0.29.0 — code-quality refactor (plan E1–E5): file splits, sqlc migration, SSH unification, test coverage

E1: split monolithic files — cmd/nomos (main.go → server.go + mcp.go + workers.go),
    internal/mcp/tools.go → entity_tools/ops_tools/knowledge_tools/analysis_tools,
    internal/httpapi/impl.go → domain files (entities, events, signals, ontology,
    fleet_health, client_context, client_lifecycle, entity_mutations, query_audit).
E2: migrate raw pool.Exec queries to sqlc (entities/relationships queries + generated).
E3: unify SSH — consolidate crypto/ssh dial into actuator/client.go (+client_test).
E4/E5: add tests — db/lifecycle, checkdefaults/build, ontology/preconditions, policy/risk.

internal/db/sqlcgen/relationships.sql.go

@@ -31,6 +31,42 @@ func (q *Queries) EndCurrentRelationship(ctx context.Context, arg EndCurrentRela
 	return result.RowsAffected(), nil
 }
 
+const insertRelationshipIfAbsent = `-- name: InsertRelationshipIfAbsent :execrows
+INSERT INTO relationships (source_id, target_id, type, attributes, valid_from)
+SELECT $1, $2, $3,
+       $4::jsonb, now()
+WHERE NOT EXISTS (
+    SELECT 1 FROM relationships
+    WHERE source_id = $1
+      AND target_id = $2
+      AND type = $3
+      AND valid_to IS NULL
+)
+`
+
+type InsertRelationshipIfAbsentParams struct {
+	SourceID   uuid.UUID
+	TargetID   uuid.UUID
+	Type       string
+	Attributes []byte
+}
+
+// Idempotent relationship insert (the create_relationship surface): no-op if
+// an active edge of the same source/target/type already exists. Replaces the
+// raw INSERT...WHERE NOT EXISTS used in entity_tools.go.
+func (q *Queries) InsertRelationshipIfAbsent(ctx context.Context, arg InsertRelationshipIfAbsentParams) (int64, error) {
+	result, err := q.db.Exec(ctx, insertRelationshipIfAbsent,
+		arg.SourceID,
+		arg.TargetID,
+		arg.Type,
+		arg.Attributes,
+	)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected(), nil
+}
+
 const listEntityRelations = `-- name: ListEntityRelations :many
 SELECT se.slug AS source_slug, te.slug AS target_slug, r.type, r.attributes,
        r.valid_from, r.valid_to