Default to anchors and remove automatic channel acceptance #4354

elnosh · 2026-01-27T19:36:13Z

Changes negotiate_anchors_zero_fee_htlc_tx default to true and removes the manually_accept_inbound_channels config option.

Edit: Left the tests with default to non-anchor

ldk-reviews-bot · 2026-01-27T19:36:16Z

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TheBlueMatt · 2026-01-27T20:30:57Z

Changing the negotiate_anchors_zero_fee_htlc_tx default to true in the tests causes +100 test failures

Hmm, can you ask claude to change those to use the test_default_config() thing? Our test config default has diverged somewhat from our actual default config for reasons like this but that's okay...

codecov · 2026-01-28T22:14:35Z

Codecov Report

❌ Patch coverage is 85.05747% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.02%. Comparing base (f43803d) to head (306eea7).
⚠️ Report is 41 commits behind head on main.

Files with missing lines	Patch %	Lines
lightning/src/ln/channelmanager.rs	70.73%	11 Missing and 1 partial ⚠️
lightning/src/ln/functional_test_utils.rs	94.73%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4354   +/-   ##
=======================================
  Coverage   86.01%   86.02%           
=======================================
  Files         156      156           
  Lines      102857   102827   -30     
  Branches   102857   102827   -30     
=======================================
- Hits        88474    88453   -21     
+ Misses      11876    11865   -11     
- Partials     2507     2509    +2

Flag	Coverage Δ
tests	`86.02% <85.05%> (+<0.01%)`	⬆️

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ldk-reviews-bot · 2026-01-31T00:00:24Z

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ldk-reviews-bot · 2026-02-02T00:00:54Z

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lightning/src/events/mod.rs

lightning/src/ln/reorg_tests.rs

lightning/src/util/config.rs

lightning/src/ln/functional_test_utils.rs

lightning/src/ln/channelmanager.rs

pending_changelog/4337-manual-channel-accept-default-anchors.txt

lightning/src/ln/functional_test_utils.rs

wpaulino · 2026-02-04T00:14:05Z

This also needs a rebase

elnosh · 2026-02-04T15:58:22Z

rebased and renamed channel config to default to anchors

wpaulino · 2026-02-05T17:16:59Z

Feel free to squash

When accepting channels manually, it would fail if the # of peers without funded channels was == `MAX_UNFUNDED_CHANNEL_PEERS`, however, it should fail if the # of peers > `MAX_UNFUNDED_CHANNEL_PEERS`.

Removes the `manually_accept_inbound_channels` config option. In upcoming commit we will default to anchor channels which requires users checking if they have enough onchain funds to cover fees in case of a force close. Hence, we move to always require users to manually accept inbound channels.

Set `negotiate_anchors_zero_fee_htlc_tx` default to true.

Now that anchor channels are the default, rename `test_default_anchors_channel_config` to `test_default_channel_config` and the previous default to legacy.

ldk-reviews-bot · 2026-02-09T19:32:24Z

✅ Added second reviewer: @valentinewallace

valentinewallace

Some nits but nothing blocking, feel free to take or leave the feedback for follow-up. Thank you for this update! 🫡

valentinewallace · 2026-02-09T21:30:32Z

lightning/src/ln/channel_open_tests.rs

-	// Assert that `nodes[1]` has no `MessageSendEvent::SendAcceptChannel` in `msg_events` before
-	// rejecting the inbound channel request.


nit: isn't this comment still relevant? and below

yeah it applies but it felt redundant. Can re-add if you prefer.

valentinewallace · 2026-02-09T21:33:39Z

lightning/src/ln/channelmanager.rs

 		num_unfunded_channels + peer.inbound_channel_request_by_id.len()
 	}

-	#[rustfmt::skip]


In the future, we generally prefer to have rustfmt::skip removals in a separate commit, no need to bother for this PR though.

valentinewallace · 2026-02-09T21:38:41Z

lightning/src/ln/functional_tests.rs

+			revoked_htlc_txn[0].input[0].previous_output
 		);
 		assert_eq!(
 			node_txn[1].input[1].previous_output,
-			revoked_htlc_txn[0].input[0].previous_output
+			revoked_htlc_txn[1].input[0].previous_output
 		);


What's the reason for this diff?

I'm honestly not quite sure. At some point this was failing and changing them fixed it. This ordering seems correct though?

valentinewallace · 2026-02-09T21:47:16Z

lightning/src/util/config.rs

-	/// [`Event::OpenChannelRequest`]: crate::events::Event::OpenChannelRequest
-	/// [`msgs::OpenChannel`]: crate::ln::msgs::OpenChannel
-	/// [`msgs::AcceptChannel`]: crate::ln::msgs::AcceptChannel
-	pub manually_accept_inbound_channels: bool,


There's still several occurrences of manually_accept in the codebase atm. Not crucial, but I think at least the pending_changelog one should be updated

valentinewallace · 2026-02-09T21:47:51Z

lightning/src/ln/async_signer_tests.rs

 	} else {
-		let msgs = nodes[1].node.get_and_clear_pending_msg_events();
-		assert!(msgs.is_empty(), "Expected no message events; got {:?}", msgs);
+		let events = nodes[1].node.get_and_clear_pending_events();


nit: I think we can use the new handle_and_accept_open_channel helper here?

valentinewallace · 2026-02-09T21:56:05Z

lightning/src/ln/channelmanager.rs

 	/// [`ChannelManager::list_recent_payments`] for more information.
 	///
-	/// Routes are automatically found using the [`Router] provided on startup. To fix a route for a
+	/// Routes are automatically found using the [`Router`] provided on startup. To fix a route for a


Nbd, but usually it's not recommended to put unrelated fixes in a commit, even if trivial

valentinewallace · 2026-02-09T21:58:47Z

lightning/src/ln/reorg_tests.rs

 	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
-	let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None, None]);
+	let legacy_cfg = test_legacy_channel_config();
+	let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[Some(legacy_cfg), None, None]);


nit: pre-existing but only need 2 cfgs here and below

valentinewallace · 2026-02-09T22:06:18Z

lightning/src/ln/splicing_tests.rs

 	let chanmon_cfgs = create_chanmon_cfgs(2);
 	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
-	let config = test_default_anchors_channel_config();
+	let config = test_default_channel_config();


nit: here and throughout the file's diff, we can just pass in None for the config rather than explicitly setting test_default_channel_config

valentinewallace · 2026-02-09T22:08:22Z

lightning/src/ln/functional_test_utils.rs


-pub fn test_default_anchors_channel_config() -> UserConfig {
-	let mut config = test_default_channel_config();
+pub fn test_default_channel_config() -> UserConfig {


I do wonder if there's an opportunity with these updates to have the default test config match LDK's actual default config. Did you look into how hard that would be? Probably would require too many test updates...

hmmm yeah when I tried using the now test_default_channel_config instead of the legacy one, 100+ tests were failing. I didn't go one-by-one in detail but it didn't seem trivial and I think most of them would require specific fixes. Perhaps something for an LLM

elnosh · 2026-02-10T02:03:50Z

@valentinewallace sorry for the intermingling of unrelated fixes in some of the commits. Addressed some of the follow-ups here #4407

elnosh force-pushed the manual-channel-acceptance branch 2 times, most recently from ef441ac to b1ee9e3 Compare January 28, 2026 20:38

elnosh marked this pull request as ready for review January 28, 2026 20:38

ldk-reviews-bot requested a review from jkczyz January 28, 2026 20:39

jkczyz requested a review from wpaulino January 29, 2026 18:32

wpaulino reviewed Feb 2, 2026

View reviewed changes

elnosh force-pushed the manual-channel-acceptance branch from b1ee9e3 to 96719d6 Compare February 3, 2026 00:52

jkczyz removed their request for review February 3, 2026 17:12

elnosh force-pushed the manual-channel-acceptance branch from 96719d6 to daf61b3 Compare February 4, 2026 15:48

elnosh force-pushed the manual-channel-acceptance branch from daf61b3 to 927b6c1 Compare February 4, 2026 18:44

jkczyz assigned elnosh Feb 5, 2026

jkczyz added this to Weekly Goals Feb 5, 2026

elnosh added 4 commits February 5, 2026 17:48

Fix off-by-one for unfunded channel peers

b6bd386

When accepting channels manually, it would fail if the # of peers without funded channels was == `MAX_UNFUNDED_CHANNEL_PEERS`, however, it should fail if the # of peers > `MAX_UNFUNDED_CHANNEL_PEERS`.

Default to anchor channels

aebcd1f

Set `negotiate_anchors_zero_fee_htlc_tx` default to true.

Rename test default channel config

306eea7

Now that anchor channels are the default, rename `test_default_anchors_channel_config` to `test_default_channel_config` and the previous default to legacy.

elnosh force-pushed the manual-channel-acceptance branch from 927b6c1 to 306eea7 Compare February 5, 2026 22:59

wpaulino approved these changes Feb 9, 2026

View reviewed changes

ldk-reviews-bot requested a review from valentinewallace February 9, 2026 19:32

valentinewallace approved these changes Feb 9, 2026

View reviewed changes

valentinewallace merged commit 7baafe2 into lightningdevkit:main Feb 9, 2026
20 of 21 checks passed

github-project-automation bot moved this to Done in Weekly Goals Feb 9, 2026

elnosh mentioned this pull request Feb 10, 2026

4354 follow up #4407

Open

		// Assert that `nodes[1]` has no `MessageSendEvent::SendAcceptChannel` in `msg_events` before
		// rejecting the inbound channel request.

Default to anchors and remove automatic channel acceptance #4354

Default to anchors and remove automatic channel acceptance #4354

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