BE: SQL refactor presence

docs/NOTIFICATIONS.md

@@ -40,6 +40,10 @@ On almost all plugins there are 2 core settings, `<plugin>_WATCH` and `<plugin>_
 
 Click the **Read more in the docs.** Link at the top of each plugin to get more details on how the given plugin works.
 
+### Plugin-level per-row overrides
+
+A plugin author can also mark individual rows it reports as `quiet` via the `scanNotificationMode` data column, independent of any user-facing setting above - e.g. a bulk inventory import that shouldn't spam notifications for known-offline devices. This is a plugin-authoring concept, not something configured in the UI - see [Data contract](https://docs.netalertx.com/PLUGINS_DEV_DATA_CONTRACT#import-behavior-columns) for the full behavior (when it applies, and how it combines with the **Alert Events**/**Alert Down** device settings above when multiple plugins report the same device).
+
 ## Global settings ⚙
 
 ![Global notification settings](./img/NOTIFICATIONS/Global-notification-settings.png)

docs/PLUGINS_DEV_DATA_CONTRACT.md

@@ -164,7 +164,7 @@ Three optional `CurrentScan` columns, all independent of each other, control wha
 | Column | Type | Default | Meaning |
 |---|---|---|---|
 | `scanCreatesDevice` | boolean | `1` | Whether this row can originate a *new* `Devices` entry. `0` lets an enrich-only plugin (e.g. a hostname resolver) update an already-existing device's fields without ever being able to create one. |
-| `scanNotificationMode` | text (`normal` \| `quiet`) | `normal` | Whether creating/reconnecting this device should dispatch a notification. `quiet` still writes the `Events` row (audit trail intact) but suppresses the outbound email/push. Creation-time-only: it seeds `devAlertDown`/`devAlertEvents` to `0` on the device when it's first created, rather than being an ongoing, per-cycle re-evaluated policy — reclassifying a plugin's row later does not retroactively change an already-created device's alert settings. |
+| `scanNotificationMode` | text (`normal` \| `quiet`) | `normal` | Whether this row's notifications are suppressed. `quiet` still writes the `Events` row (audit trail intact) but suppresses the outbound email/push. Checked two different ways depending on the event: **live**, as a per-cycle aggregate, for any event fired from a row that's actually present this cycle (`New Device`, `Connected`, `Down Reconnected`, `IP Changed`) — reclassifying a plugin's row does change these going forward. **Frozen**, via `devAlertDown`/`devAlertEvents` seeded onto the device at creation time, for events fired from row *absence* (`Device Down`, `Disconnected`) — there's no live `CurrentScan` row to read at that moment, so reclassifying later does not retroactively change an already-created device's alert settings for these two event types. |
 | `scanPresence` | boolean | `1` | Whether this row asserts the device is *currently online*. `0` means "identity/inventory data, no presence claim" — not "offline". A reservation, a lease record, or a static IPAM entry are typical `0` cases. |
 
 **Missing vs. invalid values — these behave differently, not interchangeably:**