feat(bmx): SiriusXM live-adapter logging stub

bmx_services.json advertises SIRIUSXM_EVEREST at
`{BMX_SERVER}/core02/svc-bmx-adapter-siriusxm-everest-eco1/prod/live-adapter`
and bmx_services_availability.json lists it as available, so speakers
that try SiriusXM hit that path. Without a route we 404'd silently
and the call was invisible in our logs.

  - HandleSiriusXMLiveAdapter at the bare base URL returns the
    SIRIUSXM_EVEREST service descriptor (selected by id.name from
    bmx_services.json, with {BMX_SERVER}/{MEDIA_SERVER} substitution).
    Mirrors deborahgu/soundcork main.py:805 in shape.

  - HandleSiriusXMLiveAdapterSubpath catches every sub-path advertised
    by the descriptor's _links (/availability, /token, /navigate,
    /logout) plus the playback URLs the speaker discovers via navigate.
    Logs the request with method+path+UA+Authorization+RawQuery, then
    404s — giving the next implementation pass concrete data about
    what the speaker actually asks for.

Two helpers added to handlers_bmx.go (shared with any future
BMX-segment stub):

  - extractBMXService(json, name) — find a service entry by id.name.
  - (*Server).applyBMXTemplate(content) — {BMX_SERVER}/{MEDIA_SERVER}
    substitution, identical to what HandleBMXRegistry does inline.

Routes registered next to Orion at the top level — same convention
(no /bmx/ prefix) because bmx_services.json advertises baseUrl without
that prefix and speakers reach the path verbatim under either
migration mode.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pkg/service/handlers/handlers_bmx.go

@@ -12,6 +12,8 @@
 package handlers
 
 import (
+	"encoding/json"
+	"fmt"
 	"net/http"
 	"strings"
 )
@@ -43,6 +45,60 @@ func (s *Server) HandleBMXServicesAvailability(w http.ResponseWriter, _ *http.Re
 	_, _ = w.Write(bmxServicesAvailabilityJSON)
 }
 
+// extractBMXService finds a single service entry in bmx_services.json by
+// its `id.name` (e.g. "SIRIUSXM_EVEREST", "TUNEIN"). Returns the raw JSON
+// segment for that service so callers can apply {BMX_SERVER} / {MEDIA_SERVER}
+// substitution and write it back to the wire.
+func extractBMXService(bmxJSON []byte, name string) (json.RawMessage, error) {
+	var wrapper struct {
+		BMXServices []json.RawMessage `json:"bmx_services"`
+	}
+
+	if err := json.Unmarshal(bmxJSON, &wrapper); err != nil {
+		return nil, fmt.Errorf("parse bmx_services.json: %w", err)
+	}
+
+	for _, raw := range wrapper.BMXServices {
+		var idOnly struct {
+			ID struct {
+				Name string `json:"name"`
+			} `json:"id"`
+		}
+
+		if err := json.Unmarshal(raw, &idOnly); err != nil {
+			continue
+		}
+
+		if idOnly.ID.Name == name {
+			return raw, nil
+		}
+	}
+
+	return nil, fmt.Errorf("service %q not found in bmx_services.json", name)
+}
+
+// applyBMXTemplate runs the same {BMX_SERVER} / {MEDIA_SERVER} substitution
+// HandleBMXRegistry uses, so service-descriptor responses produced from
+// sub-segments of bmx_services.json land at the same hostnames the
+// registry advertises.
+func (s *Server) applyBMXTemplate(content string) string {
+	baseURL := s.serverURL
+
+	s.mu.RLock()
+	dnsEnabled := s.dnsEnabled
+	s.mu.RUnlock()
+
+	bmxServer := baseURL
+	if dnsEnabled {
+		bmxServer = "https://content.api.bose.io"
+	}
+
+	content = strings.ReplaceAll(content, "{BMX_SERVER}", bmxServer)
+	content = strings.ReplaceAll(content, "{MEDIA_SERVER}", baseURL+"/media")
+
+	return content
+}
+
 // writeBMXUnauthorized writes the canonical 401 used by every BMX adapter
 // handler that requires an Authorization header (TuneIn variants, Orion
 // playback). Currently unused because all gate sites are temporarily

pkg/service/handlers/handlers_bmx_siriusxm.go

@@ -0,0 +1,53 @@
+// Package handlers — SiriusXM BMX adapter (logging stub).
+//
+// bmx_services.json declares SIRIUSXM_EVEREST at
+// `{BMX_SERVER}/core02/svc-bmx-adapter-siriusxm-everest-eco1/prod/live-adapter`,
+// and bmx_services_availability.json lists it as available — so speakers
+// that try SiriusXM hit this path. The bare URL returns the service
+// descriptor; sub-paths advertised by the descriptor's _links
+// (/availability, /token, /navigate, /logout, plus the playback paths
+// the speaker discovers via navigate) currently log + 404 so we have
+// visibility into real speaker calls for the next implementation pass.
+//
+// Reference: deborahgu/soundcork main.py:805 takes the same shape —
+// returns the SiriusXM service descriptor from the BMX services array
+// (hardcoded index 2). We select by id.name instead of array index.
+package handlers
+
+import (
+	"log"
+	"net/http"
+)
+
+// HandleSiriusXMLiveAdapter returns the SIRIUSXM_EVEREST service descriptor
+// from bmx_services.json for the bare live-adapter base URL.
+func (s *Server) HandleSiriusXMLiveAdapter(w http.ResponseWriter, r *http.Request) {
+	log.Printf("[BMX SiriusXM] %s %s ua=%q auth=%q query=%q",
+		r.Method, r.URL.Path, r.UserAgent(),
+		r.Header.Get("Authorization"), r.URL.RawQuery)
+
+	svc, err := extractBMXService(bmxServicesJSON, "SIRIUSXM_EVEREST")
+	if err != nil {
+		log.Printf("[BMX SiriusXM] failed to extract service descriptor: %v", err)
+		http.Error(w, "service descriptor unavailable", http.StatusInternalServerError)
+
+		return
+	}
+
+	body := s.applyBMXTemplate(string(svc))
+
+	w.Header().Set("Content-Type", "application/json")
+	_, _ = w.Write([]byte(body))
+}
+
+// HandleSiriusXMLiveAdapterSubpath logs and 404s any unimplemented sub-path
+// under the SiriusXM live-adapter. Visibility for the next implementation
+// pass — the _links in the descriptor publish /availability, /token,
+// /navigate, /logout; playback URLs come dynamically from navigate.
+func (s *Server) HandleSiriusXMLiveAdapterSubpath(w http.ResponseWriter, r *http.Request) {
+	log.Printf("[BMX SiriusXM] UNIMPLEMENTED %s %s ua=%q auth=%q query=%q",
+		r.Method, r.URL.Path, r.UserAgent(),
+		r.Header.Get("Authorization"), r.URL.RawQuery)
+
+	http.Error(w, "not implemented", http.StatusNotFound)
+}