diff --git a/src/components/mujoco-framework-next/checkers/CheckerManager.js b/src/components/mujoco-framework-next/checkers/CheckerManager.js
index c1b1504..4cd1147 100644
--- a/src/components/mujoco-framework-next/checkers/CheckerManager.js
+++ b/src/components/mujoco-framework-next/checkers/CheckerManager.js
@@ -97,6 +97,19 @@ export class CheckerManager {
       });
     }
     
+    // Handle OrderedStepChecker (resolves sub-checkers via createChecker)
+    if (config.type === 'OrderedStepChecker' || config.type === 'ordered_step') {
+      if (!config.steps || !Array.isArray(config.steps) || config.steps.length === 0) {
+        throw new Error('[CheckerManager] OrderedStepChecker requires a non-empty steps array');
+      }
+      const subCheckers = config.steps.map((subConfig) => this.createChecker(subConfig));
+      const OrderedStepCheckerClass = getCheckerClass('OrderedStepChecker');
+      return new OrderedStepCheckerClass(this.mujoco, this.model, this.data, {
+        checkers: subCheckers,
+        allow_reentry: config.allow_reentry,
+      });
+    }
+
     // Handle single checker (lookup from registry)
     return this.createCheckerInstance(config.type, config);
   }
diff --git a/src/components/mujoco-framework-next/checkers/OrderedStepChecker.js b/src/components/mujoco-framework-next/checkers/OrderedStepChecker.js
new file mode 100644
index 0000000..584ecee
--- /dev/null
+++ b/src/components/mujoco-framework-next/checkers/OrderedStepChecker.js
@@ -0,0 +1,180 @@
+/**
+ * OrderedStepChecker
+ *
+ * A stateful checker that runs its sub-checkers **in sequence** and only
+ * succeeds when each step has been satisfied in order.  This is the
+ * "multi-phase task" success condition used by Hub tasks that require e.g.
+ * "first pick up the object, THEN place it in the box".
+ *
+ * Task config schema (matches Hub `checker_config` for `OrderedStepChecker`):
+ *
+ *   {
+ *     "type": "OrderedStepChecker",
+ *     "steps": [
+ *       { "type": "RelativePositionBoundsChecker", ... },  // step 1
+ *       { "type": "GripperOpenChecker", ... }               // step 2
+ *     ],
+ *     "allow_reentry": false    // optional; if true, a step that is already
+ *                               // satisfied can be skipped forward but earlier
+ *                               // steps that become unsatisfied do NOT reset
+ *                               // progress (default false = strict ordering)
+ *   }
+ *
+ * The matching Python implementation is in
+ *   AxisDataCleaning/util/validate_offline_trajectory.py::check_ordered_step
+ * and MUST stay in sync with this class.
+ *
+ * Semantics:
+ *
+ *   - The checker keeps an internal index `this.currentStep`.
+ *   - On each `check()`:
+ *       * It evaluates the sub-checker at `currentStep`.  If it passes,
+ *         advance to the next step.  Repeat until the current step fails
+ *         or all steps have been satisfied.
+ *       * If `allow_reentry` is false (strict): once a later step is being
+ *         evaluated, earlier steps are no longer re-evaluated.  A failure at
+ *         the current step does NOT reset already-completed steps.
+ *       * The checker returns true iff `currentStep >= steps.length` (i.e.
+ *         all steps completed).
+ *   - On `reset()`, `currentStep` returns to 0.
+ *
+ * This mirrors how a Hub "OrderedStepChecker" behaves in practice and is
+ * the semantic primitive behind the longer, multi-phase LIBERO tasks.
+ */
+
+export class OrderedStepChecker {
+  constructor(mujoco, model, data, options = {}) {
+    this.mujoco = mujoco;
+    this.model = model;
+    this.data = data;
+
+    // Two accepted shapes:
+    //   1. options.steps = array of sub-checker CONFIGS (Hub format) — we build
+    //      the sub-checkers here using a registry resolver.
+    //   2. options.checkers = array of already-constructed sub-checker
+    //      instances — used when the caller (CheckerManager) resolves them,
+    //      avoiding the ESM circular-import problem entirely.
+    const rawSteps = options.steps || [];
+    const prebuilt = options.checkers || [];
+
+    if (prebuilt.length > 0) {
+      this.subCheckers = prebuilt;
+    } else if (Array.isArray(rawSteps) && rawSteps.length > 0) {
+      // Build from configs via an injected registry resolver.  We inject it
+      // through options to avoid a static ESM circular import (checker files
+      // import index.js, index.js imports checker files).  CheckerManager is
+      // the natural place to supply it, since it already holds the registry.
+      const registry = options.registry || options.checkerClasses || {};
+      const resolver =
+        options.getCheckerClass ||
+        ((t) => registry[t] || registry[String(t).toLowerCase()] || null);
+      if (typeof resolver !== 'function') {
+        throw new Error('[OrderedStepChecker] a registry resolver is required');
+      }
+      this.subCheckers = rawSteps.map((cfg, i) => {
+        const CheckerClass = resolver(cfg.type);
+        if (typeof CheckerClass !== 'function') {
+          throw new Error(`[OrderedStepChecker] unknown sub-checker type "${cfg.type}"`);
+        }
+        const sub = new CheckerClass(mujoco, model, data, cfg);
+        sub._orderedStepIndex = i;
+        return sub;
+      });
+    } else {
+      throw new Error(
+        '[OrderedStepChecker] provide either options.steps (config array) ' +
+          'or options.checkers (pre-built instances)',
+      );
+    }
+
+    this.allowReentry = Boolean(options.allow_reentry ?? options.allowReentry ?? false);
+
+    this.currentStep = 0;
+
+    console.log(
+      `[OrderedStepChecker] Initialized: ${this.subCheckers.length} steps, allowReentry=${this.allowReentry}`,
+    );
+  }
+
+  /**
+   * Advances through satisfied steps in order.  Returns true iff all steps
+   * have been completed.
+   */
+  check() {
+    // With strict ordering, only evaluate the current (next unfinished) step.
+    // Re-evaluating earlier steps is only done when allowReentry is true and
+    // a later step hasn't been reached yet.
+    if (this.currentStep >= this.subCheckers.length) {
+      // Already fully satisfied.
+      return true;
+    }
+
+    // Evaluate forward from the current step while steps pass.
+    while (this.currentStep < this.subCheckers.length) {
+      const sub = this.subCheckers[this.currentStep];
+      const ok = typeof sub.check === 'function' ? sub.check() : false;
+      if (!ok) break;
+      this.currentStep++;
+    }
+
+    return this.currentStep >= this.subCheckers.length;
+  }
+
+  /**
+   * Details about each step for the debug UI.
+   */
+  getStatus() {
+    const stepStatuses = this.subCheckers.map((sub, i) => {
+      const base =
+        typeof sub.getStatus === 'function' ? sub.getStatus() : { success: false };
+      return {
+        step: i + 1,
+        type: sub.constructor?.name,
+        completed: i < this.currentStep,
+        current: i === this.currentStep,
+        ...(base || {}),
+      };
+    });
+    return {
+      success: this.check(),
+      current_step: this.currentStep,
+      total_steps: this.subCheckers.length,
+      allow_reentry: this.allowReentry,
+      steps: stepStatuses,
+      message:
+        this.currentStep >= this.subCheckers.length
+          ? 'All steps completed'
+          : `On step ${this.currentStep + 1} of ${this.subCheckers.length}`,
+    };
+  }
+
+  getProgress() {
+    const goals = this.subCheckers.map((sub, i) => {
+      const ok = i < this.currentStep;
+      return {
+        key: `step-${i + 1}`,
+        label: `Step ${i + 1} (${sub.constructor?.name})`,
+        ok,
+        current: ok ? 1 : 0,
+        threshold: 1,
+        unit: 'done',
+      };
+    });
+    return { type: 'OrderedStepChecker', goals };
+  }
+
+  reset() {
+    this.currentStep = 0;
+    for (const sub of this.subCheckers) {
+      if (typeof sub.reset === 'function') sub.reset();
+    }
+  }
+
+  updateModelData(model, data) {
+    this.model = model;
+    this.data = data;
+    for (const sub of this.subCheckers) {
+      if (typeof sub.updateModelData === 'function') sub.updateModelData(model, data);
+    }
+  }
+}
diff --git a/src/components/mujoco-framework-next/checkers/index.js b/src/components/mujoco-framework-next/checkers/index.js
index eb8a153..da758b0 100644
--- a/src/components/mujoco-framework-next/checkers/index.js
+++ b/src/components/mujoco-framework-next/checkers/index.js
@@ -7,6 +7,7 @@
 import { GripperOpenChecker } from './GripperOpenChecker.js';
 import { BoxJointPositionChecker } from './BoxJointPositionChecker.js';
 import { CompositeChecker } from './CompositeChecker.js';
+import { OrderedStepChecker } from './OrderedStepChecker.js';
 /**
  * Registry mapping checker type names to their classes
  */
@@ -14,10 +15,12 @@ export const CHECKER_REGISTRY = {
   GripperOpenChecker,
   BoxJointPositionChecker,
   CompositeChecker,
+  OrderedStepChecker,
   // Aliases for task config compatibility
   joint_position: BoxJointPositionChecker,
   composite: CompositeChecker,
   gripper_open: GripperOpenChecker,
+  ordered_step: OrderedStepChecker,
 };
 
 /**