Conformance posture: OGC SensorThings

Adapter: src/nous/interop/sensorthings.py (BL-025)

Standard: OGC SensorThings v1.1, the JSON API for IoT observations. Spec: https://www.ogc.org/standard/sensorthings/.

Current posture: Encode emits a single-observation JSON envelope with @iot.id, result, phenomenonTime and resultTime (both normalised to UTC ISO-8601 with the Z suffix per OGC SensorThings v1.1 §6.5), and Datastream.name. Encoder refuses to emit when the source estimate is older than max_age_s (default 60 s); both encode and decode enforce max_payload_len (default 64 KiB) to bound the attack surface against oversized payloads. Decode parses inbound JSON envelopes back to a dictionary, returning {"error": ...} on parse failure rather than raising.

What is supported: Observation envelopes, the SOSA / SSN-aligned field names. The encoded JSON is suitable for POST /Observations against a compliant SensorThings server.

What is omitted: Streaming via MQTT or websockets (use the MQTT adapter for the smoke test), batch insertion, FeatureOfInterest linking, complex result types (Categorical, Truth, Count).

Conformance claim: None. The 2026-05-23 audit confirmed UTC normalisation of phenomenonTime (closes the baseline H4 finding).