feat: add decorate feature

src/bot.ts

@@ -8,6 +8,7 @@ import {
 	type MaybeArray,
 	PhotoAttachment,
 	type UpdateName,
+	contextsMappings,
 } from "@gramio/contexts";
 import { convertJsonToFormData, isMediaUpload } from "@gramio/files";
 import { FormattableMap } from "@gramio/format";
@@ -464,6 +465,23 @@ export class Bot<
 		return this;
 	}
 
+	decorate<Name extends string, Value>(name: Name, value: Value) {
+		for (const contextName of Object.keys(contextsMappings)) {
+			// @ts-expect-error
+			Object.defineProperty(contextsMappings[contextName].prototype, name, {
+				value,
+			});
+		}
+
+		return this as unknown as Bot<
+			Errors,
+			Derives & {
+				global: {
+					[K in Name]: Value;
+				};
+			}
+		>;
+	}
 	/**
 	 * This hook called when the bot is `started`.
 	 *
@@ -737,6 +755,10 @@ export class Bot<
 			this.use(plugin._.composer.composed);
 		}
 
+		for (const [key, value] of Object.entries(plugin._.decorators)) {
+			this.decorate(key, value);
+		}
+
 		for (const [key, value] of Object.entries(plugin._.errorsDefinitions)) {
 			if (this.errorsDefinitions[key]) this.errorsDefinitions[key] = value;
 		}

src/plugin.ts

@@ -108,6 +108,7 @@ export class Plugin<
 			string,
 			{ new (...args: any): any; prototype: Error }
 		>,
+		decorators: {} as Record<string, unknown>,
 	};
 
 	/** Create new Plugin. Please provide `name` */
@@ -181,6 +182,19 @@ export class Plugin<
 		return this;
 	}
 
+	decorate<Name extends string, Value>(name: Name, value: Value) {
+		this._.decorators[name] = value;
+
+		return this as unknown as Plugin<
+			Errors,
+			Derives & {
+				global: {
+					[K in Name]: Value;
+				};
+			}
+		>;
+	}
+
 	/** Register handler to one or many Updates */
 	on<T extends UpdateName>(
 		updateName: MaybeArray<T>,