fix: Prevent deletion of MPTokens with active escrow

[Kassaking7]

High Level Overview of Change

This change prevents MPTokens from being deleted while there is still an active escrow associated with them. It ensures that token state remains consistent and avoids situations where escrowed tokens reference non-existent objects.

Context of Change

The removeEmptyHolding function in src/libxrpl/ledger/View.cpp can delete an MPToken ledger object even when it has a non-zero sfLockedAmount (i.e., funds are currently held in escrow). This orphans the escrowed funds: the Escrow ledger object still exists, but the MPToken it references has been removed. Any subsequent attempt to finish or cancel the escrow fails, resulting in permanent loss of the escrowed tokens.

API Impact

• Public API: New feature (new methods and/or new fields)
• Public API: Breaking change (in general, breaking changes should only impact the next api_version)
• libxrpl change (any change that may affect libxrpl or dependents of libxrpl)
• Peer protocol change (must be backward compatible or bump the peer protocol version)

[mvadari]

This change needs to be amendment-gated, since it has already been released with Supported::yes

[PeterChen13579]

Good job on your first PR! Small changes requested to make the tests more readable

[Kassaking7]

Do we have any other fix needed. Maybe we can batch those fixes with one amendment-gate?

[kennyzlei]

Do we have any other fix needed. Maybe we can batch those fixes with one amendment-gate?

@Kassaking7 it is likely we may have one amendment containing other fixes too, @bthomee any suggestions for the fix amendment name here?

[mvadari]

/ai-review

[xrplf-ai-reviewer]

⚠️ Review Error — The automated review failed to complete. Please re-trigger with /ai-review.

Error: Failed to post review to GitHub after 3 attempts: Server error '500 Internal Server Error' for url 'https://api.github.com/repos/XRPLF/rippled/pulls/6635/reviews'

Review by Claude Opus 4.6 · Prompt: v12

[bthomee]

Do we have any other fix needed. Maybe we can batch those fixes with one amendment-gate?

@Kassaking7 it is likely we may have one amendment containing other fixes too, @bthomee any suggestions for the fix amendment name here?

We don't have a name for that amendment yet, but I'll add this PR to my local release tracker sheet so when the time comes we can ask @Kassaking7 to update this PR.

In the meantime, @Kassaking7, please guard the changes by a new fix amendment with a suitable name, and then later we can swap out the amendment by the collective fix amendment before merging.

Name suggestion for now:

XRPL_FIX    (MPTLockedAmount, Supported::no, VoteBehavior::DefaultNo)

[bthomee]

/ai-review

[xrplf-ai-reviewer]

No issues.

Review by Claude Opus 4.6 · Prompt: V12

[PeterChen13579]

LGTM

[github-actions]

This PR has conflicts, please resolve them in order for the PR to be reviewed.

[bthomee]

@Kassaking7 we merged the change that introduces the fix amendment, named fixSecurity_1_3_1 for now. Would you be able to update your PR to use that amendment instead?

[github-actions]

All conflicts have been resolved. Assigned reviewers can now start or resume their review.

[Kassaking7]

Hey @mvadari, this PR is ready for review :D

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.4%. Comparing base (c0ee813) to head (6cd9143).
⚠️ Report is 16 commits behind head on develop.

Additional details and impacted files

@@            Coverage Diff            @@
##           develop   #6635     +/-   ##
=========================================
- Coverage     81.4%   81.4%   -0.0%     
=========================================
  Files         1006    1006             
  Lines        74451   74454      +3     
  Branches      7557    7561      +4     
=========================================
- Hits         60629   60622      -7     
- Misses       13822   13832     +10     

Files with missing lines	Coverage Δ
src/libxrpl/ledger/helpers/MPTokenHelpers.cpp	96.2% <100.0%> (+<0.1%)	⬆️

... and 4 files with indirect coverage changes

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• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[bthomee]

@Kassaking7 can you please sign your commits? Feel free to squash all commits so you only need to sign a single one.

[bthomee]

@Kassaking7 thanks for signing the commit(s) - is this PR now ready to merge?

[mvadari]

@bthomee I think this should count as a 3-reviewer PR

[yinyiqian1]

this should be runTest(amendments)

[bthomee]

@Kassaking7 is this PR ready to merge?

[Kassaking7]

@bthomee yes it's ready to merge :D

[bthomee]

@Kassaking7 can you please do the following:

1. Change the PR title such that, when you skip over fix: and prefix it with "When merged, this change will...." you get a proper sentence.
   a. For instance, maybe it can be changed to "Prevent deletion of MPTokens with active escrow".
   b. PR titles also use normal sentence capitalization, so do not capitalize nouns unless they are regularly capitalized.
2. Update the PR description by following the provided template.
   a. In the first section (## High Level Overview of Change) you provide a short summary of what the change actually does. This will be similar to the PR title but will have some more details. This is currently missing.
   b. In the second section (### Context of Change) you provide background information. This is more similar to the content you have right now, as it provides the rationale for the change.

[mvadari]

This PR should be rebased onto ripple/release-313

[bthomee]

This PR should be rebased onto ripple/release-313

Actually @Kassaking7, I think it would be easiest if this PR gets merged as it is, and you then create a separate PR that cherry-picked just the squashed merged commit, and then targets the ripple/staging-313 branch. You will likely have to resolve some conflicts, so it's better that you do that than me since you wrote this code.