Implemented admin pane + user permission

internal/datasource/synthetic/synthetic.go

@@ -462,6 +462,65 @@ func outTypeOf(st *signalState) dsp.ValType {
 	return st.rg.outType
 }
 
+// TraceNode is a single node's computed value in a debug trace.
+type TraceNode struct {
+	Value  any    `json:"value"`
+	Type   string `json:"type"` // "scalar" | "array"
+	Approx bool   `json:"approx,omitempty"`
+}
+
+// TraceResult is the per-node outcome of a single-shot evaluation of an
+// (unsaved) synthetic graph, used by the editor's live/debug overlay.
+type TraceResult struct {
+	Nodes map[string]TraceNode `json:"nodes"`
+	Error string               `json:"error,omitempty"`
+}
+
+// Trace compiles def and evaluates it once with fresh state, returning the value
+// computed for every node. Source node values are obtained via read(ds, name)
+// (typically a broker ReadNow snapshot); a source that cannot be read defaults to
+// scalar 0. Stateful ops are flagged Approx since their true running value
+// depends on accumulated state this single-shot pass does not have. A per-node
+// evaluation error is returned in Error with the partial values still populated.
+func (s *Synthetic) Trace(def SignalDef, read func(ds, name string) (any, error)) (TraceResult, error) {
+	rg, err := compileGraph(def)
+	if err != nil {
+		return TraceResult{}, err
+	}
+	sourceVals := make(map[string]dsp.Sample, len(rg.sources))
+	for _, src := range rg.sources {
+		raw, rerr := read(src.ref.DS, src.ref.Name)
+		if rerr != nil || raw == nil {
+			sourceVals[src.id] = dsp.Scalar(0)
+			continue
+		}
+		sourceVals[src.id] = toSample(raw)
+	}
+	vals, evalErr := rg.evalSampleTrace(sourceVals)
+
+	opType := make(map[string]string, len(rg.order))
+	for _, n := range rg.order {
+		if n.kind == "op" && n.op != nil {
+			opType[n.id] = n.op.Type()
+		}
+	}
+	res := TraceResult{Nodes: make(map[string]TraceNode, len(vals))}
+	for id, sample := range vals {
+		tn := TraceNode{Value: sample.AsAny(), Type: "scalar"}
+		if sample.IsArray {
+			tn.Type = "array"
+		}
+		if ot, ok := opType[id]; ok && dsp.IsStateful(ot) {
+			tn.Approx = true
+		}
+		res.Nodes[id] = tn
+	}
+	if evalErr != nil {
+		res.Error = evalErr.Error()
+	}
+	return res, nil
+}
+
 // toSample coerces a datasource.Value.Data into a dsp.Sample: arrays become
 // array Samples (waveforms), everything else a scalar Sample.
 func toSample(v any) dsp.Sample {