Description

Implements balance-aware Swap defaults only for the sticky Swap button in Token Details.

When users tap the sticky Swap CTA from Token Details:

• If the viewed token has a positive balance, Swap opens with:
  • From = current token
  • To = swap default
• If the viewed token has zero balance, Swap opens with:
  • From = best available token (same existing selection logic used by sticky Buy flow)
  • To = current token

Scope is intentionally narrow to avoid regressions in other swap entry points:

• Added a dedicated handleStickySwapPress in useTokenActions
• Wired TokenDetailsStickyFooter to call onSwap (sticky-only handler)
• Kept existing non-sticky/legacy swap navigation behavior unchanged
• Updated Security & Trust screen to continue using generic swap behavior

Changelog

CHANGELOG entry: Fixed Token Details sticky Swap button defaults to use a balance-aware source token selection.

Related issues

Fixes: N/A
Refs: https://consensyssoftware.atlassian.net/browse/ASSETS-2972 #28050

Manual testing steps

Feature: Token Details sticky swap defaults

  Scenario: Token has positive balance
    Given user has balance in token X
    And user opens Token Details for token X
    When user taps the sticky Swap button
    Then Swap opens with token X as the source token
    And destination token is not prefilled as token X

  Scenario: Token has zero balance but user has other eligible assets
    Given user has zero balance in token X
    And user has positive balance in another eligible token Y
    And user opens Token Details for token X
    When user taps the sticky Swap button
    Then Swap opens with token Y as the source token
    And token X is prefilled as the destination token

  Scenario: Legacy/non-sticky swap path remains unchanged
    Given user opens Token Details
    When user navigates via non-sticky swap entry path
    Then existing swap defaults behave as before

Screenshots/Recordings

Before

N/A

After

Tested in Offsite - Approval from @bergarces and @AmarildoGr

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Mobile Coding Standards.
• I've completed the PR template to the best of my ability
• I've included tests if applicable
• I've documented my code using JSDoc format if applicable
• I've applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.