> C[ViewManager requests rebuild]
  C --> D[Default viewport uses new first canvas]
  C --> E[Moved controller binds to new canvas]

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_{Reviews (1) · Last reviewed commit: "fix(core): refresh default multi-canvas ..." · Reviewed by Greptile}

[greptile-apps]

Controller movement remains untested

Neither view enables a controller, so this test cannot catch a controller left listening on the former canvas. getEventManager('left') reads the current canvas mapping, not the controller's event manager. Enable controller: true on the default view and check that its controller uses canvas B's event manager after reorder and canvas A's after restore.