policy-engine: AgentControl::new(runtime) leaves parts=None, making with_telemetry a no-op and revalidating against Limits::default #3941

Activity

1. chopmob-cloud commented on Sep 20, 2026

   

   AlgoVoi (Christopher Hopley) (chopmob-cloud)

   on Sep 20, 2026

   Contributor

   More actions

   On agent-control-spec =0.4.0-alpha.3, AgentControl::new(runtime) cannot populate parts from the runtime: Runtime stores annotations and limits as private fields with no public accessors (only manifest(), policy_dispatcher(), perf_telemetry() are exposed), and EvaluationResult carries only verdict/policy_input. So new receives an already-built Runtime it cannot read those back from. The working constructor only captures parts because it builds the runtime itself.

   The fail-open is confirmed: with parts = None, evaluate_intervention_point revalidates a Transform snapshot against Limits::default() (via unwrap_or_default()), so a caller who tightened e.g. max_snapshot_bytes gets the transformed snapshot checked against the looser default.

   Given that, the options are: (A) fail closed on Transform when parts is None (smallest, non-breaking; also rejects transforms for callers who legitimately used default limits; does not fix the with_telemetry no-op); (B) A plus #[deprecated] on new and a parts-aware constructor so telemetry/limits work correctly (non-breaking, matches "reject construction paths that cannot"); (C) make new fallible / require limits+annotations (breaking); (D) add Runtime accessors upstream in agent-control-spec and bump the pin, then populate parts in new (your option 1, done properly, but a separate crate + coordinated release).

   I would lean (B), with (D) as the eventual full fix. Which direction do you prefer? Happy to open the PR once you confirm, so it does not fight your intended shape.