Phase 1: Edge schema consolidation infrastructure (Decision 004)

Add metadata and thread_id columns to dependencies table to support:
- Edge metadata: JSON blob for type-specific data (similarity scores, etc.)
- Thread queries: O(1) conversation threading via thread_id

Changes:
- New migration 020_edge_consolidation.go
- Updated Dependency struct with Metadata and ThreadID fields
- Added new entity types: authored-by, assigned-to, approved-by
- Relaxed DependencyType validation (any non-empty string ≤50 chars)
- Added IsWellKnown() and AffectsReadyWork() methods
- Updated SQL queries to include new columns
- Updated tests for new behavior

This enables HOP knowledge graph requirements and Reddit-style threading.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

internal/storage/sqlite/dependencies.go

@@ -21,7 +21,7 @@ const (
 func (s *SQLiteStorage) AddDependency(ctx context.Context, dep *types.Dependency, actor string) error {
 	// Validate dependency type
 	if !dep.Type.IsValid() {
-		return fmt.Errorf("invalid dependency type: %s (must be blocks, related, parent-child, or discovered-from)", dep.Type)
+		return fmt.Errorf("invalid dependency type: %q (must be non-empty string, max 50 chars)", dep.Type)
 	}
 
 	// Validate that both issues exist
@@ -125,11 +125,11 @@ func (s *SQLiteStorage) AddDependency(ctx context.Context, dep *types.Dependency
 			dep.IssueID, dep.DependsOnID, dep.IssueID)
 	}
 
-	// Insert dependency
+	// Insert dependency (including metadata and thread_id for edge consolidation - Decision 004)
 	_, err = tx.ExecContext(ctx, `
-		INSERT INTO dependencies (issue_id, depends_on_id, type, created_at, created_by)
-		VALUES (?, ?, ?, ?, ?)
-	`, dep.IssueID, dep.DependsOnID, dep.Type, dep.CreatedAt, dep.CreatedBy)
+		INSERT INTO dependencies (issue_id, depends_on_id, type, created_at, created_by, metadata, thread_id)
+		VALUES (?, ?, ?, ?, ?, ?, ?)
+	`, dep.IssueID, dep.DependsOnID, dep.Type, dep.CreatedAt, dep.CreatedBy, dep.Metadata, dep.ThreadID)
 	if err != nil {
 		return fmt.Errorf("failed to add dependency: %w", err)
 	}
@@ -151,8 +151,8 @@ func (s *SQLiteStorage) AddDependency(ctx context.Context, dep *types.Dependency
 		}
 
 		// Invalidate blocked issues cache since dependencies changed (bd-5qim)
-		// Only invalidate for 'blocks' and 'parent-child' types since they affect blocking
-		if dep.Type == types.DepBlocks || dep.Type == types.DepParentChild {
+		// Only invalidate for types that affect ready work calculation
+		if dep.Type.AffectsReadyWork() {
 			if err := s.invalidateBlockedCache(ctx, tx); err != nil {
 				return fmt.Errorf("failed to invalidate blocked cache: %w", err)
 			}
@@ -174,7 +174,7 @@ func (s *SQLiteStorage) RemoveDependency(ctx context.Context, issueID, dependsOn
 		// Store whether cache needs invalidation before deletion
 		needsCacheInvalidation := false
 		if err == nil {
-			needsCacheInvalidation = (depType == types.DepBlocks || depType == types.DepParentChild)
+			needsCacheInvalidation = depType.AffectsReadyWork()
 		}
 
 		result, err := tx.ExecContext(ctx, `
@@ -369,7 +369,8 @@ func (s *SQLiteStorage) GetDependencyCounts(ctx context.Context, issueIDs []stri
 // GetDependencyRecords returns raw dependency records for an issue
 func (s *SQLiteStorage) GetDependencyRecords(ctx context.Context, issueID string) ([]*types.Dependency, error) {
 	rows, err := s.db.QueryContext(ctx, `
-		SELECT issue_id, depends_on_id, type, created_at, created_by
+		SELECT issue_id, depends_on_id, type, created_at, created_by,
+		       COALESCE(metadata, '{}') as metadata, COALESCE(thread_id, '') as thread_id
 		FROM dependencies
 		WHERE issue_id = ?
 		ORDER BY created_at ASC
@@ -388,6 +389,8 @@ func (s *SQLiteStorage) GetDependencyRecords(ctx context.Context, issueID string
 			&dep.Type,
 			&dep.CreatedAt,
 			&dep.CreatedBy,
+			&dep.Metadata,
+			&dep.ThreadID,
 		)
 		if err != nil {
 			return nil, fmt.Errorf("failed to scan dependency: %w", err)
@@ -402,7 +405,8 @@ func (s *SQLiteStorage) GetDependencyRecords(ctx context.Context, issueID string
 // This is optimized for bulk export operations to avoid N+1 queries
 func (s *SQLiteStorage) GetAllDependencyRecords(ctx context.Context) (map[string][]*types.Dependency, error) {
 	rows, err := s.db.QueryContext(ctx, `
-		SELECT issue_id, depends_on_id, type, created_at, created_by
+		SELECT issue_id, depends_on_id, type, created_at, created_by,
+		       COALESCE(metadata, '{}') as metadata, COALESCE(thread_id, '') as thread_id
 		FROM dependencies
 		ORDER BY issue_id, created_at ASC
 	`)
@@ -421,6 +425,8 @@ func (s *SQLiteStorage) GetAllDependencyRecords(ctx context.Context) (map[string
 			&dep.Type,
 			&dep.CreatedAt,
 			&dep.CreatedBy,
+			&dep.Metadata,
+			&dep.ThreadID,
 		)
 		if err != nil {
 			return nil, fmt.Errorf("failed to scan dependency: %w", err)

internal/storage/sqlite/migrations.go

@@ -36,6 +36,7 @@ var migrationsList = []Migration{
 	{"close_reason_column", migrations.MigrateCloseReasonColumn},
 	{"tombstone_columns", migrations.MigrateTombstoneColumns},
 	{"messaging_fields", migrations.MigrateMessagingFields},
+	{"edge_consolidation", migrations.MigrateEdgeConsolidation},
 }
 
 // MigrationInfo contains metadata about a migration for inspection
@@ -79,6 +80,7 @@ func getMigrationDescription(name string) string {
 		"close_reason_column":          "Adds close_reason column to issues table for storing closure explanations (bd-uyu)",
 		"tombstone_columns":            "Adds tombstone columns (deleted_at, deleted_by, delete_reason, original_type) for inline soft-delete (bd-vw8)",
 		"messaging_fields":             "Adds messaging fields (sender, ephemeral, replies_to, relates_to, duplicate_of, superseded_by) for inter-agent communication (bd-kwro)",
+		"edge_consolidation":           "Adds metadata and thread_id columns to dependencies table for edge schema consolidation (Decision 004)",
 	}
 	
 	if desc, ok := descriptions[name]; ok {

internal/storage/sqlite/migrations/020_edge_consolidation.go

@@ -0,0 +1,60 @@
+package migrations
+
+import (
+	"database/sql"
+	"fmt"
+)
+
+// MigrateEdgeConsolidation adds metadata and thread_id columns to the dependencies table.
+// This is Phase 1 of the Edge Schema Consolidation (Decision 004):
+// - metadata: JSON blob for type-specific edge data (similarity scores, reasons, etc.)
+// - thread_id: For efficient conversation threading queries
+//
+// These columns enable:
+// - Edge metadata without schema changes (extensibility)
+// - O(1) thread queries for Reddit-style conversations
+// - HOP knowledge graph foundation
+func MigrateEdgeConsolidation(db *sql.DB) error {
+	columns := []struct {
+		name       string
+		definition string
+	}{
+		{"metadata", "TEXT DEFAULT '{}'"},
+		{"thread_id", "TEXT DEFAULT ''"},
+	}
+
+	for _, col := range columns {
+		var columnExists bool
+		err := db.QueryRow(`
+			SELECT COUNT(*) > 0
+			FROM pragma_table_info('dependencies')
+			WHERE name = ?
+		`, col.name).Scan(&columnExists)
+		if err != nil {
+			return fmt.Errorf("failed to check %s column: %w", col.name, err)
+		}
+
+		if columnExists {
+			continue
+		}
+
+		_, err = db.Exec(fmt.Sprintf(`ALTER TABLE dependencies ADD COLUMN %s %s`, col.name, col.definition))
+		if err != nil {
+			return fmt.Errorf("failed to add %s column: %w", col.name, err)
+		}
+	}
+
+	// Add index for thread queries - only index non-empty thread_ids
+	_, err := db.Exec(`CREATE INDEX IF NOT EXISTS idx_dependencies_thread ON dependencies(thread_id) WHERE thread_id != ''`)
+	if err != nil {
+		return fmt.Errorf("failed to create thread_id index: %w", err)
+	}
+
+	// Add composite index for finding all edges in a thread by type
+	_, err = db.Exec(`CREATE INDEX IF NOT EXISTS idx_dependencies_thread_type ON dependencies(thread_id, type) WHERE thread_id != ''`)
+	if err != nil {
+		return fmt.Errorf("failed to create thread_type index: %w", err)
+	}
+
+	return nil
+}

internal/storage/sqlite/schema.go

@@ -43,13 +43,15 @@ CREATE INDEX IF NOT EXISTS idx_issues_assignee ON issues(assignee);
 CREATE INDEX IF NOT EXISTS idx_issues_created_at ON issues(created_at);
 -- Note: idx_issues_external_ref is created in migrations/002_external_ref_column.go
 
--- Dependencies table
+-- Dependencies table (edge schema - Decision 004)
 CREATE TABLE IF NOT EXISTS dependencies (
     issue_id TEXT NOT NULL,
     depends_on_id TEXT NOT NULL,
     type TEXT NOT NULL DEFAULT 'blocks',
     created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
     created_by TEXT NOT NULL,
+    metadata TEXT DEFAULT '{}',    -- JSON blob for type-specific edge data
+    thread_id TEXT DEFAULT '',     -- For efficient conversation threading queries
     PRIMARY KEY (issue_id, depends_on_id),
     FOREIGN KEY (issue_id) REFERENCES issues(id) ON DELETE CASCADE,
     FOREIGN KEY (depends_on_id) REFERENCES issues(id) ON DELETE CASCADE
@@ -59,6 +61,8 @@ CREATE INDEX IF NOT EXISTS idx_dependencies_issue ON dependencies(issue_id);
 CREATE INDEX IF NOT EXISTS idx_dependencies_depends_on ON dependencies(depends_on_id);
 CREATE INDEX IF NOT EXISTS idx_dependencies_depends_on_type ON dependencies(depends_on_id, type);
 CREATE INDEX IF NOT EXISTS idx_dependencies_depends_on_type_issue ON dependencies(depends_on_id, type, issue_id);
+CREATE INDEX IF NOT EXISTS idx_dependencies_thread ON dependencies(thread_id) WHERE thread_id != '';
+CREATE INDEX IF NOT EXISTS idx_dependencies_thread_type ON dependencies(thread_id, type) WHERE thread_id != '';
 
 -- Labels table
 CREATE TABLE IF NOT EXISTS labels (