BOS - Probe Command

Why Probe?

The primary purpose of $ bos probe is to find out if a payment to a specific node will succeed without actually sending the payment. This can be useful for a few reasons.
Let's say you want to find out the max sats you can send to a specific node. First you would get the pubkey of the node you want to send to and then do
$ bos probe <pubkey> --find-max
What if you wanted to probe a pubkey out of a specific channel?
$ bos probe <pubkey> --out <pubkey of channel peer you want to spend out of> --find-max
To get more information on subcommands you can always run -help or -h at the end. Example:
#bos probe -h
would return:
When in doubt you can always do -h and see what the options are.
Let's do the whole process. In the following example we are going to be probing the LOOP node because we want to run a loop out but don't know what the max we can LOOP is out of a specific channel that has a lot of outbound liquidity. First thing we would do is get the LOOP node pubkey from 1ml.com or amboss.space.
We would begin our command as follows:
$ bos probe 021c97a90a411ff2b10dc2a8e32de2f29d2fa49d41bfbb52bd416e460db0747d0d
Looks good so far, but remember we are trying to probe the LOOP node out of a specific channel. Let's look in Thunderhub and find a channel with heavy outbound that we would like to loop-out.
Great. Now we have all the information we need. The final command will be:
bos probe 021c97a90a411ff2b10dc2a8e32de2f29d2fa49d41bfbb52bd416e460db0747d0d --out 02a974fba302ef9eb7b0c994baed4371266d2d08bb6e01bd72347a65e377567138 --find-max
After running, here is the results I got:
With this result, even though the channel has 5,000,000 sats of outbound capacity, it cannot route to LOOP more than about 187,000 sats. This is quite poor, and would likely not be worth doing. However, by running the probe first, we have saved time that we would have wasted constantly attempting to LOOP OUT and getting failures. With this one command we have quickly and easily found out how much we could do.