Lock for Tickets

In this case people will never able to add comments, analysis, or change the status for example...

Neither will it be possible with locked tickets ...

It is easier to lock when ticket confirmed and selected for the project and unlock to close it

But how will developers be able to work on ticker ?
=> start work
=> add comments
=> resquest for notes for completion
=> change status
=> enter result description
...

I understand the need, but am not sure locking is the answer.

That is the object of my question :

What do you mean by "scope of the project"

It means, instead of locking, it could be better to "fix scope".
But what would it cover ?
Fix description section...
Fix target version ...
Fix links ...
Not fix result...
Not fix status...
Allow new notes...