feat: publish standalone worker

Separate worker packaging and service lifecycle from the control plane.

internal/webapp/handlers_peer.go

@@ -0,0 +1,59 @@
+package webapp
+
+import (
+	"encoding/json"
+	"net/http"
+	"time"
+)
+
+// peerStatusResponse is the JSON returned at GET /api/peer/status.
+// The shape matches distworker.PeerStatus exactly so the peer
+// poller on the other end can decode it without a separate
+// type. Kept here as a local view to keep the webapp package free
+// of any concrete dependency on the distworker peer types; the
+// fields are JSON-stable.
+//
+// Up == nil means "no probe has run yet" so peer workers that
+// query this endpoint right after boot do not get a misleading
+// "true" verdict while the selfcheck is still spinning up.
+type peerStatusResponse struct {
+	WorkerID   string     `json:"worker_id"`
+	Up         *bool      `json:"up"`
+	ObservedAt *time.Time `json:"observed_at"`
+}
+
+// handlePeerStatus serves the most recent local selfcheck verdict
+// to peer workers over HTTP. The endpoint is intentionally
+// unauthenticated for now: a worker with basic auth configured
+// (WORKER_LOGIN / WORKER_PASSWORD) still exposes the verdict
+// because the path lives outside the /web/api/* prefix that the
+// basic-auth middleware gates. This matches the
+// "keep simple for local trusted workers if no peer auth exists
+// yet" directive in
+// docs/distributed/worker-to-worker-raft.md (slice 1).
+//
+// The endpoint never returns a 5xx: a runner that has not yet
+// produced a verdict simply returns {"up": null, ...} so the
+// peer poller can keep the slot in cache as "unknown" instead of
+// treating the absence as a hard failure.
+func (s *Server) handlePeerStatus(w http.ResponseWriter, _ *http.Request) {
+	resp := peerStatusResponse{}
+	if s.deps.Runner != nil {
+		up, at := s.deps.Runner.MasterStatus()
+		resp.WorkerID = s.deps.Runner.WorkerID()
+		resp.Up = up
+		if !at.IsZero() {
+			// Copy the timestamp so callers see a value
+			// (json omitempty is not used on purpose: an
+			// explicit zero time communicates "no probe" and
+			// an RFC3339 string communicates "probed at").
+			atCopy := at.UTC()
+			resp.ObservedAt = &atCopy
+		}
+	}
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.WriteHeader(http.StatusOK)
+	if err := json.NewEncoder(w).Encode(resp); err != nil {
+		s.deps.Logger.Printf("peer status encode: %v", err)
+	}
+}