I ran a small experiment on Bitcoin Inquisition Signet using: OP_INTERNALKEY OP_CHECKSIGFROMSTACK.Confirmed spend:https://mempool.space/signet/tx/8d0b2156e9425afe64cabf3c906da255b6b86c51cb8968f828d5253fc261dd8fIn plain CSFS, the witness provides (sig, msg, pubkey), so the script checks whether someone signed the message.With OP_INTERNALKEY, the pubkey comes from Taproot context instead of witness.A possible framing:CSFS: “did someone sign this message?”IK + CSFS: “did the Taproot internal key holder sign this message?”This seems to turn CSFS into a kind of identity-bound authorization primitive.Is this a useful way to think about it?Where does this interpretation break?