Read-only comparison of the retail DLC-2 map envelope, the installed alias candidate, and the available save. No Steam file or save was modified.
Measured
Retail dlc_2/base/packagemapspec.json for game/dlc/c02/c2v1:
{"basechunkid": 6, "chunkid": 22, "isbasechunk": false,
"layer": -1, "refchunks": [9, 13], "patchlevel": 3}
The installed alias used the same chunk filename/ID and basechunkid/layer, but had patchlevel: 4 and omitted refchunks. This constitutes a concrete bundle-mismatch hypothesis for File Corrupt; the installer was corrected to use patchlevel 3 and refs [9, 13].
IDCL comparison:
- Retail chunk 22: 6,985 entries,
+0x08 = 0xcda7783767c0c98f. - Alias candidate: 243 entries, same
+0x08;+0x20differs as expected after rebuilding the string table.
Thus +0x08/chunk identity is not the first mismatch. The candidate remains unproven runtime-valid because its reduced entry set and internal asset references differ from the retail bundle.
Save comparison showed that the available retail save still carries game/dlc/c02/c2v1 in checkpoint.dat, checkpoint_mapstart.dat, and game.details. A custom test requires the alias in all three locations; leaving one retail map string is an independent corruption cause.
Reproduction
python tools/check_tnc_map_identity.py `
--game <Steam library>\steamapps\common\Wolfenstein.II.The.New.Colossus `
--candidate <Steam library>\steamapps\common\Wolfenstein.II.The.New.Colossus\dlc\dlc_4
The check is read-only and confirms the mapspec/IDCL/save hypotheses before a new runtime attempt.