fix: Bidirection Object Storage for delegation

[Kassaking7]

High Level Overview of Change

When account A (the delegatee) is deleted, any Delegate ledger objects in other accounts' owner directories that reference A via sfAuthorize were not cleaned up, leaving dangling objects on-ledger.

This PR fixes the issue by storing the Delegate object in both the delegating account's (B) and the authorized account's (A) owner directories, mirroring the pattern used by EscrowCreate. When either party deletes their account, AccountDelete walks their owner directory, finds the ltDELEGATE entry, and deleteDelegate cleans up both sides.

Context of Change

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)

I conducted a local test using standalone mode. The core commands I had:

% curl -s -X POST http://127.0.0.1:5005 \
  -H 'Content-Type: application/json' \
  -d '{
    "method": "account_objects",
    "params": [{"account": "rGkPsFGDkKprjswvPjtqHVt4VwvRRbz7nM"}]
  }' | python3 -m json.tool
{
    "result": {
        "account": "rGkPsFGDkKprjswvPjtqHVt4VwvRRbz7nM",
        "account_objects": [
            {
                "Account": "rGkPsFGDkKprjswvPjtqHVt4VwvRRbz7nM",
                "Authorize": "rK27ECzvntUQPQRnpQfT4ByMKpYdPYktua",
                "DestinationNode": "0",
                "Flags": 0,
                "LedgerEntryType": "Delegate",
                "OwnerNode": "0",
                "Permissions": [
                    {
                        "Permission": {
                            "PermissionValue": "Payment"
                        }
                    }
                ],
                "PreviousTxnID": "ED79B04396CA6D34C74483B8FC5FD14BAFB3F9A8321609A14E2352EB9362FDA6",
                "PreviousTxnLgrSeq": 6,
                "index": "07349519B9ED9599FF6C84C206735741C5C24F4C456AB30EFAAC69C42FC45D77"
            }
        ],
        "ledger_current_index": 7,
        "status": "success",
        "validated": false
    }
}


%curl -s -X POST http://127.0.0.1:5005 \
  -H 'Content-Type: application/json' \
  -d '{
    "method": "account_objects",
    "params": [{"account": "rK27ECzvntUQPQRnpQfT4ByMKpYdPYktua"}]
  }' | python3 -m json.tool
{
    "result": {
        "account": "rK27ECzvntUQPQRnpQfT4ByMKpYdPYktua",
        "account_objects": [
            {
                "Account": "rGkPsFGDkKprjswvPjtqHVt4VwvRRbz7nM",
                "Authorize": "rK27ECzvntUQPQRnpQfT4ByMKpYdPYktua",
                "DestinationNode": "0",
                "Flags": 0,
                "LedgerEntryType": "Delegate",
                "OwnerNode": "0",
                "Permissions": [
                    {
                        "Permission": {
                            "PermissionValue": "Payment"
                        }
                    }
                ],
                "PreviousTxnID": "ED79B04396CA6D34C74483B8FC5FD14BAFB3F9A8321609A14E2352EB9362FDA6",
                "PreviousTxnLgrSeq": 6,
                "index": "07349519B9ED9599FF6C84C206735741C5C24F4C456AB30EFAAC69C42FC45D77"
            }
        ],
        "ledger_current_index": 7,
        "status": "success",
        "validated": false
    }
}

%for i in $(seq 1 256); do
  curl -s -X POST http://127.0.0.1:5005 \
    -H 'Content-Type: application/json' \
    -d '{"method":"ledger_accept","params":[{}]}' > /dev/null
done
echo "done"
done

%curl -s -X POST http://127.0.0.1:5005 \
  -H 'Content-Type: application/json' \
  -d '{
    "method": "submit",
    "params": [{
      "secret": "ssT5qnHJRAFZ6aRK1By3AfkD64Jqn",
      "tx_json": {
        "TransactionType": "AccountDelete",
        "Account": "rK27ECzvntUQPQRnpQfT4ByMKpYdPYktua",
        "Destination": "rGkPsFGDkKprjswvPjtqHVt4VwvRRbz7nM",
        "Fee": "2000000",
        "Sequence": 5
      }
    }]
  }' | python3 -m json.tool | grep engine_result
        "engine_result": "tesSUCCESS",
        "engine_result_code": 0,
        "engine_result_message": "The transaction was applied. Only final in a validated ledger.",

% curl -s -X POST http://127.0.0.1:5005 \
  -H 'Content-Type: application/json' \
  -d '{"method":"ledger_accept","params":[{}]}' | python3 -m json.tool | grep ledger_current
        "ledger_current_index": 264,

% curl -s -X POST http://127.0.0.1:5005 \
  -H 'Content-Type: application/json' \
  -d '{
    "method": "account_objects",
    "params": [{"account": "rGkPsFGDkKprjswvPjtqHVt4VwvRRbz7nM"}]
  }' | python3 -m json.tool
{
    "result": {
        "account": "rGkPsFGDkKprjswvPjtqHVt4VwvRRbz7nM",
        "account_objects": [],
        "ledger_current_index": 264,
        "status": "success",
        "validated": false
    }
}
% curl -s -X POST http://127.0.0.1:5005 \
  -H 'Content-Type: application/json' \
  -d '{
    "method": "account_info",
    "params": [{"account": "rK27ECzvntUQPQRnpQfT4ByMKpYdPYktua"}]
  }' | python3 -m json.tool | grep -E "error|Sequence"
        "error": "actNotFound",
        "error_code": 19,
        "error_message": "Account not found.",
        "status": "error",

We can see that now we don't have delegate object for delegator after delegatee's account got deleted.

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[yinyiqian1]

LGTM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.6%. Comparing base (653a383) to head (13770c1).

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #6681   +/-   ##
=======================================
  Coverage     81.6%   81.6%           
=======================================
  Files         1010    1010           
  Lines        75992   76009   +17     
  Branches      7601    7599    -2     
=======================================
+ Hits         62013   62032   +19     
+ Misses       13979   13977    -2     

Files with missing lines	Coverage Δ
include/xrpl/protocol/detail/ledger_entries.macro	100.0% <ø> (ø)
...de/xrpl/protocol_autogen/ledger_entries/Delegate.h	100.0% <100.0%> (ø)
include/xrpl/tx/transactors/delegate/DelegateSet.h	100.0% <ø> (ø)
...c/libxrpl/tx/transactors/account/AccountDelete.cpp	96.3% <100.0%> (ø)
...rc/libxrpl/tx/transactors/delegate/DelegateSet.cpp	100.0% <100.0%> (ø)

... and 2 files with indirect coverage changes

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[github-actions]

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

[github-actions]

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

[PeterChen13579]

LGTM, feel free to implement the suggestion I have, if you want. I'm okay either way

[Kassaking7]

Hi @bthomee , this PR is ready to merge. Thanks!

[ximinez]

Unless I'm massively missing something, these changes need to be amendment gated.

[Copilot]

Pull request overview

Fixes cleanup of ltDELEGATE ledger entries when either the delegator or authorized (delegatee) account is deleted by making Delegate objects discoverable from both parties’ owner directories (mirroring the sfOwnerNode/sfDestinationNode pattern used by other bi-directional objects like Escrow).

Changes:

• Store ltDELEGATE in both the delegator’s and authorized account’s owner directories and persist the authorized-side directory page in sfDestinationNode.
• Update DelegateSet::deleteDelegate to remove the directory entry from both sides (and keep owner-count accounting on the delegator only).
• Extend protocol-autogen schema/wrappers and add/expand unit tests to validate the new optional field and AccountDelete behavior.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/libxrpl/tx/transactors/delegate/DelegateSet.cpp	Inserts Delegate into both owner dirs and deletes from both using sfDestinationNode.
include/xrpl/tx/transactors/delegate/DelegateSet.h	Updates deleteDelegate signature to no longer require an explicit account parameter.
src/libxrpl/tx/transactors/account/AccountDelete.cpp	Uses updated deleteDelegate signature when sweeping ltDELEGATE from owner dirs.
include/xrpl/protocol/detail/ledger_entries.macro	Adds sfDestinationNode as an optional field of ltDELEGATE.
include/xrpl/protocol_autogen/ledger_entries/Delegate.h	Adds wrapper getter/has-check and builder setter for sfDestinationNode.
src/tests/libxrpl/protocol_autogen/ledger_entries/DelegateTests.cpp	Adds coverage for sfDestinationNode round-trip and absence when unset.
src/test/app/Delegate_test.cpp	Adds AccountDelete scenarios validating cleanup from both directories and reserve recovery.

Comments suppressed due to low confidence (1)

src/libxrpl/tx/transactors/delegate/DelegateSet.cpp:78

• When updating an existing Delegate (sle already present) you only update sfPermissions. If this ledger entry was created by older code it may lack sfDestinationNode and may not be present in the authorized account’s owner directory, so deleting the authorized account would still leave a dangling Delegate in the delegator’s directory. Consider backfilling here: if sfDestinationNode is absent, dirInsert into keylet::ownerDir(authAccount), set sfDestinationNode, and update the SLE so the bidirectional cleanup works for pre-existing entries too.

        sle->setFieldArray(sfPermissions, permissions);
        ctx_.view().update(sle);
        return tesSUCCESS;

---

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[yinyiqian1]

Unless I'm massively missing something, these changes need to be amendment gated.

This change is in DelegateSet transaction, its amendment PermissionDelegationV1_1, is not enabled yet.

[ximinez]

Unless I'm massively missing something, these changes need to be amendment gated.

This change is in DelegateSet transaction, its amendment PermissionDelegationV1_1, is not enabled yet.

That's what I missed. Thanks!

LMK when the Copilot comments are addressed, and I'll merge.

Amendment not needed

[Kassaking7]

Unless I'm massively missing something, these changes need to be amendment gated.

This change is in DelegateSet transaction, its amendment PermissionDelegationV1_1, is not enabled yet.

That's what I missed. Thanks!

LMK when the Copilot comments are addressed, and I'll merge.

All comments addressed. Ready to merge. Thanks!

[github-actions]

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

[github-actions]

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