diff --git a/internal/cloud/m3-io-control.mjs b/internal/cloud/m3-io-control.mjs
index 0170ad1e..8ad97d6a 100644
--- a/internal/cloud/m3-io-control.mjs
+++ b/internal/cloud/m3-io-control.mjs
@@ -897,6 +897,14 @@ async function tryRuntimeWrite(label, write) {
   }
   try {
     const result = await write();
+    if (result === undefined) {
+      return {
+        label,
+        written: false,
+        skipped: true,
+        reason: "runtimeStore method unavailable"
+      };
+    }
     return {
       label,
       written: true,
diff --git a/internal/cloud/m3-io-control.test.mjs b/internal/cloud/m3-io-control.test.mjs
index 509462cc..5202f901 100644
--- a/internal/cloud/m3-io-control.test.mjs
+++ b/internal/cloud/m3-io-control.test.mjs
@@ -97,6 +97,48 @@ test("M3 DO write dispatches through gateway-simu, ticks patch-panel, reads DI,
   assert.equal(evidence.records[0].operationId, result.operationId);
 });
 
+test("M3 DO write can prove control reachability while durable trusted persistence stays blocked", async () => {
+  const fixture = createM3ControlFixture();
+  const result = await handleM3IoControl(
+    {
+      action: "do.write",
+      gatewayId: "gwsimu_1",
+      resourceId: "res_boxsimu_1",
+      boxId: "boxsimu_1",
+      port: "DO1",
+      value: true,
+      traceId: "trc_m3_control_durable_blocked",
+      requestId: "req_m3_control_durable_blocked",
+      actorId: "usr_m3_operator"
+    },
+    {
+      runtimeStore: createBlockedDurableRuntimeStore(),
+      now: () => fixedNow,
+      env: {
+        HWLAB_M3_GATEWAY_SIMU_1_URL: "http://gateway-1",
+        HWLAB_M3_GATEWAY_SIMU_2_URL: "http://gateway-2",
+        HWLAB_M3_PATCH_PANEL_URL: "http://patch-panel"
+      },
+      requestJson: fixture.requestJson
+    }
+  );
+
+  assert.equal(result.status, "succeeded");
+  assert.equal(result.accepted, true);
+  assert.equal(result.result.value, true);
+  assert.equal(result.result.targetReadback.value, true);
+  assert.equal(result.controlPath.status, "succeeded");
+  assert.equal(result.controlPath.patchPanel, true);
+  assert.equal(result.evidenceState.status, "blocked");
+  assert.equal(result.evidenceState.sourceKind, "BLOCKED");
+  assert.equal(result.evidenceState.durable, false);
+  assert.equal(result.evidenceState.blocker, "runtime_durable_adapter_query_blocked");
+  assert.equal(result.persistence.runtime.status, "blocked");
+  assert.equal(result.persistence.runtime.liveRuntimeEvidence, false);
+  assert.equal(result.persistence.writes.every((write) => write.written !== true), true);
+  assert.match(result.evidenceState.reason, /操作链路可达性与可信持久化分离/u);
+});
+
 test("M3 DI read returns structured value through gateway-simu without patch-panel mutation", async () => {
   const fixture = createM3ControlFixture();
   writeBoxPort({
@@ -206,6 +248,38 @@ test("M3 IO control blocks invalid port direction instead of allowing generic wr
   assert.match(result.blocker.zh, /端口方向|资源越界/u);
 });
 
+test("M3 IO control blocks invalid DI target before calling gateway-simu", async () => {
+  const result = await handleM3IoControl(
+    {
+      action: "di.read",
+      gatewayId: "gwsimu_2",
+      resourceId: "res_boxsimu_1",
+      port: "DO1",
+      traceId: "trc_m3_invalid_di_target",
+      requestId: "req_m3_invalid_di_target",
+      actorId: "usr_m3_operator"
+    },
+    {
+      runtimeStore: createCloudRuntimeStore({ now: () => fixedNow }),
+      now: () => fixedNow,
+      env: {
+        HWLAB_M3_GATEWAY_SIMU_1_URL: "http://gateway-1",
+        HWLAB_M3_GATEWAY_SIMU_2_URL: "http://gateway-2",
+        HWLAB_M3_PATCH_PANEL_URL: "http://patch-panel"
+      },
+      requestJson: async () => {
+        throw new Error("gateway must not be called for invalid DI target");
+      }
+    }
+  );
+
+  assert.equal(result.status, "blocked");
+  assert.equal(result.blocker.code, M3_IO_BLOCKER_CODES.portDirectionInvalid);
+  assert.match(result.blocker.zh, /DI read|端口方向|资源越界/u);
+  assert.equal(result.controlPath.gatewaySimu, false);
+  assert.equal(result.controlPath.frontendBypass, false);
+});
+
 test("M3 IO control fails closed when indexed gateway identity drifts", async () => {
   const fixture = createM3ControlFixture({
     gateway1Id: "gwsimu_2"
@@ -283,6 +357,25 @@ test("M3 IO control blocks when patch-panel wiring does not deliver DO1 to DI1",
   assert.match(result.blocker.zh, /wiring 不存在|未路由/u);
 });
 
+function createBlockedDurableRuntimeStore() {
+  return {
+    async readiness() {
+      return {
+        adapter: "postgres",
+        durable: false,
+        durableRequested: true,
+        durableCapable: false,
+        ready: false,
+        status: "blocked",
+        blocker: "runtime_durable_adapter_query_blocked",
+        reason: "Postgres runtime adapter could not complete a live runtime schema query",
+        liveRuntimeEvidence: false,
+        fixtureEvidence: false
+      };
+    }
+  };
+}
+
 function createM3ControlFixture({ patchPanelBody, gateway1Id = "gwsimu_1", gateway2Id = "gwsimu_2" } = {}) {
   const calls = [];
   const box1 = createBoxState({