Per-substrate transition history now survives restart. Each entry's
steady_clock timestamp is written as a system_clock-millis snapshot;
on replay the steady_clock time_point is reconstructed relative to
the current (steady_now, system_now) pair, so inter-event spacing
is preserved across restarts even if the FSM is in a different
process. Absolute wall-clock accuracy degrades by any NTP step
that happened between write and read; that's a documented caveat.
Record format goes v1 → v2. v1 (history-less) records still load,
just with empty history.
Test updates:
- the old "history is NOT journaled" test is REPLACED with one
that asserts every axis + event + label round-trips.
- hand-crafted v1 record on disk still loads (proves backwards
compat).
- 15 ms-spaced events restore with their spacing intact (±slop
for scheduler jitter).
Closes the "substrate history persistence" caveat from the post-#1-13
status writeup.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Same pattern as carriers: per-substrate binary record (.sub) with
atomic .tmp+rename, replay on enable, delete on remove. Records
current state across all three E90 axes (location / processing /
ID-status), plus substid / carrierid / slot / free-form location
label. History is deliberately NOT journaled — it's an in-memory
ring buffer and rebuilding from replayed state would mislead.
Five new tests cover full-axis replay, every terminal processing
state, remove-deletes-journal, corrupt-record drop, and the
history-is-transient invariant.
Closes#2 in the test-gap backlog.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
raphael