Deleting an instruction now stops it applying, immediately

Deleting an instruction from the Instructions page removed it from the picker, so new agent versions could no longer select it. But any agent version that already used it (including the one live in front of your shoppers) kept applying it. The instruction stayed in the conversation while disappearing from every screen in the dashboard, so there was no way to see it, read it, or edit it.

That is now fixed in both directions.

A deleted instruction stops applying at once, on every agent version that references it, live ones included. The delete confirmation says so, and names the agents it affects, because confirming it changes what your shoppers get straight away.

Its text stays readable. Open the version that referenced it (Agent → Versions) and you'll find it listed under "No longer in force", with its content, so you can copy it somewhere before it's gone for good.

Agents that referenced a deleted instruction can be saved again. This is the part worth knowing about if you hit it: an agent whose live version pointed at a deleted instruction could not be saved or published at all. Every attempt (adding an instruction, enabling a tool, renaming the assistant) failed with "Could not complete the action. Please try again." Saving now simply leaves the deleted instruction behind, and tells you which one was dropped.

When a save does fail, the message says why instead of asking you to try again: an unavailable instruction, an unavailable connector, or a language your store hasn't enabled.

Nothing to change on your side. If one of your agents was stuck, it will save normally now. Check its Instructions tab, since an instruction someone deleted may no longer be part of it.