VQC:

At this point, a good strategy would be to have a thread that is used to post patterns from The End grid.

Patterns that apply to all c in the grid.

Patterns that apply to all cells in a row.

Patterns that apply to all cells in a column.

Special rows.

Special columns.

It was hinted before and was useful to me, by enumerating all the patterns in one place, the answer will materialise.

You are looking for a key shortcut.

The grid does the ALL the work for you.

Suggestion…

Either here or a worker thread(s), discuss each rule or pattern.

When consensus is reached, put the rule or pattern in the key thread.

This process and result of this process may surprise you, more than you think.

It may change the way you think.

It may be advantage you can apply in other problem solving.

This is how you win.