Qui doen't contract before a vowel

Question

Qu'est-ce que tu penses?
but,
Qui est-ce qui vient ce soir?

Just wondering why 'Qui', which ends in a vowel, wouldn't contract when the following word begins with a vowel, as does the example with 'Que'?

Cécile Janty-Davies · Accepted Answer

Hi Lewis,
 In answer to your question logically, it is probably to differentiate the meanings which would be lost if you could elide both vowels - 
Qu'est-ce -que ...? = What is ...?
Qui est-ce que ...? = Who is ...?
Hope this helps.

Chris Wirt · Answer

Only words ending in "e" contract.

Alan Graham · Answer

Mainly it's words ending in "e", but also "la" and "si".
The rules are explained here:
https://french.kwiziq.com/revision/glossary/contraction/l-elision-elision

Chris Wirt · Answer

But si does not contract if the following vowel is an "e". It only contracts in cases such as si+il = s'il or s+ils = s'ils.
If you want a more complete summary on elisions, you can check, e.g.,here:https://www.lawlessfrench.com/pronunciation/elision/