fix: let unannounced channels take full-size payments

[ovitrif]

Refs:

• bug: incoming lightning payments above 10% of the channel size fail bitkit-android#1388
• bug: incoming lightning payments above 10% of the channel size fail bitkit-ios#850

Description

• Sets the maximum inbound HTLC value in flight to 100% of the channel value for nodes that cannot announce channels (no node alias or no listening addresses), so a single incoming payment can use the whole channel instead of 10% of it. Such a node only accepts unannounced channels, and ldk-node already sets 100% for the unannounced channels it opens itself.
• The limit is part of the channel handshake, so channels opened before this change keep their 10% limit; only new channels benefit.
• Adds inbound_htlc_in_flight_limit_for_unannounced_node: opens a 1,000,000 sat channel to a node without an alias, pays it 9% (works with and without the change) and 20% of the channel value (fails with PaymentSendingFailed without the change).
• Adds the unit test inbound_htlc_value_in_flight_limit_follows_announce_ability for the default_user_config branch: no alias and no listening addresses, only one of them missing, and a node that can announce channels (keeps LDK's default).
• Upstream rust-lightning makes 100% the default for unannounced channels (2867d5c1a, in the 0.3 pre-releases); the fork is on LDK 0.2.0, where it is still 10%.
• The changelog line goes into the release PR, per the fork's single-section CHANGELOG rule.

Out of Scope

• src/builder.rs, src/event.rs: the LSPS2 paths keep their own 100% override.
• Nodes that can announce keep LDK's default for every inbound channel, unannounced ones included; no config option is added.
• Existing channels: the limit is fixed at channel open, so they stay at 10%.
• Version bump and release: separate release PR, followed by the bump PRs in the Bitkit apps.
• Newer LDK defaults 100% for unannounced channels (unannounced_channel_max_inbound_htlc_value_in_flight_percentage); when the fork moves to an LDK release with that option, this override can be removed.
• The Rust CI workflow (rust.yml, manual dispatch only) fails on main in its UniFFI build, see QA Notes; fixing it is a separate change.

QA Notes

Automated Checks

• added inbound_htlc_in_flight_limit_for_unannounced_node in tests/integration_tests_rust.rs: fails on main (a payment above 10% of the channel value must be routable: PaymentSendingFailed), passes with the change.
• added inbound_htlc_value_in_flight_limit_follows_announce_ability in src/config.rs: fails with the default_user_config change removed (left: 10, right: 100), passes with it.
• ran the steps of rust.yml locally on the rebased head fdb891c1 (stable 1.98.1): cargo fmt --check, cargo build, cargo doc (release and private items) and cargo check --release pass, as do the 120 unit tests with --features uniffi.
• ran the integration suites with --cfg no_download, with and without --features uniffi: all pass except the tests below. reorg_test and the 110 tests of multi_address_types_tests pass (test_multi_wallet_all_combinations failed once with InvalidSocketAddress in a parallel run and passes alone).
• not completed locally: splice_channel and the eight channel_full_cycle* tests hang at their splice step. splice_channel hangs the same way on main (6d24c44), so the cause is not this change; these need the hosted run.
• the hosted Rust CI cannot reach the tests today. build (ubuntu-latest, stable) fails in the step Build with UniFFI support on Rust stable (cargo build --features uniffi with RUSTFLAGS=-D warnings) with 5 errors: four unused imports in src/ffi/types.rs and the deprecated bitcoin::FeeRate::from_sat_per_vb_unchecked used by the FeeRate constructor in bindings/ldk_node.udl. They are warnings in a plain build, which is why the app builds work, and the same 5 errors appear with main's tree; this PR touches none of those files. rust.yml only runs on manual dispatch and no recent merged PR (fix: report on-chain broadcast outcomes #119, fix: restore android release publishing #121) ran it.

Manual Tests

• Bitkit Android master (2.5.0) on a regtest LND channel of 1,000,000 sats, with a libldk_node built from 0.7.0-rc.66 plus this one-line change swapped in: the channel is accepted with max_htlc_value_in_flight_msat: 1000000000 (was 100000000), and single payments of 110,000 sats (11%) and 500,000 sats (50%) succeed with "Received Instant Bitcoin". Without the change the 11% payment fails.

[ovitrif]

Pushed 555d5db: dropped the changelog entry from this PR; the release PR adds it in the fork's single section. Dispatched the Rust CI on this branch: https://github.com/synonymdev/ldk-node/actions/runs/36661558748

[ovitrif]

The Rust CI run on this branch (https://github.com/synonymdev/ldk-node/actions/runs/36661558748) failed in "build (ubuntu-latest, stable)", and fail-fast cancelled the other jobs. The failure is on main too (26664614): with --features uniffi and -D warnings, rustc 1.98.1 rejects four unused imports in src/ffi/types.rs (lines 45, 48-50, 54, 63) and the deprecated bitcoin::FeeRate::from_sat_per_vb_unchecked used by the constructor at bindings/ldk_node.udl:416. This PR touches neither. The same build passes on 1.85.0 and on beta, so the test steps never ran; they need a run once main builds on stable.

[ovitrif]

Pushed fdb891c: rebased onto main (0 behind, includes #119 and #121) and folded the changelog add/remove pair into the single fix commit; the diff is still src/config.rs and the test only.

On the failed Rust CI run: the failing step is Build with UniFFI support on Rust stable (cargo build --features uniffi with RUSTFLAGS=-D warnings), where rustc 1.98.1 turns four unused imports in src/ffi/types.rs and the deprecated FeeRate::from_sat_per_vb_unchecked into errors. It reproduces locally with the same command and it is unrelated to this change; a plain cargo build --features uniffi only warns, which is why the app builds work. #119 and #121 merged without a rust.yml run, since it is manual dispatch only. Local results for the workflow's steps and tests are in the PR body.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-01T21:35:10.004727Z	fdb891c	Draft marked ready

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: fdb891c145

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[ovitrif]

Pushed 4a7e44d: adds the unit test inbound_htlc_value_in_flight_limit_follows_announce_ability in src/config.rs, answering the Codex review on default_user_config. It covers a node without alias and listening addresses, one missing only the listening addresses, one missing only the alias (all 100%) and an announcement-capable node (keeps LDK's default); it fails with the production change removed. No production code changed, still 0 behind main. The integration suite results in the body were taken on fdb891c1, which has the same production code.