feat(gadgets): add Finish gadget for early agent termination

src/agents/base.ts

@@ -10,6 +10,7 @@ import { getIterationTrailingMessage } from '../config/hintConfig.js';
 import { getRateLimitForModel } from '../config/rateLimits.js';
 import { getRetryConfig } from '../config/retryConfig.js';
 import { EditFile } from '../gadgets/EditFile.js';
+import { Finish } from '../gadgets/Finish.js';
 import { ListDirectory } from '../gadgets/ListDirectory.js';
 import { ReadFile } from '../gadgets/ReadFile.js';
 import { Sleep } from '../gadgets/Sleep.js';
@@ -303,6 +304,8 @@ function createAgentBuilderWithGadgets(
 		// new GetMyRecentActivity(), // Temporarily disabled
 		new AddChecklistToCard(),
 		new UpdateChecklistItem(),
+		// Session control
+		new Finish(),
 	];
 
 	const allGadgets = auEnabled ? [...baseGadgets, auList, auRead] : baseGadgets;

src/gadgets/Finish.ts

@@ -0,0 +1,21 @@
+import { Gadget, TaskCompletionSignal, z } from 'llmist';
+
+export class Finish extends Gadget({
+	name: 'Finish',
+	description:
+		'Call this gadget when you have completed all tasks and want to end the session. This should be your final gadget call.',
+	schema: z.object({
+		comment: z.string().min(1).describe('A brief summary of what was accomplished'),
+	}),
+	examples: [
+		{
+			params: { comment: 'Created PR with all requested changes and tests passing' },
+			output: 'Session ended: Created PR with all requested changes and tests passing',
+			comment: 'End session after completing all work',
+		},
+	],
+}) {
+	override execute(params: this['params']): never {
+		throw new TaskCompletionSignal(params.comment);
+	}
+}