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docs/command-line-parameters.md

@@ -151,14 +151,76 @@ What is now materially tighter:
 - it uses the token as the `path` component to `Filespec_GetFullPath`
 - it uses the mutable filename template at `1478:07a0`, which is `eusecode.flx`, as the fixed `filename` component
 - it forces that template's first byte to `'e'` before the existence probe and final load call
+- the path builder uses DOS-style backslashes via the literal `"\\"` string from `FILE\\FILESPEC.C`
+- the existence probe goes through the DOS file-search path in `File_Exists`, so the override must resolve inside the game's DOS-visible filesystem
+- the parser copies the token into the `0x1e`-byte buffer at `1478:065a`, so the practical maximum is `29` visible characters plus the terminator
 
 So the safest current retail read is:
 
 - `-u <arg>` expects a directory/resource-root style path argument for the standard `eusecode.flx` archive family
 - it does **not** currently look like a free-form arbitrary filename override
+- the safest token spelling uses DOS-style backslashes, not forward slashes
+
+That gives a direct explanation for failed attempts like:
+
+- `-u USECODE/FLICTEST.FLX`
+- `-u FLICTEST.FLX`
+- `-u C:\MADDOCODE` when that path only exists on the Windows host and not inside the guest DOS drive mapping
+
+Those forms fit the recovered helper badly because the token is used as the `Filespec_GetFullPath` path component while the filename remains the fixed template `eusecode.flx`. Current safest interpretation is therefore:
+
+- pass a directory or resource-root to `-u`
+- put the replacement archive at `<that root>/EUSECODE.FLX`
+- do not expect `-u` to open `FLICTEST.FLX` directly as the final archive name
+
+The current safest syntax examples are:
+
+- `-u MADDOCODE`
+- `-u .\MADDOCODE`
+- `-u \MADDOCODE`
+- `-u C:\MADDOCODE`
+
+But for real DOS-facing installs, the safer practical examples are the `8.3`-safe variants:
+
+- `-u MADDOC~1`
+- `-u .\MADDOC~1`
+
+with these current best path interpretations:
+
+- `MADDOCODE` = relative to the game's current DOS working directory
+- `.\MADDOCODE` = explicit relative DOS path
+- `\MADDOCODE` = root-relative path on the current DOS drive
+- `C:\MADDOCODE` = absolute DOS path on drive `C:` as seen by the DOS game, not automatically the Windows host path
+
+In the current GOG install used for this investigation, Windows reports the short alias:
+
+- `MADDOCODE` -> `MADDOC~1`
+
+That makes `MADDOC~1` the highest-probability next token for this specific setup.
+
+Current safest negative guidance:
+
+- avoid forward slashes for `-u`
+- avoid long path tokens because silent truncation at `1478:065a` can change the real lookup target
+- do not use the archive filename itself as the `-u` argument
+- prefer `8.3`-safe directory names or explicit DOS short aliases when testing under DOSBox-like environments
 
 But the important uncertainty is now only `exact naming rules`, not `whether the switch is real`. In the regular non-Japanese `CRUSADER.EXE`, the switch is clearly still live.
 
+## Expected Console Output For `-u`
+
+Current best answer: probably none.
+
+The recovered `-u` parser case does not print a banner, and the startup helper that probes and swaps the override path also has no recovered `ConsolePrintf` call. So unlike `-debug`, `-warp`, `-skill`, `-mapoff`, `-egg`, or `-demo`, `-u` does not currently appear to advertise itself on the console before the game loads.
+
+The safest current expectation is:
+
+- success: no dedicated `-u` console message
+- missing path/file: no dedicated `-u` console message, likely silent fallback to stock usecode
+- malformed but existing replacement: no dedicated `-u` status line from the parser/helper path; later behavior depends on the deeper loader/runtime path
+
+This also sharpens the practical diagnosis for the current `MADDOCODE` setup. In the tested GOG install, only `EUSECODE.FLX` differs between `USECODE` and `MADDOCODE`; the sidecar files are byte-identical. So if replacing `USECODE\EUSECODE.FLX` with the hacked file produces the expected obvious no-usecode-style breakage, but `-u MADDOCODE` behaves like stock gameplay instead, the strongest current read is that the override path was probably not accepted and startup silently fell back to the stock usecode root.
+
 This also aligns with the already-stronger JP Win32 result, where the matching `-u` lane was recovered as the same kind of usecode override.
 
 For the deeper runtime-side investigation of whether `-u` replaces or augments the stock usecode root, and what game systems that replacement feeds, see [docs/usecode-startup-override.md](docs/usecode-startup-override.md).