test(p0): retail-trace golden captured — membership criterion divergence pinned (P0 GATE MET)

P0 Task 6 complete. Captured live retail membership at the 0031<->0170<->0171
doorway via cdb on CPhysicsObj::change_cell (symbol-driven; offsets verified by
discover-types.cdb; PDB MATCH). 22 transitions, clean monotonic sequence, NO
ping-pong (retail is correct-by-construction). Golden:
Conformance/Fixtures/find-cell-list-threshold.log.

ROOT-CAUSE FINDING (the central P1 work): retail transitions membership at the
PORTAL CROSSING (CEnvCell::find_transit_cells @ 0x52c820 pc:309968 — sphere crosses
the doorway polygon plane), while acdream's FindCellList re-picks by POINT-IN-CELL
containment at the foot. Retail commits room 0171 while the foot is STILL inside
vestibule 0170's BSP (in_0171=0); acdream lags. ALL 22 transitions diverge for this
one criterion mismatch — not a per-cell hysteresis or a building-entry-only split.
This is master-plan §0 'hysteresis gap' confirmed against the real client.

FindCellList_DoorwayThreshold_DivergesFromRetail_PendingP1 (documents-the-bug, GREEN)
+ ThresholdDivergenceDiagnosticTests (per-transition containment print) pin it; both
flip when P1 ports the directed portal crossing. Conformance 59 pass / 1 skip / 0 fail;
full Core 1308 pass / 5 fail (baseline) / 1 skip — no new failures.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tools/cdb/decode_fcl_capture.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python
+"""Decode a find-cell-list-capture.log into the golden fixture format.
+
+The cdb capture (tools/cdb/find-cell-list-capture.cdb) writes player world
+origin as raw IEEE-754 hex:
+    [fcl] seed=0xHHHHHHHH px=0xHHHHHHHH py=0xHHHHHHHH pz=0xHHHHHHHH picked=0xHHHHHHHH
+This rewrites px/py/pz to decimals (RetailTrace.ParseFindCellList format):
+    [fcl] seed=0xHHHHHHHH px=<f> py=<f> pz=<f> picked=0xHHHHHHHH
+
+Usage: py tools/cdb/decode_fcl_capture.py <capture.log> <out.log>
+"""
+import re
+import struct
+import sys
+
+LINE = re.compile(
+    r"\[fcl\]\s+seed=0x([0-9a-fA-F]+)\s+px=0x([0-9a-fA-F]+)\s+py=0x([0-9a-fA-F]+)"
+    r"\s+pz=0x([0-9a-fA-F]+)\s+picked=0x([0-9a-fA-F]+)")
+
+
+def hex_to_float(h: str) -> float:
+    return struct.unpack("<f", struct.pack("<I", int(h, 16)))[0]
+
+
+def main() -> int:
+    src, dst = sys.argv[1], sys.argv[2]
+    out = []
+    seen = set()
+    with open(src, "r", encoding="utf-8", errors="ignore") as f:
+        for line in f:
+            m = LINE.search(line)
+            if not m:
+                continue
+            seed, px, py, pz, picked = m.groups()
+            # Dedupe identical (seed, picked, rounded-pos) rows to keep the golden tight.
+            x, y, z = hex_to_float(px), hex_to_float(py), hex_to_float(pz)
+            key = (seed.lower(), picked.lower(), round(x, 2), round(y, 2), round(z, 2))
+            if key in seen:
+                continue
+            seen.add(key)
+            out.append(
+                f"[fcl] seed=0x{int(seed,16):08X} "
+                f"px={x:.4f} py={y:.4f} pz={z:.4f} "
+                f"picked=0x{int(picked,16):08X}")
+    with open(dst, "w", encoding="utf-8") as f:
+        f.write("\n".join(out) + "\n")
+    print("\n".join(out))
+    print(f"\n{len(out)} unique picks -> {dst}")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())