Apparatus only — no fix attempt. Per the systematic-debugging skill's
"3+ failures = question architecture" rule, the 6 hypotheses we
tested speculatively on the harness's airborne-at-tick-1 bug all
failed because we kept guessing what state the harness lacks. This
commit ships the evidence-driven path: capture the EXACT player
ResolveWithTransition call (every input + body-before + body-after +
result) into a JSON Lines fixture, then a comparison test loads the
fixture and replays it against the test engine. The first per-field
divergence pinpoints the missing apparatus state — no more guessing.
Adds:
- src/AcDream.Core/Physics/PhysicsResolveCapture.cs — new static module
with CapturePath (env var ACDREAM_CAPTURE_RESOLVE), PhysicsBodySnapshot
record, JSON Lines writer (thread-safe, flushes per record), process-
exit hook for clean shutdown.
- PhysicsEngine.ResolveWithTransition probe wiring: snapshot body at
method entry, snapshot again before return, refactor the two returns
into one path so the capture call site is single. Filtered to
IsPlayer mover flag so NPC/remote DR calls don't pollute.
- CellarUpTrajectoryReplayTests.cs:
• Capture_WritesJsonLinesRecordsWhenIsPlayerAndEnabled — drives 3
ticks with capture on, reads file back, verifies round-trip of
inputs + body-before/after snapshots.
• Capture_SkipsNonPlayerCalls — drives 3 NPC-style ticks (no
IsPlayer flag), confirms the file is not created.
Off by default. Set ACDREAM_CAPTURE_RESOLVE=<path> to a writable file
path; capture starts on the next player ResolveWithTransition call.
Test baseline: 1172 + 8 pre-existing failures + 2 new smoke tests
that pass = 1174 + 8. Verified by stashed-baseline comparison.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
