Function sqlite_lossy_cast_checks 

pub fn sqlite_lossy_cast_checks(
    state: &ProjectState,
    op: &Operation,
) -> Vec<SqliteCastCheck>

Columns of op whose SQLite rebuild CAST could lose data.

Only AlterField type changes need a probe. Same-type edits (length, nullability, defaults) copy verbatim, anything -> TEXT/BLOB stores every value, and int -> REAL compares equal (5 IS 5.0), so those skip.