Wallet core synced height regresses across abrupt app termination — scan floor collapses to checkpoint, forcing full filter re-scans

[QuantumExplorer]

Problem

The wallet's core-chain committed/synced height is not reliably durable across ABRUPT app terminations (crash, force-kill). On the next launch the SPV filter scan floor collapses to max(birthHeight, header checkpoint floor), forcing a full filter re-scan of millions of blocks — and, before rust-dashcore#893, combining with a filter-storage island (rust-dashcore#894) into a hard startup crash-loop.

Evidence (device logs, testnet, same shape observed on mainnet):

session A ends cleanly:  19:30:04  Committed batch 2504884-2504884, committed_height now 2504884
session B, 70s later:    19:31:15  Starting filter download (scan_start=200000, download_start=2504885, stored_filters_tip=2504884, …)

• PersistentWallet.syncedHeight today holds 2504884 — the value is persisted eventually, so this is about WHEN it is stamped and/or re-applied.
• Restarts following abrupt kills collapsed the floor (two observed); the restart following a long healthy session resumed correctly at committed+1 (scan_start=2505047).
• Vicious cycle pre-fix(dashmate): api binds to all interfaces #893: the crash-loop guaranteed abrupt terminations, so the floor collapse re-armed on every relaunch.

Suspected area

Sync-height persistence cadence in rs-platform-wallet / the Swift persister: the height appears to be stamped on some pulse or graceful path that abrupt terminations miss, and/or the load path only applies it under certain conditions. Needs a trace of where syncedHeight is written (which event, how often) and where the reloaded ManagedWalletInfo's committed height is seeded from on restore.

Impact

• Full filter re-scan (observed: 2.3M filters) on every unlucky restart — user-visible "sync starts over" / chain-stall-like behavior.
• Pre-fix(dashmate): api binds to all interfaces #893 pins: hard startup SIGABRT crash-loop in debug builds when a filter-storage island exists.

Related: rust-dashcore#892 (crash), rust-dashcore#893 (self-heal fix, merged pin pending), rust-dashcore#894 (island-manufacturer T1 half).

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