Each Substrate now retains an append-only history of state transitions
(both location and processing axes), the triggering event captured as
a std::variant<SubstrateEvent, SubstrateProcessingEvent>, the location
label at the time, and a steady_clock timestamp.
E90 §6.6 requires the equipment to be able to report a wafer's
processing history — typically queried via S6F11 batched reports or
SVID reads. This commit lays the runtime substrate; wire query
plumbing is the natural follow-up.
set_history_limit(n) caps per-substrate retention (default 256, 0 =
unbounded). Oldest entries are dropped when the cap is reached;
vector-erase is fine at this scale (typical wafer lifecycle is a few
dozen transitions).
Two new test cases cover the recording invariants (every fire results
in one history entry on the right axis) and history_limit eviction.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
raphael
a28a8b5982