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fix(common): use real fee token for gas estimation when fee_payer is true #405

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Merged
Slokh merged 3 commits into from
Apr 6, 2026
Merged

fix(common): use real fee token for gas estimation when fee_payer is true #405

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51a4105
fix(common): use real fee token for gas estimation when fee_payer is …
skyc1e Apr 2, 2026
4001010
docs: add changelog entry for fee-payer gas estimation fix
skyc1e Apr 4, 2026
f321c9c
Merge branch 'main' into fix/fee-payer-gas-estimation-token
Slokh Apr 6, 2026
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6 changes: 6 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
@@ -1,5 +1,11 @@
# Changelog

## Unreleased

### Patch Changes

- Fix gas estimation failure when `feePayer: true` by using the real fee token address for `eth_estimateGas` instead of the zero address. The final signed transaction still uses `Address::ZERO` for server-side sponsor co-signing.

## 0.3.0 (2026-03-31)

### Minor Changes
Expand Down
11 changes: 7 additions & 4 deletions crates/tempo-common/src/payment/session/tx.rs
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Expand Up @@ -99,7 +99,10 @@ pub async fn resolve_and_sign_tx_with_fee_payer(
) -> ChannelResult<Vec<u8>> {
let nonce = 0u64;
let valid_before = Some(expiring_valid_before());
let effective_fee_token = if fee_payer { Address::ZERO } else { fee_token };
// The final transaction uses Address::ZERO when fee_payer is true (the sponsor
// co-signs server-side), but gas estimation must always use the real token so
// the node can price the transaction correctly.
let final_fee_token = if fee_payer { Address::ZERO } else { fee_token };

// Optimistic: assume key is already provisioned (no key_authorization).
let mut key_auth = wallet.signing_mode.key_authorization();
Expand All @@ -112,7 +115,7 @@ pub async fn resolve_and_sign_tx_with_fee_payer(
key_authorization: key_auth.cloned(),
..Default::default()
}
.with_fee_token(effective_fee_token)
.with_fee_token(fee_token)
.with_nonce_key(EXPIRING_NONCE_KEY);

if let Some(valid_before) = valid_before {
Expand Down Expand Up @@ -145,7 +148,7 @@ pub async fn resolve_and_sign_tx_with_fee_payer(
key_authorization: key_auth.cloned(),
..Default::default()
}
.with_fee_token(effective_fee_token)
.with_fee_token(fee_token)
.with_nonce_key(EXPIRING_NONCE_KEY);

if let Some(valid_before) = valid_before {
Expand Down Expand Up @@ -177,7 +180,7 @@ pub async fn resolve_and_sign_tx_with_fee_payer(
let tx = tx_builder::build_tempo_tx(tx_builder::TempoTxOptions {
calls,
chain_id,
fee_token: effective_fee_token,
fee_token: final_fee_token,
nonce,
nonce_key: EXPIRING_NONCE_KEY,
gas_limit,
Expand Down
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