Idiom for knowing someone so well you can tell what they're thinking going to do by small indications [duplicate]

I'm trying to think of an idiom for knowing/ predicting what someone is thinking or about to do because you know them well.

The saying is actually Chinese or Cantonese 你翘一下尾巴我就知道你在想什么了 and roughly translates to "I'll know what you are thinking if you raise your tail".

To illustrate with a situation, it would be something involving two people. One person reacts to something, say they look up and see rain clouds and then the other person knows that the first person will want to go back to get an umbrella. Because they saw them look at the cloud and know their thinking, they were able to guess what they would do.

Another example, someone is eating salad and makes and looks around the table, then the other person hands them the salt. Because they know them so well they knew what they were thinking.

For idioms, I suggest:

I know you inside out.

know someone or something inside out

to know someone or something extremely well Collins

"I trained her. I knew her inside out, what she liked, what she loathed, how she reasoned, how she thought, how she felt, every last bit of her." Margaret Garth; The Beginning of Unity

While we were the greatest rivals we're also the greatest friends. We sat beside each other in weighing rooms nearly every day for twenty years, he knew me inside out, I knew him inside out, and in my view it was one of the best, healthiest and friendliest rivalries any two sportsmen could ever have A. P. McCoy; Winner: My Racing Life

I didn't usually have to ask her anything, because I knew all her answers. I knew her inside out. Haf Llewelyn; Empty Chair

A similar idiom is:

know something like the back of your hand

to know something very well Collins

I actually knew him like the back of my hand; all of his likes, his dislikes, his moods, his goals, his everything. T. A. Samuels; All the Time in the World