Pretty much. The stumbling block won't be if your transaction is or is not opted in to RBF, but whether your wallet software supports creating and broadcasting an RBF transaction.

There are already several major pools mining full RBF replacements, such as F2Pool and AntPool. And even although a lot of nodes have not enabled full RBF, it is still fairly easy to get a full RBF replacement broadcast through the network. Given that the average node makes 8 connections to peers, with only 25% of the network running full RBF then each node still has a 90% chance of connecting to at least one full RBF node.

You can take a look here to see all the full RBF replacements being mined: https://mempool.space/rbf#fullrbf

Correct. If you cannot run an Electrum server, or you don't want to, then you can connect Sparrow directly to Core, with the downside that you will need to perform a full rescan for any addresses you import as I explained above.

If you are already running your own Electrum server, then I would preferentially connect to that.

If you connect directly to Bitcoin Core, Sparrow will create a wallet in Bitcoin Core for the relevant addresses, and then have to perform a full blockchain scan to get the history of those addresses (if there is any). Any time you create or import new addresses or wallets to Sparrow, then again, you'll have to perform a full scan to get any relevant history. This is just how it works for Bitcoin Core itself.

If you connect it to a full Electrum server such as Fulcrum or ElectrumX, then any addresses you add or wallets you import are updated almost instantly, just as they are when you connect your Electrum wallet to a third party server.

If you are connecting to your own full node, or you own Electrum server which is built upon your own full node, then no, there is no difference. If you start adding third party servers or nodes in to the mix, then it depends on what you are comparing.

Then why put it on your laptop at all? All you are doing is doubling the attack surface, doubling the chance your wallet is hacked, and greatly increasing the chance you accidentally leak your seed phrase when importing it in to a new wallet.

If you are going to use your laptop very infrequently, then just keep the wallet on your phone. If you absolutely must interact with the wallet from both your phone and your laptop, then get a hardware wallet and pair it with both devices.

There are 20 P2PK outputs of 50 BTC each which funded that address. These are 20 block rewards from blocks between 87,580 and 90,656, which were mined in October and November 2010. This is only one month before Satoshi's last post on this forum, and there were plenty of other miners involved in bitcoin by then.

So it's almost certainly just some early miner moving their coins. Nothing of any note.

The real question is why do you need to do this?

If you are going to spend bitcoin in person or make transactions on the go, then you want your hot wallet on your phone. Is there ever a time you are using your computer and you don't have your phone with you, which would require you to have the wallet duplicated on your computer? For most people the answer to that is no.

If you are not going to spend bitcoin in person or make transactions on the go, then you don't need your wallet on your phone.

Every additional piece of software you import the same seed phrase to increases the attack surface for that wallet. Similarly, every additional device you import the same seed phrase to increases the attack surface for that wallet. There is nothing stopping you duplicating the same wallet across multiple pieces of software on multiple device, but is the increased risk really worth it?

Your node will continually prune blocks as time goes on, so the earliest you will be able to scan for transactions will also advance in time. Therefore any other wallets you create or import in to Sparrow will need to have later and later birthdays, or you will be unable to view their transactions and balances.

As long as Bitcoin Core has the Sparrow "cormorant" wallet, then it will continue to scan incoming blocks for transactions relevant to your addresses. If for any reason the cormorant wallet is moved, removed, doesn't load, etc., then you could miss transactions in blocks that are later pruned.

I do agree with you, and do not use contacts myself. Indeed, they are a bad idea altogether since they encourage address reuse. Having said that, contacts are saved within the wallet file, and thus are encrypted along with everything else (provided you choose to encrypt your wallet file, which you obviously should). Any person or malware which can bypass this encryption to access or modify your contacts can just as easily bypass this encryption and access your private keys.

There is one match for such an error on the Electrum GitHub here: https://github.com/spesmilo/electrum/issues/7657

It doesn't provide a solution, but seems to match up with what Cricktor has hypothesized above. It sounds like there is nothing you can do on your end but to wait for the relevant pending channels to be opened or timeout, or choose to open a channel with a different node as you have already done.

Nothing is impossible to forget. A simple accident and blow to the head can result in you forgetting who your family members are. It can certainly result in you forgetting your homebrewed encryption.

So all three of them only know a part of the puzzle? So again, if anything happens to one of these people, your funds are inaccessible?

I would prefer to use something like 2-of-3 multi-sig here, where each of your three trusted contacts hold a single seed phrase (and the necessary xpubs). That provides security against a single malicious party as well as redundancy against the loss of one share.

It's barely been a couple of months

As Loyce says, there was a period of over 6 months at the end of 2017 and start of 2018 where you couldn't get 1 sat/vbyte transactions mined, and the peak fees then were much higher than they were a couple of months ago as well. Go and take a look at literally any of the heavily shilled ICOs which were launched during that ICO craze, and the few which still exist are down >99% from their peak during that time.

The ordinal craze is already going the same way. The hype is over. The prices are falling. 3 months ago a fast fee was around 30 sats/vybte. 6 weeks ago it was around 17 sats/vbyte. Today it's around 7 sats/vbytes.

We just have to hope that the next ICO/DeFi/NFT/Ordinal pump and dump scam isn't built directly on top of bitcoin.

It does not depend on the number of addresses, but the number of outputs. It does not matter if you are spending five outputs across five addresses or five outputs all on the same address - the transaction size, and therefore the necessary fee, will be identical.

As per my analogy earlier in this thread with physical cash, it does not matter if you take five physical coins out of your pocket, or if you take five physical coins from five different people. If you put these five coins in an envelope and send them through the mail, the price you pay for postage will be the same.

I've explained the size structure in this post. 1 inputs and 2 outputs will be 140 vbytes for a segwit transaction. Each additional input adds 68 vbytes, and each additional output adds 31 vbytes.

It's clear from the context of my text you have quoted that I am talking about outputs here as in unspent outputs or UTXOs, and not as in inputs/outputs of an individual transaction.

That's a bit of an exaggeration.

The $0.33 comes from mempool.space applying a rate of 8 sats/vbyte to a 140 byte segwit transaction, which will have one input and two outputs. Adding additional inputs to such a transaction adds 68 vbytes per input, and adding additional outputs adds 31 vbytes per output. You would have to go up to around 13 inputs and 13 outputs before you reached a fee of $3 at 8 sats/vbyte.

It works if you include "www". It doesn't if you don't.

We are all accustomed these days to including/excluding "www" at will, since every major site will redirect you to the correct landing page, but www is actually a subdomain. Type in www.bitcointalk.org and you will redirected to https://bitcointalk.org. Type in reddit.com, and you will be redirected to www.reddit.com. The owner of this site simply hasn't configured their top level domain to redirect to the www subdomain.

So what I'm hearing is hot dogs and whipped cream on a pizza? I'm sure fillippone will agree this sounds like a truly authentic pizza!

Yes. No. Maybe.

Bitcoin transaction are based on the number of outputs, not the value of those outputs. If I have a single output of 1 BTC, then to spend that I only need to pay for one output. If I have ten outputs of 0.0001 BTC, then to spend that I will need to pay for all ten outputs. It will be cheaper for me to spend one output of 1 BTC than it would be for me to spend ten outputs of 0.0001 BTC, even though those ten outputs of 0.0001 BTC are only worth a fraction of the one output of 1 BTC.

An analogy is like sending cash in the post, where you are charged for the weight of the cash you are sending. If I send a single $100 bill it will be very cheap. If I send a few dozen coins it will be very expensive, even though the total value of the coins will be much less than that of the $100 bill.

The $0.33 flat fee given by mempool.space is based on an "average" segwit transaction which spends a single input (regardless of the value of that input). If your $10 payment and your $1000 payment are both from a single input, then yes, they will pay the same fee. If they require more than one input, then the total fee will vary, although the fee rate (in satoshis per virtual byte, or sats/vbyte) will remain the same.

Bitcoin transactions are based on outputs, not on balances. Every time you receive some bitcoin, that creates a new output, even if you receive to the same address multiple times. Each of those outputs remains separate until you combine them in a transaction as you just did, and when you do you must pay a fee for each individual output, regardless of how much bitcoin is on that output. I can see you had outputs ranging from around 10,000 sats up to 0.02 BTC.

Think of it like receiving physical coins and putting them in your pocket. Even if you receive hundreds of coins, they don't magically turn in to a $20 bill in your pocket. Only by spending them altogether and getting back a $20 bill in change can you combine them in to a single output.

Yes, this was the reason for the high fee. You had plenty of outputs which could have made the 20,000 sat payment on their own. Instead your wallet chose to consolidate every output you had in the same address and return the rest to you in a single output as change. This will benefit you in the future by saving you fees in the long run, but as I said above, you could have performed this consolidation at a better time to pay less fees now as well.

Electrum has a feature known as coin control which allows you to spend just a single output when making such a transaction rather than consolidating all your outputs, if you wish.

There will always be a change address unless you spend an output completely. Bitcoin cannot "leave behind" some part of an output. If you have an output of 20,000 sats and you send it all to the recipient (minus the fee) there will be no change. If you have an output of 100,000 sats and you pay 20,000 sats, the rest will be sent back to a fresh change address you control. You cannot skim off 20,000 and leave the other 80,000 behind.

If you don't need to spend those other outputs now, then just wait. At some point in the coming weeks or months the fee will be likely to reduce somewhat.

A private key which starts with "K" is already at a derivation path. It was reached by deriving to the specified path and then calculating the wallet import format key at that path. You cannot use that key in isolation to derive further child keys.

Only if you have either a seed phrase, or a master private key or extended private key beginning with xprv, can you then start deriving child keys and derive the key at m/0/58.

No offense, but this is a terrible idea.

You are in one of two situations here. Situation one is that you have backed up your method and the numbers/patterns/whatever used on a separate piece of paper. If this is the case, then whatever system you have come up with will be vastly inferior to using a proper encryption method such as AES, with the decryption key backed up on paper. Situation two is that you are relying on your brain remembering what you did to transform your seed phrase. It's widely known that you should never rely on your memory alone for something as important as your back ups, and I've spoken about why before: https://bitcointalk.org/index.php?topic=5402270.msg60342177#msg60342177.

So either you have much less security than you think you do, or you have a much higher risk of being unable to access your back ups if you need them. If you want to use something like this, then you should use a proper encryption method with the decryption key backed up on paper separately.