Interesting to hear you say that, I was thinking (but hadn't said) that using WalEx to dispatch to some workers where the agent lived would be a better solution. The worker would then update the row (or more likely insert a new one in a different table with more constraints/different columns). I would be curious to hear what advantage you see in a `claw` type/`agent` column? I can't make heads or tails of it but I regard you as knowing a lot more about Postgres than me.
You could probably use listen/subscribe trigger to accomplish that.