はずだ

はずだ expresses a speaker’s expectation or assumption based on information or evidence, not a definite fact. It conveys what you believe should be true given circumstances, often implying a degree of confidence. It is commonly used in everyday situations to talk about things that are likely, expected, or appropriate to happen. It can also reference expectations from the speaker’s knowledge, rather than a certainty. Past form はずだった refers to a past expectation that should have been the case.