M4/QUA-006: log takeVaultSnapshot failures and notify popup on quota

@@ -2068,9 +2068,19 @@20682068 20692069     history.snapshots = [snapshot, ...history.snapshots].slice(0, HISTORY_MAX);20702070     await chrome.storage.local.set({ [HISTORY_KEY]: history });2071-  } catch {2071+  } catch (err) {20722072     // Non-fatal — history must never block a save. A failed snapshot just20732073     // means the user loses one rung of the safety ladder for this write.2074+    // M4/QUA-006: log so the failure is visible; if it looks like a quota2075+    // problem, notify the popup so the user can prune history themselves.2076+    console.warn('[Peach] takeVaultSnapshot failed:', err);2077+    if (String(err).includes('QUOTA') || String(err).includes('quota')) {2078+      try {2079+        await chrome.runtime.sendMessage({ type: 'VAULT_STORAGE_QUOTA_WARNING' });2080+      } catch {2081+        // popup may be closed; surfaced via console.warn above2082+      }2083+    }20742084   }20752085 }20762086 @@ -2262,8 +2272,21 @@22622272     throw new Error('invalid_incoming_vault_blob');22632273   }22642274 2265-  // Snapshot before overwriting — failure is non-fatal2266-  await takeVaultSnapshot('sync_received').catch(() => {});2275+  // Snapshot before overwriting — non-fatal but user-visible.2276+  // M4/QUA-006: a silent snapshot failure leaves the user without their2277+  // safety net for an incoming sync write; surface it.2278+  try {2279+    await takeVaultSnapshot('sync_received');2280+  } catch (snapshotErr) {2281+    console.warn('[Peach] vault snapshot failed during sync:', snapshotErr);2282+    if (String(snapshotErr).includes('QUOTA') || String(snapshotErr).includes('quota')) {2283+      try {2284+        await chrome.runtime.sendMessage({ type: 'VAULT_STORAGE_QUOTA_WARNING' });2285+      } catch {2286+        // popup may be closed; surfaced via console.warn above2287+      }2288+    }2289+  }22672290 22682291   await writeSlot(SLOT_A, a);22692292   if (hasValidVaultSchema(b)) await writeSlot(SLOT_B, b);