[bug] EnsureCEALibraryLoaded mutates the whole Excel process's DLL search path via SetDllDirectoryW

[djkees]

Summary
EnsureCEALibraryLoaded (source/bind/excel/vba/modCEADeclare.bas) calls the Win32 SetDllDirectoryW API when resolving cea_excel.dll's folder. This call changes the DLL search order for the entire Excel process, not just this workbook, and is never reset afterward.

Reproduction

• Interface: Excel/VBA
• Open two macro-enabled workbooks in the same Excel session, one using the CEA Excel wrapper; inspect DLL search behavior for the other workbook's add-ins afterward.

Expected behavior
DLL directory scoping should be workbook-local (e.g. via LOAD_LIBRARY_SEARCH_* flags on LoadLibraryExW, or restoring the previous SetDllDirectoryW value after loading) rather than a persistent process-wide side effect.

Actual behavior
Loading the CEA wrapper in one workbook can affect DLL resolution for unrelated add-ins/workbooks open in the same Excel session.

Environment

• OS: 64-bit Windows Excel
• CEA version/commit: main as of 2026-09-02

Additional context
source/bind/excel/vba/modCEADeclare.bas, EnsureCEALibraryLoaded, around the SetDllDirectoryW call.

Drafted with Claude's assistance

• Confirmed by reading EnsureCEALibraryLoaded in full and noting no corresponding reset/restore call exists anywhere in the module.