[bug]: Always add local channels to the GraphCache even though Policies is disabled

[ziggie1984]

Happened to a node operator, had a channel with a node which is basically a wallet (is always offline except when receiving or sending money) it happened that both channel policies for this channel where disabled and now the channel will not be added to our GraphCache and hence becomes unusable. I therefore highly suggest always adding our local channels to the GraphCache:

Relevant code:

lnd/graph/db/graph_cache.go

Lines 167 to 171 in f4bf99b

	if policy1 != nil && policy1.IsDisabled() &&
	policy2 != nil && policy2.IsDisabled() {
	return
	}

[starius]

An additional bug discovered in lncli:

lncli updatechanstatus xxx enable
[lncli] unable to decode output index: strconv.ParseUint: parsing "enable": invalid syntax

According to lncli updatechanstatus --help such format should work though:

USAGE:
   lncli updatechanstatus [command options] funding_txid [output_index] action

[ziggie1984]

So to give more background so the issue is more clear:

The operator had a channel which had both policies (disabled=true, not sure why both sides). He was seeing this channel as active tho, because as soon as the peer cam online the channel was fully functional. However he could not send funds to this direct peer and the logs didn't reveal anything because in our payment logic we call the graph to get information about our local channels and the channel would not be part of it:

if the user specified the outgoing_chan_id the logging said insufficient funds and failed here:

lnd/routing/pathfind.go

Line 643 in f4bf99b

max, total, err := getOutgoingBalance(

if outgoing constraint was specified it failed by never considering the channel:

https://github.com/lightningnetwork/lnd/blob/f4bf99b1611b8daeca5f66ff95a537d28790e175/routing/pathfind.go#L1038C3-L1039

[ziggie1984]

Moreover when one of the channel policies is enabled, the channel is not added to the cache, so this should also be take into account when fixing this issue.

[starius]

If the graph cache is disabled via --db.no-graph-cache option, the payment succeeds.
This looks as a bug to me. Cache should optimize accesses, not affect results.