What is the timing of building and paying debt?

Question

To reiterate on previous questions (1, 2), the general timing goes like so:

1. Players decide which card to play.
2. Players decide how to play that card (build, discard, wonder).
3. Players decide how to pay building costs (who to buy from), and then announce/reveal their play.
4. Players complete the action and resolve building effects.

In the Cities expansion, there are building effects that cause debt, forcing other players to pay money or take negative VP tokens.

Let's assume that an opponent will play a debt 2 building this turn, and I start the turn with no money. Also assume that I know this will happen (from passing them the card and them playing a black card strategy). What happens in the following situations?

1. My neighbour pays me 2 coins to build the debt building. From the turn timing, it seems clear that I can pay the debt, since building costs are paid before their effects (I've included this for completeness).
2. I build a yellow card that gives me enough coins to pay the debt. Since the money gain and the debt happen at the same time, can I pay with the income?
3. I discard a card to get enough coins to pay the debt. Does money from discarding come in in step 4 (above), or earlier (step 2 or 3)? If it's earlier, it seems clear I should be able to pay, but if it's 4 (or after) then it's similar to the second case above.

Answer 1

According to the cities rulebook, p. 4:

Important: Monetary losses are always resolved at the end of a turn, after players have played their cards, possibly having paid for trade and/or obtained money...

Therefore, for all your examples, you do have enough money to pay the debt. Monetary losses is the last effect to resolve itself, even following the "take a card from the discard pile" ability of Halikarnassós.

Answer 2

The question has ben answered that all monetary losses happen at the end of a stage but the following should be clarified. You have 'decide what card to play' and 'decide who to but resources from' as a separate action.

You should have decided who to but resources from, if needed, before revealing your card. The payment for your action is done as soon as your card is revealed. there isn't the chance to look at what other people have done first. A player may not spend money received that turn to buy resources themselves. They may however use that money to pay off debt.