BE: Fix: NIC-Covered Parent Devices Miss Connected/Down Reconnected Events #1821

.github/skills/pr-analysis/SKILL.md

@@ -28,6 +28,10 @@ Run through this before creating or editing any file under `test/`:
 2. Load `testing-workflow` skill — any test additions or changes must follow it.
 3. Load any domain-specific skill relevant to the files being changed (e.g. `database-patterns` for DB writes, `settings-management` for config).
 
+## Verifying a Claim About Generated Code
+
+A finding that claims a specific SQL/code expansion result (an alias collision, a macro substitution, an interpolation outcome) can't be verified by checking the caller's own internal consistency alone - the caller can be perfectly self-consistent and still collide with something the callee does internally that isn't visible at the call site. Open and read the callee's actual definition before accepting or rejecting the claim, and if it's a runtime-behavior claim (not just syntax), run a minimal repro to confirm rather than reasoning about it in the abstract. A real case: a finding claimed two same-named aliases collided across a caller/helper boundary; checking only that the caller used its alias consistently looked like it disproved the finding, but the helper had its own same-named internal alias that was never inspected - the finding was correct.
+
 ## Comment Classification
 
 For each comment, determine:

.github/skills/scan-pipeline/SKILL.md

@@ -56,7 +56,7 @@ This is the scan-pipeline-local half of a bigger attribution system — see `dat
 5. **A blank/null-equivalent `scanMac` can create a phantom `Devices` row.** `create_new_devices()`'s two creation-path queries filter `scanMac NOT IN (NULL_EQUIVALENTS_SQL)` (`server/scan/device_handling.py`, `const.NULL_EQUIVALENTS_SQL`) as a backstop, because `scanCreatesDevice` defaults to `1` — any plugin reporting a row with no real MAC, without setting `scanCreatesDevice = 0` itself, would otherwise create a `devMac = ''` device, and every other blank-MAC row from every other plugin would then silently write onto it. The filter doesn't replace `scanCreatesDevice = 0` as the correct thing for a plugin to set on such rows; it keeps a MAC-less row inert when some other plugin forgets to. Check any new creation-adjacent query against blank `scanMac` too.
 6. **`app.sql` is not dead code.** `install/production-filesystem/entrypoint.d/25-first-run-db.sh` pipes it into `sqlite3` to bootstrap a brand-new database on first install; `scripts/db_cleanup/regenerate-database.sh` uses it too. `CurrentScan`, `Parameters`, and `Settings` are safe from drift: each has a dedicated `ensure_X()` function (`server/db/db_upgrade.py`) that drops and recreates the table on every startup, superseding whatever `app.sql` bootstrapped. `Plugins_Language_Strings` gets the same treatment inside the shared `ensure_plugins_tables()`. `AppEvents` gets its own drop/recreate via `AppEvent_obj.__init__()` (`server/workflows/app_events.py`), independent of `db_upgrade.py`. `Devices` has no drop/recreate, but `server/database.py` has 18 explicit `ensure_column()` calls that backfill any column missing from an older `app.sql` snapshot on every startup. `Events`, `Sessions`, and `Notifications` get the same backfill via `ensure_table_columns()` (`server/db/db_upgrade.py`), driven by one Python column-list constant per table (`server/db/schema_columns.py`) that's diffed against `app.sql` in CI (`test/db/test_schema_drift_guard.py`). `AppEvents`/`Notifications` each also have a second schema-definition surface — their own inline `CREATE TABLE IF NOT EXISTS` in `server/workflows/app_events.py`/`server/models/notification_instance.py` — kept in sync by the same drift-check test. Check any new query here with `EXPLAIN QUERY PLAN` at a realistic row count rather than assuming it's fine because it resembles an existing one — a correlated subquery re-evaluated per row (an accidental self-join) is the pattern most likely to look reasonable while actually being quadratic at this scale.
 7. **`LatestEventsPerMAC` is intentionally `CurrentScan`-gated - correct for its one existing caller, a trap for a new one.** It `INNER JOIN`s `CurrentScan`, which is exactly right for the mainline "New Connections" query (every MAC it looks up is already known to be in `CurrentScan` this cycle, via its own `present_agg`). It is not a general-purpose "last event for any MAC" lookup. A caller that needs the last event for a MAC *not* in `CurrentScan` this cycle (e.g. a NIC-covered parent with no direct scan row of its own) gets no row at all from this view, regardless of that MAC's real event history - silently, not an error. `insert_events()`'s NIC-derived reconnect query reads `Events` directly instead (a correlated `ORDER BY eveDateTime DESC LIMIT 1`, covered by `idx_eve_mac_datetime_desc`), sidestepping the view entirely rather than trying to make it handle both shapes.
-8. **A correlated helper's own internal subquery alias can be shadowed by an identically-named alias at the call site, silently collapsing its `EXISTS` into a table-wide tautology.** SQL scoping makes the innermost alias declaration win. `nic_derived_presence_condition()` used to alias its own inner scan as `nic_parent`; `insert_events()`'s NIC-derived reconnect query aliases its own row the same way, so `nic_derived_presence_condition("nic_parent.devMac")` silently checked "does any device in `Devices` satisfy this," not "does this one" - any NIC-covered parent anywhere in the table made every other absent parent look NIC-derived-present too. Fixed by renaming the helper's internal alias to `nic_presence_parent` and rejecting it as a `mac_column` argument, matching `current_scan_presence_condition()`'s existing `presence_scan` guard. Only caught by a test with two sibling devices in one DB where one should match and the other shouldn't - every single-device test passed regardless, because "any row" and "this row" are the same row when there's only one.
+8. **A correlated helper's `mac_column` argument silently binds to the helper's own inner row, not the caller's, whenever the helper's inner table already has a column of that name in scope - alias or no alias.** SQL resolves an unqualified name in the innermost enclosing scope first and only searches outward if nothing matches there; `nic_derived_presence_condition()`'s inner scan is `FROM Devices`, and `Devices` has a `devMac` column, so *any* bare `"devMac"` argument - not just one that happens to collide with an alias name - bound to the helper's own inner row. Every bare-`"devMac"` call site (both `Device Down` queries, `Disconnected`, `update_devLastConnection_from_CurrentScan()`) was affected: any NIC-covered device anywhere in `Devices` made every *other* absent device, including one with no NIC children at all, look NIC-derived-present, silently suppressing its real event or bumping its `devLastConnection`. (A qualified-but-colliding argument, e.g. `"nic_parent.devMac"` passed from a caller aliasing its own row `nic_parent` while the helper's own inner alias was also `nic_parent`, is the same root cause in a narrower form.) Fixed by requiring every caller to pass a qualified reference to *its own* table/alias (`"Devices.devMac"`, `"DevicesView.devMac"`) and having `nic_derived_presence_condition()` reject a bare `mac_column` outright, on top of the existing `presence_scan`/`nic_presence_parent`-collision guards. `current_scan_presence_condition()` doesn't need this: its inner scan is `FROM CurrentScan`, which has no `devMac` column, so a bare `"devMac"` has nothing to bind to inward and correctly falls back to the caller's row. Only caught by a test with two sibling devices in one DB where one should match and the other shouldn't - every single-device test passed regardless, because "any row" and "this row" are the same row when there's only one.
 
 ## When to read this vs. other docs/skills