rs-sdk address-sync silently discards platform-returned balance updates for addresses not in the pre-RPC pending_addresses snapshot

[lklimek]

Component

packages/rs-sdk — dash_sdk::platform::address_sync

Mechanism

sync_address_balances (packages/rs-sdk/src/platform/address_sync/mod.rs) builds a key_to_tag lookup once from a single provider.pending_addresses() snapshot and passes it by immutable reference into the private incremental_catch_up. In both the compacted apply loop and the recent apply loop the predicate if let Some(&(tag, address)) = address_lookup.get(&addr_bytes) had no else branch: any balance change the platform returns for an address absent from the frozen snapshot was dropped with no log, metric, or error. Unlike the tree-scan path, incremental_catch_up never re-polled pending_addresses() (contrast after_branch_iteration, which does refresh during the branch loop).

Repro

Within one sync pass, derive a fresh receive address A after the pass's snapshot is taken (routine under concurrent multi-identity funding), fund A, let it chain-confirm. The recent/compacted balance-changes RPC returns A's balance but the SDK discards it: result.found never gets A, on_address_found is never called, and the wallet's local sync map shows A empty. On single-threaded runs the derive usually precedes the snapshot, hiding the bug — hence "flaky", not "always red", in live e2e.

Impact

Root cause of repeated e2e flakes in the rs-platform-wallet suite: TK-001 / TK-007 / TK-013 / TK-014 / id_005, all funding-gate Found-025 under parallel multi-identity churn.

Fix (implemented)

PR #PLACEHOLDER on v3.1-dev:

• Extract the two inline apply loops into a pure pub(crate) apply_address_changes seam (no Sdk/network/async) that returns applied updates plus the addresses absent from the snapshot.
• apply_block_changes re-polls pending_addresses() when an unknown address appears (mirroring the tree-scan refresh) and replays only the previously-unknown subset, so a freshly-derived address is recovered and known-address AddToCredits deltas are never double-counted.
• Addresses still unknown after the refresh are logged at warn (observable, never silently dropped).
• Known-address behavior is byte-for-byte identical.
• Three deterministic #[cfg(test)] regression guards on the pure seam (red on pre-fix logic, green post-fix).

Deterministic-test enablement

The extracted pub(crate) pure seam makes the discard a pure-data assertion (no Sdk/proof) that is pinned in rs-sdk's own test module.

Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

[lklimek]

Fix implemented in #3650 (draft, base v3.1-dev).

[lklimek]

Superseded by PR #3650.

Per our team workflow convention, a PR is the self-sufficient unit of work tracking — we do not keep a companion GitHub issue for work delivered by a PR. PR #3650 now contains all of this issue's unique context (root cause: stale key_to_tag snapshot → missing else → silent balance-change discard in packages/rs-sdk/src/platform/address_sync/mod.rs; reproduction steps; the single-threaded-hides-it flaky explanation; affected e2e funding gates TK-001 / TK-007 / TK-013 / TK-014 / id_005; the apply_address_changes pure-seam design; and the 3 red-pre/green-post regression guards).

Closing this issue as redundant. Tracking continues on PR #3650: #3650

_{Co-authored by Claudius the Magnificent AI Agent}