feat: finish remaining inbound protocols (models, completions, native /route)

- GET /v1/models: pool + virtual cortiq-auto
- POST /v1/completions (legacy): non-stream + streaming text_completion
- POST /route: native passthrough returning the routing decision
- all inbound protocol adapters now implemented; admin meta + README/CHANGELOG updated
- bump to 0.2.1

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/protocols/mod.rs

@@ -3,8 +3,11 @@
 
 pub mod anthropic_messages;
 pub mod mcp;
+pub mod native_passthrough;
 pub mod openai_chat;
+pub mod openai_completions;
 pub mod openai_embeddings;
+pub mod openai_models;
 
 use crate::state::SharedState;
 use axum::Router;
@@ -15,8 +18,10 @@ use axum::Router;
 pub fn build_router() -> Router<SharedState> {
     Router::new()
         .merge(openai_chat::routes())
+        .merge(openai_completions::routes())
         .merge(openai_embeddings::routes())
+        .merge(openai_models::routes())
         .merge(anthropic_messages::routes())
         .merge(mcp::routes())
-    // TODO: openai_completions, openai_models, native_passthrough.
+        .merge(native_passthrough::routes())
 }

src/protocols/native_passthrough.rs

@@ -0,0 +1,86 @@
+//! Native passthrough adapter: `POST /route`.
+//! Returns the gateway's routing decision (task type, complexity, candidate models)
+//! without calling a model — direct access for clients that route themselves.
+
+use crate::error::{GatewayError, Result};
+use crate::state::SharedState;
+use axum::{extract::State, response::IntoResponse, routing::post, Json, Router};
+use serde::Deserialize;
+
+pub fn routes() -> Router<SharedState> {
+    Router::new().route("/route", post(handler))
+}
+
+#[derive(Deserialize)]
+struct RouteRequest {
+    /// `{ "input": { "text": "..." } }` (router-style) — optional.
+    #[serde(default)]
+    input: serde_json::Value,
+    /// `{ "text": "..." }` — convenience shorthand.
+    #[serde(default)]
+    text: Option<String>,
+    #[serde(default)]
+    profile: Option<String>,
+}
+
+async fn handler(
+    State(state): State<SharedState>,
+    Json(req): Json<RouteRequest>,
+) -> Result<impl IntoResponse> {
+    let live = state.live();
+    if !live.cfg.protocols.native_passthrough {
+        return Err(GatewayError::InvalidRequest(
+            "native_passthrough protocol is disabled".into(),
+        ));
+    }
+
+    let text = req
+        .text
+        .clone()
+        .or_else(|| req.input["text"].as_str().map(|s| s.to_string()))
+        .or_else(|| req.input.as_str().map(|s| s.to_string()))
+        .unwrap_or_default();
+    if text.is_empty() {
+        return Err(GatewayError::InvalidRequest(
+            "missing input text (use {\"text\": ...} or {\"input\": {\"text\": ...}})".into(),
+        ));
+    }
+
+    let profile = req
+        .profile
+        .clone()
+        .unwrap_or_else(|| live.cfg.route.profile.clone());
+
+    let (decision, source, candidates) = match live.router.route(&text, &profile).await {
+        Ok(Some(d)) => {
+            let cands = live.routing.candidates(&d.complexity_tier);
+            (Some(d), "router", cands)
+        }
+        _ => (
+            None,
+            "fallback",
+            vec![live.routing.default_model().to_string()],
+        ),
+    };
+
+    let selected = candidates.first().cloned().unwrap_or_default();
+    let decision_json = match &decision {
+        Some(d) => serde_json::json!({
+            "task_label": d.task_label,
+            "complexity": { "score": d.complexity_score, "tier": d.complexity_tier },
+            "router_request_id": d.router_request_id,
+        }),
+        None => serde_json::json!({
+            "task_label": "degraded",
+            "complexity": { "score": 0.5, "tier": "degraded" },
+            "router_request_id": serde_json::Value::Null,
+        }),
+    };
+
+    Ok(Json(serde_json::json!({
+        "decision": decision_json,
+        "source": source,
+        "candidates": candidates,
+        "selected_model": selected,
+    })))
+}

src/protocols/openai_completions.rs

@@ -0,0 +1,183 @@
+//! Inbound OpenAI Completions (legacy) adapter: `POST /v1/completions`.
+//! Converts the legacy `prompt` into a single user message, runs the pipeline, and
+//! returns the legacy `text_completion` shape (non-streaming JSON or streaming SSE).
+
+use crate::error::{GatewayError, Result};
+use crate::model::{ChatRequest, GenParams, Message, RequestMeta, RoutingDirective};
+use crate::protocols::openai_chat::cortiq_headers;
+use crate::state::SharedState;
+use axum::response::{IntoResponse, Response};
+use axum::{extract::State, routing::post, Json, Router};
+use serde::Deserialize;
+
+pub fn routes() -> Router<SharedState> {
+    Router::new().route("/v1/completions", post(handler))
+}
+
+#[derive(Deserialize)]
+struct CompletionsRequest {
+    model: String,
+    prompt: serde_json::Value,
+    #[serde(default)]
+    temperature: Option<f32>,
+    #[serde(default)]
+    max_tokens: Option<u32>,
+    #[serde(default)]
+    top_p: Option<f32>,
+    #[serde(default)]
+    stream: bool,
+}
+
+fn parse_routing(model: &str) -> RoutingDirective {
+    if let Some(rest) = model.strip_prefix("cortiq-auto") {
+        RoutingDirective::Auto {
+            profile: rest.strip_prefix(':').map(|p| p.to_string()),
+        }
+    } else {
+        RoutingDirective::Pinned {
+            model_id: model.to_string(),
+        }
+    }
+}
+
+fn prompt_to_string(v: &serde_json::Value) -> String {
+    if let Some(s) = v.as_str() {
+        return s.to_string();
+    }
+    if let Some(arr) = v.as_array() {
+        return arr
+            .iter()
+            .filter_map(|x| x.as_str())
+            .collect::<Vec<_>>()
+            .join("\n");
+    }
+    String::new()
+}
+
+async fn handler(
+    State(state): State<SharedState>,
+    Json(req): Json<CompletionsRequest>,
+) -> Result<Response> {
+    if !state.live().cfg.protocols.openai_completions {
+        return Err(GatewayError::InvalidRequest(
+            "openai_completions protocol is disabled".into(),
+        ));
+    }
+    let prompt = prompt_to_string(&req.prompt);
+    if prompt.is_empty() {
+        return Err(GatewayError::InvalidRequest(
+            "prompt must not be empty".into(),
+        ));
+    }
+
+    let canonical = ChatRequest {
+        routing: parse_routing(&req.model),
+        messages: vec![Message {
+            role: "user".into(),
+            content: prompt,
+            tool_calls: vec![],
+        }],
+        tools: vec![],
+        params: GenParams {
+            temperature: req.temperature,
+            max_tokens: req.max_tokens,
+            top_p: req.top_p,
+            stop: Vec::new(),
+            passthrough: Default::default(),
+        },
+        stream: req.stream,
+        meta: RequestMeta {
+            protocol: "openai_completions".into(),
+            ..Default::default()
+        },
+    };
+
+    if req.stream {
+        let (info, stream) = state.pipeline.run_stream(canonical, &state).await?;
+        let mut headers = cortiq_headers(&info);
+        headers.insert(
+            axum::http::header::CONTENT_TYPE,
+            axum::http::HeaderValue::from_static("text/event-stream"),
+        );
+        return Ok((
+            headers,
+            axum::body::Body::from_stream(chat_to_completions_sse(stream)),
+        )
+            .into_response());
+    }
+
+    let resp = state.pipeline.run(canonical, &state).await?;
+    let answer = resp
+        .choices
+        .first()
+        .map(|c| c.message.content.clone())
+        .unwrap_or_default();
+    let finish = resp
+        .choices
+        .first()
+        .map(|c| c.finish_reason.clone())
+        .unwrap_or_else(|| "stop".into());
+    let headers = cortiq_headers(&resp.cortiq);
+    let body = serde_json::json!({
+        "id": resp.id,
+        "object": "text_completion",
+        "created": std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap_or_default()
+            .as_secs(),
+        "model": resp.model_used,
+        "choices": [{ "text": answer, "index": 0, "logprobs": serde_json::Value::Null, "finish_reason": finish }],
+        "usage": {
+            "prompt_tokens": resp.usage.prompt_tokens,
+            "completion_tokens": resp.usage.completion_tokens,
+            "total_tokens": resp.usage.total_tokens,
+        },
+    });
+    Ok((headers, Json(body)).into_response())
+}
+
+/// Translate chat `chat.completion.chunk` SSE into legacy `text_completion` SSE
+/// (`delta.content` → `text`).
+fn chat_to_completions_sse(
+    stream: crate::providers::ChatStream,
+) -> impl futures::Stream<Item = Result<bytes::Bytes>> + Send + 'static {
+    use futures::StreamExt;
+    async_stream::stream! {
+        let mut buf = String::new();
+        futures::pin_mut!(stream);
+        while let Some(item) = stream.next().await {
+            let bytes = match item { Ok(b) => b, Err(e) => { yield Err(e); break; } };
+            if let Ok(s) = std::str::from_utf8(&bytes) {
+                buf.push_str(s);
+            }
+            while let Some(idx) = buf.find("\n\n") {
+                let chunk: String = buf.drain(..idx + 2).collect();
+                for line in chunk.lines() {
+                    let Some(data) = line.trim_start().strip_prefix("data:") else { continue };
+                    let data = data.trim();
+                    if data.is_empty() { continue; }
+                    if data == "[DONE]" {
+                        yield Ok(bytes::Bytes::from("data: [DONE]\n\n"));
+                        continue;
+                    }
+                    let Ok(v) = serde_json::from_str::<serde_json::Value>(data) else { continue };
+                    if let Some(u) = v.get("usage").filter(|u| !u.is_null()) {
+                        yield Ok(bytes::Bytes::from(format!(
+                            "data: {}\n\n",
+                            serde_json::json!({"object": "text_completion", "choices": [], "usage": u})
+                        )));
+                    }
+                    if let Some(t) = v["choices"][0]["delta"]["content"].as_str() {
+                        yield Ok(bytes::Bytes::from(format!(
+                            "data: {}\n\n",
+                            serde_json::json!({
+                                "object": "text_completion",
+                                "choices": [{"text": t, "index": 0, "finish_reason": null}]
+                            })
+                        )));
+                    }
+                }
+            }
+        }
+    }
+}

src/protocols/openai_models.rs

@@ -0,0 +1,32 @@
+//! Inbound OpenAI Models adapter: `GET /v1/models`.
+//! Lists the configured pool (plus the virtual `cortiq-auto`) for client discovery.
+
+use crate::error::{GatewayError, Result};
+use crate::state::SharedState;
+use axum::{extract::State, response::IntoResponse, routing::get, Json, Router};
+
+pub fn routes() -> Router<SharedState> {
+    Router::new().route("/v1/models", get(handler))
+}
+
+async fn handler(State(state): State<SharedState>) -> Result<impl IntoResponse> {
+    let live = state.live();
+    if !live.cfg.protocols.openai_models {
+        return Err(GatewayError::InvalidRequest(
+            "openai_models protocol is disabled".into(),
+        ));
+    }
+    let mut data = vec![serde_json::json!({
+        "id": "cortiq-auto",
+        "object": "model",
+        "owned_by": "cortiq",
+    })];
+    for m in &live.cfg.models {
+        data.push(serde_json::json!({
+            "id": m.id,
+            "object": "model",
+            "owned_by": m.provider,
+        }));
+    }
+    Ok(Json(serde_json::json!({ "object": "list", "data": data })))
+}