refactor: unify tags and edges into single rels table

store/store.go

@@ -3,26 +3,25 @@ package store
 import "axolotl/models"
 
 // Store is a primitive graph persistence interface. It provides basic
-// operations for nodes, tags, and directed edges. No business logic lives here.
+// operations for nodes and directed rels. No business logic lives here.
+// "Tag" rels are rels with an empty toID (e.g. "_type::issue" or "backend").
 type Store interface {
 	// Nodes
 	AddNode(id, title, content, dueDate, createdAt, updatedAt string) error
-	GetNode(id string) (*models.Node, error) // returns node with tags and edges populated
+	GetNode(id string) (*models.Node, error) // returns node with tags and rels populated
 	UpdateNode(id, title, content, dueDate, updatedAt string) error // empty dueDate stores NULL
 	DeleteNode(id string) error
 	NodeExists(id string) (bool, error)
 	GenerateID() (string, error) // returns a random 5-char ID guaranteed unique in the store
 
-	// Tags
-	AddTag(nodeID, tag string) error
-	RemoveTag(nodeID, tag string) error
+	// Rels: relName is the relation name; toID is empty for "tag" rels (properties/labels).
+	AddRel(nodeID, relName, toID string) error
+	RemoveRel(nodeID, relName, toID string) error
 
-	// Edges (directed, typed)
-	AddEdge(fromID, toID string, relType models.RelType) error
-	RemoveEdge(fromID, toID string, relType models.RelType) error
-
-	// Query returns fully-populated nodes matching all given tag prefixes and edge filters.
-	FindNodes(tagPrefixes []string, edgeFilters []*models.Rel) ([]*models.Node, error)
+	// FindNodes returns fully-populated nodes matching all given filters.
+	// Filters with empty Target match nodes by rel_name prefix with empty toID (tag/property).
+	// Filters with non-empty Target match nodes by exact rel_name and toID (edge).
+	FindNodes(filters []*models.Rel) ([]*models.Node, error)
 
 	// Transaction runs fn inside an atomic transaction. If fn returns an error
 	// the transaction is rolled back; otherwise it is committed.