diff --git a/internal/lsp/debug/serve.go b/internal/lsp/debug/serve.go
index aec976ad6f..473518e433 100644
--- a/internal/lsp/debug/serve.go
+++ b/internal/lsp/debug/serve.go
@@ -181,6 +181,7 @@ type Client struct {
 	Logfile      string
 	GoplsPath    string
 	ServerID     string
+	Service      protocol.Server
 }
 
 // A Server is an outgoing connection to a remote LSP server.
@@ -314,6 +315,16 @@ func (i *Instance) getInfo(r *http.Request) interface{} {
 	return template.HTML(buf.String())
 }
 
+func (i *Instance) AddService(s protocol.Server, session *cache.Session) {
+	for _, c := range i.State.clients {
+		if c.Session == session {
+			c.Service = s
+			return
+		}
+	}
+	stdlog.Printf("unable to find a Client to add the protocol.Server to")
+}
+
 func getMemory(r *http.Request) interface{} {
 	var m runtime.MemStats
 	runtime.ReadMemStats(&m)
@@ -785,6 +796,29 @@ Using session: <b>{{template "sessionlink" .Session.ID}}</b><br>
 {{if .DebugAddress}}Debug this client at: <a href="http://{{localAddress .DebugAddress}}">{{localAddress .DebugAddress}}</a><br>{{end}}
 Logfile: {{.Logfile}}<br>
 Gopls Path: {{.GoplsPath}}<br>
+<h2>Diagnostics</h2>
+{{/*Service: []protocol.Server; each server has map[uri]fileReports;
+	each fileReport: map[diagnosticSoure]diagnosticReport
+	diagnosticSource is one of 5 source
+	diagnosticReport: snapshotID and map[hash]*source.Diagnostic
+	sourceDiagnostic: struct {
+		Range    protocol.Range
+		Message  string
+		Source   string
+		Code     string
+		CodeHref string
+		Severity protocol.DiagnosticSeverity
+		Tags     []protocol.DiagnosticTag
+
+		Related []RelatedInformation
+	}
+	RelatedInformation: struct {
+		URI     span.URI
+		Range   protocol.Range
+		Message string
+	}
+	*/}}
+<ul>{{range $k, $v := .Service.Diagnostics}}<li>{{$k}}:<ol>{{range $v}}<li>{{.}}</li>{{end}}</ol></li>{{end}}</ul>
 {{end}}
 `))
 
diff --git a/internal/lsp/diagnostics.go b/internal/lsp/diagnostics.go
index 4941f007ea..adf19ad86d 100644
--- a/internal/lsp/diagnostics.go
+++ b/internal/lsp/diagnostics.go
@@ -50,6 +50,23 @@ type fileReports struct {
 	reports       map[diagnosticSource]diagnosticReport
 }
 
+func (d diagnosticSource) String() string {
+	switch d {
+	case modSource:
+		return "FromSource"
+	case gcDetailsSource:
+		return "FromGCDetails"
+	case analysisSource:
+		return "FromAnalysis"
+	case typeCheckSource:
+		return "FromTypeChecking"
+	case orphanedSource:
+		return "FromOrphans"
+	default:
+		return fmt.Sprintf("From?%d?", d)
+	}
+}
+
 // hashDiagnostics computes a hash to identify diags.
 func hashDiagnostics(diags ...*source.Diagnostic) string {
 	source.SortDiagnostics(diags)
@@ -546,3 +563,34 @@ func (s *Server) shouldIgnoreError(ctx context.Context, snapshot source.Snapshot
 	})
 	return !hasGo
 }
+
+// Diagnostics formattedfor the debug server
+// (all the relevant fields of Server are private)
+// (The alternative is to export them)
+func (s *Server) Diagnostics() map[string][]string {
+	ans := make(map[string][]string)
+	s.diagnosticsMu.Lock()
+	defer s.diagnosticsMu.Unlock()
+	for k, v := range s.diagnostics {
+		fn := k.Filename()
+		for typ, d := range v.reports {
+			if len(d.diags) == 0 {
+				continue
+			}
+			for _, dx := range d.diags {
+				ans[fn] = append(ans[fn], auxStr(dx, d, typ))
+			}
+		}
+	}
+	return ans
+}
+
+func auxStr(v *source.Diagnostic, d diagnosticReport, typ diagnosticSource) string {
+	// Tags? RelatedInformation?
+	msg := fmt.Sprintf("(%s)%q(source:%q,code:%q,severity:%s,snapshot:%d,type:%s)",
+		v.Range, v.Message, v.Source, v.Code, v.Severity, d.snapshotID, typ)
+	for _, r := range v.Related {
+		msg += fmt.Sprintf(" [%s:%s,%q]", r.URI.Filename(), r.Range, r.Message)
+	}
+	return msg
+}
diff --git a/internal/lsp/lsprpc/lsprpc.go b/internal/lsp/lsprpc/lsprpc.go
index 623533f22a..51267910cf 100644
--- a/internal/lsp/lsprpc/lsprpc.go
+++ b/internal/lsp/lsprpc/lsprpc.go
@@ -61,6 +61,7 @@ func (s *StreamServer) ServeStream(ctx context.Context, conn jsonrpc2.Conn) erro
 	server := s.serverForTest
 	if server == nil {
 		server = lsp.NewServer(session, client)
+		debug.GetInstance(ctx).AddService(server, session)
 	}
 	// Clients may or may not send a shutdown message. Make sure the server is
 	// shut down.