Correlate Rust logger lines to the active OTel trace + tee to tracing

.changeset/rust-otel-correlation.md

@@ -0,0 +1,12 @@
+---
+'@smooai/logger': patch
+---
+
+Rust: log lines now carry the active OTel span's real W3C `traceId`/`spanId`
+(guarded on `span_context.is_valid()`), falling back to the correlation uuid,
+and are teed into `tracing` so a single subscriber sees both.
+
+`ContextKey` is now `#[non_exhaustive]`. It gains a variant whenever the family
+learns a new correlation field — `SpanId` is this release's — and without that
+attribute each addition is a source-breaking change for any downstream crate
+matching on it exhaustively.

rust/logger/Cargo.toml

@@ -28,11 +28,21 @@ uuid = { version = "1", features = ["v4"] }
 chrono = { version = "0.4", features = ["serde", "clock"] }
 colored = "2"
 url = "2"
+# OpenTelemetry **API only** (no SDK, no `@smooai/observability` — that would be
+# circular): read the active span's trace_id/span_id for log↔trace correlation,
+# and the `tracing` facade to tee lines into the observability OTLP appender.
+tracing = { version = "0.1", default-features = false, features = ["std"] }
 lambda_runtime = { version = "0.13", optional = true }
 aws_lambda_events = { version = "0.16", default-features = false, features = [
   "apigw",
   "sqs",
 ], optional = true }
+opentelemetry = { version = "0.32.0", default-features = false, features = ["trace"] }
 
 [dev-dependencies]
 tempfile = "3"
+# Correlation + tee tests: a real SDK tracer to mint an active span, and a
+# tracing subscriber to capture the teed events (dev-only — the SDK dep is not
+# circular; the crate itself depends on the OTel API only).
+opentelemetry_sdk = { version = "0.32", features = ["trace"] }
+tracing-subscriber = { version = "0.3", default-features = false, features = ["registry", "std"] }