chanstate: move commitment diff types

diff --git a/channeldb/channel.go b/channeldb/channel.go
index 7ded835..f509d50 100644
--- a/channeldb/channel.go
+++ b/channeldb/channel.go
@@ -238,6 +238,10 @@ type (
 	// LogUpdate represents a pending update to the remote commitment
 	// chain.
 	LogUpdate = cstate.LogUpdate
+
+	// CommitDiff represents the delta needed to apply the state
+	// transition between two subsequent commitment states.
+	CommitDiff = cstate.CommitDiff
 )
 
 // openChannelTlvData houses the new data fields that are stored for each
@@ -2757,61 +2761,6 @@ func deserializeLogUpdate(r io.Reader) (*LogUpdate, error) {
 	return l, nil
 }
 
-// CommitDiff represents the delta needed to apply the state transition between
-// two subsequent commitment states. Given state N and state N+1, one is able
-// to apply the set of messages contained within the CommitDiff to N to arrive
-// at state N+1. Each time a new commitment is extended, we'll write a new
-// commitment (along with the full commitment state) to disk so we can
-// re-transmit the state in the case of a connection loss or message drop.
-type CommitDiff struct {
-	// ChannelCommitment is the full commitment state that one would arrive
-	// at by applying the set of messages contained in the UpdateDiff to
-	// the prior accepted commitment.
-	Commitment ChannelCommitment
-
-	// LogUpdates is the set of messages sent prior to the commitment state
-	// transition in question. Upon reconnection, if we detect that they
-	// don't have the commitment, then we re-send this along with the
-	// proper signature.
-	LogUpdates []LogUpdate
-
-	// CommitSig is the exact CommitSig message that should be sent after
-	// the set of LogUpdates above has been retransmitted. The signatures
-	// within this message should properly cover the new commitment state
-	// and also the HTLC's within the new commitment state.
-	CommitSig *lnwire.CommitSig
-
-	// OpenedCircuitKeys is a set of unique identifiers for any downstream
-	// Add packets included in this commitment txn. After a restart, this
-	// set of htlcs is acked from the link's incoming mailbox to ensure
-	// there isn't an attempt to re-add them to this commitment txn.
-	OpenedCircuitKeys []models.CircuitKey
-
-	// ClosedCircuitKeys records the unique identifiers for any settle/fail
-	// packets that were resolved by this commitment txn. After a restart,
-	// this is used to ensure those circuits are removed from the circuit
-	// map, and the downstream packets in the link's mailbox are removed.
-	ClosedCircuitKeys []models.CircuitKey
-
-	// AddAcks specifies the locations (commit height, pkg index) of any
-	// Adds that were failed/settled in this commit diff. This will ack
-	// entries in *this* channel's forwarding packages.
-	//
-	// NOTE: This value is not serialized, it is used to atomically mark the
-	// resolution of adds, such that they will not be reprocessed after a
-	// restart.
-	AddAcks []AddRef
-
-	// SettleFailAcks specifies the locations (chan id, commit height, pkg
-	// index) of any Settles or Fails that were locked into this commit
-	// diff, and originate from *another* channel, i.e. the outgoing link.
-	//
-	// NOTE: This value is not serialized, it is used to atomically acks
-	// settles and fails from the forwarding packages of other channels,
-	// such that they will not be reforwarded internally after a restart.
-	SettleFailAcks []SettleFailRef
-}
-
 // serializeLogUpdates serializes provided list of updates to a stream.
 func serializeLogUpdates(w io.Writer, logUpdates []LogUpdate) error {
 	numUpdates := uint16(len(logUpdates))
diff --git a/channeldb/forwarding_package.go b/channeldb/forwarding_package.go
index c393a53..8ba2c95 100644
--- a/channeldb/forwarding_package.go
+++ b/channeldb/forwarding_package.go
@@ -7,10 +7,20 @@ import (
 	"fmt"
 	"io"
 
+	cstate "github.com/lightningnetwork/lnd/chanstate"
 	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/lnwire"
 )
 
+type (
+	// AddRef is used to identify a particular Add in a FwdPkg.
+	AddRef = cstate.AddRef
+
+	// SettleFailRef is used to locate a Settle/Fail in another channel's
+	// FwdPkg.
+	SettleFailRef = cstate.SettleFailRef
+)
+
 // ErrCorruptedFwdPkg signals that the on-disk structure of the forwarding
 // package has potentially been mangled.
 var ErrCorruptedFwdPkg = errors.New("fwding package db has been corrupted")
@@ -327,55 +337,6 @@ func (f *FwdPkg) String() string {
 		f, f.Source, f.Height, len(f.Adds), len(f.SettleFails))
 }
 
-// AddRef is used to identify a particular Add in a FwdPkg. The short channel ID
-// is assumed to be that of the packager.
-type AddRef struct {
-	// Height is the remote commitment height that locked in the Add.
-	Height uint64
-
-	// Index is the index of the Add within the fwd pkg's Adds.
-	//
-	// NOTE: This index is static over the lifetime of a forwarding package.
-	Index uint16
-}
-
-// Encode serializes the AddRef to the given io.Writer.
-func (a *AddRef) Encode(w io.Writer) error {
-	if err := binary.Write(w, binary.BigEndian, a.Height); err != nil {
-		return err
-	}
-
-	return binary.Write(w, binary.BigEndian, a.Index)
-}
-
-// Decode deserializes the AddRef from the given io.Reader.
-func (a *AddRef) Decode(r io.Reader) error {
-	if err := binary.Read(r, binary.BigEndian, &a.Height); err != nil {
-		return err
-	}
-
-	return binary.Read(r, binary.BigEndian, &a.Index)
-}
-
-// SettleFailRef is used to locate a Settle/Fail in another channel's FwdPkg. A
-// channel does not remove its own Settle/Fail htlcs, so the source is provided
-// to locate a db bucket belonging to another channel.
-type SettleFailRef struct {
-	// Source identifies the outgoing link that locked in the settle or
-	// fail. This is then used by the *incoming* link to find the settle
-	// fail in another link's forwarding packages.
-	Source lnwire.ShortChannelID
-
-	// Height is the remote commitment height that locked in this
-	// Settle/Fail.
-	Height uint64
-
-	// Index is the index of the Add with the fwd pkg's SettleFails.
-	//
-	// NOTE: This index is static over the lifetime of a forwarding package.
-	Index uint16
-}
-
 // SettleFailAcker is a generic interface providing the ability to acknowledge
 // settle/fail HTLCs stored in forwarding packages.
 type SettleFailAcker interface {
diff --git a/chanstate/commitment.go b/chanstate/commitment.go
index 6f7bc77..db8d102 100644
--- a/chanstate/commitment.go
+++ b/chanstate/commitment.go
@@ -4,6 +4,7 @@ import (
 	"github.com/btcsuite/btcd/btcutil/v2"
 	"github.com/btcsuite/btcd/wire/v2"
 	"github.com/lightningnetwork/lnd/fn/v2"
+	"github.com/lightningnetwork/lnd/graph/db/models"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/tlv"
 )
@@ -229,3 +230,58 @@ type LogUpdate struct {
 	// we're left with a dangling update on restart.
 	UpdateMsg lnwire.Message
 }
+
+// CommitDiff represents the delta needed to apply the state transition between
+// two subsequent commitment states. Given state N and state N+1, one is able
+// to apply the set of messages contained within the CommitDiff to N to arrive
+// at state N+1. Each time a new commitment is extended, we'll write a new
+// commitment (along with the full commitment state) to disk so we can
+// re-transmit the state in the case of a connection loss or message drop.
+type CommitDiff struct {
+	// ChannelCommitment is the full commitment state that one would arrive
+	// at by applying the set of messages contained in the UpdateDiff to
+	// the prior accepted commitment.
+	Commitment ChannelCommitment
+
+	// LogUpdates is the set of messages sent prior to the commitment state
+	// transition in question. Upon reconnection, if we detect that they
+	// don't have the commitment, then we re-send this along with the
+	// proper signature.
+	LogUpdates []LogUpdate
+
+	// CommitSig is the exact CommitSig message that should be sent after
+	// the set of LogUpdates above has been retransmitted. The signatures
+	// within this message should properly cover the new commitment state
+	// and also the HTLC's within the new commitment state.
+	CommitSig *lnwire.CommitSig
+
+	// OpenedCircuitKeys is a set of unique identifiers for any downstream
+	// Add packets included in this commitment txn. After a restart, this
+	// set of htlcs is acked from the link's incoming mailbox to ensure
+	// there isn't an attempt to re-add them to this commitment txn.
+	OpenedCircuitKeys []models.CircuitKey
+
+	// ClosedCircuitKeys records the unique identifiers for any settle/fail
+	// packets that were resolved by this commitment txn. After a restart,
+	// this is used to ensure those circuits are removed from the circuit
+	// map, and the downstream packets in the link's mailbox are removed.
+	ClosedCircuitKeys []models.CircuitKey
+
+	// AddAcks specifies the locations (commit height, pkg index) of any
+	// Adds that were failed/settled in this commit diff. This will ack
+	// entries in *this* channel's forwarding packages.
+	//
+	// NOTE: This value is not serialized, it is used to atomically mark the
+	// resolution of adds, such that they will not be reprocessed after a
+	// restart.
+	AddAcks []AddRef
+
+	// SettleFailAcks specifies the locations (chan id, commit height, pkg
+	// index) of any Settles or Fails that were locked into this commit
+	// diff, and originate from *another* channel, i.e. the outgoing link.
+	//
+	// NOTE: This value is not serialized, it is used to atomically acks
+	// settles and fails from the forwarding packages of other channels,
+	// such that they will not be reforwarded internally after a restart.
+	SettleFailAcks []SettleFailRef
+}
diff --git a/chanstate/forwarding.go b/chanstate/forwarding.go
new file mode 100644
index 0000000..9cc830f
--- /dev/null
+++ b/chanstate/forwarding.go
@@ -0,0 +1,57 @@
+package chanstate
+
+import (
+	"encoding/binary"
+	"io"
+
+	"github.com/lightningnetwork/lnd/lnwire"
+)
+
+// AddRef is used to identify a particular Add in a FwdPkg. The short channel ID
+// is assumed to be that of the packager.
+type AddRef struct {
+	// Height is the remote commitment height that locked in the Add.
+	Height uint64
+
+	// Index is the index of the Add within the fwd pkg's Adds.
+	//
+	// NOTE: This index is static over the lifetime of a forwarding package.
+	Index uint16
+}
+
+// Encode serializes the AddRef to the given io.Writer.
+func (a *AddRef) Encode(w io.Writer) error {
+	if err := binary.Write(w, binary.BigEndian, a.Height); err != nil {
+		return err
+	}
+
+	return binary.Write(w, binary.BigEndian, a.Index)
+}
+
+// Decode deserializes the AddRef from the given io.Reader.
+func (a *AddRef) Decode(r io.Reader) error {
+	if err := binary.Read(r, binary.BigEndian, &a.Height); err != nil {
+		return err
+	}
+
+	return binary.Read(r, binary.BigEndian, &a.Index)
+}
+
+// SettleFailRef is used to locate a Settle/Fail in another channel's FwdPkg. A
+// channel does not remove its own Settle/Fail htlcs, so the source is provided
+// to locate a db bucket belonging to another channel.
+type SettleFailRef struct {
+	// Source identifies the outgoing link that locked in the settle or
+	// fail. This is then used by the *incoming* link to find the settle
+	// fail in another link's forwarding packages.
+	Source lnwire.ShortChannelID
+
+	// Height is the remote commitment height that locked in this
+	// Settle/Fail.
+	Height uint64
+
+	// Index is the index of the Add with the fwd pkg's SettleFails.
+	//
+	// NOTE: This index is static over the lifetime of a forwarding package.
+	Index uint16
+}