From ecb242a47c3fc9f3c1671b791112e2d60e73d471 Mon Sep 17 00:00:00 2001
From: Ricart <93732312+capitaharlock@users.noreply.github.com>
Date: Fri, 9 Jan 2026 18:15:12 +0100
Subject: [PATCH] feat(wasm): add extractSpellOnly for mock proof support in
 browsers

Enable mock proof verification in WASM environments for browser usage.
The new extractSpellOnly function allows spell extraction without
cryptographic verification, intended for development and testing scenarios.
---
 charms-client/src/bitcoin_tx.rs |  2 +-
 charms-lib/src/lib.rs           | 44 +++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/charms-client/src/bitcoin_tx.rs b/charms-client/src/bitcoin_tx.rs
index b595214..7d29ae9 100644
--- a/charms-client/src/bitcoin_tx.rs
+++ b/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 {
diff --git a/charms-lib/src/lib.rs b/charms-lib/src/lib.rs
index 48699f3..a1afd64 100644
--- a/charms-lib/src/lib.rs
+++ b/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::*;