Where does VSIDE store/cache extra source file search folders told by user?

Question

I find such a weird problem. A screenshot shows this.

Using Visual Studio 2019 v16.11,

• when debugging, I see a function named _except_handler3 on the callstack.
• I double click the _except_handler3 item, VSIDE pops up "Find Source" dialog asking for file location of d:\a01\_work\5\s\src\vctools\crt\vcruntime\src\eh\i386\exsup3.asm.
• Hmm, it looks like this is a Microsoft internal source file, and I don't have it.
• I take the chance to try something wacky. From leaked windows NT5 source code, grab the a file with the same name exsup3.asm, and place it into D:\test\src123 and tell VSIDE to use it.
• VSIDE accepts it, and, not surprisingly, VSIDE can not display the ASM source code correctly, because that 20-year-old faking exsup3.asm probably does not match VC2019's _except_handler3 machine code.

Now my question comes up: VSIDE seems to store/cache my D:\test\src123 directory path somewhere in the system, so that each time [ I restart debugging my program and try to double click _except_handler ], VSIDE always asks me whether I need to use D:\test\src123\exsup3.asm as source code.

I try three ways to clear the "cache", but in vain.

(1) Delete .sln/.vcxproj and their whole folder from hard disk.

(2) Search registry node HKCU and HKLM, but find no appearance of src123 .

(3) Delete whole %AppData%\Microsoft\VisualStudio\16.0_08fbc860 folder and see it re-created next time I start VSIDE.

By saying "in vain", I mean, VSIDE keeps asking me whether I want to use the source file D:\test\src123\exsup3.asm .

Then I'd like to ask, where on earth does VSIDE store my directory string D:\test\src123 ?