diff --git a/libwallet/src/contract/slate.rs b/libwallet/src/contract/slate.rs
index 4cc65fe..6bc33aa 100644
--- a/libwallet/src/contract/slate.rs
+++ b/libwallet/src/contract/slate.rs
@@ -26,11 +26,6 @@ use super::types::ProofArgs;
 use crate::contract::proofs::InvoiceProof;
 use ed25519_dalek::PublicKey as DalekPublicKey;
 
-/// TODO: Removed for now, consider secp error in sign function
-/// The secret key we replace the actual key with after we have signed with the Context keys. This is
-/// to prevent possibility of signing with the same key twice.
-/// pub const SEC_KEY_FAKE: [u8; 32] = [0; 32];
-
 /// Add payment proof data to slate, noop for sender
 pub fn add_payment_proof<'a, T: ?Sized, C, K>(
 	w: &mut T,
@@ -192,7 +187,10 @@ pub fn transition_state(slate: &mut Slate) -> Result<(), Error> {
 }
 
 /// Add partial signature to the slate.
-// TODO: Should be a sign & forget pubkey+nonce implementation.
+// Nonce reuse is prevented by forgetting the signing context after a signed step:
+// save_step deletes the private context (which holds sec_key/sec_nonce) once is_signed
+// (except the deliberately-retained step2 context used for safe cancel). The context is
+// keyed by slate.id, so a given nonce is only ever used for one message.
 pub fn sign<'a, T: ?Sized, C, K>(
 	w: &mut T,
 	keychain_mask: Option<&SecretKey>,
@@ -213,13 +211,6 @@ where
 	);
 	debug!("contract::slate::sign => done");
 
-	// TODO: This produces a secp error, probably need a valid key. Verify that this is what we want to do.
-	// let fake_key = SecretKey::from_slice(keychain.secp(), &SEC_KEY_FAKE)?;
-	// context.sec_key = fake_key.clone();
-	// context.sec_nonce = fake_key.clone();
-	// context.initial_sec_key = fake_key.clone();
-	// context.initial_sec_nonce = fake_key.clone();
-
 	Ok(())
 }
 
diff --git a/libwallet/src/contract/utils.rs b/libwallet/src/contract/utils.rs
index 2499689..3e81d26 100644
--- a/libwallet/src/contract/utils.rs
+++ b/libwallet/src/contract/utils.rs
@@ -285,8 +285,22 @@ where
 	}
 
 	batch.commit()?;
+	drop(batch);
 
-	// TODO: Assert we don't have the context to avoid potentially leaking it! Also write tests around this.
+	// Defense in depth: once we have signed (and are past the step2 context that is kept
+	// deliberately for safe cancel), the signing context holding sec_key/sec_nonce must be
+	// gone so the nonce can never be reused. It is deleted in the is_signed && !is_step2
+	// branch above; verify the deletion actually took effect.
+	if is_signed && !is_step2 {
+		if w
+			.get_private_context(keychain_mask, slate.id.as_bytes())
+			.is_ok()
+		{
+			return Err(Error::GenericError(
+				"signing context was not removed after signing".into(),
+			));
+		}
+	}
 	debug!("contract::utils::save_step => Atomic updated done");
 
 	Ok(())