diff --git a/web/app/cad/actions/actionSystemPlugin.js b/web/app/cad/actions/actionSystemPlugin.js
deleted file mode 100644
index 21e23aae..00000000
--- a/web/app/cad/actions/actionSystemPlugin.js
+++ /dev/null
@@ -1,94 +0,0 @@
-import {enableAnonymousActionHint} from './anonHint';
-import * as stream from 'lstream';
-import {LOG_FLAGS} from '../logFlags';
-
-export function activate(context) {
-  
-  let {streams} = context;
-  
-  streams.action = {
-    appearance: {},
-    state: {},
-    hint: stream.state(null)
-  }; 
-  
-  let runners = {};
-  
-  let showAnonymousActionHint = enableAnonymousActionHint(context);
-  
-  function run(id, data) {
-    let state = streams.action.state[id].value;
-    let runner = runners[id];
-    if (!state||!runner) {
-      console.warn('request to run nonexistent action')
-      return;
-    } 
-    if (state.enabled) {
-      if (LOG_FLAGS.ACTION_RUN) {
-        console.log("RUNNING ACTION: " + id);
-      }
-      runner(context, data);
-    } else {
-      showAnonymousActionHint(id);
-    }
-  }
-
-  function register(action) {
-    streams.action.appearance[action.id] = stream.state(action.appearance);
-
-    runners[action.id] = action.invoke;
-
-    let initialState = {
-      hint: '',
-      enabled: true,
-      visible: true
-    };
-
-    let actionStateStream = stream.state(initialState);
-    streams.action.state[action.id] = actionStateStream;
-
-    if (action.update && action.listens) {
-
-      action.listens(streams).attach(data => {
-        actionStateStream.mutate(v => {
-          v.hint = '';
-          v.enabled = true;
-          v.visible = true;
-          action.update(v, data, context)
-          return v;
-        })
-      });
-    }
-  }
-
-  function registerAction(action) {
-    register(action);
-  }
-
-  function registerActions(actions) {
-    actions.forEach(action => register(action));
-  }
-
-  function showHintFor(request) {
-    if (request) {
-      let {actionId, x, y, requester} = request;
-      let actionState = streams.action.state[actionId].value;
-      let actionAppearance = streams.action.appearance[actionId].value;
-      if (actionState && actionAppearance) {
-        streams.action.hint.value = {
-          actionId, x, y, requester,
-          info: actionAppearance.info,
-          hint: actionState.hint
-        };
-      }
-    } else {
-      if (streams.action.hint.value !== null) {
-        streams.action.hint.value = null;
-      }
-    }
-  }
-
-  context.services.action = {run, registerAction, registerActions, showHintFor}
-}
-
-
diff --git a/web/app/cad/actions/actionSystemPlugin.ts b/web/app/cad/actions/actionSystemPlugin.ts
new file mode 100644
index 00000000..005869d0
--- /dev/null
+++ b/web/app/cad/actions/actionSystemPlugin.ts
@@ -0,0 +1,165 @@
+import {enableAnonymousActionHint} from './anonHint';
+import * as stream from 'lstream';
+import {state, StateStream, Stream} from 'lstream';
+import {LOG_FLAGS} from '../logFlags';
+import {ApplicationContext} from "context";
+import {IconType} from "react-icons";
+
+export function activate(context: ApplicationContext) {
+  
+  let {streams} = context;
+
+
+  const appearanceStreams: ActionAppearanceStreams = {};
+  const stateStreams: ActionStateStreams = {};
+  const hint$: StateStream<Hint> = state(null);
+
+  streams.action = {
+    appearance: appearanceStreams,
+    state: stateStreams,
+    hint: hint$
+  };
+  
+  let runners = {};
+  
+  let showAnonymousActionHint = enableAnonymousActionHint(context);
+  
+  function run(id: string, data: any): void {
+    let state = streams.action.state[id].value;
+    let runner = runners[id];
+    if (!state||!runner) {
+      console.warn('request to run nonexistent action');
+      return;
+    } 
+    if (state.enabled) {
+      if (LOG_FLAGS.ACTION_RUN) {
+        console.log("RUNNING ACTION: " + id);
+      }
+      runner(context, data);
+    } else {
+      showAnonymousActionHint(id);
+    }
+  }
+
+  function register(action: ActionDefinition): void {
+    streams.action.appearance[action.id] = stream.state(action.appearance);
+
+    runners[action.id] = action.invoke;
+
+    let initialState = {
+      hint: '',
+      enabled: true,
+      visible: true
+    };
+
+    let actionStateStream = stream.state(initialState);
+    streams.action.state[action.id] = actionStateStream;
+
+    if (action.update && action.listens) {
+
+      action.listens(context).attach(data => {
+        actionStateStream.mutate(v => {
+          v.hint = '';
+          v.enabled = true;
+          v.visible = true;
+          action.update(v, data, context);
+          return v;
+        })
+      });
+    }
+  }
+
+  function registerAction(action: ActionDefinition): void {
+    register(action);
+  }
+
+  function registerActions(actions: ActionDefinition[]): void {
+    actions.forEach(action => register(action));
+  }
+
+  function showHintFor(request: HintRequest) {
+    if (request) {
+      let {actionId, x, y, requester} = request;
+      let actionState = streams.action.state[actionId].value;
+      let actionAppearance = streams.action.appearance[actionId].value;
+      if (actionState && actionAppearance) {
+        streams.action.hint.value = {
+          actionId, x, y, requester,
+          info: actionAppearance.info,
+          hint: actionState.hint
+        };
+      }
+    } else {
+      if (streams.action.hint.value !== null) {
+        streams.action.hint.value = null;
+      }
+    }
+  }
+
+  context.actionService = {run, registerAction, registerActions, showHintFor, appearanceStreams, stateStreams, hint$};
+
+  context.services.action = context.actionService;
+}
+
+
+export interface ActionAppearanceStreams {
+  [actionId: string]: StateStream<ActionAppearance>
+}
+
+export interface ActionStateStreams {
+  [actionId: string]: StateStream<ActionState>
+}
+
+export interface ActionState {
+  hint: string,
+  enabled: boolean,
+  visible: boolean
+}
+
+export interface HintRequest {
+  actionId: string;
+  x: number;
+  y: number;
+  requester: any;
+}
+
+export interface Hint extends HintRequest {
+  info: string;
+  hint: string;
+}
+
+export interface ActionAppearance {
+  info: string,
+  label: string,
+  icon32?: string,
+  icon96?: string,
+  icon?: IconType
+}
+
+export interface ActionDefinition<T = void> {
+  id: string,
+  appearance: ActionAppearance,
+  invoke: (ApplicationContext, any) => void;
+  update?: (ActionState, T, ApplicationContext) => void;
+  listens?: (ApplicationContext) => Stream<T>;
+}
+
+export interface ActionService {
+
+  run(id: string, data: any): void;
+  registerAction(action: ActionDefinition): void;
+  registerActions(actions: ActionDefinition[]): void;
+  showHintFor(request: HintRequest): void;
+
+  appearanceStreams: ActionAppearanceStreams;
+  stateStreams: ActionStateStreams;
+  hint$: StateStream<Hint>;
+}
+
+declare module 'context' {
+  interface ApplicationContext {
+
+    actionService: ActionService;
+  }
+}
+