diff --git a/src/action/handlers/create-cross-association.js b/src/action/handlers/create-cross-association.js
index 8862c93..17ef5f4 100644
--- a/src/action/handlers/create-cross-association.js
+++ b/src/action/handlers/create-cross-association.js
@@ -1,17 +1,19 @@
 import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
+import Association from 'model/entities/Association';
+
 import getIdea from 'action/utils/get-idea';
 import patchRootPaths from 'action/utils/patch-root-paths';
 import normalizePatch from 'action/utils/normalize-patch';
 import weighAssociation from 'model/utils/weigh-association';
 
-import Association from 'model/entities/Association';
-
 /**
  * Creates association between two existing ideas
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.headIdeaId
  * @param {string} data.tailIdeaId
diff --git a/src/action/handlers/create-idea.js b/src/action/handlers/create-idea.js
index 84af1a9..ea6bce9 100644
--- a/src/action/handlers/create-idea.js
+++ b/src/action/handlers/create-idea.js
@@ -1,6 +1,8 @@
 import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import isValidPathWeight from 'utils/graph/is-valid-path-weight';
 
 import getIdea from 'action/utils/get-idea';
@@ -13,9 +15,9 @@ import Point from 'model/entities/Point';
 /**
  * Creates idea
  *
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
- * @param {string} [data.parentIdeaId]
+ * @param {string} data.parentIdeaId
  * @return {Patch}
  */
 export default function createIdea(state, data) {
diff --git a/src/action/handlers/init.js b/src/action/handlers/init.js
index 3847da6..938427a 100644
--- a/src/action/handlers/init.js
+++ b/src/action/handlers/init.js
@@ -9,6 +9,8 @@ import Mindmap from 'model/entities/Mindmap';
 import Idea from 'model/entities/Idea';
 import Point from 'model/entities/Point';
 
+import StateType from 'boot/client/State';
+
 import MainVM from 'vm/main/Main';
 import MindmapVM from 'vm/main/Mindmap';
 
@@ -21,7 +23,7 @@ import toGraph from 'vm/map/mappers/mindmap-to-graph';
 /**
  * Inits state
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @return {Promise.<Patch>}
  */
diff --git a/src/action/handlers/remove-association.js b/src/action/handlers/remove-association.js
index 4d309bd..d22ecb9 100644
--- a/src/action/handlers/remove-association.js
+++ b/src/action/handlers/remove-association.js
@@ -1,6 +1,8 @@
 import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import withoutItem from 'utils/get-array-without-item';
 import patchRootPaths from 'action/utils/patch-root-paths';
 import normalizePatch from 'action/utils/normalize-patch';
@@ -9,7 +11,7 @@ import getAssociation from 'action/utils/get-association';
 /**
  * Removes association
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.assocId
  * @return {Patch}
diff --git a/src/action/handlers/remove-idea.js b/src/action/handlers/remove-idea.js
index 7a73976..38992f0 100644
--- a/src/action/handlers/remove-idea.js
+++ b/src/action/handlers/remove-idea.js
@@ -1,6 +1,8 @@
 import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import withoutItem from 'utils/get-array-without-item';
 import normalizePatch from 'action/utils/normalize-patch';
 import getIdea from 'action/utils/get-idea';
@@ -8,7 +10,7 @@ import getIdea from 'action/utils/get-idea';
 /**
  * Removes idea with corresponding associations
  *
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {object} data.ideaId
  * @return {Patch}
diff --git a/src/action/handlers/set-association-value.js b/src/action/handlers/set-association-value.js
index 0f70271..8a1a45c 100644
--- a/src/action/handlers/set-association-value.js
+++ b/src/action/handlers/set-association-value.js
@@ -1,12 +1,14 @@
 import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import getAssociation from 'action/utils/get-association';
 
 /**
  * Sets association value
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.assocId
  * @param {string} data.value
diff --git a/src/action/handlers/set-idea-color.js b/src/action/handlers/set-idea-color.js
index 0fdb042..f39fdf2 100644
--- a/src/action/handlers/set-idea-color.js
+++ b/src/action/handlers/set-idea-color.js
@@ -1,12 +1,14 @@
 import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import getIdea from 'action/utils/get-idea';
 
 /**
  * Sets idea color
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.ideaId
  * @param {string} data.color
diff --git a/src/action/handlers/set-idea-position.js b/src/action/handlers/set-idea-position.js
index bef4f60..44ea80b 100644
--- a/src/action/handlers/set-idea-position.js
+++ b/src/action/handlers/set-idea-position.js
@@ -1,6 +1,10 @@
 import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
+import PointType from 'model/entities/Point';
+
 import getDescendants from 'utils/graph/get-descendants';
 import weighAssociation from 'model/utils/weigh-association';
 import isValidPosition from 'model/utils/is-valid-position';
@@ -11,10 +15,10 @@ import getIdea from 'action/utils/get-idea';
 /**
  * Sets position of idea and its child-subtree
  * 
- * @param {object} state
- * @param {object} data
- * @param {string} data.ideaId
- * @param {Point}  data.pos
+ * @param {StateType} state
+ * @param {object}    data
+ * @param {string}    data.ideaId
+ * @param {PointType} data.posAbs
  * @return {Patch|undefined}
  */
 export default function setIdeaPosition(state, data) {
diff --git a/src/action/handlers/set-idea-value.js b/src/action/handlers/set-idea-value.js
index 90e2139..082b737 100644
--- a/src/action/handlers/set-idea-value.js
+++ b/src/action/handlers/set-idea-value.js
@@ -1,12 +1,14 @@
 import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import getIdea from 'action/utils/get-idea';
 
 /**
  * Sets value for idea
  *
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.ideaId
  * @param {string} data.value
diff --git a/src/action/handlers/set-mindmap-position.js b/src/action/handlers/set-mindmap-position.js
index e470bda..dfe8f1b 100644
--- a/src/action/handlers/set-mindmap-position.js
+++ b/src/action/handlers/set-mindmap-position.js
@@ -1,13 +1,17 @@
 import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
+import PointType from 'model/entities/Point';
+
 /**
  * Sets mindmap position
  * 
- * @param {object} state
- * @param {object} data
- * @param {string} data.mindmapId
- * @param {Point}  data.pos - new position of viewbox on canvas
+ * @param {StateType} state
+ * @param {object}     data
+ * @param {string}     data.mindmapId
+ * @param {PointType}  data.pos - new position of viewbox on canvas
  * @return {Patch}
  */
 export default function setMindmapPosition(state, data) {
diff --git a/src/action/handlers/set-mindmap-scale.js b/src/action/handlers/set-mindmap-scale.js
index 2605443..61be86b 100644
--- a/src/action/handlers/set-mindmap-scale.js
+++ b/src/action/handlers/set-mindmap-scale.js
@@ -1,14 +1,18 @@
 import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
+import PointType from 'model/entities/Point';
+
 /**
  * Sets mindmap scale
  * 
- * @param {object} state
- * @param {object} data
- * @param {string} data.mindmapId
- * @param {number} data.scale - target scale
- * @param {Point}  data.pos - new position of viewbox on canvas
+ * @param {StateType} state
+ * @param {object}    data
+ * @param {string}    data.mindmapId
+ * @param {number}    data.scale - target scale
+ * @param {PointType} data.pos - new position of viewbox on canvas
  * @return {Patch}
  */
 export default function setMindmapScale(state, data) {
diff --git a/src/action/utils/search-ideas.js b/src/action/utils/search-ideas.js
index a3f3021..f09d567 100644
--- a/src/action/utils/search-ideas.js
+++ b/src/action/utils/search-ideas.js
@@ -1,4 +1,3 @@
-import required from 'utils/required-params';
 import values from 'utils/get-map-values';
 
 import IdeaType from 'model/entities/Idea';
@@ -13,8 +12,7 @@ import MindmapType from 'model/entities/Mindmap';
  * @return {Array.<IdeaType>}
  */
 export default function searchIdeas(mindmap, opts) {
-    const {phrase} = required(opts);
-    const {excludeIds} = opts;
+    const {phrase, excludeIds} = opts;
     
     if (!phrase) {
         throw Error('Search string is empty');
diff --git a/src/boot/client/initial-state.js b/src/boot/client/State.js
similarity index 59%
rename from src/boot/client/initial-state.js
rename to src/boot/client/State.js
index fea6f7b..1a64496 100644
--- a/src/boot/client/initial-state.js
+++ b/src/boot/client/State.js
@@ -1,11 +1,12 @@
-// @ts-nocheck
+import MindmapType from 'model/entities/Mindmap';
+import MainVMType from 'vm/main/Main';
 
 /**
  * Application state structure
  */
-export default {
+export default class State {
 
-    data: {
+    data = {
 
         /** @type {PouchDB.Database} */
         ideas: undefined,
@@ -15,24 +16,24 @@ export default {
 
         /** @type {PouchDB.Database} */
         mindmaps: undefined
-    },
+    }
 
-    model: {
+    model = {
 
-        /** @type {Mindmap} */
+        /** @type {MindmapType} */
         mindmap: undefined
-    },
+    }
 
-    vm: {
+    vm = {
 
-        /** @type {Main} */
+        /** @type {MainVMType} */
         main: undefined
-    },
+    }
 
-    view: {
+    view = {
 
         /** @type {Element} */
         root: undefined
     }
 
-};
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/src/boot/client/client.js b/src/boot/client/client.js
index e4d4d82..39ddf55 100644
--- a/src/boot/client/client.js
+++ b/src/boot/client/client.js
@@ -5,7 +5,7 @@ import Handler from 'utils/state/Handler';
 
 import commonHandler from 'action/handler';
 import vmHandler from 'vm/action/handler';
-import initialState from './initial-state';
+import State from './State';
 import combine from 'utils/state/combine-mutators';
 
 import logger from 'utils/state/middlewares/logger';
@@ -44,7 +44,7 @@ async function start() {
             mutateVM,
             mutateView
         ]),
-        initialState,
+        new State(),
         middlewares);
 
     const storeDispatch = store.dispatch.bind(store);
diff --git a/src/data/mutators/index.js b/src/data/mutators/index.js
index a4875a2..19830fd 100644
--- a/src/data/mutators/index.js
+++ b/src/data/mutators/index.js
@@ -1,6 +1,8 @@
 import PatchType from 'utils/state/Patch';
 import MutationType from 'utils/state/Mutation';
 
+import StateType from 'boot/client/State';
+
 import AsyncTaskQueue from 'utils/AsyncTaskQueue';
 
 import * as ideaDB from '../db/ideas';
@@ -19,7 +21,7 @@ const _queue = new AsyncTaskQueue();
 
 /**
  * Applies patch to data state
- * @param {object} state
+ * @param {StateType} state
  * @param {PatchType} patch
  */
 export default async function mutate(state, patch) {
@@ -34,7 +36,7 @@ export default async function mutate(state, patch) {
 
 /**
  * Applies single mutation to state
- * @param {object} state
+ * @param {StateType} state
  * @param {MutationType} mutation
  */
 async function apply(state, mutation) {
diff --git a/src/model/mutators/add-association.js b/src/model/mutators/add-association.js
index 594bc50..23c7424 100644
--- a/src/model/mutators/add-association.js
+++ b/src/model/mutators/add-association.js
@@ -1,11 +1,15 @@
 import required from 'utils/required-params';
 
+import StateType from 'boot/client/State';
+
+import AssociationType from 'model/entities/Association';
+
 /**
  * Adds association
  * 
- * @param {object}      state 
- * @param {object}      data
- * @param {Association} data.assoc
+ * @param {StateType} state 
+ * @param {object}          data
+ * @param {AssociationType} data.assoc
  */
 export default function addAssociation(state, data) {
     const {model: {mindmap}} = state;
diff --git a/src/model/mutators/add-idea.js b/src/model/mutators/add-idea.js
index c02d15f..c457ff1 100644
--- a/src/model/mutators/add-idea.js
+++ b/src/model/mutators/add-idea.js
@@ -1,11 +1,15 @@
 import required from 'utils/required-params';
 
+import StateType from 'boot/client/State';
+
+import IdeaType from 'model/entities/Idea';
+
 /**
  * Adds idea
  * 
- * @param {object} state 
- * @param {object} data
- * @param {Idea}   data.idea
+ * @param {StateType} state 
+ * @param {object}   data
+ * @param {IdeaType} data.idea
  */
 export default function addIdea(state, data) {
     const {model: {mindmap}} = state;
diff --git a/src/model/mutators/index.js b/src/model/mutators/index.js
index aaaec39..515b5d7 100644
--- a/src/model/mutators/index.js
+++ b/src/model/mutators/index.js
@@ -1,6 +1,8 @@
 import regMutatorsFolder from 'utils/reg-mutators-folder';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 // eslint-disable-next-line no-undef
 const context = require.context('.', true, /\.js$/);
 const mutators = regMutatorsFolder(context);
@@ -8,7 +10,7 @@ const mutators = regMutatorsFolder(context);
 /**
  * Applies patch to model state
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {PatchType} patch
  */
 export default function mutate(state, patch) {
diff --git a/src/model/mutators/init.js b/src/model/mutators/init.js
index 82a9ae6..0c11c65 100644
--- a/src/model/mutators/init.js
+++ b/src/model/mutators/init.js
@@ -1,13 +1,13 @@
 import required from 'utils/required-params';
 
+import StateType from 'boot/client/State';
+
 /**
  * Inits model state
  * 
- * @param {object}  state 
- * @param {object}  data 
- * @param {PouchDB.Database} data.ideas
- * @param {PouchDB.Database} data.associations
- * @param {PouchDB.Database} data.mindmaps
+ * @param {StateType} state 
+ * @param {object} data 
+ * @param {object} data.model
  */
 export default function init(state, data) {
     const {model} = state;
diff --git a/src/model/mutators/remove-association.js b/src/model/mutators/remove-association.js
index dc28a8e..30ef91f 100644
--- a/src/model/mutators/remove-association.js
+++ b/src/model/mutators/remove-association.js
@@ -1,9 +1,11 @@
 import required from 'utils/required-params';
 
+import StateType from 'boot/client/State';
+
 /**
  * Removes association
  * 
- * @param {object} state 
+ * @param {StateType} state 
  * @param {object} data
  * @param {string} data.id
  */
diff --git a/src/model/mutators/remove-idea.js b/src/model/mutators/remove-idea.js
index 8bc0daf..d9f226f 100644
--- a/src/model/mutators/remove-idea.js
+++ b/src/model/mutators/remove-idea.js
@@ -1,9 +1,11 @@
 import required from 'utils/required-params';
 
+import StateType from 'boot/client/State';
+
 /**
  * Removes idea
  * 
- * @param {object} state 
+ * @param {StateType} state 
  * @param {object} data
  * @param {string} data.id
  */
diff --git a/src/model/mutators/update-association.js b/src/model/mutators/update-association.js
index b9efb26..1a86c53 100644
--- a/src/model/mutators/update-association.js
+++ b/src/model/mutators/update-association.js
@@ -1,9 +1,11 @@
 import update from 'utils/update-object';
 
+import StateType from 'boot/client/State';
+
 /**
  * Updates association
  * 
- * @param {object} state 
+ * @param {StateType} state 
  * @param {object} data
  */
 export default function updateAssociation(state, data) {
diff --git a/src/model/mutators/update-idea.js b/src/model/mutators/update-idea.js
index 3b9acd1..34bc976 100644
--- a/src/model/mutators/update-idea.js
+++ b/src/model/mutators/update-idea.js
@@ -1,9 +1,11 @@
 import update from 'utils/update-object';
 
+import StateType from 'boot/client/State';
+
 /**
  * Updates idea
  * 
- * @param {object} state 
+ * @param {StateType} state 
  * @param {object} data
  */
 export default function updateIdea(state, data) {
diff --git a/src/model/mutators/update-mindmap.js b/src/model/mutators/update-mindmap.js
index 2d19bfa..31d9880 100644
--- a/src/model/mutators/update-mindmap.js
+++ b/src/model/mutators/update-mindmap.js
@@ -1,9 +1,11 @@
 import update from 'utils/update-object';
 
+import StateType from 'boot/client/State';
+
 /**
  * Updates mindmap
  * 
- * @param {object} state 
+ * @param {StateType} state 
  * @param {object} data
  */
 export default function updateMindmap(state, data) {
diff --git a/src/utils/graph/build-graph-from-matrix.js b/src/utils/graph/build-graph-from-matrix.js
index 654abc7..d553d83 100644
--- a/src/utils/graph/build-graph-from-matrix.js
+++ b/src/utils/graph/build-graph-from-matrix.js
@@ -1,23 +1,33 @@
-import required from 'utils/required-params';
 import isValidPathWeight from 'utils/graph//is-valid-path-weight';
 
+import IdeaType from 'model/entities/Idea';
+import AssocType from 'model/entities/Association';
+
+import NodeType from 'vm/map/entities/Node';
+import LinkType from 'vm/map/entities/Link';
+
 const charCodeA = 65;
 const charCount = 26;
 
+/**
+ * @typedef {{new(...args: any[]): IdeaType|NodeType}} VertexConstructorType
+ * @typedef {{new(...args: any[]): AssocType|LinkType}} EdgeConstructorType
+ */
+
 /**
  * Generic function for building object graph from adjacency matrix
  * 
  * Q: Why input matrix is array of strings and not array of number arrays?
  * A: Because it is possible to align columns without violating lint rules.
  * 
- * @param {object}         opts
- * @param {Array.<string>} opts.matrix
- * @param {function}       opts.VertexConstructor
- * @param {function}       opts.EdgeConstructor
+ * @param {object}                opts
+ * @param {Array.<string>}        opts.matrix
+ * @param {VertexConstructorType} opts.VertexConstructor
+ * @param {EdgeConstructorType}   opts.EdgeConstructor
  * @return {object} root vertex
  */
 export default function buildGraphFromMatrix(opts) {
-    const {matrix: m, VertexConstructor, EdgeConstructor} = required(opts);
+    const {matrix: m, VertexConstructor, EdgeConstructor} = opts;
 
     // validate input
     const vertexCount = m.length;
@@ -30,6 +40,7 @@ export default function buildGraphFromMatrix(opts) {
     const vertices = [];
     for (let i = 0; i < vertexCount; i++) {
         const id = String.fromCharCode(charCodeA + i);
+
         const vertex = new VertexConstructor({id});
         vertex.edgesIn = [];
         vertex.edgesOut = [];
diff --git a/src/utils/graph/build-graph-from-objects.js b/src/utils/graph/build-graph-from-objects.js
index 817b4e6..768e616 100644
--- a/src/utils/graph/build-graph-from-objects.js
+++ b/src/utils/graph/build-graph-from-objects.js
@@ -1,4 +1,3 @@
-import required from 'utils/required-params';
 import traverseGraph from 'utils/graph/traverse-graph';
 
 /**
@@ -12,7 +11,7 @@ import traverseGraph from 'utils/graph/traverse-graph';
  * @return {object} root vertex
  */
 export default function buildGraph(opts) {
-    const {vertices, edges, isRootVertex} = required(opts);
+    const {vertices, edges, isRootVertex} = opts;
 
     let rootVertex = null;
 
diff --git a/src/utils/graph/calc-root-paths.js b/src/utils/graph/calc-root-paths.js
index 3aa41ec..5184560 100644
--- a/src/utils/graph/calc-root-paths.js
+++ b/src/utils/graph/calc-root-paths.js
@@ -1,4 +1,3 @@
-import required from 'utils/required-params';
 import PriorityQueue from 'utils/PriorityQueue';
 import isValidPathWeight from 'utils/graph/is-valid-path-weight';
 
@@ -40,8 +39,8 @@ import isValidPathWeight from 'utils/graph/is-valid-path-weight';
  */
 export default function calcRootPaths(opts) {
 
-    const {root} = required(opts);
     const {
+        root,
         ignoreEdges = [],
         replaceEdgesOut = [],
         replaceEdgeWeights = []
diff --git a/src/utils/graph/map-graph.js b/src/utils/graph/map-graph.js
index 64448ed..7aa20e1 100644
--- a/src/utils/graph/map-graph.js
+++ b/src/utils/graph/map-graph.js
@@ -1,4 +1,3 @@
-import required from 'utils/required-params';
 import WeightZone from 'utils/graph/WeightZone';
 import isValidPathWeight from 'utils/graph/is-valid-path-weight';
 
@@ -93,7 +92,7 @@ export default function mapGraph(opts) {
  * @param {object} internalOpts
  * @param {Map}    internalOpts.visitedOriginalVertices 
  * @param {array}  internalOpts.allVertices 
- * @param {array}  internalOpts.allEdges 
+ * @param {array}  internalOpts.allEdges
  * @return {{rootVertex, vertices, edges}}
  */
 function mapGraphInternal(opts, internalOpts) {
@@ -104,13 +103,13 @@ function mapGraphInternal(opts, internalOpts) {
         mapEdge,
         focusZoneMax,
         shadeZoneAmount
-    } = required(opts);
+    } = opts;
 
     const {
         visitedOriginalVertices,
         allVertices,
         allEdges
-    } = required(internalOpts);
+    } = internalOpts;
 
     // check if vertex was already visited
     // to not fall into infinite loop in graph cycles
diff --git a/src/utils/graph/traverse-graph.js b/src/utils/graph/traverse-graph.js
index a3b7a4d..bcf0b52 100644
--- a/src/utils/graph/traverse-graph.js
+++ b/src/utils/graph/traverse-graph.js
@@ -1,5 +1,3 @@
-import required from 'utils/required-params';
-
 /**
  * Generic function for graph traversal
  * 
@@ -17,9 +15,12 @@ import required from 'utils/required-params';
  */
 export default function traverseGraph(opts) {
     
-    const {root, visit} = required(opts);
-    const alg = opts.alg || 'dfs-pre';
-    const isTree = opts.isTree || false;
+    const {
+        root,
+        visit,
+        alg = 'dfs-pre',
+        isTree = false
+    } = opts;
 
     switch (alg) {
     case 'dfs-pre':
diff --git a/src/utils/required-params.js b/src/utils/required-params.js
index 03b8968..a977817 100644
--- a/src/utils/required-params.js
+++ b/src/utils/required-params.js
@@ -1,29 +1,44 @@
 /**
- * Wraps parameters object into proxy which throws error
- * when someone tries to get param which does not exist
+ * Run-time checks for required function parameters
  * 
- * Why even need to check required params?
- * Prefer to throw ASAP. Need more confidence on arguments.
- * The language cannot currently afford that.
+ * NOTE: always prefer static type checks over run-time checks.
+ *       use as last resort in case static analisys is not possible.
  * 
- * Why not just throw error with simple asserts?
- * Too much noise. Looking for brevity.
+ * Current usecases:
+ * - Store action handlers (until #65 is fixed)
+ * - Store mutators
+ * - EventEmitter event handlers
  * 
- * Why not use Flow?
- * Because it does not support type annotations inside destructuring
- * https://github.com/facebook/flow/issues/235
+ * Q: Why not use static type check system (eg. Typescript or Flow)?
+ * A: 1. It is not always possible to use static analisys, eg.
+ *       a. you have a project which is not 100% type covered, and some of your
+ *          functions not called directly but through another generic function
+ *          which loose types info (eg. EventEmitter#emit)
+ *       b. you write a library and should not expect all of its users to use
+ *          static type check system.
  * 
- * Why not just throw error from default value getter?
- * like, function(requiredParam = req())
- * Because:
- * 1. It requires more space in param list, since added to each 
- *    required parameter
- * 2. It does not throw descriptive error with what param was 
- *    exactly missed (or need to pass param name into req function,
- *    which is #1 again)
+ *    2. Flow does not support type annotations inside destructuring,
+ *       which blocks passing params in 'option bag'-objects
+ *       https://github.com/facebook/flow/issues/235
  * 
- * BTW, all ways look nasty to me.
- * Using this one until native spec is arrived.
+ * Q: Why even need to check required params?
+ * A: Prefer to throw ASAP. Need more confidence on arguments.
+ *    The language cannot currently afford that natively.
+ * 
+ * Q: Why not just throw error with simple asserts?
+ * A: Too much noise. Looking for brevity.
+ * 
+ * Q: Why not just throw error from default value getter?
+ *    like, function(requiredParam = req())
+ * A: Because:
+ *    1. It requires more space in param list, since added to each
+ *       required parameter
+ *    2. It does not throw descriptive error with what param was 
+ *       exactly missed (or need to pass param name into req function,
+ *       which is #1 again)
+ * 
+ * BTW, all run-time param check options look nasty to me.
+ * But this one looks least nasty :)
  * 
  * @example required vs optional parameters
  * function(params) {
@@ -31,10 +46,9 @@
  *      const {optionalParam} = params;
  * }
  * 
- * TODO: try typedef generic function function(T): T
- * 
- * @param {object} params
- * @return {object}
+ * @template T
+ * @param {T} params
+ * @return {T}
  */
 export default function requiredParams(params) {
 
@@ -48,6 +62,7 @@ export default function requiredParams(params) {
         return params;
     }
     
+    // @ts-ignore
     return new Proxy(params, {
         get: function(target, name) {
             if (!(name in target)) {
diff --git a/src/utils/state/Handler.js b/src/utils/state/Handler.js
index a87ded4..e2cc847 100644
--- a/src/utils/state/Handler.js
+++ b/src/utils/state/Handler.js
@@ -1,6 +1,7 @@
-import required from 'utils/required-params';
 import Patch from './Patch';
 
+import ActionType from './Action';
+
 /**
  * Collection of registered action handlers
  * 
@@ -51,20 +52,21 @@ export default class Handler {
     [Symbol.iterator]() {
         return this._handlers[Symbol.iterator]();
     }
-    
+
     /**
      * Executes registered handler for an action
      * 
      * @param {object} state
      * @param {object} action
+     * @param {string} action.type
+     * @param {*}     [action.data]
      * @param {function} [dispatch]
      * @param {function} [mutate]
      * @return {Promise<Patch>|Patch} if handler is async - promise patch,
-     *                 if handler is sync - sync patch.
+     *                                if handler is sync - sync patch.
      */
     handle(state, action, dispatch, mutate) {
-        const {type} = required(action);
-        const {data} = action;
+        const {type, data} = action;
 
         const handlerDescriptor = this._handlers
             .find(ah => ah.type === type);
diff --git a/src/utils/state/middlewares/logger/LogEntry.js b/src/utils/state/middlewares/logger/LogEntry.js
index e08b2b4..8e88566 100644
--- a/src/utils/state/middlewares/logger/LogEntry.js
+++ b/src/utils/state/middlewares/logger/LogEntry.js
@@ -3,6 +3,8 @@ import assert from 'utils/assert';
 import PatchType from 'utils/state/Patch';
 import ActionType from 'utils/state/Action';
 
+import StateType from 'boot/client/State';
+
 /**
  * Log entry for store action
  */
@@ -112,7 +114,7 @@ export default class LogEntry {
 
     /**
      * Gets state before action
-     * @return {object}
+     * @return {StateType}
      */
     get prevState() {
         return this._prevState;
@@ -120,7 +122,7 @@ export default class LogEntry {
 
     /**
      * Sets state before action
-     * @param {object} state
+     * @param {StateType} state
      */
     set prevState(state) {
         this._prevState = {
@@ -136,7 +138,7 @@ export default class LogEntry {
 
     /**
      * Gets state after action
-     * @return {object}
+     * @return {StateType}
      */
     get nextState() {
         return this._nextState;
@@ -144,7 +146,7 @@ export default class LogEntry {
 
     /**
      * Sets state after action
-     * @param {object} state
+     * @param {StateType} state
      */
     set nextState(state) {
         this._nextState = {
diff --git a/src/view/mutators/index.js b/src/view/mutators/index.js
index c26d3ab..e439a30 100644
--- a/src/view/mutators/index.js
+++ b/src/view/mutators/index.js
@@ -5,12 +5,14 @@ import required from 'utils/required-params';
 import MutationType from 'utils/state/Mutation';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import Main from 'view/main/Main';
 import Provider from 'view/utils/connect/Provider';
 
 /**
  * Applies patch to view state
- * @param {object} state
+ * @param {StateType} state
  * @param {PatchType} patch
  */
 export default function mutate(state, patch) {
@@ -21,7 +23,7 @@ export default function mutate(state, patch) {
 
 /**
  * Applies single mutation to state
- * @param {object} state
+ * @param {StateType} state
  * @param {MutationType} mutation
  */
 function apply(state, mutation) {
@@ -84,7 +86,7 @@ function apply(state, mutation) {
 
 /**
  * Mounts component tree
- * @param {object} state
+ * @param {StateType} state
  */
 function mount(state) {
     ReactDom.render(
diff --git a/src/vm/action/handlers/animate-graph-zoom.js b/src/vm/action/handlers/animate-graph-zoom.js
index d2d1eed..51453d8 100644
--- a/src/vm/action/handlers/animate-graph-zoom.js
+++ b/src/vm/action/handlers/animate-graph-zoom.js
@@ -1,6 +1,8 @@
 import required from 'utils/required-params';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import view from 'vm/utils/view-patch';
 import animate from 'vm/utils/animate';
 import Point from 'model/entities/Point';
@@ -12,7 +14,7 @@ import toCanvasCoords from 'vm/map/utils/map-viewport-to-canvas-coords';
 /**
  * Animates graph scale towards certain canvas position
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object}   data
  * @param {object}   data.up  - scale up or down
  * @param {object}   data.pos - target viewport position
diff --git a/src/vm/action/handlers/animate-to-node.js b/src/vm/action/handlers/animate-to-node.js
index 8a8989f..229be73 100644
--- a/src/vm/action/handlers/animate-to-node.js
+++ b/src/vm/action/handlers/animate-to-node.js
@@ -2,6 +2,8 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import clone from 'clone';
 
+import StateType from 'boot/client/State';
+
 import Point from 'model/entities/Point';
 import NodeType from 'vm/map/entities/Node';
 
@@ -12,7 +14,7 @@ import getGraphScaleForNode from 'vm/map/utils/get-graph-scale-for-node-scale';
 /**
  * Animates graph position and scale to target node
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object}   data
  * @param {NodeType} data.node - target node
  * @param {function} dispatch
diff --git a/src/vm/action/handlers/on-association-tails-lookup-keydown.js b/src/vm/action/handlers/on-association-tails-lookup-keydown.js
index b5a26a9..0728cc7 100644
--- a/src/vm/action/handlers/on-association-tails-lookup-keydown.js
+++ b/src/vm/action/handlers/on-association-tails-lookup-keydown.js
@@ -2,12 +2,14 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import onKeyDown from 'vm/shared/Lookup/methods/on-keydown';
 
 /**
  * Handles key down event on association tails lookup
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.key
  * @param {function} dispatch
diff --git a/src/vm/action/handlers/on-association-tails-lookup-phrase-change.js b/src/vm/action/handlers/on-association-tails-lookup-phrase-change.js
index cca3ff4..f37b57e 100644
--- a/src/vm/action/handlers/on-association-tails-lookup-phrase-change.js
+++ b/src/vm/action/handlers/on-association-tails-lookup-phrase-change.js
@@ -2,12 +2,14 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import onPhraseChange from 'vm/shared/Lookup/methods/on-phrase-change';
 
 /**
  * Handles phrase change event on association tails lookup
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.phrase
  * @param {function} dispatch
diff --git a/src/vm/action/handlers/on-association-tails-lookup-suggestion-select.js b/src/vm/action/handlers/on-association-tails-lookup-suggestion-select.js
index e9a717d..5c0b651 100644
--- a/src/vm/action/handlers/on-association-tails-lookup-suggestion-select.js
+++ b/src/vm/action/handlers/on-association-tails-lookup-suggestion-select.js
@@ -2,13 +2,18 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
+import LookupSuggestionType from 'vm/shared/LookupSuggestion';
+
 /**
  * Handles suggestion select event of association tails lookup
  * 
- * @param {object} state
- * @param {object} data
- * @param {string} data.headIdeaId
- * @param {string} data.tailIdeaId
+ * @param {StateType} state
+ * @param {object}               data
+ * @param {string}               data.headIdeaId
+ * @param {string}               data.tailIdeaId
+ * @param {LookupSuggestionType} data.suggestion
  * @param {function} dispatch
  * @return {PatchType}
  */
diff --git a/src/vm/action/handlers/on-graph-click.js b/src/vm/action/handlers/on-graph-click.js
index 59f3a22..64cbbea 100644
--- a/src/vm/action/handlers/on-graph-click.js
+++ b/src/vm/action/handlers/on-graph-click.js
@@ -1,10 +1,12 @@
 import Patch from 'utils/state/Patch';
 import view from 'vm/utils/view-mutation';
 
+import StateType from 'boot/client/State';
+
 /**
  * Handles graph click event
  * 
- * @param {object} state
+ * @param {StateType} state
  * @return {Patch}
  */
 export default function(state) {
diff --git a/src/vm/action/handlers/on-graph-key-press.js b/src/vm/action/handlers/on-graph-key-press.js
index 3970d8d..3ad227a 100644
--- a/src/vm/action/handlers/on-graph-key-press.js
+++ b/src/vm/action/handlers/on-graph-key-press.js
@@ -1,11 +1,13 @@
 import required from 'utils/required-params';
 
+import StateType from 'boot/client/State';
+
 import Point from 'model/entities/Point';
 
 /**
  * Handles key press event on graph
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.key
  * @param {function} dispatch
diff --git a/src/vm/action/handlers/on-graph-mouse-leave.js b/src/vm/action/handlers/on-graph-mouse-leave.js
index 51e875e..6ba8d95 100644
--- a/src/vm/action/handlers/on-graph-mouse-leave.js
+++ b/src/vm/action/handlers/on-graph-mouse-leave.js
@@ -1,5 +1,7 @@
 import view from 'vm/utils/view-mutation';
 
+import StateType from 'boot/client/State';
+
 import Patch from 'utils/state/Patch';
 import getNode from 'vm/action/utils/get-node';
 import stopDrag from 'vm/map/entities/Graph/methods/stop-drag';
@@ -7,7 +9,7 @@ import stopDrag from 'vm/map/entities/Graph/methods/stop-drag';
 /**
  * Handles mouse leave action on graph
  * 
- * @param {object} state
+ * @param {StateType} state
  * @return {Patch|undefined}
  */
 export default function(state) {
diff --git a/src/vm/action/handlers/on-graph-mouse-move.js b/src/vm/action/handlers/on-graph-mouse-move.js
index 3f7b334..249a05a 100644
--- a/src/vm/action/handlers/on-graph-mouse-move.js
+++ b/src/vm/action/handlers/on-graph-mouse-move.js
@@ -1,16 +1,20 @@
 import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
+import PointType from 'model/entities/Point';
+
 import view from 'vm/utils/view-mutation';
 import toViewboxCoords from 'vm/map/utils/map-viewport-to-viewbox-coords';
 
 /**
  * Handles mouse move on graph
  * 
- * @param {object} state
- * @param {object} data
- * @param {Point}  data.viewportShift
- * @param {string} data.pressedMouseButton - left or null
+ * @param {StateType} state
+ * @param {object}     data
+ * @param {PointType}  data.viewportShift
+ * @param {string}     data.pressedMouseButton - left or null (TODO: or null?)
  * @return {Patch|undefined}
  */
 export default function(state, data) {
diff --git a/src/vm/action/handlers/on-graph-mouse-up.js b/src/vm/action/handlers/on-graph-mouse-up.js
index 3d6ce8d..fc860a6 100644
--- a/src/vm/action/handlers/on-graph-mouse-up.js
+++ b/src/vm/action/handlers/on-graph-mouse-up.js
@@ -1,13 +1,15 @@
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import Point from 'model/entities/Point';
 import stopDrag from 'vm/map/entities/Graph/methods/stop-drag';
 
 /**
  * Handles mouse up event on graph
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {function} dispatch
  * @return {PatchType|undefined}
diff --git a/src/vm/action/handlers/on-graph-node-mouse-down.js b/src/vm/action/handlers/on-graph-node-mouse-down.js
index 96bb276..ba24d49 100644
--- a/src/vm/action/handlers/on-graph-node-mouse-down.js
+++ b/src/vm/action/handlers/on-graph-node-mouse-down.js
@@ -2,15 +2,19 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
+import NodeType from 'vm/map/entities/Node';
+
 import getDescendants from 'utils/graph/get-descendants';
 
 /**
  * Handles mouse down event on graph node
  * 
- * @param {object} state
- * @param {object} data
- * @param {Node}   data.node
- * @param {string} data.button
+ * @param {StateType} state
+ * @param {object}   data
+ * @param {NodeType} data.node
+ * @param {string}   data.button
  * @return {PatchType|undefined}
  */
 export default function(state, data) {
diff --git a/src/vm/action/handlers/on-graph-viewport-resize.js b/src/vm/action/handlers/on-graph-viewport-resize.js
index a0e271d..ed22e7a 100644
--- a/src/vm/action/handlers/on-graph-viewport-resize.js
+++ b/src/vm/action/handlers/on-graph-viewport-resize.js
@@ -2,13 +2,15 @@ import clone from 'clone';
 import required from 'utils/required-params';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import view from 'vm/utils/view-patch';
 import computeViewbox from 'vm/map/entities/Graph/methods/compute-viewbox-size';
 
 /**
  * Handlers graph viewport resize event
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {object} data.size
  * @param {number} data.size.width
diff --git a/src/vm/action/handlers/on-graph-wheel.js b/src/vm/action/handlers/on-graph-wheel.js
index 63a215d..e557de7 100644
--- a/src/vm/action/handlers/on-graph-wheel.js
+++ b/src/vm/action/handlers/on-graph-wheel.js
@@ -1,12 +1,16 @@
 import required from 'utils/required-params';
 
+import StateType from 'boot/client/State';
+
+import PointType from 'model/entities/Point';
+
 /**
  * Handles graph mouse wheel event
  * 
- * @param {object} state
- * @param {object} data
- * @param {string} data.up  - wheel up or down
- * @param {Point}  data.pos - target viewport position
+ * @param {StateType} state
+ * @param {object}    data
+ * @param {string}    data.up  - wheel up or down
+ * @param {PointType} data.pos - target viewport position
  * @param {function} dispatch
  */
 export default function onGraphWheel(state, data, dispatch) {
diff --git a/src/vm/action/handlers/on-idea-color-selected.js b/src/vm/action/handlers/on-idea-color-selected.js
index 9af28d5..6a0b03c 100644
--- a/src/vm/action/handlers/on-idea-color-selected.js
+++ b/src/vm/action/handlers/on-idea-color-selected.js
@@ -2,10 +2,12 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 /**
  * Handles idea color selected with color picker
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.ideaId
  * @param {string} data.color
diff --git a/src/vm/action/handlers/on-link-click.js b/src/vm/action/handlers/on-link-click.js
index f7141b7..9b6a32e 100644
--- a/src/vm/action/handlers/on-link-click.js
+++ b/src/vm/action/handlers/on-link-click.js
@@ -1,15 +1,19 @@
 import required from 'utils/required-params';
 
+import StateType from 'boot/client/State';
+
+import PointType from 'model/entities/Point';
+
 import getDistance from 'utils/get-distance-between-points';
 import toCanvasCoords from 'vm/map/utils/map-viewport-to-canvas-coords';
 
 /**
  * Handles link click event
  * 
- * @param {object} state
- * @param {object} data
- * @param {string} data.linkId
- * @param {string} data.viewportPos - mouse viewport position
+ * @param {StateType} state
+ * @param {object}    data
+ * @param {string}    data.linkId
+ * @param {PointType} data.viewportPos - mouse viewport position
  * @param {function} dispatch
  */
 export default function(state, data, dispatch) {
diff --git a/src/vm/action/handlers/on-link-mouse-leave.js b/src/vm/action/handlers/on-link-mouse-leave.js
index 2b88890..5ed04a2 100644
--- a/src/vm/action/handlers/on-link-mouse-leave.js
+++ b/src/vm/action/handlers/on-link-mouse-leave.js
@@ -2,10 +2,12 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 /**
  * Handles link mouse leave event
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.linkId
  * @return {PatchType}
diff --git a/src/vm/action/handlers/on-link-mouse-move.js b/src/vm/action/handlers/on-link-mouse-move.js
index 8a66945..463c1eb 100644
--- a/src/vm/action/handlers/on-link-mouse-move.js
+++ b/src/vm/action/handlers/on-link-mouse-move.js
@@ -2,16 +2,20 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
+import PointType from 'model/entities/Point';
+
 import toCanvasCoords from 'vm/map/utils/map-viewport-to-canvas-coords';
 import getDistance from 'utils/get-distance-between-points';
 
 /**
  * Handles link mouse move event
  * 
- * @param {object} state
- * @param {object} data
- * @param {string} data.linkId
- * @param {string} data.viewportPos - mouse viewport position
+ * @param {StateType} state
+ * @param {object}    data
+ * @param {string}    data.linkId
+ * @param {PointType} data.viewportPos - mouse viewport position
  * @return {PatchType}
  */
 export default function onLinkMouseMove(state, data) {
diff --git a/src/vm/action/handlers/on-node-title-blur.js b/src/vm/action/handlers/on-node-title-blur.js
index 58bca95..bf66684 100644
--- a/src/vm/action/handlers/on-node-title-blur.js
+++ b/src/vm/action/handlers/on-node-title-blur.js
@@ -2,12 +2,14 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import getNode from 'vm/action/utils/get-node';
 
 /**
  * Handles blur event on graph node title
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.nodeId
  * @return {PatchType|undefined}
diff --git a/src/vm/action/handlers/on-node-title-change.js b/src/vm/action/handlers/on-node-title-change.js
index 6ea7eb2..e0981b3 100644
--- a/src/vm/action/handlers/on-node-title-change.js
+++ b/src/vm/action/handlers/on-node-title-change.js
@@ -1,9 +1,11 @@
 import required from 'utils/required-params';
 
+import StateType from 'boot/client/State';
+
 /**
  * Handles change event on node title
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.nodeId
  * @param {string} data.title
diff --git a/src/vm/action/handlers/on-node-title-double-click.js b/src/vm/action/handlers/on-node-title-double-click.js
index 750ef00..32674d9 100644
--- a/src/vm/action/handlers/on-node-title-double-click.js
+++ b/src/vm/action/handlers/on-node-title-double-click.js
@@ -2,12 +2,14 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import getNode from 'vm/action/utils/get-node';
 
 /**
  * Handles double click event on graph node title
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.nodeId
  * @return {PatchType|undefined}
diff --git a/src/vm/action/handlers/search-association-tails-for-lookup.js b/src/vm/action/handlers/search-association-tails-for-lookup.js
index 2d88cd0..683013d 100644
--- a/src/vm/action/handlers/search-association-tails-for-lookup.js
+++ b/src/vm/action/handlers/search-association-tails-for-lookup.js
@@ -2,6 +2,8 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import searchIdeas from 'action/utils/search-ideas';
 import getIdea from 'action/utils/get-idea';
 
@@ -11,7 +13,7 @@ import LookupSuggestion from 'vm/shared/LookupSuggestion';
  * Searches and sets suggesting ideas to lookup
  * which selects tail idea for cross-association
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.phrase 
  * @param {string} data.headIdeaId 
diff --git a/src/vm/action/handlers/show-association-tails-lookup.js b/src/vm/action/handlers/show-association-tails-lookup.js
index 7184b16..85325cc 100644
--- a/src/vm/action/handlers/show-association-tails-lookup.js
+++ b/src/vm/action/handlers/show-association-tails-lookup.js
@@ -2,16 +2,20 @@ import required from 'utils/required-params';
 import Patch from 'utils/state/Patch';
 import view from 'vm/utils/view-patch';
 
+import StateType from 'boot/client/State';
+
+import PointType from 'model/entities/Point';
+
 import showLookup from 'vm/shared/Lookup/methods/show-lookup';
 
 /**
  * Shows association tails lookup
  * which helps selecting tail idea for cross-association
  *
- * @param {object} state
- * @param {object} data
- * @param {Point}  data.pos - target canvas position for lookup
- * @param {string} data.headIdeaId - ID of head idea
+ * @param {StateType} state
+ * @param {object}    data
+ * @param {PointType} data.pos - target canvas position for lookup
+ * @param {string}    data.headIdeaId - ID of head idea
  * @return {Patch}
  */
 export default function(state, data) {
diff --git a/src/vm/action/handlers/show-color-picker-for-idea.js b/src/vm/action/handlers/show-color-picker-for-idea.js
index e6f7f00..261c973 100644
--- a/src/vm/action/handlers/show-color-picker-for-idea.js
+++ b/src/vm/action/handlers/show-color-picker-for-idea.js
@@ -2,10 +2,12 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 /**
  * Shows color picker
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  * @param {string} data.ideaId - ID of target idea
  * @return {PatchType}
diff --git a/src/vm/action/handlers/show-context-menu-for-association.js b/src/vm/action/handlers/show-context-menu-for-association.js
index 16e2935..9f94d1e 100644
--- a/src/vm/action/handlers/show-context-menu-for-association.js
+++ b/src/vm/action/handlers/show-context-menu-for-association.js
@@ -2,17 +2,21 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
+import PointType from 'model/entities/Point';
+
 import getAssociation from 'action/utils/get-association';
 import MenuItem from 'vm/shared/MenuItem';
 
 /**
  * Shows context menu for association
  * 
- * @param {object} state
- * @param {object} data
- * @param {Point}  data.pos - viewport position of mouse
- *                            TODO: rename to viewportPos
- * @param {string} data.associationId - ID of target association
+ * @param {StateType} state
+ * @param {object}    data
+ * @param {PointType} data.pos - viewport position of mouse
+ *                               TODO: rename to viewportPos
+ * @param {string}    data.associationId - ID of target association
  * @param {boolean}   data.shaded - indicates target association is shaded
  * @return {PatchType|undefined}
  */
diff --git a/src/vm/action/handlers/show-context-menu-for-idea.js b/src/vm/action/handlers/show-context-menu-for-idea.js
index 3d3f91a..4297e13 100644
--- a/src/vm/action/handlers/show-context-menu-for-idea.js
+++ b/src/vm/action/handlers/show-context-menu-for-idea.js
@@ -2,16 +2,20 @@ import required from 'utils/required-params';
 import view from 'vm/utils/view-patch';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
+import PointType from 'model/entities/Point';
+
 import MenuItem from 'vm/shared/MenuItem';
 
 /** 
  * Shows context menu for idea
  * 
- * @param {object} state
- * @param {object} data
- * @param {Point}  data.pos - viewport position of mouse
+ * @param {StateType} state
+ * @param {object}    data
+ * @param {PointType} data.pos - viewport position of mouse
  *                            TODO: rename to viewportPos
- * @param {string} data.ideaId - ID of target idea
+ * @param {string}    data.ideaId - ID of target idea
  * @param {boolean}   data.shaded - indicates target idea is shaded
  * @return {PatchType|undefined}
  */
diff --git a/src/vm/map/entities/Graph/methods/check-scale-limits.js b/src/vm/map/entities/Graph/methods/check-scale-limits.js
index 70204d8..c7f1efb 100644
--- a/src/vm/map/entities/Graph/methods/check-scale-limits.js
+++ b/src/vm/map/entities/Graph/methods/check-scale-limits.js
@@ -1,5 +1,4 @@
 import assert from 'utils/assert';
-import required from 'utils/required-params';
 import isValidScale from 'model/utils/is-valid-scale';
 
 /**
@@ -11,7 +10,7 @@ import isValidScale from 'model/utils/is-valid-scale';
  * @return {boolean}
  */
 export default function checkGraphScaleLimits(opts) {
-    const {viewbox, up} = required(opts);
+    const {viewbox, up} = opts;
 
     const {scale, scaleMin, scaleMax} = viewbox;
 
diff --git a/src/vm/map/entities/Graph/methods/compute-viewbox-size.js b/src/vm/map/entities/Graph/methods/compute-viewbox-size.js
index 4dbc344..709079c 100644
--- a/src/vm/map/entities/Graph/methods/compute-viewbox-size.js
+++ b/src/vm/map/entities/Graph/methods/compute-viewbox-size.js
@@ -1,6 +1,5 @@
 import clone from 'clone';
 import assert from 'utils/assert';
-import required from 'utils/required-params';
 
 /**
  * Computes viewbox size
@@ -12,7 +11,7 @@ import required from 'utils/required-params';
  * @return {object}
  */
 export default function computeViewboxSize(opts) {
-    const {viewport, viewbox: vb} = required(opts);
+    const {viewport, viewbox: vb} = opts;
 
     assert(viewport.width > 0, `Invalid viewport width '${viewport.width}'`);
     assert(viewport.height > 0, `Invalid viewport height '${viewport.height}'`);
diff --git a/src/vm/map/entities/Graph/methods/zoom.js b/src/vm/map/entities/Graph/methods/zoom.js
index c443080..4ed9ab5 100644
--- a/src/vm/map/entities/Graph/methods/zoom.js
+++ b/src/vm/map/entities/Graph/methods/zoom.js
@@ -1,6 +1,7 @@
 import assert from 'utils/assert';
 import clone from 'clone';
-import required from 'utils/required-params';
+
+import PointType from 'model/entities/Point';
 
 import computeViewboxSize from './compute-viewbox-size';
 import checkScaleLimits from './check-scale-limits';
@@ -8,15 +9,15 @@ import checkScaleLimits from './check-scale-limits';
 /**
  * Changes graph scale towards certain canvas position
  * 
- * @param {object} opts
- * @param {object} opts.viewbox   - graph viewbox
- * @param {object} opts.viewport  - graph viewport
- * @param {object} opts.scale     - target scale
- * @param {Point}  opts.canvasPos - target canvas position
+ * @param {object}    opts
+ * @param {object}    opts.viewbox   - graph viewbox
+ * @param {object}    opts.viewport  - graph viewport
+ * @param {object}    opts.scale     - target scale
+ * @param {PointType} opts.canvasPos - target canvas position
  * @return {object} viewbox
  */
 export default function zoomGraph(opts) {
-    const {viewbox: vb, viewport, scale, canvasPos} = required(opts);
+    const {viewbox: vb, viewport, scale, canvasPos} = opts;
 
     if (!checkScaleLimits({viewbox: vb, up: scale > vb.scale})) {
         // do not scale out of limits
diff --git a/src/vm/mutators/default.js b/src/vm/mutators/default.js
index b834d06..f7ccaf3 100644
--- a/src/vm/mutators/default.js
+++ b/src/vm/mutators/default.js
@@ -1,9 +1,11 @@
 import toGraph from 'vm/map/mappers/mindmap-to-graph';
 import update from 'utils/update-object';
 
+import StateType from 'boot/client/State';
+
 /**
  * Applies all mutations that do not have correspoding mutators
- * @param {object} state
+ * @param {StateType} state
  */
 export default function defaultMutator(state) {
 
diff --git a/src/vm/mutators/index.js b/src/vm/mutators/index.js
index de61c48..7c6f746 100644
--- a/src/vm/mutators/index.js
+++ b/src/vm/mutators/index.js
@@ -1,6 +1,8 @@
 import regMutatorsFolder from 'utils/reg-mutators-folder';
 import PatchType from 'utils/state/Patch';
 
+import StateType from 'boot/client/State';
+
 import defaultMutator from './default';
 
 // eslint-disable-next-line no-undef
@@ -9,7 +11,7 @@ const mutators = regMutatorsFolder(context);
 
 /**
  * Applies patch to vm state
- * @param {object} state
+ * @param {StateType} state
  * @param {PatchType} patch
  */
 export default function mutate(state, patch) {
diff --git a/src/vm/mutators/init.js b/src/vm/mutators/init.js
index bfb9bda..026df86 100644
--- a/src/vm/mutators/init.js
+++ b/src/vm/mutators/init.js
@@ -1,8 +1,10 @@
 import required from 'utils/required-params';
 
+import StateType from 'boot/client/State';
+
 /**
  * Applies 'init' mutation
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  */
 export default function init(state, data) {
diff --git a/src/vm/mutators/update-association-tails-lookup.js b/src/vm/mutators/update-association-tails-lookup.js
index d76ff11..31af02a 100644
--- a/src/vm/mutators/update-association-tails-lookup.js
+++ b/src/vm/mutators/update-association-tails-lookup.js
@@ -1,9 +1,11 @@
 import update from 'utils/update-object';
 
+import StateType from 'boot/client/State';
+
 /**
  * Updates association tails lookup
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  */
 export default function updateAssociationTailsLookup(state, data) {
diff --git a/src/vm/mutators/update-color-picker.js b/src/vm/mutators/update-color-picker.js
index 604001b..0296d26 100644
--- a/src/vm/mutators/update-color-picker.js
+++ b/src/vm/mutators/update-color-picker.js
@@ -1,9 +1,11 @@
 import update from 'utils/update-object';
 
+import StateType from 'boot/client/State';
+
 /**
  * Updates color picker
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  */
 export default function updateColorPicker(state, data) {
diff --git a/src/vm/mutators/update-context-menu.js b/src/vm/mutators/update-context-menu.js
index f6d5576..d8a00a5 100644
--- a/src/vm/mutators/update-context-menu.js
+++ b/src/vm/mutators/update-context-menu.js
@@ -1,9 +1,11 @@
 import update from 'utils/update-object';
 
+import StateType from 'boot/client/State';
+
 /**
  * Updates context menu
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  */
 export default function updateContextMenu(state, data) {
diff --git a/src/vm/mutators/update-graph.js b/src/vm/mutators/update-graph.js
index 0b50264..2b58a9c 100644
--- a/src/vm/mutators/update-graph.js
+++ b/src/vm/mutators/update-graph.js
@@ -1,9 +1,11 @@
 import update from 'utils/update-object';
 
+import StateType from 'boot/client/State';
+
 /**
  * Updates graph
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  */
 export default function updateGraph(state, data) {
diff --git a/src/vm/mutators/update-link.js b/src/vm/mutators/update-link.js
index 8ef4c66..66acb05 100644
--- a/src/vm/mutators/update-link.js
+++ b/src/vm/mutators/update-link.js
@@ -1,9 +1,11 @@
 import update from 'utils/update-object';
 
+import StateType from 'boot/client/State';
+
 /**
  * Updates link
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  */
 export default function updateLink(state, data) {
diff --git a/src/vm/mutators/update-node.js b/src/vm/mutators/update-node.js
index 31163c5..02714f3 100644
--- a/src/vm/mutators/update-node.js
+++ b/src/vm/mutators/update-node.js
@@ -1,9 +1,11 @@
 import update from 'utils/update-object';
 
+import StateType from 'boot/client/State';
+
 /**
  * Updates node
  * 
- * @param {object} state
+ * @param {StateType} state
  * @param {object} data
  */
 export default function updateNode(state, data) {
diff --git a/src/vm/shared/Lookup/methods/get-next-highlighted-suggestion-id.js b/src/vm/shared/Lookup/methods/get-next-highlighted-suggestion-id.js
index ff255c7..3fa6320 100644
--- a/src/vm/shared/Lookup/methods/get-next-highlighted-suggestion-id.js
+++ b/src/vm/shared/Lookup/methods/get-next-highlighted-suggestion-id.js
@@ -1,5 +1,3 @@
-import required from 'utils/required-params';
-
 import LookupType from 'vm/shared/Lookup';
 
 /**
@@ -11,7 +9,7 @@ import LookupType from 'vm/shared/Lookup';
  * @return {number|null} ID of next highlighted suggesion
  */
 export default function getNextHighlightedSuggestionId(opts) {
-    const {lookup, forward} = required(opts);
+    const {lookup, forward} = opts;
 
     if (!lookup.suggestions.length) {
         // skip since no suggestions
diff --git a/src/vm/shared/Lookup/methods/on-keydown.js b/src/vm/shared/Lookup/methods/on-keydown.js
index 5c41c93..007bab5 100644
--- a/src/vm/shared/Lookup/methods/on-keydown.js
+++ b/src/vm/shared/Lookup/methods/on-keydown.js
@@ -1,5 +1,3 @@
-import required from 'utils/required-params';
-
 import LookupType from 'vm/shared/Lookup';
 
 import clearLookup from './clear-lookup';
@@ -15,7 +13,7 @@ import getNextSuggestionId from './get-next-highlighted-suggestion-id';
  * @return {object} lookup update object
  */
 export default function onKeyDown(opts) {
-    const {key, lookup, onSuggestionSelect} = required(opts);
+    const {key, lookup, onSuggestionSelect} = opts;
 
     let update = {};
 
diff --git a/src/vm/shared/Lookup/methods/on-phrase-change.js b/src/vm/shared/Lookup/methods/on-phrase-change.js
index b96eabb..b8f34cc 100644
--- a/src/vm/shared/Lookup/methods/on-phrase-change.js
+++ b/src/vm/shared/Lookup/methods/on-phrase-change.js
@@ -1,4 +1,3 @@
-import required from 'utils/required-params';
 import debounce from 'debounce';
 
 import LookupType from 'vm/shared/Lookup';
@@ -15,7 +14,7 @@ import clearLookup from './clear-lookup';
  * @return {object} lookup update object
 */
 export default function onPhraseChange(opts) {
-    const {phrase, lookup, onPhraseChangeAction} = required(opts);
+    const {phrase, lookup, onPhraseChangeAction} = opts;
 
     let update = null;
 
diff --git a/src/vm/shared/Lookup/methods/show-lookup.js b/src/vm/shared/Lookup/methods/show-lookup.js
index 5960a99..be006dc 100644
--- a/src/vm/shared/Lookup/methods/show-lookup.js
+++ b/src/vm/shared/Lookup/methods/show-lookup.js
@@ -1,4 +1,3 @@
-import required from 'utils/required-params';
 import clearLookup from './clear-lookup';
 
 /**
@@ -10,7 +9,7 @@ import clearLookup from './clear-lookup';
  * @return {object} lookup update object
  */
 export default function show(opts) {
-    const {onSelectAction, onPhraseChangeAction} = required(opts);
+    const {onSelectAction, onPhraseChangeAction} = opts;
 
     return Object.assign(
         clearLookup(),
diff --git a/src/vm/utils/animate.js b/src/vm/utils/animate.js
index c8b2e07..7041d4e 100644
--- a/src/vm/utils/animate.js
+++ b/src/vm/utils/animate.js
@@ -1,4 +1,3 @@
-import required from 'utils/required-params';
 import pms from 'utils/pms';
 
 /**
@@ -34,7 +33,7 @@ import pms from 'utils/pms';
  * @return {Promise}
  */
 export default function animate(opts) {
-    const {values, duration, onStep} = required(opts);
+    const {values, duration, onStep} = opts;
     let {scheduleAnimationStep} = opts;
 
     // made scheduler as optional parameter
diff --git a/test/unit/tests/data/mutators.test.js b/test/unit/tests/data/mutators.test.js
index c06aa45..020e099 100644
--- a/test/unit/tests/data/mutators.test.js
+++ b/test/unit/tests/data/mutators.test.js
@@ -2,6 +2,7 @@ import {expect, createDB} from 'test/utils';
 
 import mutate from 'data/mutators';
 
+import State from 'src/boot/client/State';
 import Patch from 'utils/state/Patch';
 import Idea from 'model/entities/Idea';
 import Association from 'model/entities/Association';
@@ -14,7 +15,7 @@ describe('mutators', () => {
         it('should init db', async () => {
     
             // setup
-            const state = {data: {}};
+            const state = new State();
     
             const patchData = {
                 db: {
@@ -52,7 +53,8 @@ describe('mutators', () => {
         it('should add idea', async () => {
     
             // setup
-            const state = {data: {ideas: createDB()}};
+            const state = new State();
+            state.data.ideas = createDB();
     
             const patch = new Patch({
                 type: 'add-idea',
@@ -90,7 +92,8 @@ describe('mutators', () => {
             const ideasDB = createDB();
             ideasDB.put({_id: 'id', value: 'old', color: 'white'});
     
-            const state = {data: {ideas: ideasDB}};
+            const state = new State();
+            state.data.ideas = ideasDB;
     
             const patch = new Patch({
                 type: 'update-idea',
@@ -118,7 +121,8 @@ describe('mutators', () => {
             const ideasDB = createDB();
             ideasDB.put({_id: 'id', value: 'old', color: 'white'});
     
-            const state = {data: {ideas: ideasDB}};
+            const state = new State();
+            state.data.ideas = ideasDB;
     
             const patch1 = new Patch({
                 type: 'update-idea',
@@ -162,7 +166,8 @@ describe('mutators', () => {
             ideasDB.put({_id: 'live'});
             ideasDB.put({_id: 'die'});
     
-            const state = {data: {ideas: ideasDB}};
+            const state = new State();
+            state.data.ideas = ideasDB;
     
             const patch = new Patch({
                 type: 'remove-idea',
@@ -187,7 +192,8 @@ describe('mutators', () => {
         it('should add association', async () => {
     
             // setup
-            const state = {data: {associations: createDB()}};
+            const state = new State();
+            state.data.associations = createDB();
     
             const patch = new Patch({
                 type: 'add-association',
@@ -220,7 +226,8 @@ describe('mutators', () => {
             const assocDB = createDB();
             assocDB.put({_id: 'id', value: 'old', from: 'from'});
     
-            const state = {data: {associations: assocDB}};
+            const state = new State();
+            state.data.associations = assocDB;
     
             const patch = new Patch({
                 type: 'update-association',
@@ -253,7 +260,8 @@ describe('mutators', () => {
             assocDB.put({_id: 'live'});
             assocDB.put({_id: 'die'});
     
-            const state = {data: {associations: assocDB}};
+            const state = new State();
+            state.data.associations = assocDB;
     
             const patch = new Patch({
                 type: 'remove-association',
@@ -281,7 +289,8 @@ describe('mutators', () => {
             const mindmapDB = createDB();
             mindmapDB.put({_id: 'id', scale: 1, x: 100});
     
-            const state = {data: {mindmaps: mindmapDB}};
+            const state = new State();
+            state.data.mindmaps = mindmapDB;
     
             const patch = new Patch({
                 type: 'update-mindmap',
diff --git a/test/unit/tests/model/mutators/add-association.test.js b/test/unit/tests/model/mutators/add-association.test.js
index 35a405d..1788975 100644
--- a/test/unit/tests/model/mutators/add-association.test.js
+++ b/test/unit/tests/model/mutators/add-association.test.js
@@ -2,6 +2,7 @@ import {expect} from 'test/utils';
 
 import values from 'src/utils/get-map-values';
 
+import State from 'src/boot/client/State';
 import Patch from 'src/utils/state/Patch';
 import Mindmap from 'src/model/entities/Mindmap';
 import Association from 'src/model/entities/Association';
@@ -13,7 +14,8 @@ describe('add-association', () => {
     it('should add association to mindmap', () => {
 
         // setup
-        const state = {model: {mindmap: new Mindmap()}};
+        const state = new State();
+        state.model.mindmap = new Mindmap();
     
         const patch = new Patch({
             type: 'add-association',
diff --git a/test/unit/tests/model/mutators/add-idea.test.js b/test/unit/tests/model/mutators/add-idea.test.js
index 6abac5d..1bcee83 100644
--- a/test/unit/tests/model/mutators/add-idea.test.js
+++ b/test/unit/tests/model/mutators/add-idea.test.js
@@ -2,6 +2,7 @@ import {expect} from 'test/utils';
 
 import values from 'src/utils/get-map-values';
 
+import State from 'src/boot/client/State';
 import Patch from 'src/utils/state/Patch';
 import Mindmap from 'src/model/entities/Mindmap';
 import Idea from 'src/model/entities/Idea';
@@ -13,7 +14,8 @@ describe('add-idea', () => {
     it('should add idea to mindmap', () => {
         
         // setup
-        const state = {model: {mindmap: new Mindmap()}};
+        const state = new State();
+        state.model.mindmap = new Mindmap();
     
         const patch = new Patch({
             type: 'add-idea',
diff --git a/test/unit/tests/model/mutators/remove-association.test.js b/test/unit/tests/model/mutators/remove-association.test.js
index 9ec34a4..392d9c4 100644
--- a/test/unit/tests/model/mutators/remove-association.test.js
+++ b/test/unit/tests/model/mutators/remove-association.test.js
@@ -2,6 +2,7 @@ import {expect} from 'test/utils';
 
 import values from 'src/utils/get-map-values';
 
+import State from 'src/boot/client/State';
 import Patch from 'src/utils/state/Patch';
 import Mindmap from 'src/model/entities/Mindmap';
 import Association from 'src/model/entities/Association';
@@ -20,7 +21,8 @@ describe('remove-association', () => {
             value: 'old'
         }));
 
-        const state = {model: {mindmap}};
+        const state = new State();
+        state.model.mindmap = mindmap;
 
         const patch = new Patch({
             type: 'remove-association',
@@ -39,9 +41,8 @@ describe('remove-association', () => {
     it('should fail if target association was not found', () => {
         
         // setup
-        const mindmap = new Mindmap();
-
-        const state = {model: {mindmap}};
+        const state = new State();
+        state.model.mindmap = new Mindmap();
 
         const patch = new Patch({
             type: 'remove-association',
diff --git a/test/unit/tests/model/mutators/remove-idea.test.js b/test/unit/tests/model/mutators/remove-idea.test.js
index e49675f..9467220 100644
--- a/test/unit/tests/model/mutators/remove-idea.test.js
+++ b/test/unit/tests/model/mutators/remove-idea.test.js
@@ -2,6 +2,7 @@ import {expect} from 'test/utils';
 
 import values from 'src/utils/get-map-values';
 
+import State from 'src/boot/client/State';
 import Patch from 'src/utils/state/Patch';
 import Mindmap from 'src/model/entities/Mindmap';
 import Idea from 'src/model/entities/Idea';
@@ -21,7 +22,8 @@ describe('remove-idea', () => {
             color: 'white'
         }));
 
-        const state = {model: {mindmap}};
+        const state = new State();
+        state.model.mindmap = mindmap;
 
         const patch = new Patch({
             type: 'remove-idea',
@@ -40,7 +42,8 @@ describe('remove-idea', () => {
     it('should fail if target idea was not found', () => {
 
         // setup
-        const state = {model: {mindmap: new Mindmap()}};
+        const state = new State();
+        state.model.mindmap = new Mindmap();
         
         const patch = new Patch({
             type: 'remove-idea',
diff --git a/test/unit/tests/model/mutators/update-association.test.js b/test/unit/tests/model/mutators/update-association.test.js
index 684f245..ed2bf65 100644
--- a/test/unit/tests/model/mutators/update-association.test.js
+++ b/test/unit/tests/model/mutators/update-association.test.js
@@ -2,6 +2,7 @@ import {expect} from 'test/utils';
 
 import values from 'src/utils/get-map-values';
 
+import State from 'src/boot/client/state';
 import Patch from 'src/utils/state/Patch';
 import Mindmap from 'src/model/entities/Mindmap';
 import Association from 'src/model/entities/Association';
@@ -20,7 +21,8 @@ describe('update-association', () => {
             value: 'old'
         }));
 
-        const state = {model: {mindmap}};
+        const state = new State();
+        state.model.mindmap = mindmap;
 
         const patch = new Patch({
             type: 'update-association',
@@ -45,7 +47,8 @@ describe('update-association', () => {
         // setup
         const mindmap = new Mindmap();
 
-        const state = {model: {mindmap}};
+        const state = new State();
+        state.model.mindmap = mindmap;
 
         const patch = new Patch({
             type: 'update-association',
diff --git a/test/unit/tests/model/mutators/update-idea.test.js b/test/unit/tests/model/mutators/update-idea.test.js
index d885804..820539a 100644
--- a/test/unit/tests/model/mutators/update-idea.test.js
+++ b/test/unit/tests/model/mutators/update-idea.test.js
@@ -2,6 +2,7 @@ import {expect} from 'test/utils';
 
 import values from 'src/utils/get-map-values';
 
+import State from 'src/boot/client/State';
 import Patch from 'src/utils/state/Patch';
 import Mindmap from 'src/model/entities/Mindmap';
 import Idea from 'src/model/entities/Idea';
@@ -21,7 +22,8 @@ describe('update-idea', () => {
             color: 'white'
         }));
 
-        const state = {model: {mindmap}};
+        const state = new State();
+        state.model.mindmap = mindmap;
 
         const patch = new Patch({
             type: 'update-idea',
@@ -45,7 +47,8 @@ describe('update-idea', () => {
     it('should fail if target idea was not found', () => {
 
         // setup
-        const state = {model: {mindmap: new Mindmap()}};
+        const state = new State();
+        state.model.mindmap = new Mindmap();
         
         const patch = new Patch({
             type: 'update-idea',
diff --git a/test/unit/tests/model/mutators/update-mindmap.test.js b/test/unit/tests/model/mutators/update-mindmap.test.js
index dc0774d..2c33a54 100644
--- a/test/unit/tests/model/mutators/update-mindmap.test.js
+++ b/test/unit/tests/model/mutators/update-mindmap.test.js
@@ -2,6 +2,7 @@ import {expect} from 'test/utils';
 
 import mutate from 'model/mutators';
 
+import State from 'src/boot/client/State';
 import Patch from 'src/utils/state/Patch';
 import Mindmap from 'src/model/entities/Mindmap';
 import Point from 'src/model/entities/Point';
@@ -17,7 +18,8 @@ describe('update-mindmap', () => {
             pos: new Point({x: 100, y: 0})
         });
 
-        const state = {model: {mindmap}};
+        const state = new State();
+        state.model.mindmap = mindmap;
         
         const patch = new Patch({
             type: 'update-mindmap',
diff --git a/test/unit/tests/utils/required-params.test.js b/test/unit/tests/utils/required-params.test.js
index 2cf581c..f8e5f61 100644
--- a/test/unit/tests/utils/required-params.test.js
+++ b/test/unit/tests/utils/required-params.test.js
@@ -96,6 +96,8 @@ describe('required-params', () => {
         const params = requiredParams({});
 
         // check
+        
+        // @ts-ignore
         const result = () => params.X;
         expect(result).to.not.throw();