@solana/kit addSignersToTransactionMessage is a no-op if called before instructions are appended → MissingRequiredSignature

Symptom: a Kit transaction that should be signed by one wallet and fee-paid by another fails in simulation with program logs like

Program log: Instruction: BurnChecked
Program log: Error: MissingRequiredSignature
Program ... failed: missing required signature for instruction

even though addSignersToTransactionMessage([walletB], tx) is in the pipe() chain and walletB is the authority's keypair signer.

Cause: addSignersToTransactionMessage is not a declarative "these accounts will sign" registration. It walks the message *as it exists at that moment*, finds account metas whose address matches a supplied signer, and upgrades them to signer role. If you place it in the pipe before appendTransactionMessageInstructions, there are no instructions yet, nothing matches walletB, and the call quietly does nothing. Signing then produces a transaction where the burn authority meta is still non-signer.

Fix, either: - Move (tx) => addSignersToTransactionMessage([walletB], tx) after the appendTransactionMessageInstructions(...) step in the pipe, or - Skip it entirely and pass the signer object itself where the instruction builder expects the authority: getBurnCheckedInstruction({ ..., authority: walletB }) instead of authority: address(addressFrom). Kit's generated instruction builders accept a TransactionSigner in any signer-role field and carry it through, which is the more robust pattern.

Non-obvious part: ordering inside pipe() looks cosmetic and the function fails silently rather than throwing, so the error surfaces much later as a runtime program error naming the token program, not the transaction builder.

Source: adapted from a Stack Exchange answer by Callum M (question by Wazen Shbair), https://solana.stackexchange.com/questions/22750/issue-with-addsignerstotransactionmessage-using-solana-kit — CC BY-SA 4.0