Improving all side of app

internal/datasource/synthetic/definition.go

@@ -9,6 +9,7 @@ type SignalDef struct {
 	Signal   string        `json:"signal"`  // upstream signal name (or "" for constant)
 	Inputs   []InputRef    `json:"inputs"`  // alternative multi-input format
 	Pipeline []NodeDef     `json:"pipeline"` // ordered list of DSP nodes
+	Graph    *Graph        `json:"graph,omitempty"` // DAG form (preferred when present)
 	Meta     MetaOverride  `json:"meta"`    // optional metadata overrides
 
 	// Visibility controls who sees this signal in the signal tree:
@@ -34,6 +35,37 @@ type NodeDef struct {
 	Params map[string]any `json:"params,omitempty"`
 }
 
+// Graph is the DAG form of a synthetic signal: a set of nodes (sources, ops and
+// one output) wired together by explicit per-node ordered input lists. It
+// supersedes the linear Inputs+Pipeline form: when SignalDef.Graph is set it is
+// authoritative; otherwise the legacy linear fields are converted into an
+// equivalent graph at load time (see toGraph).
+type Graph struct {
+	Nodes  []GraphNode `json:"nodes"`
+	Output string      `json:"output"` // id of the output node
+}
+
+// GraphNode is one node in a Graph.
+//
+//	kind=="source": carries DS+Signal; has no Inputs (a graph root).
+//	kind=="op":     carries Op + Params; Inputs lists upstream node IDs in the
+//	                order the op receives them (input 0, 1, … e.g. a−b, a÷b).
+//	kind=="output": Inputs has a single upstream node whose value is the result.
+//
+// X/Y are the editor layout coordinates, persisted so a reloaded graph keeps its
+// shape; they have no effect on evaluation.
+type GraphNode struct {
+	ID     string         `json:"id"`
+	Kind   string         `json:"kind"`
+	Op     string         `json:"op,omitempty"`
+	Params map[string]any `json:"params,omitempty"`
+	DS     string         `json:"ds,omitempty"`
+	Signal string         `json:"signal,omitempty"`
+	Inputs []string       `json:"inputs,omitempty"`
+	X      float64        `json:"x,omitempty"`
+	Y      float64        `json:"y,omitempty"`
+}
+
 // MetaOverride allows the synthetic signal to override display metadata.
 type MetaOverride struct {
 	Unit        string  `json:"unit,omitempty"`