PC port: phase 2 — D48 review: re-plan D43 as offline pre-conversion (Plan B)

- D48 finding in PCPortResearch.md §F: d43_convert.py does not emit bytes
  (layout+remap validation only); Plan B = Python emit pass -> data/pcmodels-<region>/
  RZ sidecars served via port-layer hw_address/rom_size table patch (no C
  converter); Plan A kept as fallback with corrected staging guard (D_N64+D_PC<=avail)
- Moved all 23 d43_*.py investigation scripts from gitignored build-pc/ to tracked
  tools_pc/ (spec is now versioned); d43_cover.py path ref updated; converter
  re-run from new location: ALL CLEAN
- HANDOFF.md rewritten as two-session prompt: Session A = independent review of
  Plan B (8 claims, each with falsification criterion -> finding D49), Session B =
  execute (emit pass + round-trip validator, romdata plumbing, one-line hook,
  pixel-assert soak); verified-facts converter spec preserved
- AGENTS.md phase status updated to D48 re-plan

tools_pc/d43_layout.py

@@ -0,0 +1,106 @@
+# D43: full layout analysis of all model files with CORRECT N64 sizes.
+# node = 24B; records per opcode; vertex/coll arrays; GDLs. Report gaps/overlaps.
+import csv, struct, zlib, os, re
+from collections import Counter
+
+ROM = r"data/ge007.ntsc-final.z64"
+rom = open(ROM, "rb").read()
+rows = list(csv.reader(open(r"scripts/filelist.u.csv")))
+RSZ = {1:0x10, 2:0x1C, 4:0x14, 8:0x10, 9:0x24, 10:0x1C, 12:0x28, 13:0x20, 15:0x1C, 17:0x20, 18:0x8, 21:0x14, 22:0x10, 23:0x2, 24:0x20}
+hdrfiles = set()
+for root, dirs, files in os.walk("assets"):
+    for fn in files:
+        if fn.lower().endswith("modelfileheader.inc.c"): hdrfiles.add(os.path.join(root, fn))
+nsnt = {}
+for f in sorted(hdrfiles):
+    for line in open(f):
+        m = re.search(r"MODELFILEHEADER\((.*)\)\s*;?\s*$", line)
+        if not m: continue
+        a = [x.strip() for x in m.group(1).split(",")]
+        if len(a) < 9: continue
+        try: nsnt[a[0]] = (int(a[4], 0), int(a[8], 0))
+        except ValueError: pass
+
+def be32(b, o): return struct.unpack_from(">I", b, o)[0] & 0xFFFFFF
+def be16(b, o): return struct.unpack_from(">H", b, o)[0]
+def be32raw(b, o): return struct.unpack_from(">I", b, o)[0]
+
+gapstats = Counter(); problems = []
+nfiles = 0; totalnodes = 0; opcodes = Counter()
+for r in rows:
+    if len(r) < 3 or not r[2]: continue
+    base = r[2].rsplit("/",1)[-1]
+    if base.endswith(".bin"): base = base[:-4]
+    if not (base[0] in "CGP" and base.endswith("Z") and "_stan" not in base): continue
+    try: addr,size = int(r[0]),int(r[1])
+    except ValueError: continue
+    key=None
+    for cand in (base, base[1:], base[:-1], base[1:-1]):
+        if cand in nsnt: key=cand; break
+    if not key: problems.append((base,"nohdr")); continue
+    NS,NT = nsnt[key]
+    try: out = zlib.decompress(rom[addr:addr+size][2:], -15)
+    except Exception: problems.append((base,"decomp")); continue
+    D = len(out); R0 = 4*NS + 12*NT; nfiles += 1
+    stack=[R0]; seen=set(); objs=[]
+    while stack:
+        o=stack.pop()
+        if o in seen or o>=D-23: problems.append((base,"badnode %X"%o)); break
+        seen.add(o)
+        op=struct.unpack_from(">H",out,o)[0]&0xff
+        opcodes[op]+=1
+        data=be32(out,o+4)
+        objs.append((o,o+24,"node"))
+        if op in RSZ:
+            rsz = RSZ[op]
+            if data + rsz > D: problems.append((base,"rec %X+%X>D"%(data,rsz)))
+            else: objs.append((data,data+rsz,"rec%d"%op))
+        if op==22:
+            nv=struct.unpack_from(">i",out,data)[0]
+            v=be32(out,data+4)
+            p=be32(out,data+8)
+            if p: objs.append((p,None,"gdl"))
+            if v and nv>0: objs.append((v,v+16*nv,"vtx22"))
+        if op==4:
+            p=be32(out,data); s=be32(out,data+4)
+            v=be32(out,data+0xC)
+            if p: objs.append((p,None,"gdl"))
+            if s: objs.append((s,None,"gdl"))
+            if v: objs.append((v,None,"vtx?"))   # size unknown (numVertices may be 0)
+        elif op==24:
+            p=be32(out,data); s=be32(out,data+4)
+            v=be32(out,data+8); nv=be16(out,data+0xC)
+            cv=be32(out,data+0x10); nc=be16(out,data+0xE)
+            pu=be32(out,data+0x14)
+            if p: objs.append((p,None,"gdl"))
+            if s: objs.append((s,None,"gdl"))
+            if v and nv: objs.append((v,v+16*nv,"vtx"))
+            if cv and nc: objs.append((cv,cv+16*nc,"coll"))
+            if pu: objs.append((pu,None,"pointusage?"))
+        for q in (be32(out,o+0x14), be32(out,o+0xC)):
+            if q: stack.append(q)
+    totalnodes += len(seen)
+    # resolve open-ended objects using sorted starts
+    known = sorted(set(s for s,e,k in objs if e is not None))
+    for i,(s,e,k) in enumerate(objs):
+        if e is None:
+            nxt = [x for x in known if x > s]
+            objs[i] = (s, min(nxt) if nxt else D, k)
+    ivs = sorted((s,e) for s,e,k in [(0,R0,"hdr")]+objs)
+    pos = 0
+    for s,e in ivs:
+        if s < pos: problems.append((base,"overlap %X<%X"%(s,pos))); break
+        if s > pos:
+            gapstats[(s-pos)] += 1
+            if len(problems) < 40:
+                problems.append((base, "gap %X..%X (%d B)" % (pos, s, s - pos)))
+            break
+        pos = e
+    else:
+        if pos != D: problems.append((base,"tail gap %X!=D=%X"%(pos,D)))
+
+print("files:",nfiles,"nodes:",totalnodes)
+print("opcodes:",dict(sorted(opcodes.items())))
+print("gap-size histogram (first gap per file):",dict(sorted(gapstats.items())[:20]))
+print("problems:",len(problems))
+for p in problems[:40]: print("  ",p)