by the way when the applet is selected, I return
D2760001240103045343000000010000
this can be used to detect the manufacturer number

Card ATR at the cool reset
Card ATR is : 3B 9C 95 81 01 50 53 43 50 2D 53 43 53 56 31 2E 30 8E
Historical Byte is 53435356312E30
CARD ATS-to-ATR is : 3B 8C 80 01 50 53 43 50 2D 53 43 53 56 31 2E 30 0A
CARD ATS is : 11 78 80 B8 02 50 53 43 50 2D 53 43 53 56 31 2E 30
Historical Byte is 53435356312E30
This can by detected for the card type.

Line 1454 : if (!opt.pcsc_shared || app->card->cardtype != CARDTYPE_YUBIKEY)
need to remove || app->card->cardtype != CARDTYPE_YUBIKEY

You need to protect only 2 critical set of ADPU sequence Sign and Decrypt. All other can be done not safely and have a minor impact. Get generation and cards unlock can be profitable with the transaction mode... but is very rare user makes another use of the card in same time he start that’s command. The check external interference can protect from a bad start. I have started this ticket because my card suffer in exclusive mode render the use of openpgp not really usable. When my card is an pcsc-shared mode, all it's OK but the daemon not able to restore after external interference. The correction proposed is OK but I have made recommendations because this can cause a bad applet switch... if the state does not restore before trying to switch applet all it's OK. I am not actually able to set directly differential code but I have described in the patch the change I have made and this make my card very happy. Not problems and the pin was queried if another application makes interference.

OK I have finally success to test... the master version has a problem with opening pcsc readers on windows I revert back on older version to able to correct this problem. For the current patch without yubikey reference. I suggest validating the interference in the first task for the maybe_switch app function.

In fact, the trigger is not yubikey but the pcsc-shared flag... If the pcsc-shared flag is enabled, you do check for interference because you are in shared condition. It is not really a race condition because you can put the driver in transaction mode. It’s more a turn-by-turn games but you can lose the card context status between turn.
If you lock the patch only for yubikey I’m not able to test with my device. You can add my manufacturer ID in the test please.

It's not a device is a card. NXP P71 security chips on the card in the 250Kb Rom with GlobalPlateform 2.1.1 It is not possible for a card to change CCID by applet. Card depends of reader CCID. When the card is on NFC readers, the FIDO applet is accessible not when it is on contact readers. But, when I am in NFC FIDO share the CCID. For the user point of view having multiple card for each applet is a bad thing to devices for one user. User search presently for multipurpose devices. DOOR, Login, Email-crypt, ledger. Actually for app is not recommended to use a reader in exclusive mode. By designs the card is stateless and for memory management deselect applet free mem from other applet. Presently in the best case the card has 144-255 KB of eeprom and 2k or ram.

i'am not able to test... i can't build for win32. i have some trouble with my mingw32 installation and the miss match with library for build a functional version of gnupg for win32.
seem missing dll after make install folder. do you have instruction to setup dev environment for build win32 binary ? I use a ubuntu with minwg32. ntbtls seem missing ksba but libksba is already install verion 1.6.0 other project detect correctly ksba. it's seem is a little bit complicated juste for building scd project. a make it working correctly on windows environements.

Ok i have seen a problem with a double check here

Ok, I test this, this seem can be corrected 90% of all possible interference with another application on multi-applet smartcard in shared readers context. I left you the feel back when have tested… thank for the prompt response.

I have tried the case 1 with log activated
Windows switches applet for signing Adobe Acrobat doc.
This is the log from agent - Say Bad NIP but he never tries to use the nip SCDaemon have tried to decrypt only.
gpg-agent[8496]: DBG: agent_put_cache '1//'.-1 (mode 6) requested ttl=-1
gpg-agent[8496]: DBG: chan_0x000001c0 <- S SERIALNO D2760001240103045343000000010000
gpg-agent[8496]: DBG: chan_0x000001c0 <- OK
gpg-agent[8496]: DBG: chan_0x000001c0 -> KEYINFO BBD342CA5B0F978DA17F2AD9F5A1E95FF50C129E
gpg-agent[8496]: DBG: chan_0x000001c0 <- S KEYINFO BBD342CA5B0F978DA17F2AD9F5A1E95FF50C129E T D2760001240103045343000000010000 OPENPGP.2
gpg-agent[8496]: DBG: chan_0x000001c0 <- OK
gpg-agent[8496]: DBG: chan_0x000001c0 -> SETDATA 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
gpg-agent[8496]: DBG: chan_0x000001c0 <- OK
gpg-agent[8496]: DBG: chan_0x000001c0 -> PKDECRYPT BBD342CA5B0F978DA17F2AD9F5A1E95FF50C129E
gpg-agent[8496]: DBG: chan_0x000001c0 <- ERR 100663383 Mauvais code personnel <SCD>
gpg-agent[8496]: smartcard decryption failed: Mauvais code personnel
gpg-agent[8496]: command 'PKDECRYPT' failed: Mauvais code personnel <SCD>
gpg-agent[8496]: DBG: chan_0x00000270 -> ERR 100663383 Mauvais code personnel <SCD>

When a card sends 0x6982 in general rule is not really an error is a warning to say, your security environment was not correctly initialized.
This is true with almost applet. (PIV – GIDS – OPenPGP)
The instruction 0x2A to perform security operation return 0x6982 when pin is not authenticated or key is badly selected. This not decrement pin counter.