feat: bitcoin fee calc for display and error handling (#6932)

## Explanation

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Fix Bitcoin network fee computation in bridge quotes

Problem:
Bitcoin bridge quotes were not computing network fees, causing them to
always show $0 for gas costs.

Root Cause:
The appendNonEvmFees function only called the snap's computeFee method
when trade was a string. This worked for Solana (which has string
trades), but Bitcoin trades are objects with structure {
unsignedPsbtBase64: string, inputsToSign: null }.

Fix:
Remove the typeof trade === 'string' check
Extract unsignedPsbtBase64 from Bitcoin trade objects before passing to
snap
Support both 'base' (Solana) and 'priority' (Bitcoin) fee types in snap
response
Add error handling to return quotes with nonEvmFeesInNative: undefined
if snap fails.
> snap fails on bitcoin when the account does not have enough for gas.
we added this error handling to allow 'quote shopping' on bitcoin
without a runtime error causing the quote to fail.


## References

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* Fixes #12345
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Draft client PR:
MetaMask/metamask-extension#37137

## Checklist

- [x] I've updated the test suite for new or updated code as appropriate
- [x] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [x] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/contributing.md#updating-changelogs),
highlighting breaking changes as necessary
- [x] I've prepared draft pull requests for clients and consumer
packages to resolve any breaking changes

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Fix Bitcoin fee computation in bridge quotes by normalizing trade data
for snaps, supporting 'priority' fees, and adding graceful error
handling.
> 
> - **Bridge fees (non‑EVM)**:
> - Normalize trade data for snap fee computation: use string directly
(Solana) or extract `unsignedPsbtBase64` from `BitcoinTradeData`
(Bitcoin).
> - Support `'priority'` fee type (Bitcoin) in addition to `'base'`;
fallback to first returned fee.
> - Add guards for missing snap/trade; wrap in try/catch and set
`nonEvmFeesInNative` to `undefined` on failures; improved error logging
with `quote.requestId`.
> - **Types/exports**:
>   - Export `BitcoinTradeData`; consume it in `quote-fees`.
> - **Changelog**:
>   - Document fix for Bitcoin network fee computation under Unreleased.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
45987f7. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------

Co-authored-by: Micaela <[email protected]>

Author: ghgoodreau

packages/bridge-controller/CHANGELOG.md

@@ -9,7 +9,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
-- Clean up SSE stream reader after use ([#6965](https://github.com/MetaMask/core/pull/6965))p
+- Clean up SSE stream reader after use ([#6965](https://github.com/MetaMask/core/pull/6965))
+
+### Fixed
+
+- Fix Bitcoin network fee computation by extracting `unsignedPsbtBase64` from Bitcoin trade objects and supporting `'priority'` fee type from Bitcoin snap ([#XXXX](https://github.com/MetaMask/core/pull/XXXX))
 
 ## [56.0.0]
 

packages/bridge-controller/src/index.ts

@@ -40,6 +40,7 @@ export type {
   QuoteResponse,
   FeeData,
   TxData,
+  BitcoinTradeData,
   BridgeControllerState,
   BridgeControllerAction,
   BridgeControllerActions,

packages/bridge-controller/src/utils/quote-fees.ts

@@ -12,6 +12,7 @@ import type {
   NonEvmFees,
   TxData,
   BridgeControllerMessenger,
+  BitcoinTradeData,
 } from '../types';
 
 /**
@@ -109,14 +110,27 @@ const appendNonEvmFees = async (
     quotes.map(async (quoteResponse) => {
       const { trade, quote } = quoteResponse;
 
-      if (selectedAccount?.metadata?.snap?.id && typeof trade === 'string') {
+      // Skip fee computation if no snap account or trade data
+      if (!selectedAccount?.metadata?.snap?.id || !trade) {
+        return quoteResponse;
+      }
+
+      try {
         const scope = formatChainIdToCaip(quote.srcChainId);
 
+        // Normalize trade data to string format expected by snap
+        // Solana: trade is already a base64 transaction string
+        // Bitcoin: extract unsignedPsbtBase64 from trade object
+        const transaction =
+          typeof trade === 'string'
+            ? trade
+            : (trade as BitcoinTradeData).unsignedPsbtBase64;
+
         const response = (await messenger.call(
           'SnapController:handleRequest',
           computeFeeRequest(
             selectedAccount.metadata.snap?.id,
-            trade,
+            transaction,
             selectedAccount.id,
             scope,
           ),
@@ -130,16 +144,29 @@ const appendNonEvmFees = async (
           };
         }[];
 
-        const baseFee = response?.find((fee) => fee.type === 'base');
-        // Store fees in native units as returned by the snap (e.g., SOL, BTC)
-        const feeInNative = baseFee?.asset?.amount || '0';
+        // Bitcoin snap returns 'priority' fee, Solana returns 'base' fee
+        const fee =
+          response?.find((f) => f.type === 'base') ||
+          response?.find((f) => f.type === 'priority') ||
+          response?.[0];
+        const feeInNative = fee?.asset?.amount || '0';
 
         return {
           ...quoteResponse,
           nonEvmFeesInNative: feeInNative,
         };
+      } catch (error) {
+        // Return quote with undefined fee if snap fails (e.g., insufficient UTXO funds)
+        // Client can render special UI or skip the quote card row for quotes with missing fee data
+        console.error(
+          `Failed to compute non-EVM fees for quote ${quote.requestId}:`,
+          error,
+        );
+        return {
+          ...quoteResponse,
+          nonEvmFeesInNative: undefined,
+        };
       }
-      return quoteResponse;
     }),
   );