fix(workflow-form): the Form View rebuilds every card on every compilation, redrawing its controls, dropping the focus and losing a click #8844

What happened?

Every compilation result rebuilds all the Form View's input cards (workflow-form.component.ts: the getCompilationStateInfoChangedStream subscription calls rebuildFormOrDefer, which rebuilds every card through buildForm), including the compilation a card's own write triggers. Three things follow from that for any control that writes on a click (a tick box; the Move up / Move down and remove buttons of a repeated list):

• The card's controls are torn down and redrawn about a second after the click. Measured on main: 2.8 s after ticking a box the <input type="checkbox"> is a new DOM node; the row buttons of a list flicker the same way.
• The keyboard focus goes with the replaced node: 0.3 s after the click the box still has the focus, 2.8 s later the focus is on the body. A keyboard reader is sent back to the top of the page after every click.
• A click made in the last 150 ms before that rebuild is lost. The card's write-back is form.valueChanges.pipe(debounceTime(150), takeUntil(formsRebuilt)), so the rebuild cancels the pending write, and the rebuilt card is seeded from the operator, which still holds the previous state: the control jumps back. Measured on main: tick a box twice 700 ms apart and it ends in the state after the first tick (the second one is undone); for a drag-reorder row, Move down twice 700 or 750 ms apart and the second move is undone.

The canvas's property panel redraws only when the operator's schema changes; a value written there never redraws the panel.

Expected: a compilation that changed nothing a card shows leaves the card alone. Only a changed operator schema (the column enums compilation writes into it), a changed set of inputs (an operator deleted, a property exposed or removed) or an operator value the card does not hold (a co-editor's edit) rebuilds, as on the canvas; and no rebuild loses an edit.

How to reproduce?

1. On the canvas, expose a boolean property of an operator in the Form View (for example Projection's "Drop Option"); open the Form View.
2. Tick the box and keep watching it: about a second later the control is redrawn, and its focus ring disappears (pressing Space again does nothing until you Tab back to it).
3. Tick the box twice about 0.7 s apart: it ends in the state after the first tick; the second tick was undone.
4. Same with a repeated list's row buttons (a Projection's columns, once the drag-reorder list renders on the form): Move down twice 0.7 s apart and the row jumps back.

Version/Branch

1.4.0-incubating-SNAPSHOT (main)

Commit Hash (Optional)

2082021

What browsers are you seeing the problem on?

No response

Relevant log output