🚧 Add imei time varying attributes

init/01_schema.sql

@@ -83,4 +83,26 @@ COMMENT ON TABLE app_tokens IS
 COMMENT ON TABLE imei_map IS
     'Device settings (one JSONB document per IMEI), polled by the listener every 5 seconds; the API merges the current document into message payloads at read time.';
 COMMENT ON COLUMN imei_map.meta IS
-    'Settings document; "device" (non-empty string) is the device name injected at ingest, other keys are merged into message payloads at read time.';
+    'Settings document; "device" (non-empty string) is the device name injected at ingest, other keys are merged into message payloads at read time.';
+
+-- Time-varying device attributes (e.g. calibration offsets): an
+-- append-only timeline. A new value = a new row; the value valid at time T
+-- is the row with the greatest effective_from <= T. GET /messages resolves
+-- each message's attributes against the device time (payload_time,
+-- falling back to received_at). No FK to imei_map: like mqtt_messages,
+-- attributes may exist for IMEIs without a settings row. The listener
+-- never reads this table (attributes are read-time corrections).
+CREATE TABLE IF NOT EXISTS imei_attributes (
+    imei           TEXT        NOT NULL CHECK (imei ~ '^[0-9]{15}$'),
+    key            TEXT        NOT NULL CHECK (key <> ''),
+    value          JSONB       NOT NULL,
+    effective_from TIMESTAMPTZ NOT NULL DEFAULT now(),
+    note           TEXT,
+    created_at     TIMESTAMPTZ NOT NULL DEFAULT now(),
+    PRIMARY KEY (imei, key, effective_from)
+);
+
+COMMENT ON TABLE imei_attributes IS
+    'Time-varying device attributes (e.g. offsets) as an append-only timeline; the value valid at T is the row with the greatest effective_from <= T.';
+COMMENT ON COLUMN imei_attributes.effective_from IS
+    'Time from which the value applies; backdating allowed. Resolved against the device timestamp (payload_time, received_at fallback) in GET /messages.';