http: expose GET /api/version

internal/server/http/server.go

@@ -123,6 +123,7 @@ func (s *Server) routes(r chi.Router) {
 	r.Post("/api/agents/announce", s.handleAnnounce)
 	r.Get("/agent/binary", s.handleAgentBinary)
 	r.Get("/install/*", s.handleInstallAsset)
+	r.Get("/api/version", s.handleVersion)
 	if s.deps.Hub != nil {
 		r.Mount("/ws/agent", ws.AgentHandler(ws.HandlerDeps{
 			Hub:            s.deps.Hub,

internal/server/http/version.go

@@ -0,0 +1,20 @@
+package http
+
+import (
+	"encoding/json"
+	stdhttp "net/http"
+
+	"gitea.dcglab.co.uk/steve/restic-manager/internal/version"
+)
+
+// handleVersion exposes the server's build-time identifying constants
+// (set via -ldflags). Public-band — no secrets surface here, the agent
+// updater compares its own agent_version byte-for-byte against the
+// Version field to drive the "out of date" signal.
+func (s *Server) handleVersion(w stdhttp.ResponseWriter, r *stdhttp.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(map[string]string{
+		"version": version.Version,
+		"commit":  version.Commit,
+	})
+}

internal/server/http/version_test.go

@@ -0,0 +1,42 @@
+package http
+
+import (
+	"encoding/json"
+	stdhttp "net/http"
+	"testing"
+
+	"gitea.dcglab.co.uk/steve/restic-manager/internal/version"
+)
+
+func TestVersionEndpoint(t *testing.T) {
+	t.Parallel()
+
+	prevV, prevC := version.Version, version.Commit
+	version.Version = "v9.9.9-test"
+	version.Commit = "abc1234"
+	t.Cleanup(func() {
+		version.Version = prevV
+		version.Commit = prevC
+	})
+
+	_, url, _ := newTestServerWithHub(t)
+
+	res, err := stdhttp.Get(url + "/api/version")
+	if err != nil {
+		t.Fatalf("get: %v", err)
+	}
+	defer res.Body.Close()
+	if res.StatusCode != stdhttp.StatusOK {
+		t.Fatalf("status: got %d want 200", res.StatusCode)
+	}
+	var body map[string]string
+	if err := json.NewDecoder(res.Body).Decode(&body); err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	if body["version"] != "v9.9.9-test" {
+		t.Fatalf("version: got %q", body["version"])
+	}
+	if body["commit"] != "abc1234" {
+		t.Fatalf("commit: got %q", body["commit"])
+	}
+}