For years, flying back to Ottawa through Toronto from outside the country required us to collect and then drop off our bags for the connecting flight when clearing customs. Then a change was instituted a few years ago, and our bags are now checked all the way through to Ottawa with no need to collect/drop them in Toronto. So in theory, the OP's bags should be checked all the way through to Halifax.
But all of our connecting flights were within a couple of hours of arriving in Toronto, so the bags would have had little time between being offloaded and reloaded. In the OP's case, with a 9-hour layover, I don't know whether Pearson has the capacity for storing bags for an extended period time.