What kind of close was detected on chain.

An unresolved commitment transaction output.

How to resolve an output, per BOLT #5 rules.

Unsigned spending transaction, ready for caller to sign.

The caller uses bolt3 witness constructors to assemble the final witness after signing.

Context for constructing batched penalty transactions.

Expected weight of the to_local penalty transaction witness (160 bytes).

Expected weight of the offered_htlc penalty transaction witness (243 bytes).

Expected weight of the accepted_htlc penalty transaction witness (249 bytes).

Weight of a to_local penalty input (164 + 160 = 324 bytes).

Weight of an offered_htlc penalty input (164 + 243 = 407 bytes).

Weight of an accepted_htlc penalty input (164 + 249 = 413 bytes).

Weight of a to_remote P2WPKH input (108 + 164 = 272 bytes).

Base weight of a penalty transaction (4*53 + 2 = 214 bytes).

Non-witness: version(4) + input_count(1) + output_count(1) + value(8) + script_len(1) + p2wsh_script(34) + locktime(4) = 53 Witness header: 2 bytes.

Maximum standard transaction weight (400,000 bytes).

Calculate the fee for a spending transaction given its weight.

fee = feerate_per_kw * weight / 1000

Identify the type of channel close from a transaction that spends the funding output.

Compares the on-chain transaction bytes against the known local and remote commitment transaction serializations (stripped/unsigned) to determine whether it's a local or remote commitment close.

Returns Nothing if the transaction doesn't match either commitment. Mutual close and revoked commitment detection require additional checks by the caller (e.g. comparing closing tx format, checking a secret store for older commitment numbers).

Classify outputs of our local commitment transaction.

Per BOLT #5: when we discover our local commitment on chain, we must resolve each output. to_local requires a CSV-delayed spend, to_remote is resolved by the commitment itself, HTLC outputs need second-stage transactions, and anchors can be spent immediately.

Classify outputs of the remote commitment transaction.

Per BOLT #5: when we discover the remote commitment on chain, there are no CSV delays on our outputs. We can spend offered HTLCs directly after timeout, and received HTLCs directly with the preimage.

Classify outputs of a revoked commitment transaction.

Per BOLT #5: when we discover a revoked commitment, we can claim everything using the revocation key. to_local is spent via revocation, HTLCs are spent via revocation, and we can also optionally sweep to_remote.

Extract a payment preimage from an offered HTLC witness.

When the remote party claims an offered HTLC on our local commitment, the witness contains the preimage. The witness stack for a preimage claim is:

<remotehtlcsig> <paymentPreimage>

The preimage is the second item (32 bytes) and must hash to the expected payment hash.

Extract a payment preimage from an HTLC-success transaction witness.

When the remote party uses an HTLC-success tx on their commitment to claim a received HTLC, the witness contains the preimage. The witness stack is:

0 <remotehtlcsig> <localhtlcsig> <paymentPreimage>

The preimage is the fourth item (32 bytes).

Check if an HTLC has timed out at the given block height.

An HTLC has timed out when the current block height is equal to or greater than the HTLC's CLTV expiry.

Spend the to_local output of our local commitment tx.

Requires waiting for the CSV delay (to_self_delay) before broadcasting. The caller signs with the local delayed privkey and uses to_local_witness_spend from bolt3.

Returns Nothing if the fee would exceed the output value.

The input nSequence is set to the to_self_delay value.

Construct an HTLC-timeout second-stage transaction.

Used when we offered an HTLC on our local commitment and it has timed out. The bolt3 build_htlc_timeout_tx function constructs the HTLC-timeout tx; this wraps it as a SpendingTx with the witness script and sighash metadata.

Construct an HTLC-success second-stage transaction.

Used when we received an HTLC on our local commitment and have the preimage. The bolt3 build_htlc_success_tx function constructs the HTLC-success tx; this wraps it as a SpendingTx.

Spend a second-stage HTLC output (HTLC-timeout or HTLC-success output) after the CSV delay.

The output of an HTLC-timeout or HTLC-success tx uses the same to_local script. The caller signs with the local delayed privkey and uses htlc_output_witness_spend.

Returns Nothing if the fee would exceed the output value.

Spend an offered HTLC directly after timeout on the remote commitment.

On the remote commitment, their received HTLCs (our offered) have timed out and we can sweep them directly.

Returns Nothing if the fee would exceed the output value.

Spend a received HTLC directly with preimage on the remote commitment.

On the remote commitment, their offered HTLCs (our received) can be claimed with the payment preimage.

Returns Nothing if the fee would exceed the output value.

Spend a revoked to_local output using the revocation key.

The caller signs with the revocation privkey and uses to_local_witness_revoke from bolt3.

Returns Nothing if the fee would exceed the output value.

Spend a revoked HTLC output using the revocation key.

The caller signs with the revocation privkey and uses offered_htlc_witness_revoke or received_htlc_witness_revoke from bolt3, depending on the output type.

Returns Nothing if the output type is not an HTLC, or if the fee would exceed the output value.

Spend a revoked second-stage HTLC output (HTLC-timeout or HTLC-success output) using the revocation key.

The output of a revoked HTLC-timeout/success tx uses the to_local script. The caller signs with the revocation privkey and uses htlc_output_witness_revoke.

Returns Nothing if the fee would exceed the output value.

Construct a batched penalty transaction spending multiple revoked outputs.

Per BOLT #5, up to 483 bidirectional HTLCs plus to_local can be resolved in a single penalty transaction (within the 400,000 weight limit). The caller signs each input with the revocation privkey. | Returns Nothing if the total fee would exceed the total input value.

Spend an anchor output as the owner (immediately).

The caller signs with the funding privkey and uses anchor_witness_owner from bolt3.

Spend an anchor output as anyone (after 16 blocks).

Uses anchor_witness_anyone from bolt3 (empty signature).