diff --git a/src/agent-runtime.ts b/src/agent-runtime.ts
index 68652d6..5fdacdc 100644
--- a/src/agent-runtime.ts
+++ b/src/agent-runtime.ts
@@ -1090,6 +1090,15 @@ export class AgentRuntime {
     return stepEndData;
   }
 
+  /**
+   * User-friendly alias for emitStepEnd().
+   *
+   * Keeps step lifecycle naming symmetric with beginStep().
+   */
+  endStep(opts: Parameters<AgentRuntime['emitStepEnd']>[0] = {}): any {
+    return this.emitStepEnd(opts);
+  }
+
   private async captureArtifactFrame(): Promise<void> {
     if (!this.artifactBuffer) {
       return;
diff --git a/src/debugger.ts b/src/debugger.ts
index 80380eb..7a58b18 100644
--- a/src/debugger.ts
+++ b/src/debugger.ts
@@ -7,9 +7,11 @@ import { Tracer } from './tracing/tracer';
 export class SentienceDebugger {
   readonly runtime: AgentRuntime;
   private stepOpen: boolean = false;
+  private autoStep: boolean = true;
 
-  constructor(runtime: AgentRuntime) {
+  constructor(runtime: AgentRuntime, options?: { autoStep?: boolean }) {
     this.runtime = runtime;
+    this.autoStep = options?.autoStep !== undefined ? Boolean(options.autoStep) : true;
   }
 
   static attach(page: Page, tracer: Tracer, options?: AttachOptions): SentienceDebugger {
@@ -43,6 +45,13 @@ export class SentienceDebugger {
 
   check(predicate: Predicate, label: string, required: boolean = false) {
     if (!this.stepOpen) {
+      if (!this.autoStep) {
+        throw new Error(
+          `No active step. Call dbg.beginStep(...) or dbg.step(...) before check(label=${JSON.stringify(
+            label
+          )}).`
+        );
+      }
       this.beginStep(`verify:${label}`);
     }
     return this.runtime.check(predicate, label, required);
diff --git a/tests/agent-runtime-attach.test.ts b/tests/agent-runtime-attach.test.ts
index 0b50ffa..679d918 100644
--- a/tests/agent-runtime-attach.test.ts
+++ b/tests/agent-runtime-attach.test.ts
@@ -67,3 +67,15 @@ describe('AgentRuntime.fromPlaywrightPage()', () => {
     spy.mockRestore();
   });
 });
+
+describe('AgentRuntime.endStep()', () => {
+  it('aliases emitStepEnd()', () => {
+    const runtime: any = {
+      emitStepEnd: jest.fn().mockReturnValue({ ok: true }),
+    };
+
+    const out = (AgentRuntime.prototype as any).endStep.call(runtime, { action: 'noop' });
+    expect(runtime.emitStepEnd).toHaveBeenCalledWith({ action: 'noop' });
+    expect(out).toEqual({ ok: true });
+  });
+});
diff --git a/tests/debugger.test.ts b/tests/debugger.test.ts
index e3a1267..3c2f189 100644
--- a/tests/debugger.test.ts
+++ b/tests/debugger.test.ts
@@ -66,4 +66,17 @@ describe('SentienceDebugger', () => {
     expect(runtime.check).toHaveBeenCalled();
     expect(handle).toBe('handle');
   });
+
+  it('can disable auto-step (strict mode)', () => {
+    const runtime = {
+      beginStep: jest.fn().mockReturnValue('step-1'),
+      check: jest.fn().mockReturnValue('handle'),
+    } as unknown as AgentRuntime;
+
+    const dbg = new SentienceDebugger(runtime, { autoStep: false } as any);
+
+    expect(() =>
+      dbg.check((_ctx: any) => ({ passed: true, reason: '', details: {} }), 'has_cart')
+    ).toThrow(/No active step/i);
+  });
 });