The DAT file reader had several bugs inherited from the old C++ reference
code, which targeted an older format version. Verified and fixed against
real client_portal.dat and client_cell_1.dat files:
- Fix header offset: BTree root is at 0x160, not 0x148 (file size field)
- Fix BTree entry size: 24 bytes (flags+id+offset+size+timestamp), not 12
- Fix sector-chain node reading: BTree nodes span multiple sectors via
linked-list headers; must assemble node data across sector boundaries
- Fix DatStreamImpl.Read() BSTR handling: use Buffer.BlockCopy to match
C++ SysAllocStringByteLen instead of Marshal.PtrToStringAnsi
- Fix DatStreamImpl.ReadBinary() pointer lifetime: inline fixed block to
keep destination buffer pinned during Marshal.Copy
- Document LoadFilters() dependency on parameterized COM properties in
IDecalCore.Configuration that need IDispatch to call correctly
Add smoke test project (13/13 tests pass against real DAT files).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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