fix(wallet): surface silent save failures + stale-state cleanups (W5-1, W5-2, W6-1, W6-3)

P2 robustness batch (localized):

- W5-1 (Med, lite): persistAfterBroadcast returned false on a persistent post-send/shield
  save failure, but both callers discarded it and it never logged — completely silent. It
  now liteLogs the failure (the spent note re-derives on the next sync, so it's a
  robustness gap, not fund loss).

- W5-2 (Med, lite): the post-sync and post-rescan save results (in the detached scan
  threads) were ignored; both now liteLog on failure. LiteDiagnostics::log is mutex-guarded,
  so it's safe from those threads.

- W6-1 (Med): WalletState::clear() didn't reset mining/pool_mining, so a wallet switch could
  briefly show the previous wallet's hashrate/blocks. Now reset in clear() (the daemon
  restarts on switch, so mining genuinely stops).

- W6-3 (Low): AddressBook::load() cleared entries_ then threw on the first non-object array
  element — discarding EVERY contact. It now guards is_object() + per-entry try/catch,
  skipping and counting malformed entries.

Build-clean; ctest 1/1. Remaining P2: W6-2 (refresh-staleness badge — needs UI, overlaps
the diagnostics Foundation bundle). See docs/wallet-hardening.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/wallet-hardening.md

@@ -20,7 +20,7 @@ Status legend: ☐ not started · ◐ in progress · ☑ landed & verified
 | **P0-B** | W2-2/W4-2, W2-4 | Encryption integrity (never silently unencrypted) | ☑ |
 | **P1-A** | W3-1, W3-2, W3-4 ✓ · W3-3 ⚑ | Migrate-to-seed correctness (fund-adjacent) | ◐ 3/4 |
 | **P1-B** | W1-1, W1-2, W1-3, W1-4 ✓ + startup guard | Missing/wrong wallet-file safety | ☑ |
-| **P2**  | W6-2, W5-1, W5-2, W6-1, W6-3 | Stale state & lite save-failure surfacing | ☐ |
+| **P2**  | W5-1, W5-2, W6-1, W6-3 ✓ · W6-2 ☐ | Stale state & lite save-failure surfacing | ◐ 4/5 |
 | **F**   | W7-2, W7-3, W7-4, QoL | Diagnostics foundation + QoL bundle | ☐ |
 
 ---
@@ -112,6 +112,12 @@ Land W7-2 first — it unblocks the rest.
 
 ## Progress log
 
+- **P2 / W5-1 · W5-2 · W6-1 · W6-3 (localized batch)** — ☑ landed:
+  - **W5-1 (Med):** `persistAfterBroadcast` (lite send/shield save) returned false on a persistent save failure but both callers discarded it and it never logged — completely silent. It now `liteLog`s the failure (the note re-derives on next sync, so it's a robustness gap, not fund loss).
+  - **W5-2 (Med):** the post-**sync** and post-**rescan** `save` results (in the detached scan threads) were ignored; both now `liteLog` on failure (`LiteDiagnostics::log` is mutex-guarded, safe from those threads).
+  - **W6-1 (Med):** `WalletState::clear()` didn't reset `mining`/`pool_mining`, so a wallet switch could briefly show the previous wallet's hashrate/blocks. Now reset in `clear()` (the daemon restarts on switch, so mining genuinely stops).
+  - **W6-3 (Low):** `AddressBook::load()` did `entries_.clear()` then threw on the first non-object element — discarding **every** contact. Now it guards `is_object()` + per-entry try/catch, skipping and counting malformed entries.
+  Build-clean; `ctest` 1/1. **Remaining P2:** W6-2 (surface refresh staleness — the timestamps exist in `WalletState`; this needs the UI "updated Xs ago" badge, which overlaps the diagnostics/QoL Foundation bundle).
 - **P1-B / W1-3 + startup wallet-existence guard** — ☑ landed:
   - **W1-3 (Med):** `syncedHere` was stamped in the `markOpened` block at bare connect (idHash still empty), letting a freshly-restored wallet skip its needed rescan. It's now stamped only once the identity is verified (idHash non-empty), so it takes effect at the post-address-refresh index update (`updateWalletIndexForActiveWallet` after addresses load), while `lastOpenedEpoch` still records at open.
   - **Startup guard (the W1-1 launch counterpart):** `App::init` now `exists()`-checks the recorded active wallet before the daemon is configured; a **non-default** active wallet that was moved/deleted between sessions falls back to the default `wallet.dat` with a warning, instead of the daemon silently auto-creating an empty wallet under the missing name. Runs before the PIN-vault init so the vault is scoped to the wallet actually opened.

src/data/address_book.cpp

@@ -46,20 +46,25 @@ bool AddressBook::load()
         entries_.clear();
         
         if (j.contains("entries") && j["entries"].is_array()) {
+            size_t skipped = 0;
             for (const auto& entry : j["entries"]) {
-                AddressBookEntry e;
-                e.label = entry.value("label", "");
-                e.address = entry.value("address", "");
-                e.notes = entry.value("notes", "");
-                // Legacy entries (no "scope") migrate to "global" so nothing disappears when
-                // multi-wallet scoping lands — a contact you already had stays visible everywhere.
-                e.scope = entry.value("scope", "global");
-                e.avatar = entry.value("avatar", "");
-
-                if (!e.address.empty()) {
-                    entries_.push_back(e);
-                }
+                // W6-3: skip (and count) a malformed element rather than letting one bad entry throw and
+                // abort the whole load — which would discard EVERY contact (entries_ was already cleared).
+                if (!entry.is_object()) { ++skipped; continue; }
+                try {
+                    AddressBookEntry e;
+                    e.label = entry.value("label", "");
+                    e.address = entry.value("address", "");
+                    e.notes = entry.value("notes", "");
+                    // Legacy entries (no "scope") migrate to "global" so nothing disappears when
+                    // multi-wallet scoping lands — a contact you already had stays visible everywhere.
+                    e.scope = entry.value("scope", "global");
+                    e.avatar = entry.value("avatar", "");
+                    if (!e.address.empty()) entries_.push_back(e);
+                } catch (const std::exception&) { ++skipped; }
             }
+            if (skipped > 0)
+                DEBUG_LOGF("Address book: skipped %zu malformed entr%s\n", skipped, skipped == 1 ? "y" : "ies");
         }
         
         DEBUG_LOGF("Address book loaded: %zu entries\n", entries_.size());

src/data/wallet_state.h

@@ -335,6 +335,10 @@ struct WalletState {
         transactions.clear();
         peers.clear();
         bannedPeers.clear();
+        // W6-1: reset node-level mining state too — the daemon restarts on a wallet switch (mining
+        // stops), so leaving the previous wallet's hashrate/blocks would show stale mining stats.
+        mining = MiningInfo{};
+        pool_mining = PoolMiningState{};
     }
     
     // Rebuild combined addresses list from z/t lists

src/wallet/lite_wallet_controller.cpp

@@ -80,8 +80,10 @@ bool persistAfterBroadcast(LiteClientBridge& bridge)
     for (int attempt = 0; attempt < 2; ++attempt) {
         if (bridge.execute("save", "").ok) return true;
     }
-    // Persistent failure: the spent note will be re-derived from the chain on the next sync,
-    // so this is a robustness gap, not fund loss. (Retry handles the common transient case.)
+    // Persistent failure: the spent note will be re-derived from the chain on the next sync, so this
+    // is a robustness gap, not fund loss. Log it (W5-1) — both callers discard this return, so the
+    // failure was previously completely silent.
+    liteLog("save failed after send/shield — the wallet will re-derive it on the next sync");
     return false;
 }
 
@@ -600,7 +602,8 @@ void LiteWalletController::startSync()
             // The backend does NOT auto-save after a sync, so persist the freshly-scanned wallet;
             // otherwise the next launch re-scans from the checkpoint (~30 min). Set `done` only
             // after the save so a syncComplete() observer sees a fully-persisted wallet.
-            bridge->execute("save", "");
+            if (!bridge->execute("save", "").ok)   // W5-2: don't leave a failed post-sync save silent
+                liteLog("save failed after sync — the next launch will re-scan from the checkpoint");
         }
         done->store(true);
     });
@@ -631,7 +634,8 @@ bool LiteWalletController::startRescan()
             // `rescan` clears the wallet's synced block cache and re-downloads/re-scans from the
             // birthday height — a blocking, uninterruptible full scan, same as `sync`.
             bridge->execute("rescan", "");
-            bridge->execute("save", "");  // backend doesn't auto-save after a rescan
+            if (!bridge->execute("save", "").ok)   // W5-2: don't leave a failed post-rescan save silent
+                liteLog("save failed after rescan — the next launch will re-scan from the checkpoint");
         }
         done->store(true);
     });