diff --git a/ruoyi-modules/ruoyi-chat/src/test/java/org/ruoyi/service/coding/harness/loop/ExternalPlanStepVisibilityTest.java b/ruoyi-modules/ruoyi-chat/src/test/java/org/ruoyi/service/coding/harness/loop/ExternalPlanStepVisibilityTest.java
new file mode 100644
index 00000000..37f9ffb6
--- /dev/null
+++ b/ruoyi-modules/ruoyi-chat/src/test/java/org/ruoyi/service/coding/harness/loop/ExternalPlanStepVisibilityTest.java
@@ -0,0 +1,78 @@
+package org.ruoyi.service.coding.harness.loop;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import dev.langchain4j.agent.tool.Tool;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+import org.ruoyi.service.coding.harness.loop.tool.HarnessToolRegistry;
+import org.ruoyi.service.coding.harness.model.*;
+import org.ruoyi.service.coding.harness.plan.ExecutionMode;
+import org.ruoyi.service.coding.harness.plan.PlanAggregate;
+import org.ruoyi.service.coding.harness.plan.PlanTaskStep;
+import org.ruoyi.service.coding.harness.plan.tool.HarnessPlanCommandService;
+import org.ruoyi.service.coding.harness.runtime.HarnessRunRequest;
+import org.ruoyi.service.coding.harness.tool.ToolCapability;
+import org.ruoyi.service.coding.harness.tool.ToolDescriptor;
+import org.springframework.test.util.ReflectionTestUtils;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+@Tag("dev")
+class ExternalPlanStepVisibilityTest {
+    @Test
+    void externalImplementationCanExplicitlyFinishItsActiveStep() {
+        var registry = effectiveRegistry(HarnessVerificationMode.EXTERNAL);
+        assertTrue(registry.descriptor("plan_step").isPresent());
+        assertTrue(registry.descriptor("write_file").isPresent());
+        assertTrue(registry.descriptor("plan_verify").isPresent());
+    }
+
+    @Test
+    void agentVerificationRetainsAutomaticProgressionPolicy() {
+        var registry = effectiveRegistry(HarnessVerificationMode.AGENT);
+        assertTrue(registry.descriptor("write_file").isPresent());
+        assertTrue(registry.descriptor("plan_verify").isPresent());
+        assertFalse(registry.descriptor("plan_step").isPresent());
+    }
+
+    private HarnessToolRegistry effectiveRegistry(HarnessVerificationMode mode) {
+        var processor = mock(DurableHarnessRunProcessor.class, CALLS_REAL_METHODS);
+        ReflectionTestUtils.setField(processor, "planCommands", mock(HarnessPlanCommandService.class));
+        var run = mock(HarnessRunState.class, RETURNS_DEEP_STUBS);
+        var session = mock(HarnessSessionState.class);
+        var plan = mock(PlanAggregate.class, RETURNS_DEEP_STUBS);
+        var step = mock(PlanTaskStep.class);
+        when(session.verificationMode()).thenReturn(mode);
+        when(run.permissionMode()).thenReturn(HarnessPermissionMode.WORKSPACE_WRITE);
+        when(run.executionPlan()).thenReturn(plan);
+        when(plan.mode()).thenReturn(ExecutionMode.BUILD);
+        when(plan.inProgressStep()).thenReturn(Optional.of(step));
+        when(plan.contract().criteria()).thenReturn(List.of());
+        when(plan.evidence()).thenReturn(List.of());
+        when(step.acceptanceCriterionIds()).thenReturn(List.of());
+        var registry = HarnessToolRegistry.builder(new ObjectMapper()).registerAnnotated(
+            new Tools(), List.of(descriptor("plan_step"), descriptor("plan_verify"), descriptor("write_file"))).build();
+        return ReflectionTestUtils.invokeMethod(processor, "effectiveRegistry",
+            new HarnessRunRequest(new HarnessOwner("000000", 1L), "session", "run"),
+            run, session, registry, false, false);
+    }
+
+    private ToolDescriptor descriptor(String name) {
+        return new ToolDescriptor(name, Set.of(ToolCapability.CONTROL), true, 1000,
+            1024, 1024, true, "Test tool visibility only");
+    }
+
+    static class Tools {
+        @Tool(name = "plan_step", value = "Complete an active step")
+        public String step() { return "test"; }
+        @Tool(name = "plan_verify", value = "Enter verification")
+        public String verify() { return "test"; }
+        @Tool(name = "write_file", value = "Write implementation")
+        public String write() { return "test"; }
+    }
+}