[Rn86222]

Summary

This PR fixes the "zombie child" problem properly and removes the special case added in #75.

A renderer could be re-rendered by its own subscription before the list it comes from dropped it. #75 hit this when resizing a display dropped a connection:

• The renderer of the connection is subscribed to the nodes at both ends, so it re-rendered.
• It looked up a connection that was already gone.
• The list of connections still held it, because the list was cached until didUnregister arrived. A removal is announced only when its transaction ends.

#75 worked around this by announcing the removal of a connection synchronously, unlike every other store. The transaction delays didUnregister on purpose (63e7069, "guarantee store consistency on did- events"). What was wrong were the caches that relied on that announcement to learn about a change, so this PR fixes the caches instead.

Changes

• Lists are read from the store on every render (src/store/react/selectors.ts). They used to be cached with memoize-one until didUnregister arrived. The previous array is handed out again while its items are the same, so React still skips re-renders when nothing changed.
• Renderers render nothing once their object is gone.
  • The hooks reading a single object (useNode, useComponent, useComponentPin) return undefined instead of throwing.
  • The renderers of connections, nodes and interface nodes return null after all their hooks when their object is missing.
  • ensureStoreItem is removed: it checked in a wrapper, which a subscription of the inner component bypasses.
• The revision counts a change when it is made, not when it is announced.
  • The object-specific stores change their objects only through setObject and deleteObject of the base store, which count the change. The map itself is read-only to them. Moving a node still does not count.
  • The bit width cache is rebuilt when the revision differs from the one it was built at. The node pin and connection stores no longer clear it by hand after a removal, and nothing listens to events just to clear it.
  • The simulation netlist, cached on the same revision, is now exact during a transaction too.
• Connections announce their removal when the transaction ends, like the other stores (reverts the Announce the removal of connections and node pins right away #75 special case).
• Context menu:
  • Right-clicking a selected connection keeps the selection, so several connections can be deleted together. This matches the context menu of a node.
  • The menu acts only on selected objects that still exist.
  • Delete now clears the selection; it used to keep the removed connections selected.
• Cleanup:
  • didUpdate of the component and component pin stores now carries the updated object instead of the one it replaced.
  • Removed the unused isMarkedAsDeleted, useComponentPins and useNodePins.
  • Removed the memoize-one dependency. Only its entries were removed from the lockfile.

Out of scope

"Create a new component" is only offered with nodes selected, and selecting a node clears the selected connections. The connections between the selected nodes are therefore neither copied into the new component nor kept. This is left for a separate change.

Testing

• npx vitest run: 65 tests pass. New tests cover:

  • the list identity helper
  • the revision counting a removal before it is announced, and counting a config change but not a move
  • didUpdate carrying the updated object
  • a connection announcing its removal after the transaction
  • the bit widths reflecting a removed connection before the announcement

  The revision and bit width tests fail if a removal is not counted right away.

• npx tsc -p . and npx biome check src pass.

• Checked by hand in the browser, with no error in the console:

  1. Delete a connection, then drag a node at one of its ends.
  2. Delete a node with connections.
  3. Remove a split aggregate pin that has a connection.
  4. Delete an Input node inside a component used elsewhere, then open the outer component.
  5. Shift-click two connections, right-click one, and delete them, also right after deleting another connection.
  6. Delete the remaining selected connection after one of them was removed along with a pin.

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