feat(graph): add core graph types

Add Node, Edge, and Graph types for the graph database:

- Node: entity with ID, Type, Label, and extensible Attrs map
- Edge: relationship with From, To, Type, Confidence, and score
- Graph: in-memory collection with CRUD operations
- Confidence enum: EXTRACTED, INFERRED, AMBIGUOUS
- Type constants for common node and edge types

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: grokify

pkg/graph/edge.go

@@ -0,0 +1,53 @@
+// Package graph provides core types for the GraphFS graph database.
+package graph
+
+// Edge represents a relationship between two nodes.
+type Edge struct {
+	// From is the source node ID.
+	From string `json:"from"`
+
+	// To is the target node ID.
+	To string `json:"to"`
+
+	// Type categorizes the relationship (e.g., "calls", "imports", "implements").
+	Type string `json:"type"`
+
+	// Confidence indicates how the edge was determined.
+	Confidence Confidence `json:"confidence"`
+
+	// ConfidenceScore is a 0.0-1.0 score for INFERRED edges.
+	// Only meaningful when Confidence is ConfidenceInferred.
+	ConfidenceScore float64 `json:"confidence_score,omitempty"`
+
+	// Attrs holds additional attributes as key-value pairs.
+	Attrs map[string]string `json:"attrs,omitempty"`
+}
+
+// Confidence indicates how an edge relationship was determined.
+type Confidence string
+
+const (
+	// ConfidenceExtracted means the edge was directly extracted from source
+	// (e.g., import statement, function call in AST).
+	ConfidenceExtracted Confidence = "EXTRACTED"
+
+	// ConfidenceInferred means the edge was inferred by an LLM or heuristic,
+	// with an associated confidence score.
+	ConfidenceInferred Confidence = "INFERRED"
+
+	// ConfidenceAmbiguous means the relationship is uncertain and should be
+	// reviewed by a human.
+	ConfidenceAmbiguous Confidence = "AMBIGUOUS"
+)
+
+// EdgeType constants for common relationship types.
+const (
+	EdgeTypeCalls      = "calls"
+	EdgeTypeImports    = "imports"
+	EdgeTypeImplements = "implements"
+	EdgeTypeExtends    = "extends"
+	EdgeTypeUses       = "uses"
+	EdgeTypeContains   = "contains"
+	EdgeTypeDependsOn  = "depends_on"
+	EdgeTypeReferences = "references"
+)

pkg/graph/graph.go

@@ -0,0 +1,45 @@
+// Package graph provides core types for the GraphFS graph database.
+package graph
+
+// Graph represents a complete graph with nodes and edges.
+type Graph struct {
+	// Nodes maps node ID to Node.
+	Nodes map[string]*Node `json:"nodes"`
+
+	// Edges holds all edges in the graph.
+	Edges []*Edge `json:"edges"`
+}
+
+// NewGraph creates an empty graph.
+func NewGraph() *Graph {
+	return &Graph{
+		Nodes: make(map[string]*Node),
+		Edges: make([]*Edge, 0),
+	}
+}
+
+// AddNode adds a node to the graph. If a node with the same ID exists,
+// it will be overwritten.
+func (g *Graph) AddNode(n *Node) {
+	g.Nodes[n.ID] = n
+}
+
+// AddEdge adds an edge to the graph.
+func (g *Graph) AddEdge(e *Edge) {
+	g.Edges = append(g.Edges, e)
+}
+
+// GetNode returns a node by ID, or nil if not found.
+func (g *Graph) GetNode(id string) *Node {
+	return g.Nodes[id]
+}
+
+// NodeCount returns the number of nodes in the graph.
+func (g *Graph) NodeCount() int {
+	return len(g.Nodes)
+}
+
+// EdgeCount returns the number of edges in the graph.
+func (g *Graph) EdgeCount() int {
+	return len(g.Edges)
+}

pkg/graph/node.go

@@ -0,0 +1,32 @@
+// Package graph provides core types for the GraphFS graph database.
+package graph
+
+// Node represents an entity in the graph.
+type Node struct {
+	// ID is the unique, stable identifier for this node.
+	// Should be deterministic (e.g., based on content hash or path+symbol).
+	ID string `json:"id"`
+
+	// Type categorizes the node (e.g., "function", "file", "class", "module").
+	Type string `json:"type"`
+
+	// Label is a human-readable name for display.
+	Label string `json:"label,omitempty"`
+
+	// Attrs holds additional attributes as key-value pairs.
+	Attrs map[string]string `json:"attrs,omitempty"`
+}
+
+// NodeType constants for common node types.
+const (
+	NodeTypeFunction = "function"
+	NodeTypeMethod   = "method"
+	NodeTypeClass    = "class"
+	NodeTypeStruct   = "struct"
+	NodeTypeFile     = "file"
+	NodeTypePackage  = "package"
+	NodeTypeModule   = "module"
+	NodeTypeVariable = "variable"
+	NodeTypeConstant = "constant"
+	NodeTypeInterface = "interface"
+)