feat(wasm): add extractSpellOnly for mock proof support in browsers

charms-client/src/bitcoin_tx.rs

@@ -183,7 +183,7 @@ fn block_has_tx(tx_block_proof: &MerkleBlock, txid: Txid) -> anyhow::Result<()>
 }
 
 #[tracing::instrument(level = "debug", skip_all)]
-pub(crate) fn spell_with_committed_ins_and_coins(
+pub fn spell_with_committed_ins_and_coins(
     tx: &BitcoinTx,
     mut spell: NormalizedSpell,
 ) -> NormalizedSpell {

charms-lib/src/lib.rs

@@ -1,3 +1,4 @@
+use charms_client::bitcoin_tx::{BitcoinTx, parse_spell_and_proof, spell_with_committed_ins_and_coins};
 use charms_client::tx::Tx;
 pub use charms_client::{
     NormalizedCharms, NormalizedSpell, NormalizedTransaction, bitcoin_tx, cardano_tx, tx,
@@ -9,6 +10,7 @@ use wasm_bindgen::{JsValue, prelude::wasm_bindgen};
 /// (and the current protocol version).
 pub const SPELL_VK: &str = "0x00e440d40e331c16bc4c78d2dbc6bb35876e6ea944e943de359a075e07385abc";
 
+/// Extract and verify a spell from a transaction (WASM binding).
 #[cfg(feature = "wasm")]
 #[wasm_bindgen(js_name = "extractAndVerifySpell")]
 pub fn extract_and_verify_spell_js(tx: JsValue, mock: bool) -> Result<JsValue, JsValue> {
@@ -18,12 +20,54 @@ pub fn extract_and_verify_spell_js(tx: JsValue, mock: bool) -> Result<JsValue, J
     Ok(value)
 }
 
+/// Extract and verify a spell from a transaction.
+#[tracing::instrument(level = "debug", skip_all)]
 pub fn extract_and_verify_spell(tx: &Tx, mock: bool) -> Result<NormalizedSpell, String> {
     let norm_spell = charms_client::tx::committed_normalized_spell(SPELL_VK, tx, mock)
         .map_err(|e| e.to_string())?;
     Ok(norm_spell)
 }
 
+/// Extract a spell from a transaction without verification (WASM binding).
+///
+/// This is useful for mock proofs in WASM environments where the
+/// cryptographic verification libraries are not fully supported.
+#[cfg(feature = "wasm")]
+#[wasm_bindgen(js_name = "extractSpellOnly")]
+pub fn extract_spell_only_js(tx: JsValue) -> Result<JsValue, JsValue> {
+    let tx: Tx = serde_wasm_bindgen::from_value(tx)?;
+    let norm_spell = extract_spell_only(&tx)?;
+    let value = serde_wasm_bindgen::to_value(&norm_spell)?;
+    Ok(value)
+}
+
+/// Extract a spell from a transaction without verification.
+///
+/// This function parses the spell data from the transaction but does not
+/// verify the cryptographic proof. Useful for mock proofs in environments
+/// where the verification libraries are not available.
+#[tracing::instrument(level = "debug", skip_all)]
+pub fn extract_spell_only(tx: &Tx) -> Result<NormalizedSpell, String> {
+    match tx {
+        Tx::Bitcoin(btx) => extract_spell_only_bitcoin(btx),
+        Tx::Cardano(_) => Err("Cardano extraction not yet supported".to_string()),
+    }
+}
+
+#[tracing::instrument(level = "debug", skip_all)]
+fn extract_spell_only_bitcoin(btx: &BitcoinTx) -> Result<NormalizedSpell, String> {
+    let tx = btx.inner();
+
+    let Some((spell_tx_in, _)) = tx.input.split_last() else {
+        return Err("transaction does not have inputs".to_string());
+    };
+
+    let (spell, _proof) = parse_spell_and_proof(spell_tx_in)
+        .map_err(|e| e.to_string())?;
+
+    Ok(spell_with_committed_ins_and_coins(btx, spell))
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;