Completes the run-critic seam so a host adapter (mort's agentcritic) has full
fidelity, closing the two limitations gadfly surfaced on mort #1334.
- RecordStep(iter int, resp *llm.Response): the completed step's model response
is now passed to the critic (was index-only), so a host that records a trace
(mort's ProgressRecorder) can show what the agent actually produced, not just
an iteration count. The executor forwards s.Response; the battery ignores it
(its Progress is count-based).
- CriticHandle.KillCause() error + ErrCriticKill: the executor now distinguishes
an explicit critic KILL from a natural backstop expiry. runCtx uses a
cause-carrying cancel (WithCancelCause + a MaxRuntime timer cancelling with
DeadlineExceeded); the deadline-watch cancels with ErrCriticKill when
KillCause()!=nil, else DeadlineExceeded. statusFor reads context.Cause →
killed / timeout / cancelled are now distinct (were all "cancelled"). The
battery sets killCause from Decision.KillReason on a Kill.
Tests: statusFor "killed" case (cause=ErrCriticKill, err=Canceled); fake handle
+ battery RecordStep/KillCause signatures. Core stays battery-free.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
steve
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