Remember the canvas viewport per document across net switches and reloads

[kube]

Summary

Before this PR, the canvas opened every net fitted to the screen. Switching to another net and back, or reloading the app, lost the position and zoom the user had set.

Remembers the viewport per net in the user settings. Both renderers start from the saved viewport when one exists and report their moves through one context, so a net reopens where it was left.

Links

• Ticket to be filed
• Docs Drawing a net

Changes

• CanvasViewportContext exposes savedViewport and rememberViewport

  CanvasViewportProvider sits inside UserSettingsProvider and keys everything by the current petriNetId.

• Saves coalesce to one write 250 ms after the last move

  Pending saves flush when the document changes or the provider unmounts.

• canvasViewports user setting keeps the most recently moved nets

  remember-canvas-viewport.ts caps the map at 50 nets, most recent first.
  Persisted with the other settings.

• Both renderers read the saved viewport at mount and otherwise fit the net

  React Flow reports through onMoveEnd.
  Pixi subscribes to its viewport store.

• CanvasViewport type moves to the React layer

  Renderer contract re-exports it.

Known issues

• Viewports of deleted nets stay until the cap evicts them

Test coverage

• remember-canvas-viewport.test.ts:

  Insertion order, replacement and the cap.

• Headless Playwright script on both renderers:

  Pan and zoom, reload, restore, and a fresh fit for a second net.

How to test

• Open Petrinaut preview on Vercel
• Load example > SIR, zoom and pan
• Reload
• Expect same position and zoom
• Load example > any other example
• Expect fit to screen
• Switch back to SIR
• Expect previous position and zoom
• Viewport controls > Settings > Renderer > Pixi, repeat

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Project	Deployment	Actions	Updated
hash	Ready	Preview	Sep 3, 2026 11:47pm UTC
petrinaut	Ready	Preview	Sep 3, 2026 11:47pm UTC
petrinaut-docs	Ready	Preview	Sep 3, 2026 11:47pm UTC

1 Skipped Deployment

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hashdotdesign-tokens	Ignored	Preview	Sep 3, 2026 11:47pm UTC