Add Spark Control hardware backend (diarize, queue, discovery)

server/hardware-config.js

@@ -0,0 +1,92 @@
+// Resolves which (URL, model) the relay should use for each operator-
+// hardware pipeline. Spark Control is the SINGLE host the relay
+// talks to — it owns transcribe (/v1/audio/transcriptions),
+// diarize-chunk (/api/audio/diarize-chunk), AND analyze
+// (/v1/chat/completions, OpenAI-compatible) on the same port. The
+// discovery JSON Spark Control serves at /api/endpoints lists the
+// backing services SC delegates to internally (e.g. a Parakeet
+// wrapper, a vLLM instance) along with their ready state + currently-
+// loaded model name; the relay reads it ONLY to learn (a) whether
+// each service is ready, and (b) which model name to send in the
+// upstream request body. The per-service base URLs in the discovery
+// JSON are informational — clients hit Spark Control directly, not
+// those internal URLs.
+//
+// Priority order, per pipeline:
+//
+//   1. Spark Control says ready  → use the SC base URL + the model
+//                                  name discovery reports for that
+//                                  service.
+//
+//   2. SC says not_ready         → return null URL + a blocked_reason
+//                                  string. Route handlers surface
+//                                  this to the user instead of trying
+//                                  a doomed call.
+//
+//   3. SC unreachable or no URL  → null URL; planBackend treats the
+//                                  hardware path as not configured.
+//
+// History:
+//   - pre-v0.2.84: operator-typed override URLs (relay_parakeet_*,
+//     relay_gemma_*) won over discovery. Removed.
+//   - pre-v0.2.85: discovery's per-service base_urls were used
+//     directly, so transcribe went to a different host (the Parakeet
+//     wrapper) than diarize (Spark Control). That meant the relay
+//     was talking to two hosts for one logical operation, and the
+//     transcribe wrapper didn't have the diarize endpoint. Now: SC
+//     is the single host. The per-service base_urls in discovery
+//     are informational — used only for the operator's awareness in
+//     the dashboard's Service Discovery health line.
+
+import { getSparkServiceState } from "./spark-control.js";
+
+export async function resolveHardwareConfig(cfg) {
+  const sparkUrl = (cfg.relay_spark_control_url || "").trim();
+  // Spark Control base URL with the /api/endpoints suffix and any
+  // trailing slash stripped. Used as the URL for every operator-
+  // hardware call: transcribe, diarize-chunk, analyze.
+  const sparkBase = sparkUrl.replace(/\/$/, "").replace(/\/api\/endpoints$/, "");
+
+  const transcribe = await resolveOne({ sparkUrl, sparkBase, kind: "transcribe" });
+  const analyze = await resolveOne({ sparkUrl, sparkBase, kind: "analyze" });
+  const tts = await resolveOne({ sparkUrl, sparkBase, kind: "tts" });
+
+  return {
+    transcribe,
+    analyze,
+    tts,
+    sparkBase,
+  };
+}
+
+async function resolveOne({ sparkUrl, sparkBase, kind }) {
+  if (!sparkUrl || !sparkBase) {
+    return { url: null, model: null, source: null };
+  }
+  const state = await getSparkServiceState(sparkUrl, kind);
+  if (state.status === "ready") {
+    return {
+      // ALWAYS Spark Control's base URL — never the delegate's
+      // base_url. SC owns the wire-facing endpoint; the delegate
+      // URL is just where SC routes the request internally.
+      url: sparkBase,
+      // Model name comes from discovery so we send the right
+      // `model` field upstream. SC tells us what model is currently
+      // loaded on its parakeet / vllm delegate.
+      model: state.model,
+      source: "spark-control",
+    };
+  }
+  if (state.status === "not_ready") {
+    return {
+      url: null,
+      model: null,
+      source: "spark-control",
+      blocked_reason: state.reason,
+    };
+  }
+  // status === "unknown" → discovery unreachable or that service
+  // isn't listed. Return null URL; the route handler surfaces the
+  // error to the user.
+  return { url: null, model: null, source: null };
+}