diff --git a/tests/rig_engine_openai.rs b/tests/rig_engine_openai.rs
new file mode 100644
index 00000000..2edcc6d9
--- /dev/null
+++ b/tests/rig_engine_openai.rs
@@ -0,0 +1,185 @@
+//! Feature test for the Rig-backed `EngineProvider` adapter's `OpenAI` leg.
+//!
+//! End-to-end user story: a caller has an `OPENAI_API_KEY` exported in
+//! their environment. They construct a `RigEngine` via `openai_from_env`
+//! for `gpt-4o-mini`, build an Ailly `CompletionRequest` that contains a
+//! system instruction plus a user turn, and hand the request to the engine
+//! through the `EngineProvider::complete` port. The engine translates the
+//! Ailly messages into the Rig request shape, calls `OpenAI`'s completion
+//! API, and returns one `CompletionResponse` whose `content` carries the
+//! model's reply and whose `Trace` carries the provider's token usage, the
+//! actual model called, a non-empty `span_id`, a measured `latency_ms`, and
+//! at minimum one `gen_ai.completion` event whose attributes follow the
+//! OpenTelemetry `gen_ai.*` semantic conventions with `gen_ai.system` set
+//! to `"openai"`.
+//!
+//! This confirms the `OpenAI` leg of the ailly-evals project's Feature C
+//! (multi-provider live confirmation) — the code path already existed and
+//! was unit-tested; this is the first *live* round trip against it. It
+//! deliberately does not exercise tool-calling: `CompletionRequest` has no
+//! `tools` field on any provider today (tracked separately in
+//! `docs/developer/TASKS.md`, "live tool-definition wiring is completely
+//! missing"), so this test's only job is the basic-completion round trip
+//! and the OpenAI-specific system-prompt-placement rough edge the parent
+//! project's research flagged.
+//!
+//! This is a live integration test: it issues a real HTTPS call to `OpenAI`.
+//! It is gated on the `OPENAI_API_KEY` environment variable and is silently
+//! skipped when the variable is absent so `cargo test` stays green in
+//! environments without credentials.
+
+use ailly_two::content::conversation::Content;
+use ailly_two::content::conversation::Message;
+use ailly_two::content::conversation::ModelId;
+use ailly_two::content::conversation::Role;
+use ailly_two::engine::engine::CompletionRequest;
+use ailly_two::engine::engine::EngineProvider;
+use ailly_two::engine::rig_engine::openai_from_env;
+
+const LIVE_API_KEY_ENV: &str = "OPENAI_API_KEY";
+const MODEL: &str = "gpt-4o-mini";
+
+fn rendered_system(text: &str) -> Message {
+    Message {
+        role: Role::System,
+        body: Some(Content::Text(text.to_owned())),
+        cache: true,
+        trace: None,
+        _phase: std::marker::PhantomData,
+    }
+}
+
+fn rendered_user(text: &str) -> Message {
+    Message {
+        role: Role::User,
+        body: Some(Content::Text(text.to_owned())),
+        cache: false,
+        trace: None,
+        _phase: std::marker::PhantomData,
+    }
+}
+
+#[tokio::test]
+async fn rig_engine_complete_against_live_openai_populates_content_and_trace() {
+    // Arrange — load a `.env` from the workspace root if present, then skip
+    // silently when the live API key is still absent, mirroring
+    // `tests/rig_engine.rs`'s Anthropic gating so this test stays green in
+    // any environment without OpenAI credentials.
+    let _ = dotenvy::dotenv();
+    let Ok(api_key) = std::env::var(LIVE_API_KEY_ENV) else {
+        eprintln!(
+            "skipping rig_engine_openai live test: {LIVE_API_KEY_ENV} not found in environment or .env"
+        );
+        return;
+    };
+    assert!(!api_key.is_empty(), "{LIVE_API_KEY_ENV} must not be empty");
+
+    let engine = openai_from_env(MODEL).expect(
+        "openai_from_env must succeed when OPENAI_API_KEY is set and the model id is known",
+    );
+
+    let messages = vec![
+        rendered_system(
+            "You answer concisely. Reply with exactly the single word 'pong' and nothing else.",
+        ),
+        rendered_user("ping"),
+    ];
+    let request = CompletionRequest {
+        model: ModelId::from(MODEL),
+        messages: &messages,
+        debug: false,
+    };
+
+    // Act — issue the live call. A system turn placed ahead of the user
+    // turn is exactly the shape the parent research flagged as an OpenAI
+    // rough edge (system-prompt placement under Responses API churn); this
+    // call succeeding is the confirmation that shape still round-trips.
+    let response = engine
+        .complete(request)
+        .await
+        .expect("live OpenAI completion succeeds with a valid API key and a known model");
+
+    // Assert — body lowered from the response.
+    match response.content {
+        Content::Text(ref text) => {
+            assert!(
+                !text.trim().is_empty(),
+                "OpenAI reply must be a non-empty string for this prompt; got {text:?}"
+            );
+        }
+        Content::Blocks(_) => {
+            panic!(
+                "single-text response from OpenAI must lower to Content::Text, not Content::Blocks"
+            );
+        }
+    }
+
+    // Assert — trace carries the actual model called, a non-empty span id,
+    // a measured latency, and non-zero token counts in both directions.
+    let trace = &response.trace;
+    assert_eq!(
+        trace.model.as_ref(),
+        MODEL,
+        "trace.model records the model actually called"
+    );
+    assert!(
+        !trace.span_id.as_ref().is_empty(),
+        "trace.span_id must be populated"
+    );
+    assert!(
+        trace.latency_ms > 0,
+        "trace.latency_ms must reflect a measured wall-clock duration; got 0"
+    );
+    assert!(
+        trace.tokens.input > 0,
+        "OpenAI always reports non-zero input tokens; got {}",
+        trace.tokens.input
+    );
+    assert!(
+        trace.tokens.output > 0,
+        "OpenAI always reports non-zero output tokens for a non-empty reply; got {}",
+        trace.tokens.output
+    );
+
+    // Assert — at least one gen_ai.completion event, with the OpenTelemetry
+    // semantic-convention attributes present, and `gen_ai.system` reading
+    // "openai" (not "anthropic" — this is the discriminating assertion that
+    // proves the provider-identifier plumbing is correct end to end, not
+    // just for the Anthropic leg).
+    let completion_event = trace
+        .events
+        .iter()
+        .find(|event| event.name == "gen_ai.completion")
+        .expect("at least one gen_ai.completion TraceEvent must be emitted on success");
+    let attrs = &completion_event.attributes;
+
+    let system_attr = attrs
+        .get("gen_ai.system")
+        .and_then(serde_yaml_ng::Value::as_str)
+        .expect("gen_ai.system attribute is required by the OpenTelemetry semconv");
+    assert_eq!(
+        system_attr, "openai",
+        "gen_ai.system identifies the provider family"
+    );
+    let request_model = attrs
+        .get("gen_ai.request.model")
+        .and_then(serde_yaml_ng::Value::as_str)
+        .expect("gen_ai.request.model attribute is required by the OpenTelemetry semconv");
+    assert_eq!(request_model, MODEL);
+    let event_input_tokens = attrs
+        .get("gen_ai.usage.input_tokens")
+        .and_then(serde_yaml_ng::Value::as_u64)
+        .expect("gen_ai.usage.input_tokens attribute is required");
+    assert_eq!(
+        event_input_tokens, trace.tokens.input,
+        "gen_ai.usage.input_tokens must agree with trace.tokens.input"
+    );
+    let event_output_tokens = attrs
+        .get("gen_ai.usage.output_tokens")
+        .and_then(serde_yaml_ng::Value::as_u64)
+        .expect("gen_ai.usage.output_tokens attribute is required");
+    assert_eq!(
+        event_output_tokens, trace.tokens.output,
+        "gen_ai.usage.output_tokens must agree with trace.tokens.output"
+    );
+}