Change the Promise Deliberately

A developer replaces 300 lines of storage code. Another changes one entry rule.

Change	Decision to trace
New storage code	Does it preserve behavior, compatibility and pending work?
New entry rule	Who may enter now, and who owns that policy?
New engine	Where does old unfinished work remain?
Retired feature	What happens to existing consumers and obligations?

Review the consequence. Line count is a poor guide to authority.

Before	After	Same promise?
Look up the account in a vector.	Look it up in an index.	Yes, if the same facts and outcomes are preserved.
Require confirmation before entry.	Permit entry without confirmation.	No: a different group may enter.

Engineering Depth

These reference implementations produce different entry behavior:

impl EntryRule for CookieValid {
    fn permits(_: bool) -> bool {
        true
    }
}
impl EntryRule for ConfirmedOnly {
    fn permits(confirmed: bool) -> bool {
        confirmed
    }
}

Selecting ConfirmedOnly changes a product rule. Replacing how an unchanged rule reads its records may be an implementation change.

If a compiler error exposes a forbidden combination, check the requirement before widening the bound. The project owns its checks and release cadence. CS-11, CS-12.

Your Reflection

All tests pass after a bound is relaxed. What decision remains?

Worked Discussion

Determine whether the requested change authorizes the newly admitted behavior. Tests can support that decision; they cannot supply the owner's mandate.