Context

While implementing changes to the agent privilege level change API in Fleet in #237790, the question arose of how to handle agents that are already unprivileged (the API is one-way: it only allows changing the privilege level to unprivileged). We agreed that fast success made the most sense.

For the single agent endpoint (POST /api/fleet/agent/{agent_id}/privilege_level_change), a request for an already unprivileged agent will return fast with status 200 and an info message. No action is created in this case.

For the bulk (multiple agents) endpoint, this turned out to require a change in how bulk actions are formed. Currently, the result of actions is checked with the following parameters:

We expect actioned agents to either have been included in actions or failed:

Since it wouldn't have been consistent to fail already unprivileged agents, we decided to let them be processed.

Relevant comments in the above PR:
#237790 (comment)
#237790 (comment)
#237790 (comment)
#237790 (comment)
#237790 (comment)
#237790 (comment)

Possible solution

If we want to allow "early success" (essentially skipping) in bulk actions, we would probably need an additional parameter, something like nbAgentsSkipped, such that

action.nbAgentsActioned === action.nbAgentsActionCreated + action.nbAgentsFailed + action.nbAgentsSkipped

We would need to review how the action results are presented to the user.